Author : Somchai Suwanpradit

Summary : Three experiments were conducted with the male broiler chicks to determine the influence of dietary metabolizable energy (ME), crude protein (CP), and copper (Cu) levels on the total sulphur amino acid (TSAA) requirement of broilers both during the starter (0-3 wk) and the grower periods (4-6 wk) reared in the tropics. In all the experiments the parameters used to evaluate the TSAA requirements are body weight gain, feed: gain ratio and carcass composition. In the first experiment, two factorial arrangements of three ME levels (3000, 3200, and 3400 kcal/kg) x four level of TSAA (0.73, 0.83, 0.93, and 1.03 percent) and the same three ME levels (3000, 3200 and 3400 kcal/kg) x four levels of TSAA (0.65, 0.72, 0.79 and 0.86 percent) were used for the starter and the grower periods, respectively. The results showed significant differences (P<.05) in body weight gain and feed: gain ratio of the broilers with increasing dietary TSAA levels both in starter and grower periods. There were no significant interaction (P<.05) between dietary ME and TSAA levels for the performance, with the exception for feed intake of starter broilers. It indicated that for the starter period, a TSAA of 0.93 percent produced the best performance regardless of energy levels while for the grower period, the requirement of TSAA at both 0.79 and 0.86 percent were suggested. The results further showed that dietary energy levels had no effect on the TSAA requirement of the broilers. In the second experiment, two factorial arrangements of four CP levels (16, 18, 20, and 23 percent) x three levels of TSAA (0.83, 0.93, and 1.03 percent) and three CP levels (16, 18, and 20 percent) x three levels of TSAA (0.72, 0.79 and 0.86 percent) were examined for the starter and grower periods, respectively. The results showed significant influence (P<.05) of dietary CP levels on body weight gain and feed: gain ratio in both starter and grower periods. No significant interaction between dietary CP and TSAA levels.