John A. Lory
Division of Plant Sciences and Commercial Agriculture Program

Joe Zulovich
Agricultural Engineering Extension and Commercial Agriculture Program

Charles Fulhage
Agricultural Engineering Extension

The objective of this publication is to identify the differences and similarities between managing municipal wastewater and managing the manure from grow-finish pig systems.

There are two defining differences between domestic wastewater treatment and animal manure systems:

• Domestic wastewater systems discharge large volumes of treated water directly to surface waters of the state, whereas it is illegal to discharge manure from storage facilities or in runoff from agricultural fields into surface waters of the state.
• Manure is a valued fertilizer on many hog operations, whereas human excreta are a component of a waste stream that is a net cost for homeowners, towns and municipalities.

Volume of human wastewater versus grow-finish manure

Domestic wastewater systems handle high-volume waste streams with relatively low concentrations of nutrients and other components of the waste (Figure 1). Every toilet, shower, washing machine and dishwasher contributes significant amounts of water to the waste stream. Plus, many sewage treatment plants handle water from industry and any stormwater that enters the system. The variability of industrial contributions and storm water makes per capita wastewater generation quite variable. As an example of the volumes involved, the city of Columbia, Missouri (population 92,000) handles 16 million gallons of wastewater each day, or about 175 gallons per person per day. The Metropolitan St. Louis Sewer District (population 1,400,000) handles 360 million gallons of wastewater each day, or about 255 gallons per person per day.

In contrast, manure production on hog finishing operations is predominantly feces and urine generated by the animals. Added water in the buildings is limited to cleaning activities and wasted drinking water. Total manure and wastewater production averages about 1.4 gallons per animal per day for grow-finish operations. Volumes are higher on operations that have open manure storages in regions where annual rainfall exceeds annual evaporation. On these operations, manure and wastewater production still typically runs less than 3 gallons per animal per day.

Cross-species comparisons are typically based on a standard live-weight basis. Daily wastewater production for 1,000 pounds of humans (assuming 150 pounds per person average weight and 175 gallons per person per day) is 1,170 gallons per day compared with 9.3 gallons per day for 1,000 pounds of grow-finish pigs (average weight 150 pounds per pig), a ratio of 125:1.

To put the differences in volume in perspective, all the grow-finish pigs in Missouri generate less manure volume than the City of Columbia. It would take 5.3 million to 11.4 million grow-finish pigs to produce the same volume of manure and wastewater as the volume of wastewater the city of Columbia treats in a day. Pig inventory in Missouri has hovered near 3 million head in the years 2000 to 2003.

Fate of human wastewater versus grow-finish manure

The high volume of wastewater forces most domestic systems to discharge treated wastewater directly to streams and other surface waters of the state. It is infeasible to construct sufficient storage and have sufficient land base to apply all domestic wastewater to the land as a nutrient or a source of irrigation water. Domestic wastewater is processed to reduce the potential impact of discharging wastewater directly into receiving streams and surface waters. The treatment process includes steps to reduce solids in the water, reduce nutrient concentration and sometimes other treatment processes to minimize the impact on receiving waters. The solids removed from domestic wastewater before discharge typically are land applied as a fertilizer (biosolids) to agricultural land. The regulatory permit for wastewater treatment plants stipulates the quality of the water that is released by the plant into surface waters and the management practices used to land apply biosolids.

The limited added water in swine manure systems makes it feasible to contain the manure in storage structures and then land apply the manure as a fertilizer source. Permits on almost all animal feeding operations make routine discharge of manure to waters of the state illegal; the permits are called “no-discharge” permits. All manure must be land applied in a manner that prevents overflow of manure storages and runoff during manure application. The rates of manure applied to fields also are dictated by the productivity of crops. Failure to comply with these standards typically results in a notice of violation and fines from regulatory agencies.

Figure 2
Injecting manure as a fertilizer for crop production.

Fate of solids

In both systems, most of the solids and nutrients are land applied to agricultural fields (Figure 2). In domestic wastewater systems, the solids are removed from the wastewater that is discharged into surface water. The solids are then digested to reduce the volume of solids and to reduce human pathogens. This material, called biosolids, is typically land applied to agricultural fields.

In animal manure systems like anaerobic lagoons, solids are also digested before land application. In other liquid systems such as pit slurry manure, there is little digestion of the solids in the manure storage. Instead manure solids are digested by the microorganisms in the soil. Some composting takes place in manure collected in high-rise and other bedding-type manure management systems.

Biochemical oxygen demand

Biochemical oxygen demand (BOD) is a measure of the amount of oxygen required to degrade organic matter in water. One major objective of domestic wastewater treatment is to reduce BOD in wastewater before discharging it into surface waters. Releasing wastewater with high BOD can lead to low oxygen (anoxic) conditions in the receiving waters as organisms in the water break down the excess organic matter. Anoxic conditions can lead to fish kills and other negative effects on receiving waters.

The Columbia Missouri water treatment plant typically receives waste with a BOD of 300 parts per million (ppm). Waste treatment in the plant reduces BOD to 60 ppm. Columbia then further “polishes” the water through artificial wetlands so that water released to the Missouri River has less than 10 ppm BOD. This last step is not typical of most waste treatment facilities.

The ultimate fate of animal manure is land application so the BOD of the manure is not a relevant indicator of environmental impact and typically is not measured. The BOD of hog manure is typically at least 100 times higher than untreated domestic wastewater. This is expected because the manure has not been diluted by high volumes of wastewater typical in domestic waste streams. Anaerobic lagoons reduce the BOD of manure, but other manure handling systems do not attempt to reduce BOD of the manure in storage. The organic matter in manure enhances biological activity and soil structure in soils receiving manure.

Pathogens

Treatment of human waste is designed to reduce pathogens to meet permit requirements and water quality standards. Missouri water quality standards limit fecal coliform levels, an indicator for pathogens, to 200 colonies per 100 milliliters in wastewater released to recreational waters. Land-applied biosolids are also processed to reduce pathogen levels.

Manure has no regulatory requirement for treatment and no specific pathogen limits before land application. Treatment for pathogens in manure includes digestion in some manure storage systems, exposure to sun, and degradation in the soil.

The value of manure

Fertilizer value is dictated in part by its nutrient concentration. Materials with a higher nutrient concentration cost less to transport and reduce the time to deliver recommended rates of nutrients to a field. Most commercial fertilizer sources exceed 30 percent composition of fertilizer nutrients. Examples include anhydrous ammonia (82 percent), ammonium nitrate (34 percent), diammonium phosphate (64 percent) and potassium chloride (63 percent). Manure sources have much lower nutrient concentrations than most commercial fertilizer sources; manure sources typically contain less than 5 percent fertilizer nutrients and in some cases the percentage is much lower. Recent increases in fertilizer prices have increased the value of manure.

Animal manure has been recognized through history as a valuable fertilizer source and it is no different in many modern manure management systems. In a slurry operation, manure is a key component of the operation’s financial success. The MU Extension publication G9334, Optimizing Fertilizer Value of Manure from Slurry Hog Finishing Operations provides detailed information on the fertilizer value of slurry manure. A 2004 research paper found that manure value on slurry operations had the potential to be 16 percent of the net income of the operation.

Financial success of operations that use anaerobic lagoons is less dependent on extracting manure value from their manure. However, injected lagoon effluent provides nitrogen in a form that is highly available to plants and more predictable than other manure types. A high percentage of the phosphorus and significant amounts of nitrogen and potassium accumulate in the bottom of lagoons. MU research is focused on determining strategies to cover the cost of removing solids from the bottom of lagoons with the fertilizer value of the material. This sludge material can have high concentrations of fertilizer nutrients, making it a potentially valuable fertilizer source.

Conclusions

Direct comparison of human wastewater production and animal manure production is misleading and typically unproductive.

Human waste systems are characterized by high volumes of diluted material that is treated to minimize the impact of the direct release of wastewater into surface waters of the state.

In contrast, it is illegal to discharge animal manure into waters of the state; instead manure is land applied as a fertilizer for crop production.

Hog manure typically has little added wastewater, resulting in a product that has substantially higher concentrations of nutrients and organic matter than human wastewater. These higher concentrations make it feasible to use the manure as a fertilizer source for crop production.

For further information

• Columbia Waste Treatment Plant
• Lory J.A., R.E. Massey, J.M. Zulovich, J.A. Hoehne, A.M. Schmidt, M.S. Shannon and C.D. Fulhage. 2004. An Assessment of Nitrogen-Based Manure Application Rates on 39 US Swine Operations. J. Environ. Qual. 33:1106-1113.
• Metropolitan St. Louis Sewer District
• Midwest Plan Service. 2004. Manure Characteristics. MWPS-18 2nd edition. Iowa State University, Ames Iowa
• National Livestock and Poultry Environmental Learning Center. Pathogen Resources.

Bookmark With:

In these recessionary times, any business success offers a glimmer of hope for better UK fortunes ahead, and there is one small company in Somerset whose hi-tech farming solutions are seeing it play its part in shaping the economic recovery. Ann Hardy finds out more.

With full order-books, the on-going recruitment of skilled staff and apprenticeship schemes in development, Micron Bio-Systems, is emphatically bucking the wider economic trend.

Sales manager Mark Jacobsen Cox struggles to pinpoint the single reason for the company’s rising fortunes, but says cornerstone of its success is its insistence on controlling every stage of the product-development and manufacturing process.

“Very few companies do their own research and development the product backup and the manufacturing, but we do everything,” he says.

“This means when something leaves our premises, we are completely confident it will perform as intended.”

Annual sales growth of 100 per cent per year for the past three years and exports accounting for 50-60 per cent of sales both bear this out, while a projected turnover of £8 million for 2011-2012 is further tangible evidence of the company’s continued good performance.

With 90 per cent of Micron’s products destined for consumption by livestock, the company’s key agricultural product categories are mycotoxin binders (which mop up toxins produced by mould in feeds), probiotics (which help to create a desirable micro-flora in the animal’s gut) and silage and feed preservatives.

“Everything we do is categorised broadly under the banner of ‘biotechnology’ and within this field, we’re dealing mostly with microbiology and enzymology,” says Dr David Parfitt, who founded the company in 1993 and is its current managing director.

Smart science

As a microbiologist and former university lecturer himself, Dr Parfitt is keenly aware of the importance of research and development, and says the ‘smart science’ practised by Micron Bio-Systems is at the heart of everything the company does.

“Smart science is about understanding science and taking the parts which can be applied to farming and building a product that can be easily used,” he says.

“It’s about building the smart-ness into the product’s formulation, rather than relying on the farmer to be a microbiologist. “We are every farmer’s R&D department, and we aim to pro-vide the tools to solve farming’s problems.”

Close links have been forged with several university departments and once a product has been proven to work in the lab it will be assessed on-farm, and then independently trialled under university direction.

“If it doesn’t work, it doesn’t get to be a product,” says Dr Parfitt, “although in truth, we wouldn’t take it to the trial stage if we weren’t absolutely sure of its effectiveness.”

Back in the lab, the R&D-based ethos is in evidence all around, and a clear willingness to invest in technology is apparent from the facilities.

“In this box, we have a brand new Triple Quad Mass Spectrometer,” says analytical chemist Dr Deidre Norton, who recently joined the company after 30 years studying mycotoxins with Defra. “We already know there are 340 different mycotoxins, but this new equipment will allow us to look for unknowns.”

Also detecting infinitesimally small concentrations, she says the equipment will detect mycotoxins at three decimal places less than a nanogram.

“Translating this to grams, this means a decimal point followed by 12 noughts,” she says.

Emphasising the importance of this level of precision, she says: “There’s a huge diversity of mycotoxins causing a wide range of symptoms, and now we know they don’t just come from moulds in stored feed, but can also be found in contaminated pasture.

“It used to be assumed ruminants could deal with them, but if they are lactating and acidotic they are already compromised, so they can’t handle them in the same way we thought.

“The mycotoxins could cause a drop in milk production, or there are some which mimic hormones and can cause abortion,” she says.

The mass spectrometer she describes will give the company – already considered a leader in the field of mycotoxin binders – a further competitive edge.

“The hardware isn’t unique but we are developing the methods to give an absolute measurement and a detailed and objective analysis of all of the mycotoxins within a total mixed ration or in each of its component ingredients,” ex-plains Dr Parfitt.

“This is far more accurate and meaningful than the current ELISA tests widely used, and we reckon we’ll have a completely accurate test available at around£200 per sample by autumn2012.”

Cutting-edge

Other company products are equally cutting-edge, such as the probiotics which are care-fully formulated to contain across-section of live yeasts and bacteria which are complementary in function and stable in storage; and the crop-specific silage inoculants containing newly identified enzymes which significantly increase the feed value and stability of a wide cross-section of forage types.

Behind each of Micron’s products is a research team based at its Bridgwater head-quarters, including R&D manager Dr Jog Rag and technical director Dr Stephen Mann, who is a world-class enzymologist.

“Among our 13 UK staff, we have four PhDs and 18 degrees,” says Dr Parfitt, reiterating the importance of the company’s scientific base.

Fresh approach

However, the on-going recruitment of scientific staff is proving to be a challenge, and Mr Jacobsen Cox explains how the company has taken a fresh approach.

“We are aware young people don’t get enough exposure to practical science so are not skilled in this area when they come into the work-place, so we’ve supported what we call our Lab Rats programme,” he says.

“We’re working with the community, through the Bridgwater College Centre for Land-Based Studies and Richard Huish College in Taunton, whose students are coming to learn in our labs, in their own time,” he says. “We are trying to give something back to the community in an area in which we have an interest.”

