Fifty gilts crossbreed (Hampshire, Belgium Landrace, Pietran), with initial average weight of 60.23±0.49 kg and high genetic potential for lean meat deposition, were used to evaluate different lysine levels. A randomized blocks design, with five treatments, five replicates and two animals per experimental unit, was used. The treatments corresponded to a basal diet with 15.8% crude protein, supplemented with five levels of HCl-L-Lisine, resulting in diets with 0.75, 0.85, 0.95, 1.05, and 1.15% of lysine. There was no effect of treatments on daily weight gain and daily feed intake, however daily lysine intake linearly increased was the dietary lysine level increased. There was quadract effect of lysine levels on feed:gain ratio and on serum urea concentration, that increased up to the lysine level of 1.00% or 0.302%/Mcal of DE, corresponding to a estimate lysine intake of 23.9 g/day. There was no effect of treatments on protein and water percent, and protein deposition in carcass, however, the percentage of fat and fat deposition rate linearly decreased. The gilts with high genetic potential for lean meat deposition, from 60 to 95 kg, had requirement of 1.00% (.302%/Mcal of DE) or .90% ( .272%/Mcal of DE) of true digestible lysine, corresponding to total and digestible lysine intake of 23.90 and 21.50 g/day, respectively, for maximum performance.
carcass; genotype; requirement; finishing phase; urea
