PSIX-19 - Association of the rumen microbiota with carcass merit and beef quality

Abstract: The microbial community in the rumen plays an important role in the health and production of beef cattle providing up to 70% of the daily energy requirements from the metabolism of otherwise non-digestible dietary carbohydrates. Diet is often the largest determinant of rumen microbiome composition but it is also affected by host age, genetics, and sex. Performance attributes such as average daily gain and feed efficiency have all been linked to the rumen microbiome and recent studies with relatively small numbers of cattle have also suggested there may be an association with certain beef quality traits such as marbling, which largely determines the carcass value. Thus, the objective of this study was to evaluate the association of the rumen microbiota with carcass merit and beef quality traits. Two hundred steers were slaughtered and rumen samples were collected immediately post-slaughter. Subsequently, carcass merit and meat quality attributes were evaluated. The rumen microbiota of these animals was then characterized using 16S rRNA gene sequencing. Although we did not identify a significant association between marbling score and the structure of the rumen microbiota (PERMANOVA; P > 0.05), there were significant associations between rumen microbial community structure and commercial weight, dressed weight percentage, drip loss, and intramuscular fat content (P < 0.05). There were also individual bacterial taxa that were correlated with various carcass merit and beef quality traits. Members of the Acidaminococcus genus were negatively associated with both intramuscular fat content and marbling score (P < 0.10) while Coprococcus, Christensenellaceae R-7 group, Lachnospiraceae NK3A20 group, Moryella, and Prevotella were among those genera positively correlated with intramuscular fat content (P < 0.10). Christensenellaceae R-7 group, Lachnospiraceae NK3A20 group, Moryella, and Prevotella were also significantly associated with dressed weight percentage. Commercial weight was positively correlated with the genera Catonella, Prevotellaceae NK3B31 group, Pseudoramibacter, Selenomonas, and Sutterella and negatively associated with Oribacterium and Ruminococcaceae UCG-001 (P < 0.10). Therefore, bacteria within these genera may be ideal targets for future microbiome-based strategies to improve carcass merit and beef quality.