Also aiming to take on three apprentices as school leavers, he says: “We hope to catch the high fliers who don’t want the debt of going to university but will be paid a good wage, get real time training and get expo-sure to things that actually make a difference.”

The company believes it is making a difference, with growing product demand, an ever-increasing product range and cutting edge science driving future developments.

“It’s the more progressive farmers who have helped us to increase our market share,” says Mr Jacobsen Cox.  “And I’d say those who don’t use additives are definitely in decline.”

“Our products are designed to produce more milk and meat from the same feed, and also to bring better health and fertility,” says Dr Parfitt. “Our aim is to take the sesame tools and apply them across a wider range of species, using science to improve livestock performance and profitability.”

Micron Bio-Systems key facts

Biotechnology company specialising in microbiology and enzymology

Key farming products are silage additives, mycotoxin binders and probiotics

Most products are des-tined for the dairy farming industry, with lesser amounts going into beef, sheep, pigs and poultry

Feed products are largely used in compounds and blends

Distribution is through feed manufacturers and general agricultural distributors

Employs 13 UK staff based in Bridgwater, Somerset

Employs 20 staff in a sister USA company

Founded in 1993 and turnover this year will be £8m

The UK company manufactures small, specialist products combining microorganisms and enzymes

US company manufactures small, specialist and bulk products

UK company exports 50-60 per cent of output

Environmental and waste treatment

WHILE the main programmes at Micron Bio-Systems are focused on animal feed ingredients, an increasingly important part of the business is moving towards environmental and waste treatments.

Biogas

Two biogas enhancers are de-signed to increase the production of methane and maximise the energy which can be derived from a variety of forages undergoing anaerobic digestion and are based on the same breakthrough enzyme technology used in the company’s forage treatments.

“The biggest markets for our biogas enhancers are in Europe, and Germany in particular, but we see this as a growing market in the UK,” says Mr Jacobsen Cox.

The US arm of Micron Bio-Systems

FOUNDED in 1993, Micron Bio-Systems opened a sister company in the USA two years later. Both companies have developed products to serve their domestic markets and each exports a large percentage of their production. While the UK exports focus on Europe, the Middle East, Asia, New Zealand and Australia, products from America will be mostly destined for Canada, Central and South America as well as the US domestic market.

“Most people think be-cause we have an American arm, we must be subservient to them,” says Mark Jacobsen Cox. “But in fact we share some of the same products, marketing and other functions, but are maintained as separate companies.

Climates

“Of course, there are products developed for different climates,” he says. “For in-stance, we have a silage additive for tropical grasses grown in Florida and some different additives for continental European markets where there’s a greater awareness than in the UK of the need to break down lignin in some of the grasses and in maize.”

Bookmark With:

Summary:

Feed efficiency is the sum of a many variables that include but are not
exhausted by such areas as feed ingredients used, formulation of ingredients,
genetics and management practices. It is beyond the scope of this short paper
to discuss all and every aspect of the management/feed cost interaction
therefore, the purpose of this paper is to look at the practical management of
the gilt and sow on farm and specifically those management practices that can
and do have an impact on feed efficiency. The information contained herein is
a collection both of experiences, and public and PIC in-house research. The five main aspects to the management/feed cost interaction is watch body condition closely, avoid fat and thin sows, calibrate feed boxes, maximize feed intake in lactation and don’t forget about the environment.

Bookmark With:

Source: AASV

María Fuentes, MVSc; Julio Otal, DBSc, PhD; María L. Hevia, DMV, PhD; Alberto Quiles, DMV, PhD; Francisco C. Fuentes, DMV, PhD

Keywords: swine, piglet, olfactory stimulation before weaning, isoamyl acetate, behavior after weaning
Search the AASV web site for pages with similar keywords.

Received: March 18, 2010
Accepted: March 7, 2011

Early weaning (21 days) is very stressful for the piglet and causes an increase in the number of fights among piglets in order to establish social order and hierarchy.1 Fighting may cause the death of some piglets.2 This agonistic postweaning behavior makes the pigs less economically efficient, since feed conversion is poor and growth rate is low. Thus, many researchers have tried to decrease agonistic behavior, for example, through the use of tranquilizers3,4 or pheromones,5,6 design of pens with areas for pigs to hide from and avoid dominant pigs,7,8 regrouping of pigs with different proportions of siblings in each group,9,10 and combination of different litters in the same group during suckling.11-14

Moreover, there has been an attempt to reduce agonistic behavior after weaning by enriching the environment, for example, use of straw bedding, enrichment objects (eg, cotton cords, rubber strips, metal chains), or open-air systems.15-20 These authors reported that environmental enrichment improves social relations and stabilizes the social hierarchy. However, the effect of environmental enrichment by means of early stimulation on the behavior and development of the weaned piglet has never been reported. The method used in this study is early olfactory stimulation of piglets with the intention to create an olfactory attraction conditioned by a given scent (isoamyl acetate) from the moment the piglet is born until post weaning. The hypothesis was that once a positive bond between the suckling piglets and a scent is established, enriching the environment in the nursery pens with this same scent will alter agonistic behavior and development of the pigs when they are regrouped after weaning. The objective of this work was to explore whether learning a neonatal preference during suckling and the presence of this stimulus after weaning have any effect on agonistic behavior and better social integration when the pigs are regrouped after weaning.

Materials and methods

The research protocol was approved by the Bioethical Commission of Murcia University according to the European Council Directives regarding the protection of animals used for experimental purposes.

Animals and facilities

This study was developed in the Teaching Farm of the Veterinary Medicine Faculty, University of Murcia. Twelve multiparous Large White × Landrace crossbred sows were housed in two farrowing rooms with capacity for six animals each (one room per group). Piglets were weighed and identified individually. Litters were balanced, with 10 piglets each, with a minimum weight of 1.20 kg and a similar weight distribution. All sows and litters were housed indoors in farrowing crates (1.7 × 2.5 m total area, with a 0.62 × 2.20-m sow area). Daily management procedures were those generally used in the farms of the area. At 24 hours of age, piglets were routinely processed (ears notched, needle teeth clipped, tails docked, and injected with 200 mg of iron dextran). The farrowing houses were maintained at approximately 20ºC, while the piglets’ area of the farrowing crate was maintained at approximately 30ºC using electric heat lamps. Piglets were weaned at 21 days of age. After weaning, they were housed in rooms each containing six pens (floor area 2.5 m2) with 10 piglets per pen (space allowance 0.25 m2 per pig). The floor was totally slatted and temperature was maintained at 27ºC to 28ºC. During the study, commercial feed was provided, consisting of creep feed from 4 days of age until weaning, and prestarter feed during the 2 first weeks post weaning.

Experimental design and treatments

Study One: preweaning phase. The Control group consisted of six sows (mean parity 3.3, SD 0.5) with 10 piglets each. In order to avoid a differential effect in management (manipulation of the mammary glands and presence of the researchers), the mammary glands of the Control sows were treated with distilled water every day at 9:00 am and
5:00 pm. The Banana group also consisted of six sows (mean parity 3.2, SD 0.4) with 10 piglets each. The two groups were housed in different farrowing rooms. Treatment began on the second day after farrowing and consisted of daily treatment of the skin of the mammary glands at 9:00 am and 5:00 pm with a solution of sunflower oil and isoamyl acetate (banana scent, intended for human consumption), with a ratio of 1:10 sunflower oil to isoamyl acetate. The solution was sprayed on the skin at the rate of 15 mL per sow, measured with a 25-mL graduated cylinder. Control sows were always treated before the Banana group.

Piglets were weighed individually at birth. At 4 days of age, the piglets were again weighed and later were tested in the V-maze, and both groups were provided with plastic creep feeders. In the Banana group, the outside of the feeder was sprayed daily with 15 mL of isoamyl acetate solution. Creep feed was weighed when the feeders were filled, and the remaining feed was weighed at weaning. Piglets were weighed individually at weaning and then were tested a second time in the V-maze.

The V-maze was designed as described by Morrow-Tesch and McGlone,21 Pajor et al,22 and Sevelinges et al.23 The apparatus (Figure 1) included no neutral area: piglets had to choose either the right or left arm of the maze after the start box was opened. The end of one arm contained a grilled window with no olfactory stimulus. The end of the other arm had a similar grilled window where filter paper treated with the isoamyl solution was placed. Filter papers (3 × 3 cm) were saturated with isoamyl solution and stored in a sealed box outside the test room. A fresh filter paper was placed in the arm 15 seconds before each piglet was placed in the start box. The position of the olfactory stimulus (right or left arm) was changed randomly using a table of random numbers (0 = left and 1 = right) generated with the application of Microsoft Excel 2002 (Microsoft Corporation, Redmond, Washington), interchanging the entire ends of both arms and exhausting the inner air space with an electric fan. The upper part of the apparatus was covered with wire mesh to prevent piglets escaping. The floor of the apparatus was a polyvinyl chloride sheet which was replaced for each piglet.

Figure 1:Top view of a V-maze apparatus used to test pigs that had been previously conditioned to a banana scent (isoamyl acetate) and unconditioned pigs (control group). For both groups, a randomly selected filter paper treated with this scent was placed in the grilled section at the end of one maze arm, while a filter paper treated only with sunflower oil was placed in the other arm. The arms and the “choice” area were surrounded by PVC walls 50 cm high. A pig was placed in the start box, and the door was closed behind it once it left the start box. When the four legs of the pig crossed the orange “start-time” line at the threshold of one of the arms, a 3-minute test began, during which the number of times the piglet changed from one arm to the other and the total time spent in the scented arm were recorded. A change of arms was defined as the four legs of the pig crossing the “choice” line (the central orange line in front of the start-box door).

The test consisted of placing a piglet in the start box and allowing a few seconds acclimatization time. The door of the start box was opened to allow the piglet to enter the V-maze, and the door was then closed, so that the piglet could choose to go only right or left. The first arm the piglet entered and the time the piglet passed over the start-time line were recorded. A piglet was considered to be inside an arm when all four legs crossed the start line (Figure 1). An observer recorded the pig’s activity, beginning at this point, for 3 minutes using a stop-watch that sounded when the time had passed. During that 3 minutes, the number of times the piglet changed from one arm to the other was recorded, with a change of choice defined as the four legs of the piglet crossing the choice line. The time the piglet remained in the arm with the olfactory stimulus was measured by another stop-watch, and the time spent in the nonscented arm was calculated by subtracting that time from 180 seconds.

The variables analyzed in the V-maze test were the following. Entrance to the V-maze arm was the number of piglets first entering via the scented or nonscented arm. Frequency of arm change was the number of times that a piglet changed from one arm of the V-maze to the other. Time spent in an arm was the total time a piglet spent in that arm.

In order to estimate the possible interference of factors that might influence the results, two preliminary studies with a total of 120 piglets that were not part of the experiment were made before the Banana and Control test in the V-maze. First, the possible preference of pigs for the left or right arm of the maze without any external stimulus was assessed with 30 piglets 4 days of age. Since no differences were found between preferences for the two arms of the maze (P > .05; t-test), it was believed that its construction and layout would not interfere with the results. Second, the possibility was investigated that isoamyl acetate might either attract the piglets or repel them in an innate way, because the piglets used in the preliminary study had never smelled isoamyl acetate. A positive reaction was a neutral reaction, given that neither of these two effects is desired in order to carry out the test. For this test, we used a different group of 30 piglets 4 days of age. It was confirmed that isoamyl acetate neither attracts nor repels piglets that had no previous contact with it (P > .05; t test). Apart from influencing the results, this treatment might also have had a negative effect on the welfare of the piglets, which is contrary to the ethical and legal norms that apply in this kind of experiment. The same results were obtained in preliminary studies conducted in two groups of 30 piglets weaned at 21 days of age.

Study Two: postweaning phase. This study lasted for the first 2 weeks post weaning. In each treatment group, 10 pigs were removed, comprising pigs with diarrhea and pigs with lower body weight. The Control group consisted of the Control pigs from Study One. Control pigs were housed after weaning in five pens of 10 pigs each, with no more than two siblings in each group. The pigs in each pen were each identified with a number (1 to 10) marked on the pig’s back. During the 14 days of the experiment, the pen floor and the external part of the feeder were pressure washed daily with water. Feed was provided ad libitum and weighed whenever feed was added. The Banana group, including 50 pigs from the Banana group in Study One (five pens of 10 pigs each, with no more than two siblings in each group), were placed in a separate room under the same housing and management conditions as the Control group except that the pen floor and feeder were treated with isoamyl acetate solution daily.

For the first 5 hours post weaning, a behavior study was conducted on pigs in the Banana and Control groups. The behavior of the 10 pigs incorporated in every pen of each group was recorded with a camera (Samsung PRO-5780EX/27; Samsung Electronics Co, Ltd) placed 2 m above the floor in order to get an image of the whole pen. In total, 10 different cameras (five for the Banana group and five for the Control group) were connected to a video recorder (Samsung SHR-2162; Samsung Electronics Co, Ltd, Yeongtong-Gu, Suwon City, Gyeonggi-Do, Korea) permitting simultaneous recording of the 10 different cameras. The behaviour study was conducted according to the focal sampling method described by Altmann24 and Peláez del Hierro and Véa Baró.25 The first 10 minutes of every hour recorded by each camera captured the behavior of every pig. Images were studied 10 times for each pen, once for each animal present in the pen. Total time observed for both treatments was 2 groups × 5 pens per group × 10 pigs per pen × 5 first hours × 10 first minutes per hour = 5000 minutes. The ethogram of agonistic behavior applied by Jensen and Wood-Gush26 and later modified by Gonyou27 was used to analyze the pigs’ behavior.

