Eighty barrows, commercial hybrids of high genetic potential for lean meat deposition in the carcass, were used to evaluate the effect digestible tryptophan levels for pigs from 97.0 ± 2.81 to 125.0 ± 3.31 kg. A randomized experimental block design was used, with five treatments (0.124; 0.133; 0.142, 0.151 and 0.160% of digestible tryptophan, corresponding to digestible lysine ratio of 16.5, 17.7, 18.9, 20.1 and 21.3%), each one with eight replications of two animals. Diets and water were supplied ad libitum. Weight gain quadraticaly improved up to the estimated level of 0.144% of digestible tryptophan. Digestible tryptophan levels did not influence feed intake, feed:gain ratio, backfat thickness and lean meat yield. However, treatments linearly affected digestible tryptophan intake. Digestible tryptophan level of 0.144%, corresponding to a digestible lysine ratio of 19.2% provides the best weight gain in barrows with high genetic potential for lean meat deposition in the carcass in the phase from 97.0 to 125.0 kg.
amino acids; carcass; finishing; performance
