Zootecnia

Iowa State University Animal Industry Report 2004

Beef

Effect of Feed Intake on Plasma Ghrelin Concentration in Beef Cattle
A.S. Leaflet R1881
Aimee Wertz, Assistant Professor of Animal and Range Sciences, South Dakota State University, Travis Knight, Assistant Scientist III, Amanda Kreuder, Undergraduate Student of Dairy Science, Michelle Bohan, Graduate Student of Biochemistry, Don Beitz, Distinguished Professor of Animal Science and Biochemistry, and Allen Trenkle, Distinguished Professor of Animal Science Summary and Implications 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. Introduction Ghrelin is a hormone secreted from the digestive tract of many animals. For sheep, plasma ghrelin concentrations are associated with fluctuation in feed intake, peaking just before feeding time and reaching a nadir 2 to 4 h post feeding. For Japanese Black cattle, plasma ghrelin concentrations at 4 h post-feeding were intermediate to plasma ghrelin concentrations pre-feeding and 1h postfeeding. These data suggest that ghrelin acts as a signal of hunger and therefore may stimulate feed intake. Feed intake is important to beef cattle because it impacts efficiency of