The experimentwas carried out to establish the lysine requirement of females swine, from 6to 16 kg live weight. Sixty crossbreed gilts with high genetic potential forlean 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, supplementedwith five levels of HCl-L- lysine, resulting in diets with 1.3; 1.4; 1.5; 1.6and 1.7% of total lysine. There was no effect of treatments on daily weightgain. There was quadratic effect of lysine levels on daily feed intake, dailylysine intake and feed/gain ratio, that increased to the estimated lysine levelof 1.56%. There was no effect of treatments on protein percentage and carcassprotein deposition rate, otherwise, fat percentage and carcass water and fatdeposition rate increased linearly. It was concluded that gilts from 6 to 16kg, with high genetic potential for lean gain, require 1.56% total lysine or1.38% digestible lysine to achieve best development and 1.70% total lysine or1.50% digestible lysine for the best carcass composition, corresponding, respectively,to an estimated feed intake of 8.46 and 10.06 g total lysine/day.
