Ninety and six crossbred gilts with high genetic potential for lean meat gain, with average initial weight of 65.93 ± 2.78 kg and final weight of 105.50 ± 2.18 kg, were used to evaluate the effect of nutrition plans, based on the effects of lysine levels on the carcass traits of gilts in the finishing phase. A randomized block design, with four treatments, 12 replicates and two animals per box, used as experimental unit, was used. The treatments were constituted of nutritional plans (established by sequential lysine levels) for two different weights, from 65 to 95 kg and from 95 to 105 kg. The isoenergy diets and the lysine levels were obtained by changes on dietary corn and soybean proportion. There was no effect of treatments on daily weight gain and daily feed intake. There was effect of nutrition plans on feed:gain ratio, and the nutrition plan 3 showed an increase of 7.86% in relation to nutrition plan 1 and did not differ from the others. Lysine intake increased as the lysine levels of nutrition plans increased. In the nutrition plan 4, lysine intake was 25.43% higher than the other plans. There was no significant difference of nutrition plans on muscle growth ratio, muscle feed:gain ratio, carcass length, backfat thickness in the region 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. By economic analysis, the nutrition plan 2 showed the best economic return on feed intake. It can be concluded that the nutrition plan 3 (1.00-0.90% lysine) showed the best results of performance and carcass characteristics.
lysine; genotype; performance; growing phase
