The experiment was carried out to establish the lysine requirement of females swine, from 6 to 16 kg live weight. Sixty crossbreed gilts with high genetic potential for lean gain and average initial and final weight of 6.0 ± 0.21 kg and 16.0 ± 0.32 kg, respectively, were assigned to a randomized blocks design, with five treatments, four replications and three animals per experimental unit. The treatments corresponded to a basal diet with 21.60% crude protein, supplemented with five levels of HCl-L- lysine, resulting in diets with 1.3; 1.4; 1.5; 1.6 and 1.7% of total lysine. There was no effect of treatments on daily weight gain. There was quadratic effect of lysine levels on daily feed intake, daily lysine intake and feed/gain ratio, that increased to the estimated lysine level of 1.56%. There was no effect of treatments on protein percentage and carcass protein deposition rate, otherwise, fat percentage and carcass water and fat deposition rate increased linearly. It was concluded that gilts from 6 to 16 kg, with high genetic potential for lean gain, require 1.56% total lysine or 1.38% digestible lysine to achieve best development and 1.70% total lysine or 1.50% digestible lysine for the best carcass composition, corresponding, respectively, to an estimated feed intake of 8.46 and 10.06 g total lysine/day.
genotype; gilts; initial phase; lysine; requirement
