Digestible lysine requirements for barrows with high genetic potential for lean

Abstract

Fifty barrows with high genetic potential for lean gain in the carcass and initial body weight of 29.9  1.57 kg were used to evaluate the effect of feeding different lysine levels on performance and carcass protein deposition rate. A randomized block experimental design, with five treatments, five replicates and two animals per replicate was used. Treatments corresponded to five digestible lysine levels (0.70, 0.80, 0.90, 1.00, and 1.10%) with variable proportions of corn and soybean meal. Animals were kept in the experiment until they reached the final body weight of 60.5  1.74 kg. Linear (P<0.01) increasing effect was observed for the daily weight gain (DWG), but the linear response plateau model was that better fitted to the DWG data, that stabilized in a plateau starting from the level of 1.02% of digestible lysine. Significant linear effects were observed for the feed conversion, daily lysine intake and daily protein deposition by increasing dietary lysine levels but no diet effect was found for the daily feed intake. Digestible lysine level of 1.02%, corresponding to a digestible lysine intake of 19.50g/day, provides the best results of performance and protein deposition in barrows with high genetic potential for lean meat deposition in the carcass in the phase from 30 to 60 kg.