Lysine levels for gilts with high genetic potential for lean gain from 15 to 30 kg

Fifty hybrid gilts, with high genetic potential for lean gain and initial and final weight of 15.39 +/- 0.59 and 30.93 +/- 1.72 kg, respectively, were used to evaluate diet with different levels of lysine. An experimental design of randomized blocks, with five treatments, five replicates and two animals per experimental unit, was used. The treatments corresponded to a basal diet with 19% crude protein, supplemented with five levels of HCl-L-Lisine, that resulted in diets with 0.95, 1.05, 1.15, 1.25 and 1.35% of lysine. The daily weight gain and daily lysine intake linearly increased with the dietary lysine level. There was quadratic effect of lysine levels on daily feed intake and feed/gain ratio, that increased to the lysine level of 1.26% (0.365%/Mcal of DE) or 1.13% (0.328%/Mcal of DE) of true digestible lysine, corresponding to the total and digestible lysine estimated intake of 14.62 and 13.12 g/day, respectively. There was no effect of treatments on protein and water percentage in carcass and on blood serum urea levels. The treatments influenced quadraticly the fat percentage and fat deposition rate in carcass, that decreased until 1.25 and 1.18% lysine level, respectively. The protein deposition linearly increased with the dietary lysine level. It was concluded that gilts from 15 to 30 kg require 1.26% of total lysine or 1.13% of digestible lysine, corresponding to a total and digestible lysine estimated intake of 14.6 and 13.1 g/day, respectively.