The objective of this study was to evaluate the effect of digestible threonine levels on performance and carcass composition of barrows of high genetic potential for meat deposition. Eighty barrows with initial weight of 95.87 ± 1.26 kg were distributed in a randomized block design, with five treatments (0.470; 0.497; 0.528; 0.557; 0.587%, corresponding to digestible threonine:digestible lysine ratio of 58.0; 61.0; 65.0; 69.0 and 73.0%, respectively) with eight replications and two animals in each experimental unit. The experimental feeds and water were supplied ad libitum until the end of the experimental period, when the animals reached 125.26 ± 2.59 kg. The digestible threonine levels in the diets did not influence daily feed intake and weight gain, but had a quadratic effect on feed conversion, which improved up to the estimated level of 0.526% threonine in the diet. The daily digestible threonine intake increased linearly according to the levels of this amino acid in the diet. The digestible threonine levels did not influence carcass weight, lean meat gain, back fat thickness at P2 and daily lean meat deposition. The 0.526% digestible threonine level, corresponding to a ratio of 65% digestible lysine and 18.49 g/day digestible threonine intake, lead to the best feed conversion results for high genetic potential barrows, in the phase from 95 to 125 kg.
aminoacids; carcass; genotype; late finishing; nutrition; performance
