Comparative analysis of gene expression profiles in ruminal tissue from Holstein dairy cows fed high or low concentrate diets.

Cattle are often fed high concentrate (HC) diets to increase productivity, although HC diets cause changes in ruminal environment such as pH reduction. Despite those well-documented changes in cattle fed HC diets, there is currently a paucity of data describing the molecular events regulating the ruminal environment. Our objective was to gain an understanding of which genes are differentially expressed in ruminal tissue from Holstein cows fed a HC comparing to low concentrate (LC) diet using microarray analysis using a bovine 24 k microarray. A total of 5,200 differentially expressed genes (DEG) were detected for cows fed HC relative to LC. The DEG were firstly annotated with gene ontology (GO) and Kyoto encyclopedia of Genes and Genomes (KEGG), indicating that the DEG were associated with catalytic activity and MAPK pathway, respectively. Further characterization using GeneCodis identified patterns of interrelated annotations for the DEG to elucidate the relationships among annotation groups revealed that a cAMP-dependent protein kinase A catalytic subunit beta (PRKACB), may be associated with ruminal tissue maintenance. The results contributed to understanding of the regulatory mechanisms at the mRNA level for Holstein cows fed at different concentrate ratio diets.