Hepatic transcript profiling in beef cattle: Effects of feeding endophyte-infected tall fescue seeds.

Abstract

The objective of our study was to evaluate the effect of endophyte-infected tall fescue (E+) seeds intake on liver tissue transcriptome in growing Angus × Simmental steers and heifers through RNA-seq analysis. Normal weaned calves (~8 months old) received either endophyte-free tall fescue (E-; n = 3) or infected tall fescue (E+; n = 6) seeds for a 30-d period. The diet offered was ad libitum bermudagrass (Cynodon dactylon) hay combined with a nutritional supplement of 1.61 kg (DM basis) of E+ or E- tall fescue seeds, and 1.61 kg (DM basis) of energy/protein supplement pellets for a 30-d period. Dietary E+ tall fescue seeds were included in a rate of 20 μg of ergovaline/kg BW/day. Liver tissue was individually obtained through biopsy at d 30. After preparation and processing of the liver samples for RNA sequencing, we detected that several metabolic pathways were activated (i.e., upregulated) by the consumption of E+ tall fescue. Among them, oxidative phosphorylation, ribosome biogenesis, protein processing in endoplasmic reticulum and apoptosis, suggesting an active mechanism to cope against impairment in normal liver function. Interestingly, hepatic protein synthesis might increase due to E+ consumption. In addition, there was upregulation of "thermogenesis" KEGG pathway, showing a possible increase in energy expenditure in liver tissue due to consumption of E+ diet. Therefore, results from our study expand the current knowledge related to liver metabolism of growing beef cattle under tall fescue toxicosis.