色氨酸对黄颡鱼幼鱼生长性能和消化酶活性的影响
Effect of Tryptophan on Growth Performance and Digestive Enzyme Activity of Juvenile Yellow Catfish

本试验以黄颡鱼(Pelteobagrus fulvidraco)为研究对象，开展了周期为56 d的养殖试验，旨在研究饲料中不同色氨酸浓度对黄颡鱼幼鱼的生长性能和消化酶活性的影响。将300尾(1.77 ± 0.08 g)幼鱼随机分于15个养殖桶，共5个组，每组3个重复。在基础饲料中添加不同水平的色氨酸(0.44%、0.68%、0.85%、1.08%和1.32%)，制备5种等氮等脂(蛋白质水平为39%，脂肪水平为7%)的试验饲料。每天两次人工投喂，达到明显的饱食状态。试验结果表明：1) 随着饲料中色氨酸水平的升高，黄颡鱼幼鱼的终末体重和特定生长率，呈现先升后降的趋势，在0.85%组达到最大值。0.85%组的终末体重显著高于其他各处理组(P < 0.05)。2) 在0.85%组，黄颡鱼幼鱼的肝脏淀粉酶活性达到最高，胃脂肪酶、胃蛋白酶和肝脏脂肪酶活性1.08%组达到最高。结论：饲料中添加色氨酸水平为0.85%~1.08%之间，可提高黄颡鱼幼鱼的终末体重和特定生长率，增强消化吸收能力。
In this study, a 56-day culture experiment was carried out on yellow catfish (Pelteobagrus fulvidraco) to study the effects of different tryptophan concentrations in feed on the growth performance and digestive enzyme activity of juvenile yellow catfish. A total of 300 juveniles (1.77 ± 0.08 g) were randomly divided into 15 tanks in 5 groups with 3 replicates in each group. Different levels of tryptophan (0.44%, 0.68%, 0.85%, 1.08% and 1.32%) were added to the base feed to prepare five isonitrogen isolipids (protein level 39%, fat level 7%). Artificial feeding twice a day to achieve a state of apparent satiety. The results showed that: 1) With the increase of tryptophan level in the diet, the terminal body weight and specific growth rate of juvenile yellow catfish showed a trend of first increasing and then decreasing, reaching the maximum value in the 0.85% group. The terminal body weight of the 0.85% group was significantly higher than that of the other treatment groups (P < 0.05). 2) In the 0.85% group, the liver amylase activity of juvenile yellow catfish reached the highest, and the activities of gastric lipase, pepsin and liver lipase reached the highest in the 1.08% group. Conclusion: The level of tryptophan added to the feed is between 0.85% and 1.08%, which can increase the terminal body weight and specific growth rate of juvenile yellow catfish, and enhance the digestion and absorption capacity.