Behavioral measurements

The following nonagonistic behaviors were studied. Feeding: the animal approaches and touches the feeder. It was not possible to distinguish between a productive approach to the feeder (the animal eats some food) and a nonproductive approach (the animal approaches the feeder but eats no food) because of the location of the cameras. Drinking: the animal approaches and touches the water nipple. It was not possible to distinguish between a productive approach (the animal drinks some water) and a nonproductive approach (the animal approaches the water nipple but drinks no water) because of the location of the cameras. Lying: the animal lies laterally, semi-laterally, or abdominally on the floor or on any other animal. Sitting: most of the animal’s weight is on the hindquarters, which rest on the floor. On other animals: the animal passes or stays on top of other animals, either standing or lying. Nose to nose: the nose of a pig approaches the snout or head of the receiver. Nose to body: the nose approaches the body of the receiver. Anal-genital nosing: the nose approaches the anogenital area of the receiver.

The following agonistic behaviors were studied. Six aggressive behaviors were recorded. Fight: rapid and persistent biting in which bites are repeated with a delay of < 1 second between bites, and the aggressive bout lasts not less than 2 seconds. Physical injury is typically inflicted on the recipient. The recipient may or may not respond. Parallel pressing: pressing shoulders against each other, facing in the same direction. Inverse parallel pressing: pressing shoulders against each other, facing in opposite directions. Head-to-head knock: hitting the snout against the head of the receiver. Head-to-body knock: hitting the snout against the body of the receiver. Aiming: an upward-directed thrust of the snout directed at the receiver from a distance of 1 to 2 m.

Five submissive behaviors were recorded. Retreat: takes several steps away from the other animal. Body whirling: the observed individual puts up no resistance to the parallel pressure exerted by the active individual. This behavior is attributed only to the submissive pig. Immobility: the observed individual remains still when it is the object of agonistic actions, with a stance suggesting submission. Hindquarters: the observed animal whirls its body quickly before an attack or a threat, offering the aggressor its hindquarters, with a stance suggesting submission. Head down: the attacked animal puts its head down, an action that is typically submissive.

Statistical analysis

Statistical analyses were performed using the statistical package SPSS for Windows, version 15.0.1, 2006 (SPSS Inc, Chicago Illinois, EE.UU.). For the preweaning phase, a chi-square independence test for two independent samples was performed to compare the proportions of piglets of each group that started the V-maze test choosing the scented or the nonscented arm. The relative risk of entering the scented arm was also calculated. For the variable frequency of arm change, data were transformed by ln(x+1). For the effect of treatment (intergroup differences), a linear mixed model with sow as a random effect was used to analyze intergroup differences in time spent in an arm of the maze, body weight at birth, body weight at 4 days of age, body weight at 21 days of age, average daily gain (ADG), and feed consumption. For differences between Day 4 and Day 21 (intragroup differences), a linear mixed test for related measures was used, with sow as a random effect. Data for all behavioral variables in the postweaning phase were transformed by ln(x+1) and were compared between groups using the linear mixed model with pen as a random effect. The same method was used to analyze the average difference between Control and Banana group piglets in body weight at weaning (21 days of age), body weight at 36 days of age, feed consumption, and feed conversion during the postweaning phase. Values of variables without transformation are presented.

Results

Preweaning phase

Table 1 shows the V-maze test results of the piglets at 4 and 21 days of age. At 4 days of age, the ratio of Control group and Banana group piglets that entered the maze for the first time via the scented arm did not differ. The number of times that piglets changed arms (Figure 2) was significantly less in the Banana group than in the Control group (13.2 ± 3.0 versus 15.4 ± 3.8, respectively; P < .001). In this first test, Banana group piglets spent significantly more time in the scented arm than in the nonscented arm (Table 2). The Banana group piglets also spent significantly more time in the scented arm than did the Control piglets. In the Control group, times spent in the scented and nonscented arms did not differ (P > .05).

Table 1: Number of piglets entering the scented or nonscented arm of a V-maze as a first choice at 4 and 21 days of age* Age Group Scented arm Nonscented arm P† Relative risk (CI)‡ 4 days Banana 33 27 > .05 0.87 (95% CI, 0.64-1.17) Control 38 22 21days Banana 39 21 < .05 1.39 (95% CI, 1.00-1.94) Control 28 32 * Six treatment sows, each with 10 piglets (n = 60 piglets), were treated by daily topical application of isoamyl acetate (banana scent) on the skin of the mammary glands during the 21-day suckling period (Banana Days 0 to 21). Six control sows, each with 10 piglets (n = 60 piglets), were similarly treated with distilled water. The V-maze and testing procedure are described in Figure 1. † Chi-square test of independence for two independent samples was performed to compare the proportions of piglets of each group that chose the scented or the nonscented arm in the V-maze test. ‡ Relative risk and 95% confidence interval (CI) of entering the scented arm of the apparatus as the first choice.

Figure 2: Frequency of arm change (mean and SD) in the V-maze shown in Figure 1 in tests carried out in piglets 4 and 21 days of age. Six treatment sows, each with 10 piglets, were treated by daily topical application of isoamyl acetate, a banana scent, on the skin of the mammary glands during the 21-day suckling period (Banana Days 0 to 21). Six control sows, each with 10 piglets, were similarly treated with distilled water. A linear mixed model with sow as a random effect was performed to determine intergroup differences (Banana Day 4 versus Control Day 4, P < .01, and Banana Day 21 versus Control Day 21, P < .001). A linear mixed model for related measures with sow as a random effect was performed to determine intragroup differences (Banana Day 4 versus Banana Day 21, P < .001, and Control Day 4 versus Control Day 21, P< .001).

Table 2: Total time (mean ± SE) piglets remained in the scented arm of a V-maze apparatus at 4 and 21 days of age* Time (seconds) spent in the scented arm† 4 days of age 21days of age Banana (n = 60) 94.8 ± 2.4 96.5 ± 1.9 Control (n = 60) 87.3 ± 2.1 78.8 ± 1.6 P‡ < .001 < .001 * Treatments described in Table 1; V-maze described in Figure 1. † Time spent in the maze during the 3 minutes after entry was defined as the total time (seconds) a piglet remained in each arm, with time in the scented arm timed with a stop watch. Time in the nonscented arm = 180 – time in the scented arm (seconds). ‡ Linear mixed model with sow as a random effect.

In the second test, performed at 21 days of age (Table 1), the proportion of pigs that entered the maze via the scented arm was significantly higher in the Banana group than in the Control group (P < .05). The number of times the pigs changed arms (Figure 2) was lower at 21 days of age than at 4 days of age in both groups (P < .001), but Banana group pigs changed arms less often than Control group pigs (6.8 ± 0.2 versus 10.6 ± 0.31, respectively; P < .001). The Banana group pigs spent a longer period of time (Table 2) in the scented arm (P < .001) than in the nonscented arm, while Control group pigs showed a preference for the nonscented arm (P < .001).

The average birth weight of piglets did not differ between the two groups (Table 3). During the period from 1 to 4 days of age, ADG did not differ between groups (Table 3). However, during the period from 5 to 21 days of age, ADG was higher in the Banana group. During this period, the consumption of solid food did not differ between groups (Table 3).

Table 3: Effect of treating the skin of the sow’s mammary glands and the feeder with isoamyl acetate (banana scent) on piglet development and consumption of food during the 21 days of suckling (mean ± SE)* Parameter Control group Banana group P† BW at birth (kg) 1.36 ± 0.04 1.38 ± 0.04 > .05 BW at 4 days (kg) 1.79 ± 0.05 1.82 ± 0.05 > .05 BW at 21days (kg) 5.86 ± 0.14 6.19 ± 0.11 < .01 ADG 1-4 days (g/day) 107 ± 5 111 ± 6 > .05 ADG 5-21days (g/day) 240 ± 6 257 ± 5 < .01 ADG 1-21 days (g/day) 214 ± 6 229 ± 5 < .01 Feed consumption 5-21 days (g/day) 14.80 ± 0.56 13.20 ± 1.13 > .05 * Sow treatments described in Table 1. Piglets were weighed at birth, at 4 days of age, and at weaning at 21 days of age. Creep feed was weighed when the feeders were filled at 4 days of age and the remaining feed was weighed at weaning. † Linear mixed model with sow as a random effect. BW = body weight; ADG = average daily gain.

Postweaning phase

Table 4 shows the main nonagonistic behaviors observed during the first 5 hours after grouping. The frequency of feeding behavior in the Banana group was significantly higher than that in the Control group. Similarly, drinking behavior differed between groups: Banana group pigs made more approaches to the water nipple than did the Control group pigs (Table 4). There was very little feeding or drinking behavior in the Control group during the fifth hour after grouping. The Control pigs lay or sat down more frequently than did the Banana group pigs (Table 4). The maximum difference between groups regarding these two variables occurred during the third hour of observation.

Table 4: Frequencies of nonagonistic behaviors identified in the first 5 hours after weaning in piglets conditioned by treatment of the sow’s mammary glands and the nursery feeder with banana scent* Behaviours Group 1st hour 2nd hour 3rd hour 4th hour 5th hour Total Feeder Banana 3.5 ± 0.6a 8.8 ± 1.1a 8.4 ± 1.1a 15.6 ± 4.0a 22.8 ± 3.1a 59.1 ± 6.5a Control 1.7 ± 0.6b 1.7 ± 0.4b 2.8 ± 1.2b 8.4 ± 3.7b 0.8 ± 0.5b 15.5 ± 5.1b Drinker Banana 7.6 ± 2.0a 7.3 ± 1.8 7.2 ± 2.1a 10.6 ± 1.6 13.6 ± 2.4a 41.3 ± 5.2a Control 3.6 ± 0.8b 5.6 ± 1.3 4.8 ± 2.3b 8.0 ± 2.9 0.4 ± 0.4b 22.4 ± 4.0b Lying Banana 7.3 ± 1.4 4.2 ± 1.0a 8.0 ± 2.5a 10.4 ± 4.1 5.2 ± 2.2a 35.1 ± 7.2a Control 6.0 ± 1.3 8.1 ± 1.8b 18.4 ± 2.5b 11.6 ± 2.7 11.6 ± 2.0b 55.7 ± 3.9b Sitting Banana 3.9 ± 0.7a 4.1 ± 1.0 2.8 ± 1.0a 4.8 ± 1.6 1.6 ± 0.7a 17.2 ± 2.5a Control 6.5 ± 1.3b 5.2 ± 0.4 9.6 ± 2.1b 4.4 ± 1.2 4.0 ± 1.7b 29.7 ± 3.1b On other animals Banana 4.2 ± 1.3 7.5 ± 1.8 9.6 ± 2.7 7.2 ± 2.1 5.6 ± 1.4 34.1 ± 6.5 Control 3.9 ± 1.0 4.2 ± 1.1 7.2 ± 2.8 5.6 ± 2.1 5.6 ± 2.1 26.5 ± 4.1 Nose-nose Banana 9.8 ± 2.3 11.3 ± 2.5 15.2 ± 4.4 12.4 ± 2.8 15.2 ± 2.3a 63.9 ± 8.7a Control 6.1 ± 1.2 5.9 ± 1.0 5.6 ± 1.6 11.6 ± 3.5 2.4 ± 1.4b 31.6 ± 6.2b Nose-body Banana 2.2 ± 0.5 6.1 ± 1.4a 6.4 ± 1.7a 7.6 ± 1.4a 6.0 ± 1.9b 28.3 ± 4.7a Control 2.9 ± 0.9 1.9 ± 0.6b 5.3 ± 1.7b 6.4 ± 2.0b 2.8 ± 1.7a 21.5 ± 3.8b Nose-anal genital Banana 3.4 ± 0.8a 3.9 ± 0.8a 5.6 ± 2.3 4.4 ± 1.4 5.2 ± 1.4a 22.5 ± 4.1a Control 1.6 ± 0.3b 2.1 ± 0.6b 2.4 ± 1.0 2.8 ± 1.0 0.4 ± 0.4b 9.3 ± 1.6b Total Banana 19.6 ± 3.0a 28.7 ± 4.2a 36.8 ± 7.8a 31.6 ± 5.2a 32.0 ± 4.0a 148.7 ± 17.0a Control 14.4 ± 2.0b 14.2 ± 2.0b 20.2 ± 5.1b 23.5 ± 6.8b 11.2 ± 3.7b 83.5 ± 10.6b Drinker + feeder Banana 11.1 ± 2.1a 16.1 ± 2.3a 15.6 ± 2.5a 26.2 ± 5.0a 36.4 ± 5.0a 105.4 ± 9.5a Control 5.3 ± 0.9b 7.3 ± 1.5b 7.6 ± 2.8b 16.4 ± 5.3b 1.2 ± 0.6b 37.9 ± 6.4b Sitting + lying Banana 11.2 ± 1.6 8.3 ± 1.6a 10.8 ± 2.4a 15.2 ± 4.3 6.8 ± 2.7a 52.3 ± 7.2a Control 12.5 ± 2.4 13.3 ± 2.0b 28.0 ± 4.1b 16.0 ± 3.2 15.6 ± 3.2b 85.5 ± 5.3b * Five replicates per treatment (10 pens total) and 10 pigs per pen (n = 50 piglets per treatment). In the Banana group (n = 5 pens), feeders were sprayed with isoamyl acetate (banana scent), once daily during the 14-day experiment. In the Control group (n = 5 pens), feeders were not treated. Banana group pigs had been previously conditioned to the banana scent applied to the skin of the mammary glands of the sow (described in Table 1). Pigs were weaned at 21 days of age. Frequencies (mean ± SE) of nonagonistic behaviors in the observation periods were calculated from observations recorded during the first 10 minutes of each of the first 5 hours after postweaning grouping. The ethogram of agonistic behavior applied by Jensen and Wood-Gush26 and later modified by Gonyou27 was used to record the pigs’ behavior. ab For each behavior, means within a column with different superscripts differ (P < .05). Intergroup differences in each nonagonistic behavior were analyzed using a linear mixed model with pen as a random effect.

