Levels Of Energy In The Feeding Of Feedlot Lambs And The Regional And Tissue Carcass Composition

The objective of this study was to evaluate quantitative characteristics and carcass regional and tissue composition of lambs submitted to different energy levels (2.23, 2.54 and 2.85 Mcal ME/kg DM) in the diet and slaughtered with 32.2 +/- 3.8 kg body weight and at average age of 145.6 +/- 20.1 days. The diets were isoproteic (16.70% CP) and fed to 18 no castrated crossbred Texel male lambs. The lambs were confined in individual pens, in a slotted floor sheep barn. The half left-side carcasses were splitted into the shoulder, leg, loin, ribs and neck. The tissue composition (bone, muscle and fat) was also evaluated in each cut. Except for loin percentage, energy levels presented a quadratic effect on the other cuts. The percentages of shoulder and neck were greatest at the middle energy level and the percentages of leg and ribs were lowest at this level. The energy level of the diet influenced the distribution of the cuts in the carcass, but it did not affect the average tissue composition of the carcass. The shoulder was the cut with the greatest tissue variation. The different cuts can be used to predict the average tissue composition of the carcass but the shoulder is the least indicated.