Exigência de lisina digestível de suínos machos castrados em terminaçãoalimentados ou não com ractopamina

Abstract

An experiment was conducted in order to determine the digestible lysine requirement (LD) for barrows in the finishing phase with initial weight of 70.08 ± 3.78 kg and final weight of 97 ± 7.3 kg, fed or not with ractopamine (RAC). We used 180 animals distributed in randomized blocks, with 5 x 3 factorial arrangement, with five levels of LD (0.5, 0.65, 0.8, 0.95, 1.1%) and three levels of ractopamine (0, 5 and 10 ppm), withsix replicates and two animals per experimental unit. The diets fed for 27 days and were isocaloric and isonitrogenous lysine levels were obtained by adding L-Lys and when necessary was supplemented with other amino acids. Interaction was observed between LD and RAC final weight, average daily gain and gain: feed (P <0.05), whereas for feed intake and consumption of LD no interaction (P> 0.1). Carcass characteristics in vivoonly for deposition rate of lean meat daily was no interaction between LD and RAC, with a linear effect (P <0.1). There was no interaction between the levels of LD and RAC for Urea and was quadratic effect (P> 0.1) levels of LD with a minimum 0.86% in LD. Considering the values obtained, it is clear that for the best performance of pigs for this animal category requiring LD is 0.8, 0.96 and 1.1%, which corresponds to 23.51, 28.04 and 32.57 g / day when the animals are fed diets with and without 5 and 10 ppm of RAC, respectively.