# Effects of Supplementing Yeast Culture to Prepartum Cows Under Heat Stress on the Jejunal Microbiota and Metabolites of Calves

## TL;DR

Adding yeast culture to heat-stressed cows before calving improves calf gut health, immunity, and metabolism through changes in gut microbiota and metabolites.

## Contribution

This study shows that maternal yeast culture supplementation during heat stress improves offspring gut health and immunity via microbiota and metabolic changes.

## Key findings

- Calves from supplemented cows had stronger immune systems and reduced oxidative stress.
- Jejunal microbiota in YC calves showed enriched Enterococcus spp. and modulated bile acid pathways.
- Maternal yeast culture improved jejunal structure and metabolic balance in calves.

## Abstract

Heat stress during late pregnancy negatively impacts dairy cow welfare and fetal development. This study demonstrates that supplementing heat-stressed cows with yeast culture before calving significantly improves the health of their offspring. Newborn calves from supplemented dams exhibited stronger immune systems, reduced oxidative stress, and better intestinal development. These physical benefits were linked to a healthier gut microbiome and improved metabolic balance. Consequently, maternal yeast culture supplementation offers a practical nutritional strategy to mitigate the damaging effects of heat stress on the next generation, promoting better calf survival, growth, and economic sustainability for dairy producers.

Heat stress, particularly during the prepartum period, compromises dairy cow health and has lasting effects on offspring. This study aimed to investigate the effects of maternal yeast culture (YC) supplementation during heat stress on the intestinal health of newborn calves, with a specific focus on elucidating the associated changes in jejunal morphology, microbial community, and metabolic profiles. Cows receiving YC had lower rectal temperatures, confirming mitigated heat stress. Their calves showed enhanced immune status (higher IgA, IgG) and reduced oxidative stress and metabolic markers. Jejunal structure and barrier integrity were improved. While microbial diversity was similar, specific bacterial abundances differed (e.g., Enterococcus spp. enriched in YC calves). Metabolomic analysis revealed modulated bile acid pathways and metabolites in YC calves, correlating with the microbial shifts. In conclusion, maternal YC supplementation during heat stress supports calf early-life gut health and development through maternal-offspring programming, optimizing gut microbiota, metabolism, and immunity.