This study used 48 mature, gestating beef cows to determine the effect of diet type on voluntary feed intake and gene expression in muscle tissue. Diets consisted of forage-only (FOR) and an energy-dense forage/concentrate mix (CONC). Two experimental periods were used with half of the cows consuming FOR during the first period and CONC during the second period (FC sequence). The other half of the cows consumed the CONC diet during the first period and FOR during the second period (CF sequence). RNA was extracted from muscle tissue in the six highest and six lowest intake cows within each diet type and sequence (total of 24) based on intake ranking after the end of the first period. The Spearman rank correlation was high for feed intake across diet types in the FC sequence and moderate in the CF sequence. However, there was no correlation for average daily gain regardless of sequence. Hundreds of differentially expressed genes were identified with functions relating mainly to metabolism and fat synthesis. While feed intake was moderately to highly correlated between the two diets, gene expression related to mechanisms involved in feed intake differed.

Read the full article in the Journal of Animal Science.