For the variables that showed nonagonistic interactions between pigs, there were no significant differences between the groups, either in the entire 5-hour period or in any sampling period, for the number of times one piglet stayed on top of another. Nose-to-nose, nose-to-body, and anal-genital nosing approaches were considered nonagonistic contacts among the pigs, as no aggressive behavior was observed during or after these contacts. Generally, these behaviors were much more prominent in the Banana group. The sum of these four behaviors (total number of nonagonistic interactions) differed in the second, third, and fifth hours and in the entire 5-hour period.

Table 5 shows agonistic aggressive behaviors. Statistically significant differences in relation to most of the agonistic variables did not occur during the first 3 hours of observation. Within these 3 hours, significant differences between groups were observed only in relation to the head-to-head interaction variable, to the fight variable during the first and third hours, and to the head-body variable during the second hour. Whenever there were differences, the Control group values were always higher than the Banana group values. In the fourth hour, the Control group values for all except the fight variable were higher than those in the Banana group. In the fifth hour, parallel pressings and attacks were more frequent in the Banana group, and head-to-body interactions were higher in the Control group. For the total values for each variable and the hourly total values (Table 5), whenever there were significant differences, values were always higher in the Control group. The variable with the highest values was the head-to-body interactions. For total aggressive behavior, the Control group value was always significantly higher except in the 3rd and 5th hours.

Table 5: Frequency of agonistic aggressive behaviors of pigs detected in the first 5 hours after weaning* Behaviors Group 1st hour 2nd hour 3rd hour 4th hour 5th hour Total Fight Banana 3.1 ± 0.8a 2.1 ± 1.0 2.1 ± 0.6a 3.6 ± 0.7a 0.9 ± 0.5 11.9 ± 2.2a Control 5.9 ± 1.1b 3.1 ± 1.0 5.0 ± 1.0b 1.6 ± 1.0b 1.8 ± 0.8 17.4 ± 3.8b Parallel Banana 3.9 ± 1.0 5.0 ± 1.3 5.2 ± 1.4 4.0 ± 1.9a 4.4 ± 1.4a 22.5 ± 4.2 Control 5.2 ± 1.9 4.3 ± 1.2 4.4 ± 2.4 10.8 ± 6.2b 0.8 ± 0.5b 25.5 ± 10.4 Inverse Banana 3.8 ± 1.7 5.4 ± 2.9 2.0 ± 1.1 0.8 ± 0.8a 0.8 ± 0.5 12.8 ± 4.6a Control 4.6 ± 1.6 4.3 ± 1.7 3.6 ± 2.5 8.0 ± 5.6b 0.4 ± 0.4 20.9 ± 8.6b Head-head Banana 29.5 ± 8.8a 28.3 ± 7.0a 32.8 ± 9.1a 29.9 ± 8.1a 24.3 ± 6.5 144.7 ± 24.2a Control 45.5 ± 9.8b 63.3 ± 10.8b 49.8 ± 6.6b 56.0 ± 10.2b 25.7 ± 2.2 240.3 ± 28.9b Head-body Banana 4.1 ± 1.1 5.9 ± 2.2a 10.8 ± 8.3 11.3 ± 4.0 0.4 ± 0.4a 32.6 ± 10.6a Control 4.8 ± 1.0 9.8 ± 4.1b 12.4 ± 5.2 13.6 ± 4.4 17.2 ± 4.5b 57.8 ± 11.9b Attacks Banana 3.7 ± 2.5 2.3 ± 1.1 1.6 ± 1.1 1.2 ± 0.9a 2.4 ± 1.4a 11.2 ± 3.4 Control 3.3 ± 1.1 3.1 ± 1.2 0.4 ± 0.4 4.8 ± 2.6b 0.0 ± 0.0b 11.6 ± 4.3 Total aggressive Banana 48.1 ± 11.7a 49.1 ± 11.9a 54.5 ± 13.2 50.8 ± 10.2a 33.2 ± 9.0 234.9 ± 31.5a Control 69.3 ± 14.0b 87.9 ± 15.6b 75.6 ± 12.2 94.8 ± 23.6b 45.9 ± 5.2 373.5 ± 54.1b * Treatments described in Table 4. Frequencies (mean ± SE) of aggressive behaviors in the observation periods were calculated from observations recorded during the first 10 minutes of each of the first 5 hours after postweaning grouping. The ethogram of agonistic behavior applied by Jensen and Wood-Gush26 and later modified by Gonyou27 was used to record the piglets’ behavior. ab For each behavior, means within a column with different superscripts differ (P < .05). A linear mixed model with pen as a random effect was used to analyze intergroup differences in each agonistic aggressive behavior.

Results of the submissive behaviors are shown in Table 6. Three of the five variables (retreat, body whirling, and hindquarters) did not differ between groups. The other two variables (immobility and head down) differed in the first and second hours and overall. In contrast to the aggression variables, when significant differences were found in the variables related to agonistic submissive behavior , the Banana group had the highest values.

Table 6: Frequency of agonistic submissive behaviors of pigs identified in the first 5 hours after weaning* Behaviors Group 1st hour 2nd hour 3rd hour 4th hour 5th hour Total Retreat Banana 0.5 ± 0.3 0.4 ± 0.2 0.0 ± 0.0 0.4 ± 0.4 0.0 ± 0.0 1.3 ± 0.5 Control 0.2 ± 0.1 0.3 ± 0.2 0.0 ± 0.0 0.0 ± 0.0 0.0 ± 0.0 0.5 ± 0.3 Body whirling Banana 8.3 ± 2.2 5.4 ± 1.4 9.6 ± 4.5 2.8 ± 1.0 4.0 ± 2.0 30.1 ± 6.4 Control 4.5 ± 1.7 4.5 ± 1.3 3.6 ± 1.7 4.4 ± 2.1 0.8 ± 0.5 17.8 ± 4.2 Hindquarters Banana 1.0 ± 0.6 0.7 ± 0.4 0.0 ± 0.0 0.0 ± 0.0 0.4 ± 0.4 2.1 ± 0.9 Control 0.1 ± 0.1 0.2 ± 0.1 0.0 ± 0.0 0.8 ± 0.5 0.0 ± 0.0 1.1 ± 0.6 Immobility Banana 1.1 ± 0.5a 2.9 ± 0.8a 2.0 ± 0.8 0.8 ± 0.8 0.4 ± 0.4 7.3 ± 1.7a Control 0.3 ± 0.2b 0.3 ± 0.2b 2.0 ± 1.3 3.2 ± 1.7 0.0 ± 0.0 5.8 ± 3.3b Head down Banana 1.5 ± 0.4a 2.3 ± 0.8a 2.4 ± 1.4 0.8 ± 0.5 0.0 ± 0.0 7.0 ± 2.1a Control 0.3 ± 0.2b 0.7 ± 0.4b 1.6 ± 0.9 0.8 ± 0.8 0.0 ± 0.0 3.3 ± 2.0b Total submission Banana 12.5 ± 3.2a 11.7 ± 2.9a 14.0 ± 5.8 4.8 ± 1.6 4.8 ± 2.8 47.8 ± 8.6a Control 5.4 ± 1.9b 5.9 ± 1.5b 7.2 ± 3.8 9.2 ± 4.5 0.8 ± 0.5 28.5 ± 9.1b * Treatments described in Table 4. Frequencies (mean ± SE) of agonistic submissive behaviors in the observation periods were calculated from observations recorded during the first 10 minutes of each of the first 5 hours after postweaning grouping. The ethogram of agonistic behavior applied by Jensen and Wood-Gush26 and later modified by Gonyou27 was used to record the piglets’ behavior. ab For each behavior, means within a column with different superscripts differ (P < .05). A linear mixed model, with pen as a random effect, was used to analyze intergroup differences in each agonistic submissive behavior.

Table 7 shows growth and consumption of solid food during the first 15 days post weaning. Banana group pigs were heavier than Control pigs both at weaning and at 36 days of age. Growth rate (ADG) did not differ between treatment groups, so that the weight difference at weaning was maintained until the end of the test.

Table 7:Effect of treating the feeder with isoamyl acetate (banana scent) on pig growth and consumption of feed during the 15 days post weaning (mean ± SE)* Control Banana P† BW at 21 days of age (kg) 5.96 ± 0.042 6.28 ± 0.024 < .05 BW at 36 days of age (kg) 8.78 ± 0.040 9.12 ± 0.042 < .05 ADG 21-36 days of age (g/day) 188.15 ± 1.383 192.37 ± 3.130 > .05 Feed consumption (g/day) 344.01 ± 3.879 336.58 ± 5.125 > .05 Feed conversion (g feed/g gain) 1.84 ± 0.031 1.67 ± 0.026 > .05 * Treatments described in Table 4. Pigs were weaned at 21 days of age. † Intergroup differences analyzed using a linear mixed model with sow as a random effect. BW = body weight; ADG = average daily gain.

Discussion

At 4 days of age, Banana group piglets did not show an immediate preference for the scented arm of the V-maze, but later recognized and were attracted to the scent, as the total time spent in this arm was higher than that spent in the nonscented arm, in agreement with the work of authors such as Morrow-Tesch and McGlone.21 These investigators found that piglets showed greater preference for an odor they contacted at an early age and were able to identify it during the first few hours after birth. Furthermore, our results suggest that as the piglets matured, the bond between Banana group individuals and the banana odor strengthened. This conclusion is based on the preference of a greater number of Banana group piglets to enter the scented arm first and their significantly lower frequency for changing arms. Furthermore, Banana group piglets spent more time in the scented arm than did Control group piglets. The V-maze test at 21 days of age shows that the Banana group piglets, which had maintained a bond with the banana odor during suckling, opted to remain for a longer period in the scented arm of the maze, which was familiar to them, when they were experiencing a stressful situation (separation from their mother and litter siblings and placement in the V-maze test). These results agree with those of Sevelinges et al23 and Blais et al,28 who tested newborn mice, proving that subjects previously exposed to a specific scent spent more time in the scented arm of a Y-maze labyrinth.

The video-recorded images acquired post weaning showed that the number of visits to the feeder increased with time, in agreement with Campbell,29 who reported that piglets need time to adapt to a new environment and new diet. The number of visits the Banana group made to the feeder was much higher than the number made by the Control group, possibly due to the greater attraction to the feeder treated with the familiar banana scent. Thus, it is possible that the familiar smell favored an earlier and more frequent approach to the feeder in piglets that had adapted to the new environment. However, in this study, it was impossible to discriminate between productive and nonproductive approaches to the feeder because of the placement of the camera. Thus, it cannot be confirmed that the greater number of visits to the feeder by the Banana group meant a greater consumption of feed.

No aggressive behavior was observed when nose-nose, nose-body, or anal-genital nosing interactions were analyzed, as these interactions triggered neither fights nor submissive behaviors. For this reason, these norms of behavior have been included in the nonagonistic category, in contrast to the suggestions of Gonyou.27 In accordance with Morrison et al,30 these behaviors have been considered a type of tactile social interaction or a means of recognition since, as Gonyou31 acknowledges, the sense of smell is the first step in establishing recognition of an individual. In general, in this study, the Banana group showed more exploratory activity in relation to the environment (feeder and drinker) and to their cohorts, while Control group piglets remained in a sitting position or lay down for longer periods of time. According to Fernández32 and Hayne and Gonyou,33 the recumbent or sitting positions are directly related to aggressive agonistic behavior, as confrontations among group members cause physical exhaustion requiring periodic rests for recovery. This aggressive behavior is also in agreement with the results of Arey and Franklin.34 They point out that 40% of the fights observed during the first 5 days post grouping happen within the first 3 hours after grouping has taken place.

The study of agonistic behavior during the first 5 hours post weaning is important because, according to Fenández32 and Hayne and Gonyou,33 the maximum intensity of attacks occurs during this time. Of all the aggressive agonistic behaviors, head-head knocks are remarkable because of the high frequency with which they take place. In this study, the frequencies of head-head knocks were more stable in the Banana group and, with the exception of the fifth hour, when they did not differ, were significantly lower than in the Control group. The phenomenon described by other authors27,35-37 as the existence of the long phases of rest (third and fifth hours) after the intensive fight periods (second and fourth hours), occurred to a greater extent in the Control group. According to Ewbank and Meese38 and Ewbank,39 aggressive interactions taking place within the first hours after grouping are necessary to establish dominance relationships. When dominance relationships have been established, submissive behaviors occur. The results of this study appear to indicate that balance among dominance behaviors and their corresponding submissive behaviors was reached sooner and with a lower aggression level in the Banana group.

