College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, 611130, China.
Animal Nutrition Institute, Sichuan Agricultural University, Chengdu, 611130, China.
Fish Physiol Biochem. 2019 Oct;45(5):1627-1647. doi: 10.1007/s10695-019-00651-4. Epub 2019 Jun 3.
The 56-day feeding trial was carried out to investigate the effects of dietary tryptophan (Trp) on growth performance, digestive and absorptive enzyme activities, intestinal antioxidant capacity, and appetite and GH-IGF axis-related genes expression of hybrid catfish (Pelteobagrus vachelli♀ × Leiocassis longirostris♂). A total of 864 hybrid catfish (21.82 ± 0.14 g) were fed six different experimental diets containing graded levels of Trp at 2.6, 3.1, 3.7, 4.2, 4.7, and 5.6 g kg diet. The results indicated that dietary Trp increased (P < 0.05) (1) final body weight, percent weight gain, specific growth rate, feed intake, feed efficiency, and protein efficiency ratio; (2) fish body protein, lipid and ash contents, protein, and ash production values; (3) stomach weight, stomach somatic index, liver weight, intestinal weight, length and somatic index, and relative gut length; and (4) activities of pepsin in the stomach; trypsin, chymotrypsin, lipase, and amylase in the pancreas and intestine; and γ-glutamyl transpeptidase, Na, K-ATPase, and alkaline phosphatase in the intestine. Dietary Trp decreased malondialdehyde content, increased antioxidant enzyme activities and glutathione content, but downregulated Keap1 mRNA expression, and upregulated the expression of NPY, ghrelin, GH, GHR, IGF1, IGF2, IGF1R, PIK3Ca, AKT1, TOR, 4EBP1, and S6K1 genes. These results indicated that Trp improved hybrid catfish growth performance, digestive and absorptive ability, antioxidant status, and appetite and GH-IGF axis-related gene expression. Based on the quadratic regression analysis of PWG, SGR, and FI, the dietary Trp requirement of hybrid catfish (21.82-39.64 g) was recommended between 3.96 and 4.08 g kg diet (9.4-9.7 g kg of dietary protein).
这项为期 56 天的喂养试验旨在研究日粮色氨酸（Trp）对杂交鲇（Pelteobagrus vachelli♀×Leiocassis longirostris♂）生长性能、消化吸收酶活性、肠道抗氧化能力、食欲和 GH-IGF 轴相关基因表达的影响。共使用 864 尾体重为（21.82±0.14）g 的杂交鲇，投喂 6 种等氮等能但 Trp 梯度水平（2.6、3.1、3.7、4.2、4.7 和 5.6 g/kg 饲粮）的试验饲料。结果表明，饲粮 Trp 水平升高（P＜0.05）：（1）末重、增重率、特定生长率、摄食率、饲料效率和蛋白质效率比；（2）鱼体粗蛋白、粗脂肪和粗灰分含量、粗蛋白和粗灰分沉积量；（3）胃重、胃体指数、肝重、肠重、肠长和肠体指数、相对肠长；（4）胃蛋白酶活性、胰脏和肠道中胰蛋白酶、糜蛋白酶、脂肪酶和淀粉酶活性、肠道 γ-谷氨酰转肽酶、Na+-K+-ATP 酶和碱性磷酸酶活性。饲粮 Trp 水平降低了丙二醛含量，提高了抗氧化酶活性和谷胱甘肽含量，但下调了 Keap1 mRNA 表达，上调了 NPY、ghrelin、GH、GHR、IGF1、IGF2、IGF1R、PIK3Ca、AKT1、TOR、4EBP1 和 S6K1 基因的表达。这些结果表明，Trp 提高了杂交鲇的生长性能、消化吸收能力、抗氧化状态和食欲，以及 GH-IGF 轴相关基因的表达。基于增重率、特定生长率和摄食率的二次回归分析，推荐杂交鲇（21.82-39.64 g）对饲粮 Trp 的需要量为 3.96-4.08 g/kg 饲粮（9.4-9.7 g/kg 饲粮蛋白）。
