EFFECTS OF THE INTERACTION GENOTYPE X NUTRITIONAL SYSTEM ON LIVEWEIGHT AND CARCASS COMPONENT

Abstract

With the objective of evaluating the isolated effects of genotype and of nutritional system, as well as the effect of the interaction between genotype and nutrition on quantitative and qualitative aspects of the meat production, sixty Polwarth male lambs and 51 Corriedale male lamb, born at August and September, raised in three different nutritional systems (native pasture, improved pasture e confinement) and slaughtered with 122 days of age, were examined. The animals were weighed before slaughtering and, after slaughtering, the following traits were measured: cold carcass weights, shoulder, hindquarter, rib and neck weights and the weight of bone, muscle and fat of the shoulder and the hindquarter. The percentages were obtained by calculation. The experimental design was a totally randomized in a 3x2 factors (nutritional systems and genotypes). There was interaction genotype-nutrition (P <0.05) for bone of the hindquarter and of the shoulder and for the shoulder fat. Except for the weight and percentage of the bone of the shoulder, for all the other parameters of weight and of carcass studied there was not genotype effect. The nutrition influenced significantly (P <0.05) all the parameters. KEY WORDS: Interaction genotype-nutritional system, lambs, regional composition, tissue composition.