Effect of Live Yeast Supplementation on Redox Potential, Gastrointestinal Microbiota, and Short-Chain Fatty Acids in Piglets

Abstract The post-weaning period is a stressful process for piglets with compromised gut health, increasing susceptibility to diarrhea and infection. Oxygen concentration in the gut affects microbiome and fermentation profile. Live yeasts have been used to promote gut health and performance of young animals. An experiment was carried out to determine the influence of live yeast on gut conditions including redox potential, microbial composition, and short chain fatty acid (SCFA) production of piglets. Sixteen Pietrain *(Landrace*Large White) piglets were distributed into blocks by live weight and allocated at 4 per pen for a 28-d trial. Each block was composed by a combination of the 2 dietary treatments corresponding to a control diet and a diet supplemented with live yeast (1 kg/tonne Vistacell, AB Vista). At the end of trial, piglets were euthanized to measure kinetics of redox potential (Eh) and pH from caecum until 35 min post-mortem. Then, digesta samples from stomach, duodenum, jejunum, ileum, caecum, and rectum were collected for microbial composition and SCFA production. Data were analyzed using GLM procedure of SAS 9.4 and means compared with a Student-Newman-Keuls test. Redox potential decreased with time (P < 0.001) until stabilizing after 20 min, and a clear difference was observed between treatments (P < 0.001). Supplemented live yeast survives throughout gastrointestinal tract and modifies microbial populations enhancing lactic acid bacteria (P < 0.001) while reducing enterobacteria (P < 0.001) or eliminating fungi (P < 0.001). The production of SCFA from caecum digesta was 3-fold higher than in ileum with significantly different molar proportion of individual SCFA. Lactic, formic, and acetic acids predominate on ileum (> 93%) whereas acetic, propionic, and butyric dominate on caecum digesta (> 90%). Nevertheless, no differences were observed due to dietary treatments. In conclusion, live yeast supplementation of diets modifies redox conditions prevailing in the gut modifying microbial populations and helping piglets to overcome post-weaning growth check.