INFLUENCE OF ENERGY DENSITY AND METABOLIZABLE ENERGY INTAKE ON VISCERAL ORGAN GROWTH IN SHEEP.

Authors: McLeod, Kyle; Baldwin, Ransom - Randy

Submitted to: Energy Metabolism of Farm Animals Symposium Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: An experiment was conducted to determine the effects of forage versus concentrate diets and metabolizable energy intake on gut and liver weight and energy use by cells of the gut. Twenty- eight crossbred lambs were fed diets containing either 75% forage or 75% concentrate at two different intakes. Lambs were sacrificed and the gut and liver were removed, weighed, and cells were isolated from the rumen and small intestine. Absolute organ weight and organ weight as a percent of empty body weight increased in response to increasing intake. Conversely, increasing the level of concentrate in the diet decreased organ weight and organ weight as a percent of empty body weight. Energy use by isolated cells from the rumen and small intestine did not change with diet changes. Thus, greater energy use by the gut and liver associated with increasing intake, as well as increases in the efficiency of gain observed in animals fed predominantly concentrate diets, relative to forage based diets, is due to changes in gut and liver weight.

Technical Abstract: An experiment was conducted to determine the effects of dietary energy density and metabolizable energy (ME) intake on visceral organ mass and mass specific oxygen consumption. Twenty-eight crossbred lambs (20.1ñ.3 kg BW) were fed for an average of 52 d diets containing either 75% forage or 75% concentrate at either 0.416 or 0.757 MJ MEù(kg BW.75)-1ùd-1. Lambs were slaughtered and visceral organs removed, weighed, sectioned, and epithelial cells isolated from the rumen and small intestine. Absolute visceral organ mass (VOM) and organ mass as a percent of empty body weight (VOME) increased in response to increasing ME intake. Conversely, increasing dietary energy density decreased VOM and VOME. Oxygen consumption by isolated epithelial cells from the rumen and small intestine was unaffected by either ME intake or dietary energy density. Thus, greater energy use by visceral tissues associated with increasing ME intake, as well as increases in the efficiency of gain observed in animals fed predominantly concentrate diets, relative to forage based diets, may be attributable to changes in visceral organ mass.