The absence of significant differences in birth weight in the two study groups and in feed consumption during suckling seems to indicate that the weight differences obtained in this study in the preweaning phase occurred because Banana group piglets consumed more milk than Control group piglets. Thus, this might support the idea that a positive olfactory determining factor might have been established, as suggested by Sevelinges et al23 in tests carried out on mice. During the first 15 days post weaning, feed consumption, growth rate, and feed conversion were similar in the Banana and Control groups, maintaining the weight difference observed at 21 days of age.

In conclusion, the application of isoamyl acetate to the skin of the mammary glands acted as a stimulus for piglets, favoring a higher consumption of milk. The bond established with the scent on the feeder did not translate into an increase in feed consumption and correspondingly better productive parameters in the postweaning phase. However, the presence of the banana scent during the suckling phase was associated with more stable behavior in these piglets, which can be interpreted as improved welfare by means of a decrease in aggression.

Implications

• Under the conditions of this study, treatment of the skin of sows’ mammary glands with banana scent stimulates milk consumption in the piglets.

• Treatment of the feeder with banana scent after weaning is associated with less aggressive behavior, but not with better growth parameters.

References

1. Olesen LS, Nygaard CM, Friend TH, Bushong D, Knabe DA, Vestergaard KS, Vaughan RK. Effect of partitioning pens on aggressive behaviour of pigs regrouped at weaning. Appl Anim Behav Sci. 1995;46:167–174.

2. Meese GB, Ewbank R. The establishment and nature of the dominance hierarchy in the domesticated pig. Anim Behav. 1973;21:326–334.

3. Gonyou HW, Rohde Parfet KA, Anderson DB, Olson RD. Effects of amperozide and azaperone on aggression and productivity of growing-finishing pigs. J Anim Sci. 1988;66:2856–2864.

4. Tan SSL, Shackleton DM. Effects of mixing unfamiliar individuals and of azaperone on the social behaviour of finishing pigs. Appl Anim Behav Sci. 1990;26:157–168.

5. McGlone JJ, Curtis SE, Banks EM. Evidence for aggression-modulating pheromones in prepuberal pigs. Behav Neural Biol. 1987;47:27–39.

6. McGlone JJ, Morrow JL. Reduction of pig agonistic behaviour by androsterone. J Anim Sci. 1988;66:880–884.

7. Blackshaw JK. The effects of pen design and the tranquilising drug, azaperone, on the growth and behaviour of weaned pigs. Aus Vet J. 1981;57:272–275.

8. Wiegand RM, Gonyou HW, Curtis SE. Pen shape and size: effects on pig behavior and performance. Appl Anim Behav Sci.1994;39:49–61.

9. Friend TH, Knabe DA, Tanksley TD Jr. Behavior and performance of pigs grouped by three different methods at weaning. J Anim Sci. 1983;57:1406–1411.

10. Blackshaw JK, Bodero DAV, Blackshaw AW. The effect of group composition on behaviour and performance of weaned pigs. Appl Anim Behav Sci. 1987;19:73–80.

11. Pitts AD, Weary DM, Pajor EA, Fraser D. Mixing at young ages reduces fighting in unacquainted domestic pigs. Appl Anim Behav Sci. 2000;68:191–197.

12. Weary DM, Pajor EA, Bonenfant M, Ross SK, Fraser D, Kramer DL. Alternative housing for sows and litters: 2. Effects of a communal piglet area on pre- and post-weaning behaviour and performance. Appl Anim Behav Sci. 1999;65:123–135.

13. Weary DM, Pajor EA, Bonenfant M, Fraser D, Kramer DL. Alternative housing for sows and litters: Part 4. Effects of sow-controlled housing combined with a communal piglet area on pre- and post-weaning behaviour and performance. Appl Anim Behav Sci. 2002;76:279–290.

14. Parratt CA, Chapman KJ, Turner C, Jones PH, Mendl MT, Miller BG. The fighting behaviour of piglets mixed before and after weaning in the presence or absence of a sow. Appl Anim Behav Sci. 2006;101:54–67.

15. Blackshaw JK, Thomas FJ, Lee JA. The effect of a fixed or free toy on the growth rate and aggressive behaviour of weaned pigs and the influence of hierarchy on initial investigation of the toys. Appl Anim Behav Sci. 1997;53:203–212.

16. Andersen IL, Andenaes H, Boe KE, Jensen P, Bakken M. The effect of weight asymmetry and resource distribution on aggression in groups of unacquainted pigs. Appl Anim Behav Sci. 2000;68:107–120.

17. Kelly HRC, Bruce JM, English PR, Fowler VR, Edwards SA. Behaviour of 3-week weaned pigs in Straw-Flow, deep straw and flatdeck housing systems. Appl Anim Behav Sci. 2000;68:269–280.

18. Bench CJ, Gonyou HW. Effect of environmental enrichment at two stages of development on belly nosing in piglets weaned at fourteen days. J Anim Sci. 2006;84:3397–3403.

19. Bench CJ, Gonyou HW. Temperature preference in piglets weaned at 12–14 days of age. Can J Anim Sci. 2007;87:299–302.

20. Chaloupkova H, Illmann G, Neuhauserova K, Tomanek M, Valis L. Preweaning housing effects on behaviour and physiological measures in pigs during the suckling and fattening periods. J Anim Sci. 2007;85:1741–1749.

21. Morrow-Tesch J, McGlone JJ. Sources of maternal odours and the development of odour preferences in baby pigs. J Anim Sci. 1990;68:3563–3571.

22. Pajor EA, Rushen J, de Passillé AMB. Dairy cattle’s choice of handling treatments in a Y-maze. Appl Anim Behav Sci. 2003;80:93–107.

23. Sevelinges Y, Lévy F, Mouly A-M, Ferreira G. Rearing with artificially scented mothers attenuates conditioned odor aversion in adulthood but not its amygdala dependency. Behav Brain Res. 2009;198:313–320.

24. Altmann J. Observational study of behaviour: Sampling methods. Behaviour. 1974;49:227–266.

25. Peláez del Hierro F, Veá Baró J. [Ethology: The Biological Basis of Human and Animal Behavior]. Madrid, Spain: Ediciones Pirámide; 1997.

26. Jensen P, Wood-Gush GM. Social interactions in a group of free-ranging sows. Appl Anim Behav Sci. 1984;12:327–337.

27. Gonyou HW. The social behaviour of pigs. In: Keeling LJ, Gonyou HW, eds. Social Behavior in Farm Animals. Ethology: the Biological Basis of Human and Animal Behavior [in Spanish]. Madrid, Spain: Ediciones Pirámide; 1997; Wallingford, UK: CABI Publishing; 2001:147-176

28. Blais I, Terkel J, Goldblatt A. Long-term impact of early olfactory experience on later olfactory conditioning. Dev Psychobiol. 2006;48:501–507.

29. Campbell RG. A note on the use of a feed flavour to stimulate the feed intake of weaner pigs. Anim Prod. 1976;23:417–419.

30. Morrison RS, Hemsworth PH, Cronin GM, Campbell RG. The social and feeding behaviour of growing pigs in deep-litter, large group housing systems. Appl Anim Behav Sci. 2003;82:173–188.

*31. Gonyou HW. Can odours be used to reduce aggression in pigs? Prairie Swine Centre Annual Report. 1997;59–62.

32. Fernández J. [Description of feeding behavior in four pig breeds and study of their relation to productivity, the halothane gene and social hierarchy]. Doctoral thesis. Universitat Autònoma de Barcelona. 2001.

33. Hayne SM, Gonyou HW. Behavioural uniformity or diversity? Effects on behaviour and performance following regrouping in pigs. Appl Anim Behav Sci. 2006;98:28–44.

34. Arey DS, Franklin MF. Effects of straw and unfamiliarity on fighting between newly mixed growing pigs. Appl Anim Behav Sci. 1995;45:23–30.

35. McGlone JJ. A quantitative ethogram of aggressive and submissive behaviors in recently regrouped pigs. J Anim Sci. 1985;61:556–566.

36. Dudink S, Simonse H, Marks I, de Jonge FH, Spruijt BM. Announcing the arrival of enrichment increases play behaviour and reduces weaning-stress-induced behaviours of piglets directly after weaning. Appl Anim Behav Sci. 2006;101:86–101.

37. Colson V, Orgeur P, Courboulay V, Dantec S, Foury A, Mormède P. Grouping piglets by sex at weaning reduces aggressive behaviour. Appl Anim Behav Sci. 2006;97:152–171.

38. Ewbank R, Meese GB. Aggressive behaviour in groups of domesticated pigs on removal and return of individuals. Anim Prod. 1971;13:685–693.

39. Ewbank R. Social hierarchy in suckling and fattening pigs. A review. Livest Prod Sci. 1976;3:363–372.

*Non-refereed reference.

Bookmark With:

TOPIGS introduces the Nador concept. With Nador it is possible to select and use finisher boars that produce offspring with 40% less boar taint. With this innovation one of the challenges of producing with non-castrated male finishers is minimized. TOPIGS is the first breeding company that offers this solution for boar taint.

TOPIGS will introduce Nador in the Top Pi and SNW Pietrain-Select lines. This because the Pietrain is the most used finisher boar in Germany and the Netherlands. In these two countries the Nador concept is introduced first. Later the concept will be available for the other boar lines of TOPIGS and also in more countries.

The Nador concept is one of the first developments that uses the new breeding technique genomic selection. To develop a breeding protocol for Nador boars, TOPIGS scored of over 27,000 fat samples from non-castrated finisher boars and asked test panels to score the smell after heating. The result of this human nose score was linked to the information gathered from genotyping with a dedicated SNP panel. That made it possible to distinguish boars whose offspring have less risk of developing boar taint.

Besides the boars selected on low boar taint the Nador concept also contains a tracking and tracing system. This makes it possible to provide meat processors guarantees that the slaughter pigs are bred with TOPIGS boars within the Nador concept.

With a production of 1,100,000 crossbred gilts and 7 million doses of semen per year Dutch based TOPIGS is one of the biggest genetics suppliers in the world. In several countries, TOPIGS is either the market leader or one of the major suppliers. TOPIGS stands for progress in pigs. This means research, innovation and genetic improvement are the cornerstones of our company. By continuously improving our products, we enable our clients to achieve maximum results.

Bookmark With:

Summary:

Successful production requires uniformity in many areas including ventilation. Air velocity and turbulence are two important ventilation factors. The interactions of these factors have an influence on pig comfort/stress as well as disease. Studies have resulted in the development of a temperature vs. airflow velocity chart that suggests specific airflow rates (in feet/minute) that do not hinder productivity. As the temperature of the barns fluctuates the pigs will adjust their feed intake accordingly. It is believed that the greatest intake of net energy along with peak conversion occurs just above the lower critical temperature. When analyzing ventilation it is important to take into account volume, distribution, and control of air. Recommended ventilation rates are simply calculated by multiplying the number of animals in the house by the recommended rate. The distribution system will provide sufficient mixing of fresh air with appropriate maintenance. A common method of monitoring the control of air is via a sensor inside of the room in question. These can help to make control decisions. Most of the ventilation problems occur during cold or cool weather when ventilation rates are low. Air quality can be poor because of under ventilation. If relative humidity is high, other contaminants are usually above the threshold values as well. A suggested priority for ventilation testing would be temperature and humidity, air distribution pattern, ammonia, carbon monoxide, carbon dioxide, and dust.

Bookmark With:

Antibiotics have been administered to agricultural animals for disease treatment, disease prevention, and growth promotion for over 50 y. The impact of such antibiotic use on the treatment of human diseases is hotly debated. We raised pigs in a highly controlled environment, with one portion of the littermates receiving a diet containing performance-enhancing antibiotics [chlortetracycline, sulfamethazine, and penicillin (known as ASP250)] and the other portion receiving the same diet but without the antibiotics. We used phylogenetic, metagenomic, and quantitative PCR-based approaches to address the impact of antibiotics on the swine gut microbiota. Bacterial phylotypes shifted after 14 d of antibiotic treatment, with the medicated pigs showing an increase in Proteobacteria (1–11%) compared with nonmedicated pigs at the same time point. This shift was driven by an increase in Escherichia coli populations. Analysis of the metagenomes showed that microbial functional genes relating to energy production and conversion were increased in the antibiotic-fed pigs. The results also indicate that antibiotic resistance genes increased in abundance and diversity in the medicated swine microbiome despite a high background of resistance genes in nonmedicated swine. Some enriched genes, such as aminoglycoside O-phosphotransferases, confer resistance to antibiotics that were not administered in this study, demonstrating the potential for indirect selection of resistance to classes of antibiotics not fed. The collateral effects of feeding subtherapeutic doses of antibiotics to agricultural animals are apparent and must be considered in cost-benefit analyses.

Looft T, Johnson TA, Allen HK, Bayles DO, Alt DP, Stedtfeld RD, Sul WJ, Stedtfeld TM, Chai B, Cole JR, Hashsham SA, Tiedje JM, Stanton TB. 2012. In-feed antibiotic effect on the swine intestinal microbiome. Proc. Natl. Acad. Sci. USA. doi:10.1073/pnas.1120238109.

Bookmark With:

Charles D. Fulhage
Department of Agricultural Engineering

Charles E. Ellis
Extension Agricultural Engineering Specialist, Troy, Mo.

The Missouri Dead Animal Law requires that a dead animal carcass be properly disposed of within 24 hours. In Missouri there are five acceptable methods of carcass disposal. They are: rendering, composting, landfilling, incineration and burial. This publication discusses composting as a means of complying with the dead animal law for swine operations. For information on the other methods, refer to MU publication WQ216, Dead Animal Disposal Laws in Missouri.

