Two hundred and sixteen crossbred gilts with high genetic potential for lean meat gain, with average initial weight of 66.3 ± 4.24 kg and final weight of 95.5 ± 2.05 kg, were used to evaluate the effect of lysine levels on animals performance in the finishing phase. A randomized block design was used with four treatments, 27 replicates and two animals per experimental unit. Treatments were constituted of isoenergy diets, with different levels of total lysine (0.80, 0.90, 1.00, and 1.10%), obtained by changes on corn and soybean meal proportion. There was no treatment effect on daily weight gain, muscle growth rate and muscle feed:gain ratio. There was a quadratic effect of dietary lysine on feed intake, which decreased up to the level of 0.95% lysine, and on feed:gain ratio, which increased up to the level of 0.97% lysine. There was a linear effect of lysine levels on protein and fat deposition rate, that respectively, increased and reduced with dietary lysine levels. There was no effect of treatments on carcass length, backfat thickness measured between the last and last but one lumbar vertebra, backfat thickness at 6.5 cm from the midline carcass, carcass yield, lean meat yield, fat yield and ham yield. It was concluded that gilts with high genetic potential for lean meat gain require 0.97% of total lysine, that correspond to a daily intake of 24.24 g of lysine for best feed:gain ratio. Data show that to the highest protein deposition rate the requirement is above of 1.1% of total lysine.
finishing phase; genotype; lysine; performance
