Protein levels in commercial diets for growing and finishing gilts

Abstract

The effects of crude protein levels in commercial diets were evaluated on growing and finishing gilts performance. There were forty-eight commercial gilts with 30kg (growing phase) and 60kg (finishing phase) average live weights from free disease farm. The experimental design was a randomized blocks with six replications and two animals per experimental unit. The protein levels were 19.5, 18.0, 16.5, and 15.0% in growing and 18.0, 16.5, 15.0 and 13.5% in finishing phases. During growing phase it was observed a quadratic effect of protein levels on final weight, weight gain, phase length and the optimal estimate level was 17% crude protein. The economic evaluation indicated the diet with 18% crude protein for growing phase. The quadratic responses to protein level at finishing phase indicate practically the same protein levels (15.2 to 15.3% crude protein) at age with 95kg, final weight and carcass yield percentage. The greater economic gain occurred with gilts receiving 15.0% crude protein level from 60 to 95kg. Segregate gilts from commercial production system presented better performance when received diets with 17% crude protein from 30 to 60kg and 15% crude protein from 60 to 95kg.