The effect of varying levels of tryptophan on growth performance and carcass characteristics of growing and finishing broilers

The purpose of this experiment was to study the effect of varying levels of tryptophan on the performance and carcass character of broiler. Trial 1: Ninety-six, five-week-old male Hubbard chickens, average weight 1.97 kg, were used in the trial. All birds were allocated into 3 treatments of 32 birds each. Each bird was kept in an individual cage. The trial period was 3 weeks. Treatment 1: Tryptophan content 0.198%. Treatment 2: Tryptophan content 0.228%. Treatment 3: Tryptophan content 0.258%. Trial 2: Ninety-six, three-week-old male Hubbard chickens, average weight 1.23 kg, were randomly distributed into the following two treatments. Each treatment had 48 birds. Treatment 1: Tryptophan content 0.167%. Treatment 2: Tryptophan content 0.198%. Trial 3: Ninety-six, two-week-old Hubbard chickens, average body weight 0.72 kg, were used in this experiment. There were three treatments as follows. Treatment 1. Tryptophan content 0.136%. Treatment 2. Tryptophan content 0.167%. Treatment 3. Tryptophan content 0.198%. The result of Trial 1 showed that the feed intake, performance, and carcass characteristics were not influenced by tryptophan content in the diet which between 0.198% and 0.258% (p > 0.05). There was no significant difference (p > 0.05) in feed intake in either treatment in Trial 2. However, weight gain, feed conversion. efficiency, and most carcass characteristics in the 0.198% treatment were significantly better (p < 0.05) than in the 0.167% treatment. There was a trend that feed intake increased with increasing level of tryptophan, but there was no significant difference in Trial 3. The weight gain and feed conversion efficiency were significantly reduced for the broiler in the 0.136% treatment. This series of experiment showed that broilers need about 0.198% of tryptophan.