Composter location

The composter should be located away from areas of sensitive water quality such as streams, ponds and wells. A location at or near the crest of a hill will eliminate or minimize the amount of surface water approaching the composter from higher areas. If a composter must be located in the lower part of a slope, a diversion terrace should be constructed around the upper side of the composter to keep surface water out.

When locating a composter, consider the farm residence and any nearby neighbor residences that might be affected. While offensive odors are not generated if the composting process is properly managed, the handling of dead swine and compost on a daily basis may not be aesthetically pleasing. Also, consider traffic patterns required in moving dead swine to the composter, moving the required ingredients to the composter and removing finished compost from the composter. The composter site should be well-drained and provide all-weather capability for access roads and work areas.

Composting ingredients and recipe

Composting dead swine requires the addition of a carbon source to ensure proper carbon/nitrogen ratios are present for the composting process. Experience thus far suggests that sawdust an ideal carbon source due to its small particle size, ease of handling, absorbency and high carbon content. Experience using straw as the only carbon source has been less successful, with lower composting temperatures, leaching of fluids from the composting pile and longer composting times required. When sawdust is used as a carbon source, plan to provide about 100 cubic feet of sawdust per 1,000 pounds of carcass to be composted. For farrow-to-finish operations, sawdust requirements are about one-third to one-half cubic yards per sow in the herd on an annual basis. See Table 1 for a summary of compost criteria.

Table 1
Summary of swine composting design and management criteria

• Sawdust requirements
  One half cubic yard of sawdust per sow in the herd for farrow-to-finish operations (annually) or 100 cubic feet (about 4 cubic yards) of sawdust per 1,000 pound carcass composted.
• Nitrogen addition
  Up to 3 pounds ammonium nitrate per 100 pounds swine carcass as needed, mix with sawdust.
• Water addition
  If sawdust is dry, add water to obtain a damp feel and appearance, up to 1 to 1-1/2 gallons per cubic foot of sawdust.
• Composter size
  20 cubic feet of primary and secondary bin volume per pound of carcass composted daily. Size bins for floor area of 100 to 200 square feet, and depth of 5 to 6 feet.
• Temperature
  130 to 160 degrees Fahrenheit indicates active composting.
• Time
  Compost three months in primary bins, and an additional three months in secondary bins.

A precise carbon/nitrogen ratio does not seem to be necessary to obtain good composting, and most composting with sawdust as the carbon source has been done without adding supplemental nitrogen. However, if sawdust is used according to the above recommendations, some supplemental nitrogen would have to be added to obtain the ideal carbon/nitrogen ratio of 25. The addition of about 3 pounds of ammonium nitrate (NH₄NO₃) in the dry, granular form per 100 pounds of swine carcass will provide the nitrogen necessary to achieve a carbon nitrogen ratio of about 25. The ammonium nitrate should be mixed with the sawdust used to cover the carcass and can be applied by simply “hand-scattering” as carcasses are covered with sawdust. As noted previously, most composting is accomplished without the use of additional nitrogen, but this practice may help in starting up new composting operations and obtaining the desired composting temperatures.

The type of sawdust used in composting can influence the success of the operation. Although a fine or small particle size sawdust is not necessary, wood chips and shavings do not seem to work well due to their larger particle size. Sawdust or wood refuse material derived from bark and/or mulching operations may contain rocks, stones and other foreign material as well as excessively large wood particles, and should not be used for composting.

Most sawdust in Missouri is obtained from sawmills, lumbering and logging operations or cabinet making and furniture making businesses. Such sawdust is generally quite adequate for composting. The moisture content and bulk density of sawdust are important factors in composting. Bulk density is important in estimating the amount of sawdust to use; moisture content, which also affects bulk density, should be in the proper range for composting. Tests on fresh sawdust obtained from seasoned logs or kiln-dried lumber indicate a bulk density of 16 to 20 pounds per cubic foot with a moisture content of 20 to 30 percent. Sawdust stored in a pile tends to gain moisture content. Tests on aged sawdust (more than 5 years old) showed moisture content in the 50 to 70 percent range and bulk density of about 30 pounds per cubic foot. Most of the increase in bulk density is due to the increase in moisture content.

The ideal moisture content in a composting pile is 50 to 60 percent. Swine carcasses have a moisture content near this range, and much sawdust obtained from outside piles may also be near this range. Hence it may not be necessary to adjust moisture content or add water in the composting recipe. However, if the sawdust is exceptionally dry or the composting pile becomes dry due to the internal heat generated, it may be necessary to add water for optimum composting.

The moisture content of sawdust or a composting mixture can be judged somewhat by its appearance and feel. Sawdust that has a damp appearance and feel is probably near the proper moisture content for composting. If it appears wet, or free water can be squeezed out, it should be allowed to dry to a damp condition before being used. Fresh sawdust taken immediately from sawing kiln-dried lumber or seasoned logs will probably be too dry and water will have to be added. Add water as needed to obtain a damp feel and appearance in the sawdust. Very dry sawdust (20 percent moisture) may require the addition of 1 to 1-1/2 gallons of water per cubic foot of sawdust to obtain the proper moisture content. Water should be mixed with the sawdust by sprinkling or spraying as the sawdust is placed on the carcasses. Avoid the over-addition of water, as excessively wet mixtures do not compost properly and may require removal and mixing with dry sawdust to recover the process. “Green” sawdust from fresh-cut, unseasoned logs may have a moisture content as high as 80 percent. Green sawdust may be too wet for optimum composting, and should be allowed to dry somewhat or should be mixed with drier sawdust or finished compost before using. A water line and hydrant installed at the composter will facilitate water addition and general cleanup activities.

Temperature is the best indicator that the composting process is proceeding properly. Temperatures in the composting pile should rise to the 130 to 160 degrees Fahrenheit range, indicating active microbial activity and breakdown of the carcasses.

Composter design

The composting process requires the proper ingredients to be placed in composting bins in the correct proportions, allowed to compost for a period of time, then moved to a second bin for a secondary composting phase. A minimum of three months composting time is needed in both the primary and secondary phases. It may be necessary to extend this period of time if an unusual number of large carcasses are composted, or if ambient temperatures are low enough to slow the composting process.

In most cases a minimum of three bins will be required, two of which are used for primary composting and the third for secondary composting. In the typical scenario, Bin 1 is filled with three months’ death loss, at which time Bin 2 is started. At the end of the second three-month period, Bin 2 is full, and the last carcasses placed in Bin 1 have composted for three months. The contents of Bin 1 are then ready to move to Bin 3 for the secondary composting phase.

After three months of secondary composting, the material can be moved out and applied to land, and the secondary bin is available to receive the contents of Bin 2. Larger operations will require more than the minimum three bins; experience has shown that having extra bins available for storage of fresh sawdust and finished compost is beneficial.

Total bin area and volume requirements depend upon the size of operation and death loss incurred. Actual past death loss data should be used in sizing composters for existing operations. For planning purposes and sizing composters for new operations, see the average death loss data in Table 2. A minimum of 20 cubic feet of volume is needed in both primary and secondary bins per pound of carcass composted daily. Bins are typically filled to a depth of 5 to 6 feet for composting. While bin configuration is not critical, bins are usually laid out as three-sided enclosures. The open side should be wide enough (at least two feet wider than bucket width) so that the bin contents are easily accessible with a front end or skid-steer loader. Square bins offer the greatest opportunity for reduced side effects, (heat loss through walls), although length:width ratios of up to 2:1 are acceptable. Primary and secondary bins should be located close or adjacent to each other (perhaps with a common wall) to facilitate moving compost from bin-to-bin. Excessively large bins should be avoided. Experience has shown that bins with 100 to 200 square feet of surface area work well. See Table 1 for a summary of composter design criteria.

Table 2
Average annual death loss for swine in confinement

¹Includes all mature animals, farrowing, gestating, and boars.
²Includes losses in farrowing house prior to weaning.

Note
Death losses can vary significantly from the values shown above depending upon genetics, management, environmental conditions, and many other factors.

Composter construction

Prior to constructing a composter, you must decide whether or not a roof over the composter is preferable. Current Missouri regulations do not require a roof or concrete floor in a swine composter, provided that sawdust is used as the carbon source in the composter. Properly mounded and landscaped sawdust effectively sheds water; leaching of fluids from the bottom of properly managed swine composters does not occur. The use of other carbon sources, such as straw, may require a roof to exclude rainwater and leaching from the pile. Limited experience has shown that use of less absorbent carbon sources like straw may result in leaching and less effective composting even though the composter is roofed.

The primary advantage of an unroofed composter is reduced cost. Advantages of roofed composters include: fewer weather effects on the composting process; worker protection during inclement weather; and a more aesthetically pleasing appearance to match other buildings in the production unit.

Field experience suggests that composting bins can be constructed using large round bales (5 to 6 feet in diameter) of low-quality hay. Bales are placed end-to-end to form walls for three-sided enclosures or bins. A layout three bales deep and two bales wide as shown in Figure 1 has worked well for swine composters.

Figure 1
Sample composter layout using hay bales.

Another alternative for the unroofed composter is to use concrete for the bin floor and walls. Although more costly, the concrete is a more durable construction material and is less subject to weathering and mechanical damage during cleaning operations. Also, less room is required than a similar composter using large round bales.

Figure 2 and Figure 3 are schematic drawings of one possible configuration for a roofed composter. This design uses concrete bin walls and floor and pole construction for end walls and roof. The roof overhang and concrete apron in front of the composter minimize rain blowing into the bins and provide a solid work area in front of the composting bins. Many other layouts and materials and could be used in constructing a composter.

Figure 2
Schematic top view of a roofed composter with concrete bin walls.

Figure 3
Schematic side view of a roofed composter with concrete bin walls

Equipment requirements

Although composting is a simple process, certain equipment is necessary for good management of the operation.

Some type of front-end or skid steer loader is the most necessary piece of equipment in a composting operation. The loader is needed to move carcasses from the production buildings to the composter. Although small carcasses can be deposited and covered in the composter by hand, larger carcasses cannot be adequately managed by hand. The loader provides a means to properly place larger carcasses in the compost pile and adequately cover the carcasses with sawdust of finished compost. The loader is also needed to move compost from primary to secondary bins and can be useful in receiving, storing and piling fresh sawdust from the sawmill. Finally, the loader is necessary for loading out finished compost for field spreading.

A probe-type thermometer will aid in monitoring the compost to determine if it is composting properly. Dial-type thermometers with a minimum 36-inch stainless steel stem allow measurement of temperatures in the interior of the composting pile. Temperatures should rise to the 130 to 160 degree F range for good composting.

A manure spreader should be available for field spreading finished compost. A conventional beater-type spreader for handling solid manure is also adequate for land applying finished compost.

A logbook is a useful record-keeping tool in a composting operation. Dates and weights of carcasses placed in the composter provide a record of death losses and a basis for improving death loss statistics. Temperature readings, amounts of fresh sawdust inventoried and used and dates when compost is transferred from primary to secondary bins are record-keeping items that can aid in managing the composting operation. Finally, dates and amounts of finished compost removed for land spreading also provide data for future management and planning.

Composter operation and management

Although composters are simple and relatively easy to operate and manage, certain steps and procedures are necessary to ensure that the process proceeds properly. Table 3 outlines the steps that should provide acceptable finished compost in a swine operation.

Table 3
Steps in operating and managing a swine composter

1. Start a primary composting bin by placing enough sawdust in the bin so that there is at least one foot under and around the first carcasses placed in the bin. Carcasses placed directly on dirt or concrete floors or against bin walls will not compost properly.
2. Place carcasses in the primary bin as necessary. It is very important to use sufficient sawdust so each carcass is covered on all sides with a minimum of one foot of sawdust. Small pigs may be grouped or placed with less sawdust between carcasses, but a one foot covering between carcasses and the pile surface should always be maintained to minimize odors and rodent problems. Never leave hoofs legs ears or snouts sticking out of the sawdust pile. Most problems in swine composting arise when insufficient sawdust is used in covering carcasses. Use a pointed rod or dowel to measure the thickness of the sawdust cover. Large carcasses may need to be recovered after a day or two as the sawdust settles around the carcass. Keep the surface of the pile shaped so that it will shed rainwater out the front of the bin if the composter is not roofed. Do not allow pockets to form in the bin corners or elsewhere that will pool water. Carcasses placed in warm sawdust begin composting more quickly. This can be accomplished by overfilling sawdust over the previous carcasses. This allows the sawdust to heat up so that the next carcass is then buried in this pre-warmed sawdust. The loader bucket is used to “wallow-out” a cavity in the pre-warmed sawdust and the fresh carcass is placed in this cavity. If finished compost is available, it should be used to cover the carcass to provide additional heat and bacteria to start the composting process. Fresh sawdust should then be used to provide the final cover thickness needed so a new cavity can be provided for the next carcass.
3. Monitor temperature of the composting pile with a long-stem dial-type thermometer. When composting is proceeding properly temperatures will reach 130 to 160 degrees Fahrenheit. If a thermometer is not available you can obtain a rough indication of temperature by inserting a steel rod in the compost pile and feeling how hot it is when you pull it out. Primary bins started during cold weather may not begin composting immediately. However if carcasses are buried with the proper amounts of sawdust composting should begin on its own as temperatures warm up in the spring. There is usually enough heat in active (as opposed to newly started) compost piles to continue composting through cold weather regardless of ambient temperature. If sawdust is used as recommended the insulation effect is sufficient to minimize the effects of ambient temperature.
4. After the last carcasses placed in the primary bin have composted three months or longer move the contents to a secondary bin. This step provides mixing and re-aeration of the material so that the compost will “finish off” properly.
5. After the pile has composted another three months in the secondary bin it should appear as a dark granular nearly black humus-like material with very little odor. Some resistant parts such as teeth may still be identifiable but should be soft and easily crumbled.
6. Use the finished compost as noted above for a “starter” material on the new carcasses being composted in the primary bin. This provides heat and bacteria to enhance starting of the composting process. Experience has shown that up to 50 percent of the sawdust requirement for composting can be filled using “recycled” finished compost. However plan to use fresh sawdust in the amounts noted for starting up a composting operation until sufficient finished compost becomes available. Haul and spread finished compost as needed using a conventional manure spreader. Apply finished compost at agronomic rates for the crop being grown. Obtain a laboratory analysis of the compost for nitrogen (N) phosphate (P₂O₅) and potash (K₂O) for precise fertilizer content. The following table gives average values of fertilizer nutrients from several samples of finished swine compost.

