Two assays run simultaneously to evaluate the levels of metabolizable energy (ME) and digestible lysine (LYS) for growing pigs from specific strain on sanitary isolation conditions. Seventy-two castrated males averaging 23.34 ± 1.62 kg and 72 gilts averaging 21.56 ± 2.86 kg were assigned to a randomized blocks design with a 2 x 3 factorial arrangement and six replications of two animals per experimental unit. The treatments consisted of the combination of energy (3,270 and 3,500 kcal of ME/kg) and lysine levels (0.83, 1.03, and 1.23% digestible). No interaction of energy x protein levels was observed, although effects of the main factors on performance variables were detected. Castrated males showed linear increase of weight gain and quadractic of feed intake and feed:gain ratio, as the dietary lysine levels increased. Linear decrease on feed: gain ratio in response to the dietary lysine concentration was noticed for gilts. Castrated males and gilts in the growing phase on sanitary isolation conditions and healthy conditions showed positive response to the dietary digestible lysine increase. Effects of dietary lysine levels on performance of castrated males did not depend on the energy levels. Gilts fed diets with 3,500 kcal of ME/kg showed the best feed:gain ratio, that confirmed the greatest results of nutrient efficiency utilization in relation to the castrated males.
feed; weight gain; barrows; gilts
