Ninety and sixcrossbred gilts with high genetic potential for lean meat gain, with averageinitial 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 effectsof lysine levels on the carcass traits of gilts in the finishing phase. A randomizedblock design, with four treatments, 12 replicates and two animals per box, usedas experimental unit, was used. The treatments were constituted of nutritionalplans (established by sequential lysine levels) for two different weights, from65 to 95 kg and from 95 to 105 kg. The isoenergy diets and the lysine levelswere obtained by changes on dietary corn and soybean proportion. There was noeffect of treatments on daily weight gain and daily feed intake. There was effectof nutrition plans on feed:gain ratio, and the nutrition plan 3 showed an increaseof 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. Inthe 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 betweenthe last and last but one lumbar vertebra, backfat thickness at 6.5 cm fromthe midline carcass, carcass yield, lean meat yield, fat yield and ham yield.By economic analysis, the nutrition plan 2 showed the best economic return onfeed intake. It can be concluded that the nutrition plan 3 (1.00-0.90% lysine)showed the best results of performance and carcass characteristics.
