Effect of diet and genotype on carcass characteristics of feedlot hair sheep

Abstract

Itwas evaluated qualitative characteristics of confined hair sheep submitted to diets with two energy levels. Eighteen lambs from each genotype were used: Morada Nova, Santa Inez and Dorpper x Santa Inez crossbreds. The rations with the lowest and the highest energy level were made up with 2.5 and 2.94 Mcal EM/kg DM, respectively. It was evaluated conformation and finishing carcass, in addition to leg tissue composition. The score for conformation was significantly higher for animals kept in diet with the highest energy level and for Dorpper x Santa Inês crossbreds. Animals from Santa Inez and from Dorpper x Santa Inez breeds showed score for meat color close to red class, while Morada Nova genotype was close to slightly dark red. The muscle:bone ratio for Dorpper x Santa Inez crossbred and Morada Nova animals was higher than for Santa Inez animals. The muscle:fat ratio was higher in animals kept with the lowest energy concentration diet. The rib eye area of Dorpper x Santa Inez crossbred animals was similar to Morada Nova animals and higher than Santa Inez group. Carcass compactness index and subcutaneous fat thickness and maximum cover fat thickness on the surface of the 12th rib were higher for animals submitted to the diet with the highest energy level. Leg fat was the only tissue influenced by diet calory density, while bone tissue was affected by the genotypes, since Santa Inez breed showed the highest percentage in this tissue. The genotype and level of energy in the diet affect carcass conformation. Diets with higher energy density improve carcass compactness index and subcutaneous fat thickness.