Gene expression changes in muscle and liver tissue of growing beef calves with bovine respiratory disease

Abstract

Scope and Method of Study:

Bovine respiratory disease is the most costly ailment in beef cattle. It leads to decreased carcass quality and profitability. It has been shown to decrease muscle and fat accretion. Research in other species has identified several gene targets in muscle and liver whose expressions are changed in response to inflammation, but there are few studies that address these molecular mechanisms in cattle. The objectives of our studies were to collect muscle and liver biopsy samples from beef cattle with bovine respiratory disease under experimental and field conditions and identify gene targets to understand the deleterious effects of morbidity on carcass quality and metabolism.

Findings and Conclusions:

We found that bovine respiratory disease modified gene expression in muscle tissue to indicate that atrophy was occurring. Several of the genes identified were involved in the Akt/protein kinase B signaling pathway and indicated a resistance to growth stimulation and pro-apoptosis. Expression of genes encoding for adiponectin receptor 1 (ADIPOR1), atrogin-1 (FBXO32), BCL2-associated agonist of cell death protein (BAD), glutamine synthetase (GLUL), and thioesterase superfamily member 4 (THEM4) were modified in muscle tissues in response to bovine respiratory disease conditions. In the liver, we found fatty acid metabolism and inflammation to be most affected. Expression of genes encoding for acetyl-CoA carboxylase (ACACA), beta-site APP-cleaving enzyme 1 (BACE1), fatty acid desaturase 2 (FADS2), fatty acid synthase (FASN), and S100 calcium binding protein A8 (S100A8) were affected by bovine respiratory disease. The molecular targets identified in the muscle and liver help to explain the loss of muscle and fat that is often associated with this disease and future research is need to address way to manipulate their expression in ways to mitigate these losses.