PSXV-11 A Postbiotic from Saccharomyces Cerevisiae Fermentation Improves Microbiome Robustness in Young Stress-Challenged Horses in Training

Abstract

Abstract Nutritional and environmental stressors can disturb the gut microbiome of horses which may ultimately decrease their health and performance. In this study, we hypothesized that a Saccharomyces cerevisiae fermentation postbiotic (SCFP) improves the robustness of the gut microbiome in stress-challenged horses. Quarter horses (n=20) were randomized based on sex, age (22 ± 3 mo) and body weight (439 ± 3 kg) to receive a basal diet (60% forage:40% concentrate) supplemented without (CON) or with SCFP (21g/d, TruEquine, Diamond V, Cedar Rapids, IA). Treatments were implemented for 60 d. On d 57, horses were tethered with their heads elevated 35 cm above wither height for 12 h to mimic long-distance transport stress. Fecal samples were collected on d 0, 28, and 56 pre-challenge and at 0, 12, 24 and 72 h post-challenge and subjected to DNA extraction and Nanopore shotgun metagenomics. Alpha-diversity and microbial abundances were compared using non-parametric Wilcoxon-Rank-Sum test with Benjamini-Hochberg FDR correction. The SCFP stabilized alpha-diversity across all time points, whereas CON horses had more fluctuation (P < 0.05) at 12, 24 and 72 h post-challenge compared to d 56. This resulted in a significant difference between CON and SCFP at 0 and 12 h. There was no difference in beta-diversity between SCFP and CON on d 56, however, treatments grouped separately (PERMANOVA, P < 0.05) within the 12 h post-challenge showing SCFP horses maintained higher abundances (P < 0.05) of fibrolytic taxa such as Fibrobacter succinogenes, Ruminococcus species and several members of Prevotellaceae and Lachnospiraceae among others. During the post-challenge period compositional clusters in the microbiome of CON horses were characterized by low abundances (P < 0.05) of Butyrivibrio, Pseudobutyrivibrio and Blautia species versus SCFP. Overall, treatments were similar in microbiome diversity and composition pre-challenge, however, post-challenge, SCFP supplementation improved microbiome robustness indicating an ability to resist change due to stress.