PSXI-24 Vaginal microbiome is associated with breed and pregnancy status in beef cattle.

Abstract Reproductive efficiency is vital in livestock productivity, with reproductive failure being a major cause of cow culling in beef and dairy operations. Due to the complexity and low heritability of reproductive traits, further investigation into genetic and non-genetic factors is essential. Microbiomes associated with hosts play crucial roles in vertebrate biology, including reproduction, potentially serving as biomarkers for fertility. This study explored the relationship between vaginal microbiome profiles and fertility among three beef cattle genetic groups using field data. Vaginal swabs were collected from 74 cows at Fort Keogh, MT, including 23 Angus, 23 Hereford Line 1, and 28 crossbreds, and DNA was extracted and analyzed via 16S rRNA amplification. Significant differences in alpha diversity (p < 0.05) were found among Line 1 cows compared to Angus and crossbreds in 14 out of 22 different indicators of diversity, evenness and dominance. While pregnancy status also significantly influenced the Line 1 group in the diversity Fisher and Shannon indexes. PERMANOVA analysis indicated that genetic groups and pregnancy status affected group distances (p < 0.05), but their interaction was not significant. Each genetic group showed unique compositions of operational taxonomic units (OTUs), with higher proportions of Ureaplasma and Mycoplasma families in Line 1. Additionally, variations in microbial communities were observed between pregnant and non-pregnant cows, with certain uncultured bacteria more prevalent in non-pregnant cows. These results suggest variation in vaginal microbiomes across breeds and pregnancy statuses, emphasizing the need for further research to identify factors affecting these changes, though the study did not account for factors like parity and age, possibly impacting outcomes.