A trial was conduced to evaluate decreasing levelsof CP with amino acid supplementation on performance of gilts on thermoneutralenvironment. Thirty-five crossbreed gilts (Landrace x Large White) averaginginitial weight of 60.5 kg were allotted to a complete randomized design withfive treatments (17.3, 16, 14.7, 13.4 and 12.1% of CP) of seven replications(one animal per experimental unit). The experimental diets were fed ad libitumuntil the end of the experiment when the animals reached the average weightof 100.6 kg. No effect of decreasing dietary levels of crude protein on performance(feed intake, weight gain and feed gain ratio) was observed. Decreasing dietaryCP levels did not affect the carcass characteristics (carcass length, loin eyearea, backfat thickness and carcass, lean growth, fat and ham yield), but affectedthe relative and absolute weights of liver and the greatest value was observedin animals fed diet with 16.0% of CP. Decreasing dietary CP levels from 17.3to 12.1% for gilts from 60 to 100 kg on thermoneutral environment did not affectperformance, since diets are supplemented with limiting essential amino acids.
