The experiment was conducted with 300 gilts with initial weight of 25.00±0.54kg, from 60 to 100 days of age, to evaluate the effects of digestible lysine percentages on performance and carcass traits of the animals. The gilts were allotted in a randomized block design, with five treatments (percentages of digestible lysine), five replicates, and twelve animals per experimental unit. The treatments applied were 0.65; 0.75; 0.85; 0.95 and 1.05% of digestible lysine. No effects of treatments on the daily feed intake of the gilts were observed. A linear increase on digestible lysine intake as a result of increasing the concentration of digestible lysine in the diet was verified. The increase in dietary digestible lysine concentration resulted in a linear increase of daily weight gain. The increase of digestible lysine concentrations in the diet resulted in a linear improvement of feed conversion and in a linear increase in the amount of lean meat in the carcass. There was no effect of digestible lysine concentration on gilts' carcass traits. The amount of lean meat in the carcass of pigs increased linearly with the increase of the percentage of digestible lysine in the diets. The percentage of digestible lysine influenced the back fat thickness of the gilts which decreased quadratically up to 0.87% digestible lysine maximum response. The inclusion of 1.05% digestible lysine in the diet, corresponding to a daily intake of 18.5 g digestible lysine provides the greatest performance results and amount of lean meat in the carcass of gilts from 60 to 100 days of age.
amino acid digestibility; carcass; lean; backfat thickness; growth phase; swine
