The Effects of Limit Feeding a High Concentrate Diet on Feedlot Performance and Body Composition of Growing Lambs

A comparative slaughter study was conducted with lambs to determine the effects of limit feeding a high concentrate diet to achieve three different rates of gain on feedlot performance and body composition. Urea dilution space (UDS) determinations were made on the day prior to slaughter, and a 6-rib (RACK) section was removed from the cold carcass to evaluate their potential as estimators of body composition. Average daily gains in growing sheep can be regulated to a predetermined level by restricting the intake of a high concentrate diet. Feed efficiency was improved by both increasing level of feed intake (P \u3c .01) and decreasing days on feed (P \u3c .05). Body composition was not affected by intake level at lighter BW (35 or 45 kg), however restricting intake below 80% of ad libitum increased carcass (P \u3c .05), visceral (P \u3c .05) and empty body (P \u3c .05) fat at heavier BW (55 kg). A quadratic function was useful in describing body components and composition as early or late maturing in relation to empty body weight (EBW). Urea dilution space and RACK composition were correlated to empty body and carcass composition. Estimations were improved by the use of multiple regression equations involving the addition of some measure of body weight. Various procedural factors were shown to affect the correlation between UDS and empty body water. Suggestions are made pertaining to the modification of the UDS procedure for use as a predictor of body composition in growing lambs