Grazing steers utilize their rumen microbiomes to convert plant-derived carbohydrates into meat. Considering the socioeconomic importance of the beef industry, it is critical to develop strategies that maintain quality while lessening negative environmental impacts. Diet supplementation and hormonal growth implants have been shown to variably impact methane emissions and animal performance. A previous study examines grazing steers across four treatment groups: diet supplemented, hormonal implanted, combined diet and implant, and no intervention. They found no significant impact on emissions and performance. However, the rumen microbiome response to these treatments remains relatively unknown. Here, we will analyze 16S and ITS rRNA gene amplicon sequencing from those steers. We found that all treatments led to an increase in 16S and ITS alpha diversity over time; however, only the 16S diet group displayed a significant increase. Neither the 16S nor the ITS rumen microbiome composition significantly differed across treatments; however, both were significantly different over time. Future analyses will look at individual microbial and fungal responses to diet, grazing time periods, and associations with methane and performance data. Ultimately, our results will provide insight into rumen microbiome dynamics during the life cycle of a grazing steer, further informing sustainable management strategies.
