R. Bras. Zootec.01/Dec/2006;35(6):2309-13.
Dietary digestible tryptophan levels for barrows with of high genetic potential for lean deposition in the carcass from 60 to 95 kg
DOI: 10.1590/S1516-35982006000800016
Seventy commercial hybrid barrows with high genetic potential for lean deposition in the carcass averaging initial and final body weight of 60.0 ± 1.34 kg and 95.0 ± 0.97 kg, respectively, were used to evaluate the effects of dietary digestible tryptophan levels on performance and carcass characteristics. The experiment was analyzed as a randomized experimental block design with five treatments (0.128, 0.136, 0.144, 0.152, and 0.160%) of digestible tryptophan, that is correspondent to the digestible tryptophan:lysine ratios of 16, 17, 18, 19 and 20%, with seven replicates and two animals per experimental unit. No treatment effect on feed intake, weight gain, feed:gain ratio, backfat thickness and lean yield was observed. The digestible tryptophan intake linearly increased as dietary digestible tryptophan levels increased. The 0.128% digestible tryptophan level, that is correspondent to a 16% digestible tryptophan:lysine ratio, met the requirements of barrows with high genetic potential for lean deposition in the carcass from 60 to 95 kg.
Keywords: amino acids; carcass characteristics; finishing; performance