Live yeast: Healthy sows, more piglets

Author: Dr. Spenser Becker, Swine Technical Services at AB Vista

Pork producers are continually looking for ways to maximize productivity on swine farms. With the number of pigs born per litter increasing, it is critical to maintain birth and weaning weights, while reducing the number of low-birth-weight piglets. This is also important in reducing post-weaning mortality, as low-birth-weight piglets have a higher risk of mortality and slower growth rate (Fix et al., 2010; Feldpausch et al., 2019).

Yeast supplementation has been widely researched and utilized in swine nutrition to improve performance, reduce mortality, and mitigate stress. However, not all yeast products are created equal, and therefore, it is important to understand the different components in these feed additives. Yeast products can broadly be classified into four categories: yeast extract, dead yeast, yeast cell wall, and live yeast. Live yeast has the unique ability to scavenge oxygen (Figure 1). This is important when considering that pigs have a high distribution of blood vessels and large surface area of the gastrointestinal tract that allows oxygen diffusion from the blood to the lumen (Zhu et al., 1993). Dissolved oxygen concentrations in the gut can reach high levels, which stimulates aerobic microbial activity (Hillman et al., 1993) and reduces fiber-degrading bacteria. Hence, research has shown that reducing oxygen in the gastrointestinal tract can improve fermentation and SCFA production (Albenberg et al., 2015; Lizardo et al., 2012).

Live Yeast Application – Sows

In addition to oxygen scavenging, live yeast also provides a source of mannans and glucans. These components support the immune response of the animal and may partially explain the positive responses observed in sows.  In ten evaluations, the addition of live yeast in sow lactation diets increased weaning weight by an average of 0.5kg compared to controls (Figure 2; Trials 1-4, Europe; Trials 5-10, USA). Furthermore, live yeast supplementation during lactation reduced pre-weaning mortality by 19% of the control (Table 1; Figure 3). Based on the average sow response to live yeast, pre-weaning mortality could be reduced to 12.81% from 15.82% in a sow with 15.48 total pigs born (Pigchamp; 2022, Yearly Summary). That same sow would wean an extra 0.5 pig per litter or an extra 1.1 pigs weaned/sow/year when supplemented with live yeast. This improvement in pig performance and livability with live yeast addition in sow lactation diets may be explained by the improved fiber and nutrient digestion and partially by reported increases in milk output and immunoglobulin A concentrations when fed live yeast during lactation (AB Vista, internal data).

Table 1. Effects of live yeast supplementation in lactation on pre-weaning mortality.

Average response data

Live Yeast Application – Piglets

Additional benefits of live yeast have been reported in weaned piglets. Live yeast supplementation during both gestation and lactation was shown to enhance subsequent nursery pig performance when compared to piglets weaned from control sows. However, further benefits were also found when piglets were fed live yeast during the nursery period so that the best performing piglets (gain of 1.3 kg vs. control; 10 point improvement in FCR) at the end of the nursery were from sows fed live yeast and supplemented with live yeast during the nursery (Lu et al., 2019). In the same study, it was shown that supplementing diets with live yeast during the nursery period also increased nutrient digestibility with improvements in dry matter, gross energy, and phosphorus-apparent total tract digestibility.

Live Yeast Application – E. coli and Salmonella Mitigation

As an oxygen scavenger, intestinal colonization of live yeast can reduce the growth of unwanted bacteria in the gut and stimulate the growth of fibrolytic microbes. In addition, mannans that are a component of the live yeast can bind E. coli and flush the bacteria out of the system. In an internal study conducted by AB Vista, samples of piglet gastrointestinal mucosal lining were incubated with radioactive-labeled Salmonella enterica and E. coli K88 with and without live yeast. It was noted that live yeast reduced the binding of Salmonella enterica by 70% and E. coli K88 by 67%. Thus, live yeast has the capability to promote a healthy gut microbiome and improve the health status of the pig.

Live Yeast Application – Heat Stress

Lactating sows that are in heat stress conditions (> 70^oF; upper critical limit) with high humidity typically reduce feed intake and can have intestinal health challenges. These health challenges increase cell permeability, reduce nutrient utilization, and increase endotoxin transfer into the portal/systemic blood, resulting in greater inflammation and immune activation. Literature has shown that live yeast may be a potential feed ingredient that can reduce the impact of heat stress (Domingos et al., 2021) in the lactating sow. An internal study was conducted in sows that were maintained in normal enviromnental conditions that were above the upper critical temperature for lactating sows throughout the trial (77^oF to 93 ^oF and relative humidity of 52 to 97) and fed a standard lactation diet with and without a live yeast. The results showed that in heat-stessed conditions, sow that were fed the live yeast during lactation had an improved litter weaning weight (76.21 vs. 68.20 kg) that was significant in the older parities (> Parity 3). Further research by Hiscocks et al. (Midwest ASAS 2023) in sows fed live yeast from 4-weeks pre-farrow through the end of lactation showed that sows supplemented with live yeast had lower rectal temperature at weaning compared to non-suppplemented sows (38.6°C vs 39.1°C). This reduction in rectal temperature may suggest an improvement in health status of the sow. These same sows also had a higher body condition score at weaning compared to non-supplemented sows (3.4 vs. 3.0). Given that feed intake was similar between treatments, this suggests that live yeast supplementation allowed sows to better retain their condition during lactation.

Application of live yeast should be considered a useful tool for pork producers and nutritionists to maximize sow herd productivity on their farm that has the potential to help mitigate heat stress impacts on sow productivity.