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There is never a time in swine production where producers aren’t facing challenges in some form or fashion. Many challenges – whether they are nutritional, health or management related – tend to be seasonal. Fall is typically a favorite season for many producers, lending optimized weather conditions for growth. But, hot summer temperatures bring on a distinct set of obstacles.
Heat stress, for example, is a concern in the summer – especially when hot temperatures are combined with high humidity. The optimal temperature for pigs post weaning is between 65°F and 75°F. In this temperature range, pigs remain in their thermoneutral zone. In the thermoneutral zone, swine can maintain their core body temperature without altering feed intake, behavior or metabolism. Body heat production is also at its lowest in this zone. When the temperature reaches beyond the upper range of the thermoneutral zone, pigs are unable to dissipate heat without expending extra energy. Instead, heat loss occurs through panting. Additionally, pigs may exhibit signs of heat stress, increasing water intake and reducing activity – including eating. There are also other physiological changes such as increased blood cortisol, increased oxidative stress, increased inflammatory cytokines, increased blood pH (respiratory alkalosis), alterations in intestinal microflora, reduction in blood flow to the intestines and other internal organs and loss of intestinal integrity. Ultimately, in addition to being a welfare issue, heat stress leads to economic loss from decreased performance, reduction in meat quality and increased mortality.
In addition to heat stress, there are also health management considerations in the summer. Maintaining gut health and immune function is crucial to help optimize production during summer months. The intestines are one of the first organs impacted by summer heat and are responsible for both nutrition absorption and keeping toxins and bacteria out of the pig.
As with health, there are also nutritional considerations. Summer weather presents optimal conditions for mold growth, providing exposure to adequate moisture and heat. If not controlled, mold growth can lead to a decline in feed quality through loss of nutrients and vitamins. Additionally, molds can produce mycotoxins which lend their own detrimental effects, including loss of intestinal integrity and impaired immunity. There is also the risk of feed rancidity, which can reduce the fat energy levels in the feed, as well as the availability of fat-soluble vitamins.
Although we face many of the same issues from summer to summer, here are a few reminders on how to combat summertime challenges through management, nutritional and health interventions.
Nutrition
1. Adapt Your Formula for the Season
Negative performance during the summer primarily happens due to reduced feed intake. To counteract pigs backing off feed due to heat stress, there are several adjustments that can be made to dietary formulas. Formulation of nutrient dense diets can help pigs maintain nutrient intake while eating less feed. Increasing energy levels in diets may also compensate for reduced feed intake. Because protein digestion produces higher levels of metabolic heat, this is often accomplished by increasing fat levels and lowering protein. If protein levels are reduced, however, amino acid levels must be carefully balanced to compensate for example through synthetic amino acid and/or enzyme supplementation. Also avoid feeding during the peak heat stress time of day (10:00AM-4:00 PM) to increase feed intake and reduce feed wastage.
2. Maximize Feed Quality and Consider Pellet Feeding
While pigs can lose nutrients through reduced feed intake, they can also lose nutrients by having poor feed quality. Warm temperatures and high humidity lend opportunistic growing conditions to molds. Molds can reduce feed quality by utilizing the nutrients in the feed before it gets to the pigs. In addition, the mycotoxins produced by molds negatively affect almost all organ systems of the pigs along with reducing performance and feed efficiency. Performance loss from molds and mycotoxins can be combatted, by adding mold inhibitors and flow agents to feeds. Similarly, antioxidants can protect fats and oils in feed from becoming rancid through oxidation. There is also evidence that pellet feeding during summer could help with mitigating the performance loss during summer.
3. Supplement with Vitamins, Minerals and Systemic Antioxidants
Supplementation with vitamins and other additives can be useful in mitigating the effects of heat stress. Vitamins A, E and C supplementation may be beneficial not only because they are antioxidants and heat stress may cause oxidative stress in pigs, but also because they are not synthesized as readily in heat-stressed pigs. Mineral supplementation is also helpful. Selenium – also an antioxidant – can be added to ameliorate the effects of oxidative stress. Minerals such as calcium, zinc, phosphorus and magnesium, that are critical to growth and development, are lost either through reduced appetite or from lowered metabolism during heat stress. These minerals should also be properly balanced and if needed, supplemented to counteract this loss. Other minerals, such as chromium, directly combat heat stress by reducing cortisol levels. Supplementation with chromium can therefore improve growth rate and yield during heat stress. Additionally, it is critical to address electrolyte loss and acid-base imbalance due to respiratory alkalosis from panting. Salts such as sodium bicarbonate and potassium chloride can be added to the feed to maintain acid-base balance. Electrolytes may also be supplemented in the water on very hot periods.