7. Keep fresh sawdust as dry as possible because dry sawdust works better in the composting process. Fresh sawdust in a pile will shed water reasonably well if the pile is mounded, with no pockets or depressions.
8. Keep the area around the composter mowed and free of tall weeds and brush. Watch for any leaching that might occur. Using more sawdust in the bottom of the bins can help eliminate leaching.

Frequently asked questions

Certain questions regarding composting frequently arise. Some of these questions and answers are as follows.

Doesn’t a dead animal compost stink, and attract rodents and dogs?

If carcasses are properly covered with sawdust (one foot recommended), odors are sufficiently suppressed or absorbed so that they are not a problem in most cases. When operated properly, composters do not add to, or increase odor levels around a production facility. Using too little sawdust is the single greatest factor in excess odor and associated rodent problems. It is important to prevent a rodent problem when starting up a composter, because once rodents learn the composter is a source of carcasses, they can be difficult to stop.

What happens in the wintertime when temperatures are cold?

In general, the warmer the ambient temperature, the better the composting process works. However, an active compost pile contains considerable heat which, with the insulating effect of the sawdust, minimizes effects of ambient temperatures. Interior pile temperatures of 130 to 160 degrees Fahrenheit are typical in properly operating composters when ambient temperatures are as low as zero degrees Fahrenheit. Cold or frozen carcasses placed in cold (fresh) sawdust will not begin composting during cold weather. However, carcasses placed under these conditions will begin to compost as ambient temperatures warm up in the spring.

Carcasses placed in an active compost pile during cold weather should begin composting as heat is absorbed from the composting mass. Covering the carcass with warm or hot finished compost from an active secondary bin will further enhance composting fresh carcasses in cold ambient temperatures.

How large a carcass can be put in the composter?

Mature sows and boars (300 to 600 pounds) have been successfully composted. Longer composting times are required for larger carcasses. However, six months of active (temperatures 130 degrees Fahrenheit or above) composting time should be sufficient for most swine carcasses. These carcasses are composted whole (no cleaving or cutting up of the carcass).

Will Missouri DNR approve this type of composter in a waste management plan?

The primary concern of the regulatory agency is to prevent contamination of ground or surface water. Hence, any contamination problem arising from a composter (or any other part of the production facility) would have to be corrected. Contamination potential from composters located and operated as indicated in this publication is quite low. Under current policy, Missouri DNR will approve unroofed swine composters if sawdust is used as the carbon source and the composter is properly managed. Use of other carbon sources such as straw will likely require a roofed structure to minimize water absorption and leaching.

What should the finished compost look like?

Properly finished compost should appear as a dark, nearly black granular material resembling humus or potting soil. It may have a slight musty odor. Some resistant bones (skull parts, teeth) will be visible, but they should be soft and easily crumbled by hand.

What about diseases, flies and pathogens?

Temperatures above 140 degrees Fahrenheit normally occur at some time in the composting pile. This is sufficient to destroy pathogens and prevent fly incubation. Good coverage of the composting pile with sawdust eliminates the fly breeding and incubation environment. No disease outbreaks have been associated with composting to date. Spreading finished compost in fields or pastures helps assure that disease organisms do not find their way back to the production area.

I do not have sawdust available. Can I use something else for a carbon source?

Any granular organic material with a high carbon content should be a candidate as an ingredient in composting. Most successful swine composting thus far has been accomplished using sawdust as the carbon source. More research and experience is needed to evaluate other carbon sources such as straw, hay, rice hulls and cornstalks. A long, fibrous material such as straw or cornstalks would likely work much better for composting if it were ground to reduce the particle size similar to that of sawdust. This would allow the material to settle around the carcass and provide the contact needed for good bacterial activity.

Can finished compost be used as a partial or full substitute for fresh sawdust in the primary bin?

Experience to date indicates that up to 50 percent of the fresh sawdust requirement may be fulfilled using finished compost. It is unlikely that long-term viability of the process could be maintained if no fresh sawdust were used, as the source of carbon would eventually be exhausted. Advantages of recycling finished compost include: less fresh sawdust required, active bacteria and heat contained in finished compost and less finished compost to haul for land spreading.

What happens if the composting process fails, or leaching occurs?

Excessive moisture in the composting pile is the most frequent cause of leaching and failure of carcasses to compost properly. The use of adequate amounts of dry or nearly dry sawdust is the best way to eliminate excessive moisture. Any surface water should be diverted around and away from the composter. If a composting pile becomes too wet, it can usually be recovered by moving it to another bin, and mixing in additional dry ingredients during the moving process.

What should I do with finished compost?

Finished dead animal compost, which is not recycled in primary bins, should be spread following agronomic practices used for spreading manure. Compost should be spread at agronomic rates so that applied nutrients do not exceed the uptake capabilities of the crop being grown. Conventional “beater-type” manure spreaders are ideal for handling and spreading compost. Care should be taken not to spread compost in or near sensitive areas such as streams, lakes, ponds, sinkholes, public rights-of-way and road ditches.

Can I compost in just one step, rather than moving the material from primary to secondary bins?

Moving compost from primary to secondary bins provides mixing, adds oxygen, and allows the compost to “finish off” with a high degree of breakdown. The success of the primary/secondary approach has been demonstrated in many other areas of composting, as well as swine. Some producers have reported acceptable results with single-step composting, but total composting time may be longer than that required for primary/secondary composting. Also, bin volume requirements are not reduced by single-step composting.

What about using ‘green’ or wet sawdust?

Generally, the dryer the sawdust, the better, since dryer sawdust can absorb more water. However, producers have reported success when using green sawdust for some or all of the fresh sawdust requirement. Sawdust containing excessive moisture may freeze into chunks in the winter, making it difficult to handle and place around carcasses.

Will composting work for larger carcasses such as cattle?

Experience with large swine carcasses (600 to 700 pounds) suggest that cattle carcasses could be composted in this manner if properly managed. Large cattle carcasses will be more difficult to handle and properly place in a composter. Required composting time is proportional to carcass weight, hence large cattle carcasses may require up to a year of active composting time. Also, more movement, mixing, and aeration of the composting pile may be necessary. It is likely that more sawdust per pound of carcass will be required with cattle carcasses due to the amount required for adequate coverage of the legs and head. No experience has been gained to date to provide information similar to that in Table 1 for cattle.

Sizing a composter

The examples on the following pages, used with the Swine composter worksheet, illustrate a method of sizing a swine composter, and estimating annual sawdust requirements.

Example 1

Size a composter for a 200-sow, farrow-to-finish operation. Use data in Table 2 to estimate death loss. Estimate annual sawdust requirements. There are 200 mature animals (sows, boars, gilts), 700 nursery pigs, and 1,640 finishing pigs in the operation.

Swine composter worksheet

1. Calculate weight of carcasses composted. Use data from actual experience, or use Table 2.

Sow herd

Number of sows x average weight x percent (Table 2) ÷ 100 = pounds loss per year

_200_ x _375_ pounds x _7_ percent ÷ 100 = _5,250_ pounds per year

Nursery

Number of pig spaces x average weight x percent (Table 2) ÷ 100 = pounds loss per year

_700_ x _32_ pounds x _24_ percent ÷ 100 = _5,376_ pounds per year

Finishing

Number of pig spaces x average weight x percent (Table 2) ÷ 100 = pounds loss per year

_1,640_ x _150_ pounds x _11_ percent ÷ 100 = _27,060_ pounds per year

Total = _37,686_ pounds per year

pounds composted daily = (pounds per year) ÷ 365 = _37,686_ pounds per year ÷ 365 = _103_ pounds per day

2. Calculate primary and secondary bin volume.

pounds composted daily (Step 1) x 20 = primary bin volume, cubic feet

_103_ pounds per day x 20 = _2,060_ cubic feet primary bin volume

pounds composted daily (Step 1) x 20 = secondary bin volume, cubic feet

_103_ pounds per day x 20 = _2,060_ cubic feet secondary bin volume

3. Calculate bin area (use volumes from Step 2).

bin volume, cubic feet ÷ depth (usually 5 to 6 feet) = bin area, square feet

_2,060_ cubic feet ÷ _6_ feet = _343_ square feet primary bin

bin volume, cubic feet ÷ depth (usually 5 to 6 feet) = bin area, square feet

_2,060_ cubic feet ÷ _6_ feet =_343_ square feet secondary bin

4. Calculate number of bins (at least 3 bins required).

primary bin area (Step 3) ÷ (100 to 200 square feet per bin) = number of bins

_343_ square feet ÷ _110_ square feet per bin = _3.1_ primary bins

secondary bin area (Step 3) ÷ (100 to 200 square feet per bin) = number of bins

_343_ square feet ÷ _110_ square feet per bin = _3.1_ secondary bins

5. Calculate bin dimensions.

bin depth = composting depth (usually 5 to 6 feet) = _6_ feet depth

bin width = loader bucket width + 2 feet or wider = _10_ feet width

bin length = bin area (Step 3) ÷ bin width = _110_ square feet ÷ _10_ feet = _11_ feet length

6. Calculate annual sawdust requirements.

pounds composted per year (Step 1) x 0.0037 = cu yd sawdust per year

_37,686_ pounds per year x 0.0037 = _139_ cu yd sawdust per year

Example 2

Size a composter for a 2,400-sow farrowing operation. Death loss data for the operation is as follows:

Four 375 pound sows per week
200 pound small pigs and afterbirth per day

Calculate annual and daily carcass weight and enter directly in Step 1 of the worksheet.

375 pound sow x 4 sows per week x 52 weeks per year = 78,000 pounds per year

200 pound pigs and afterbirth per day x 365 days per year = 73,000 pounds per year

Total = 151,000 pounds per year = 414 pounds per day

Swine composter worksheet

1. Calculate weight of carcasses composted. Use data from actual experience, or use Table 2.

Sow herd

Number of sows x average weight x percent (Table 2) ÷ 100 = pounds loss per year

___ x ___ pounds x ___ percent ÷ 100 = ___ pounds per year

Nursery

Number of pig spaces x average weight x percent (Table 2) ÷ 100 = pounds loss per year

___ x ___ pounds x ___ percent ÷ 100 = ___ pounds per year

Finishing

Number of pig spaces x average weight x percent (Table 2) ÷ 100 = pounds loss per year

___ x ___ pounds x ___ percent ÷ 100 = ___ pounds per year

Total = _151,000_ pounds per year

pounds composted daily = (pounds per year) ÷ 365 = _151,000_ pounds per year ÷ 365 = _414_ pounds per day

2. Calculate primary and secondary bin volume.

pounds composted daily (Step 1) x 20 = primary bin volume, cubic feet

_414_ pounds per day x 20 = _8,280_ cubic feet primary bin volume

pounds composted daily (Step 1) x 20 = secondary bin volume, cubic feet

_414_ pounds per day x 20 = _8,280_ cubic feet secondary bin volume

3. Calculate bin area (use volumes from Step 2).

bin volume, cubic feet ÷ depth (usually 5 to 6 feet) = bin area, square feet

_8,280_ cubic feet ÷ _6_ feet = _1,380_ square feet primary bin

bin volume, cubic feet ÷ depth (usually 5 to 6 feet) = bin area, square feet

_8,280_ cubic feet ÷ _6_ feet = _1,380_ square feet secondary bin

4. Calculate number of bins (at least 3 bins required).

primary bin area (Step 3) ÷ (100 to 200 square feet per bin) = Number of bins

_1,380_ square feet ÷ _170_ square feet per bin = _8.1_ primary bins

secondary bin area (Step 3) ÷ (100 to 200 square feet per bin) = Number of bins

_1,380_ square feet ÷ _170_ square feet per bin = _8.1_ secondary bins

5. Calculate bin dimensions.

bin depth = composting depth (usually 5 to 6 feet) = _6_ feet depth

bin width = loader bucket width + 2 feet or wider = _12_ feet width

bin length = bin area (Step 3) ÷ bin width = _170_ square feet ÷ _12_ feet = _14_ feet length

6. Calculate annual sawdust requirements.

pounds composted per year (Step 1) x 0.0037 = cu yd sawdust per year

_151,110_ pounds per year x 0.0037 = _559_ cu yd sawdust per year

Example 3

Size a composter for an off-site nursery with a capacity of 8,400 pigs. Average weight in the nursery is 27 pounds. Use data in Table 2 to estimate death loss.

