Effect of Dietary Energy Intake on Carcass Composition and Palatability of Different Weight Carcasses from Ewe and Ram Lambs

Abstract

Sixty-eight ram and 70 ewe lambs were fed diets containing three metabolizable energy densities (2.18, 2.39 and 2.80 Mcal/kg) and were serially slaughtered after ram lambs reached approximate live-animal weights of 17, 32, 42, 54 and 66 kilograms. Feed consumption and carcass data were taken. Rib roasts were evaluated for palatability characteristics, tenderness, juiciness, flavor, aroma and overall satisfaction. One side of each carcass was ground, and the percentages of protein, moisture, fat and ash were chemically determined. Though quality grades differed between sexes, these differences were not reflected in taste panel palatability scores except for aroma. Heated fat aroma scores of ram lamb carcasses were inferior to those of ewes. Reduced percentages of carcass protein (P<.05) and ash (P<.01) were associated with the higher energy density diets. Percentages of kidney and pelvic fat increased (P<.01) with dietary energy; however, no differences in fat thickness or longissimus muscle area were observed. Carcasses of lambs receiving the high energy diets were judged to be physiologically older than those receiving the medium or low energy diets at constant hot carcass weights. These rankings were reversed when time on feed was held constant. The taste panel judged meat from the low energy diet to be inferior in tenderness (P<.05) to meat from the high energy diet. With genetic resources used in this study, ram lamb carcasses weighing up to 33 kg were produced with acceptable carcass lean to fat ratios. Lambs fed high energy rations had slightly greater amounts of kidney and pelvic fat than lambs fed low energy diets. The aroma of heated fat from ram lamb carcasses, however, was a negative factor in the production of meat from ram lambs. Copyright © 1978. American Society of Animal Science . Copyright 1978 by American Society of Animal Science.