Interpretive Summary: Transcriptome analyses indicate that heat stress-induced inflammation in white adipose tissue and oxidative stress in skeletal muscle is partially moderated by zilpaterol supplementation in beef cattle

By: Rachel R Reith, Renae L Sieck, Pablo C Grijalva, Rebecca M Swanson, Anna M Fuller, Duarte E Diaz, Ty B Schmidt, Dustin T Yates, Jessica L Petersen

Heat stress (HS) negatively impacts livestock health and carcass quality. Supplementation of livestock with β-adrenergic agonists (β-AA) increases muscle mass and decreases fat deposition. The purpose of this study was to understand how HS and zilpaterol hydrochloride (ZH), a β-AA, alter gene expression in muscle and in adipose of cattle. Twenty-four steers were assigned to thermoneutral (TN) or HS conditions and were not supplemented (NS) or supplemented with ZH for 21 d. RNA was isolated from muscle and adipose collected on days 3, 10, and 21 to identify changes in gene expression. Several individual loci were differentially expressed (DE) due to HS or ZH in both tissues while the interaction of HS and ZH altered expression in adipose. A less stringent definition of DE used to explore biological pathways predicted that both treatments alter metabolism. Pathway analyses also supported that HS increased inflammation in adipose, but that these inflammatory pathways were downregulated by ZH. HS also was predicted to induce oxidative stress in muscle although ZH moderated this response. This study provides information on how HS and β-AA act independently and interact to alter physiology, lending insight useful for the development of management and mitigation strategies for stress.

Read the full article in the Journal of Animal Science.