Effect of Feed Intake on Plasma Ghrelin Concentration in Beef Cattle

Two experiments were conducted to determine if ghrelin mRNA existed in ruminant digestive tract tissues and to establish the fluctuation in plasma ghrelin concentrations for fed and fasting steers. Tissues collected from the ruminant digestive tract indicate detectable ghrelin mRNA in the upper, middle, and lower portion of the abomasum and in the small intestine but no detectable ghrelin mRNA in the reticulum, omasum, and rumen. Plasma ghrelin concentrations are elevated by a fasting period that is as short as 22 h. Additionally, plasma ghrelin remain elevated throughout a 48-h fasting period. The magnitude of difference in plasma ghrelin concentration between the fed and fasting states warrants further investigation as to the impact that this fluctuation in hormone concentration has on feed intake, composition of gain, and energy expenditure in cattle