Live Yeast & Pig Resilience to Heat Stress: unveiling the mechanisms

Higher insulin sensitivity

A trial was conducted using metabolic chambers to evaluate the effect of live yeast supplementation and feeding frequency in male finishing pigs subjected to heat stress (Serviento et al., 2022). It complemented previous studies (Labussière et al., 2022) by looking deeper into the metabolic pathways involved in heat stress adaptation.

Findings show increased resistance to heat stress, which was possibly attributable to improved insulin sensitivity of the pigs fed live yeast. Their insulin:glucose ratio was significantly lower around meals (Figure 1). This may contribute to higher energy efficiency under heat stress. 

Figure 1: Effect of Levucell SB supplementation on the insulin:glucose ratio during heat stress (Serviento at al. 2022).

Improved sensitivity to insulin can be explained by two main mechanisms of action of the live yeast: 

1. Improvement of intestinal integrity during stress 
2. Increased production of short chain fatty acids in the gut, thanks to microbiota modulation

It is noteworthy that in humans — where the live yeast S. boulardii has been widely documented for 100 years — S. boulardii supplementation has been reported to attenuate diabetic related complications such as hyperglycemia (due to impaired insulin activity or production) by microbiota modulation and improved immune responses.

Improved thermoregulation

During heat stress, water evaporation through panting represents the main mechanism for heat dissipation in pigs and high temperatures increase water requirements. 

Interestingly, the trial conducted under controlled conditions (respiratory chambers), indicates increased water intake, especially around meals, for the live yeast supplemented pigs. This, in turn, increases the pigs’ ability to dissipate heat through water evaporation (Figure 2). 

Figure 2: Effect of Levucell SB supplementation on pigs’ body temperature during heat stress (Serviento et al. 2022)

As a result, the pigs’ body temperature went down quicker after a meal as compared to the control, indicating an improved thermoregulation response and heat dissipation with the live yeast. This represents another mechanism of adaptation to heat stress challenges assisted by live yeast (Figure 3).

Figure 3: Effect of Levucell SB supplementation on pigs body temperature during heat stress (Serviento, et al. 2022)

Preserved feeding behavior and energy metabolism

The study also evaluated the benefit of the live yeast on pigs’ feeding behavior, metabolism and growth performance. Indeed, under heat stress, pigs tended to eat less and divert their energy metabolism from growth.

In pigs supplemented with live yeast, the impact of heat stress on feeding behavior was alleviated. As previously shown by Labussière et al.: animals significantly increased their meal frequency (Figure 4) and, thus, their total feed intake.

Figure 4: Effect of Levucell SB supplementation on feeding behavior during heat stress (Serviento at al. 2022)

Better adaptation to heat stress conditions in live yeast supplemented pigs resulted in enhanced energy retention, which also confirmed previous findings (Figure 5). 

Figure 5: Effect of Levucell SB supplementation on coefficient of energy retention during heat stress (Serviento at al. 2022)

In conclusion, improved heat tolerance of live yeast supplemented pigs lies in their ability to maintain the dynamic equilibrium between heat production and loss throughout the day.

Recent research has established a relationship between the gut microbial composition and the pig’s metabolic adaptation to heat stress.

In turn, feeding behavior, water intake, energy utilization (insulin sensitivity) and, thus, growth performance and welfare are better preserved. Levucell SB represents an interesting tool to help animals cope with increasing heat stress conditions.

You may also like to read:  “Maternal Imprinting Part II: Piglet Performance & Immune Development”

REFERENCES

• Baumgard LH and Rhoads RP 2013. Effects of heat stress on postabsorptive metabolism and energetics. Annu. Rev. Anim. Biosci. 1:311-337. DOI: 10.1146/annurev-animal-031412-103644.
• Labussière, E., Achard, C., Dubois, S., Combes, S., Castex, M., & Renaudeau, D. (2022). Saccharomyces cerevisiae boulardii CNCM I-1079 supplementation in finishing male pigs helps to cope with heat stress through feeding behaviour and gut microbiota modulation. British Journal of Nutrition, 127(3), 353-368. doi:10.1017/S0007114521001756
• Serviento AM, Castex M, Renaudeau D, Labussière E. Effect of live yeast supplementation and feeding frequency in male finishing pigs subjected to heat stress. Br J Nutr. 2022 Aug 19:1-37
• Serviento AM. Dynamic responses of growing pigs to heat stress modulated by prenatal life and feeding practices. PhD Thesis, 2022