Biological and economic performance of feedlot lambs feeding on diets with different energy densities

Abstract

The objective of this study was to evaluate performance, carcass dressing and gross profit margin of lambs of different genotypes finished in feedlot with diets containing two levels of energy (2.40 Mcal/kg dry matter - DM or 2.90 Mcal/kg DM). Fifty-four non-castrated lambs of the following genotypes were used: Santa Inês, F1 Dorper × Santa Inês and F1 Santa Inês × undefined breed at approximately 150 d of age averaging 22.6 kg of live body weight. Lambs subjected to the diet containing 2.90 Mcal/kg DM stayed in feedlot for a shorter period of time. Moreover, they showed lower intake of dry matter and water in addition to greater daily weight gain and corporal score. There was interaction of feed conversion, carcass dressing yield and gross profit margin. The Dorper × Santa Inês lambs showed similar feed conversion in the two diets. However, Santa Inês lambs and Santa Inês × undefined breed lambs showed better feed conversion with the diet containing 2.90 Mcal/kg DM. The carcass dressings of the Santa Inês × undefined breed lambs were similar for both diets. Furthermore, the carcass dressing values were higher for the Santa Inês and Dorper × Santa Inês which received the diet with higher energy density. The gross profit margin is higher for Dorper × Santa Inês lambs in relation to genotype Santa Inês × undefined breed lambs when subjected to the diet with 2.40 Mcal/kg DM.

Keywords

• average daily gain
• Dorper
• dry matter intake
• feed conversion
• Santa Inês
• sheep