Swine composter worksheet

1. Calculate weight of carcasses composted. Use data from actual experience, or use Table 2.

Sow herd

Number of sows x average weight x percent (Table 2) ÷ 100 = pounds loss per year

___ x ___ pounds x ___ percent ÷ 100 = ___ pounds per year

Nursery

Number of pig spaces x average weight x percent (Table 2) ÷ 100 = pounds loss per year

_8,400_ x _27_ pounds x _24_ percent ÷ 100 = _54,432_ pounds per year

Finishing

Number of pig spaces x average weight x percent (Table 2) ÷ 100 = pounds loss per year

___ x ___ pounds x ___ percent ÷ 100 = ___ pounds per year

Total = _54,432_ pounds per year

pounds composted daily = (pounds per year) ÷ 365 =_54,432_ pounds per year ÷ 365 = _149_ pounds per day

2. Calculate primary and secondary bin volume.

pounds composted daily (Step 1) x 20 = primary bin volume, cubic feet

_149_ pounds per day x 20 = _2,980_ cubic feet primary bin volume

pounds composted daily (Step 1) x 20 = secondary bin volume, cubic feet

_149_ pounds per day x 20 = _2,980_ cubic feet secondary bin volume

3. Calculate bin area (use volumes from Step 2).

bin volume, cubic feet ÷ depth (usually 5 to 6 feet) = bin area, square feet

_2,980_ cubic feet ÷ _6_ feet = _497_ square feet primary bin

bin volume, cubic feet ÷ depth (usually 5 to 6 feet) = bin area, square feet

_2,980_ cubic feet ÷ _6_ feet = _497_ square feet secondary bin

4. Calculate number of bins (at least 3 bins required).

primary bin area (Step 3) ÷ (100 to 200 square feet per bin) = Number of bins

_497_ square feet ÷ _160_ square feet per bin = _3.1_ primary bins

secondary bin area (Step 3) ÷ (100 to 200 square feet per bin) = Number of bins

_497_ square feet ÷ _160_ square feet per bin = _3.1_ secondary bins

5. Calculate bin dimensions.

bin depth = composting depth (usually 5 to 6 feet) = _16_ feet depth

bin width = loader bucket width + 2 feet or wider = _10_ feet width

bin length = bin area (Step 3) ÷ bin width = _160_ square feet ÷ _10_ feet = _16_ feet length

6. Calculate annual sawdust requirements.

pounds composted per year (Step 1) x 0.0037 = cu yd sawdust per year

_54,432_ pounds per year x 0.0037 = _201_ cu yd sawdust per year

Swine composter worksheet

1. Calculate weight of carcasses composted. Use data from actual experience, or use Table 2.

Sow herd

Number of sows x average weight x percent (Table 2) ÷ 100 = pounds loss per year

___ x ___ pounds x ___ percent ÷ 100 = ___ pounds per year

Nursery

Number of pig spaces x average weight x percent (Table 2) ÷ 100 = pounds loss per year

___ x ___ pounds x ___ percent ÷ 100 = ___ pounds per year

Finishing

Number of pig spaces x average weight x percent (Table 2) ÷ 100 = pounds loss per year

___ x ___ pounds x ___ percent ÷ 100 = ___ pounds per year

Total = ___ pounds per year

pounds composted daily = (pounds per year) ÷ 365 = ___ pounds per year ÷ 365 = ___ pounds per day

2. Calculate primary and secondary bin volume.

pounds composted daily (Step 1) x 20 = primary bin volume, cubic feet

___ pounds per day x 20 = ___ cubic feet primary bin volume

pounds composted daily (Step 1) x 20 = secondary bin volume, cubic feet

___ pounds per day x 20 = ___ cubic feet secondary bin volume

3. Calculate bin area (use volumes from Step 2).

bin volume, cubic feet ÷ depth (usually 5 to 6 feet) = bin area, square feet

___ cubic feet ÷ ___ feet = ___ square feet primary bin

bin volume, cubic feet ÷ depth (usually 5 to 6 feet) = bin area, square feet

___ cubic feet ÷ ___ feet = ___ square feet secondary bin

4. Calculate number of bins (at least 3 bins required).

primary bin area (Step 3) ÷ (100 to 200 square feet per bin) = number of bins

___ square feet ÷ ___ square feet per bin = ___ primary bins

secondary bin area (Step 3) ÷ (100 to 200 square feet per bin) = number of bins

___ square feet ÷ ___ square feet per bin = ___ secondary bins

5. Calculate bin dimensions.

bin depth = composting depth (usually 5 to 6 feet) = ___ feet depth

bin width = loader bucket width + 2 feet or wider = ___ feet width

bin length = bin area (Step 3) ÷ bin width = ___ square feet ÷ ___ feet = ___ feet length

6. Calculate annual sawdust requirements.

pounds composted per year (Step 1) x 0.0037 = cu yd sawdust per year

___ pounds per year x 0.0037 = ___ cu yd sawdust per year

References

• Rynk, Robert, et. al. 1992, NRAES-54, Northeast Regional Agricultural Engineering Service, 152 Riley-Robb Hall, Cooperative Extension, Ithaca, N.Y. 14853-5701
• U.S. Department of Agriculture, Wood Handbook. Handbook number 72, U.S. Department of Agriculture, Forest Products Laboratory.
• Starbuck, Chris, et. al. 1994. Developing Procedures for Utilizing Missouri Sawdust in Combination with other Organic Byproducts for Large Scale Horticultural Uses. Unpublished report, MU Department of Horticulture, Columbia, Mo.

The author expresses his deep appreciation to Mel Gerber, Versailles, Mo. for his initiative and extensive cooperation and efforts in applied field research on swine composting. Many of the design and management recommendations for composting are derived from Mel’s early experiences and his desire to share those experiences for the benefit of the swine industry.

This publication was formerly printed as WQ225.

Bookmark With:

Department of Medicine, Feinberg School of Medicine, Northwestern University, 420 East Superior Street, Chicago, IL 60611, USA; Email: d-bergner@md.northwestern.edu.

Bookmark With:

Finding the optimum market weight – that is the weight that brings the most profit, isn’t as easy as it sounds states Jamie Pietig, Hubbard Feeds Swine Nutritionist. Market weight and feed cost per pound of gain are the two most important criteria in selling weight decisions. Producers must also factor other variables such as packer expectations, pig performance, genetics, barn space costs, pig facility and flows and even the use of DDGS into the calculations.

Hubbard Feeds has developed a series of market analysis models that use each individual producer’s performance data and feed costs plus the packer payment matrix to determine the most profitable market weight. A general example of the market analysis model is shown below.

The chart above represents the optimal marketing weight on a per pig basis only and does not account for pig variation within a marketed load of hogs.

The model assumes a diet that includes 300 pounds of DDGS, a base carcass price of $80/cwt.; $6.50/bu corn; $290/ton soybean meal; $185/ton DDGS; and yardage cost of $35/pig space. The green shaded area represents the optimal selling weight while the yellow shaded area represents the sale weight within $1.25/hd. of optimum. Premiums and discounts are based on the Tyson Fresh Mean Inc. Feb 7, 2011 Supreme Lean Carcass Merit Program.

Finding the optimal market weight is only one part of the equation to determining profitability. The second component is deciding which nutrition program will generate the best return over feed costs to reach that market weight. By combing ingredient costs, performance data and packer payment information, Hubbard Feeds is able to help each customer individually select the feeding program that provides the best returns for their operation. This method of incorporating feeding programs into production systems allows pork producers to capture the most value that the market will allow.

Interested in learning more about the effects of market weight and nutrition programs on your return over feed costs? Contact your Hubbard Feeds representative and ask them about the market analysis programs or call us at 1-800-869-7219.

Bookmark With:

Slaughter Health Checks: Still A Valuable Tool

TECHNICAL BULLETIN

What is a slaughter health check?

A slaughter health check involves evaluating pigs at the slaughter plant for disease lesions, pneumonia mainly due to Mycoplasma hyopneumoniae, liver scarring due to ascarid (roundworms) larval migration, atrophic rhinitis and sarcoptic mange. Other lesions can be observed such as pericarditis, pleuritis and peritonitis (scarring of the heart, chest and abdomen, respectively; often caused by Actinobacillus pleuropneumoniae, Hemophilus parasuis or Streptococcus suis), tumors, abscesses, foot lesions and arthritis. Evaluating pigs at slaughter enables assessment of disease levels in “normal” pigs, unlike necropsy examinations which focus on evaluating lesions in “sick” pigs.

Why are slaughter health checks used less frequently than in the past?

The primary reason slaughter checks were performed in the past was to validate the disease-free status of specific pathogen free (SPF) herds. The decline in the number of SPF herds, along with labor-related costs and biosecurity constraints have resulted in fewer slaughter health checks. In addition, newer herd health practices including mycoplasma vaccination, age segregated rearing (multi-site production), improved biosecurity, modern facilities, disease eradication protocols and reduced weaning age have improved the overall health status of pigs. Multi-site production in particular has changed disease patterns such that overall disease levels may be reduced, but disease in a particular group of pigs may be more severe. Accordingly, slaughter checks on a few groups may not adequately characterize the health of a whole system that has multiple flows of pigs
raised on multiple sites.

Why consider a slaughter health check now?

There are many reasons for having a slaughter health check done on your pigs with the primary reason to follow up on a well-defined clinical disease problem in a flow or site. A slaughter check will evaluate the scope of the disease in the larger population. On the other hand, the scope of disease may not be captured from the smaller number of pigs typically necropsied during a diagnostic workup. With multi-site produced pigs, it is important to select groups of pigs where disease was observed or suspected. Currently, pneumonia is the most significant concern in commercial swine operations. Recent slaughter checks conducted by Merck Animal Health technical service veterinarians have revealed a large degree of variation in the control of pneumonia, most of which appear to be related to the number of mycoplasma vaccine doses (one vs. two) administered to the pigs. The results of these checks are available in an accompanying technical bulletin.

A second reason to conduct a slaughter health check is to evaluate a change in a herd’s health program or some other production practice by providing information beyond routine production records. Although production records should be the cornerstone of evaluating the relative benefits of different products and practices, slaughter health checks, along with other disease monitoring efforts such as testing blood, oral fluids and feces for antibodies and pathogens, can be used to better understand the underlying reasons for observed performance differences. In order to use a slaughter check in this manner, a “baseline” of slaughter checks should be
in place before the production practice is changed.

A third reason is to identify a disease that is not clinically apparent in the herd. Although this may seem far fetched, in fact, our recent slaughter checks have revealed diseases in herds that were not apparent, and if left unattended, could develop into serious problems. Why? Many herds are now getting older and even though they were populated with relatively clean pigs, a lot of time has passed and new diseases have unknowingly entered these herds. Reduction in antibiotic use due to economics and food safety concerns may enable the clinical revival of bacterial diseases that were previously in check. In some operations, the frequency of necropsies has been insufficient, the disease lesions were not recognized by the person performing the necropsy or the location of the disease in the pig was not examined. For example, failing to saw snouts may result in missing an atrophic rhinitis diagnosis.

How do I get a slaughter health check done?

The first step is to contact a Merck Animal Health sales representative who will in turn forward the request to a Merck Animal Health technical services veterinarian. A plan will then be developed to accomplish the check. Communication between the producer, the buyer for the slaughter plant, the herd’s veterinarian and Merck Animal Health personnel are necessary to coordinate scheduling of the pigs to the plant at the right time and scheduling the personnel who will be doing the slaughter check. Generally, a minimum of one week of lead time is needed to get the check organized.

What are the limitations of a slaughter check?

First of all, it is important to recognize that the lesions observed at slaughter may be recent in nature. The lack of visible lesions does not mean that the pigs were free of the disease for the entire growing period. This is especially true with pneumonia lesions and liver scars, which can resolve over time. Likewise, pneumonia lesions are not specific to mycoplasma. Lesions due to swine influenza virus can look the same. To differentiate the two diseases, lung samples may be collected at slaughter and evaluated in the laboratory to determine the causative agent in groups that exhibit a high level of pneumonia.

How are slaughter checks scored?

Pneumonia lesions are scored based on the percentage of the lung surface that exhibits visible lesions. Both the group’s average score and the percentage of lungs with greater than 5 percent and 20 percent involvement are calculated. Reference values for comparison are provided by Merck Animal Health technical service veterinarians. The reference values are based on previous evaluations by Merck Animal Health and published papers. Atrophic rhinitis is scored based on the degree of turbinate atrophy and septal deviation. An average score is calculated and a relative herd severity level is assigned by the Merck Animal Health veterinarian who conducted the check. Mange is scored based on the presence of small, red papules on the skin surface after the hair has been removed from the carcass. Livers are scored based on the number of scars present on the surface. For both liver scars and mang negative status is desired in most herds, so the data is valuated more on a yes/no basis.

How does slaughter health check information fit in with other diagnostic testing, production records and observations?

The interpretation and value of the slaughter health check information will vary between herds and over time. The information needs to be evaluated and interpreted in light of previous diagnostic test results, production records and observations made by the herd’s staff, the attending veterinarian and other advisors. In some cases, the slaughter check information will provide a definitive answer to a question such as a product comparison or verification of a clinically obvious problem. Often times, the information leads to additional testing, especially when the results are unexpected such as the situation where a disease new to the herd, such as atrophic rhinitis is diagnosed or the extent of a disease, such as ascarid infestation, needs to be determined.

How much does it cost to have a slaughter health check done?

Merck Animal Health technical service veterinarians will perform the checks at no cost to the producer where appropriate. If a private practitioner performs the check, Merck Animal Health will work with the practitioner and may assist with the cost where appropriate, providing that the data collected will be made available to Merck Animal Health for inclusion in a slaughter health check database.

Bookmark With: