不同生长阶段团头鲂的赖氨酸需要量研究

Study of lysine requirement in different growth stages of blunt snout bream(Megalobrama amblycephala)

摘要:

为探讨不同生长阶段团头鲂的赖氨酸需要量,以不同生长阶段的团头鲂[规格Ⅰ:(52.49±0.18)g,规格Ⅱ:(101.85±1.8)g]为研究对象,配制赖氨酸含量为1.29%、1.71%、2.09%、2.48%、2.88%和3.27%的等氮等能饲料进行10周养殖实验。结果表明:与对照组相比,(1)2.88%和3.27%组显著提高了规格Ⅰ的增重率、特定生长率和蛋白质效率,显著降低了饵料系数和摄食量;2.48%组显著提高了规格Ⅱ的特定生长率,显著降低了饵料系数,3.27%组提高了规格Ⅱ的特定生长率和摄食量;(2)2.88%和3.27%组分别显著提高了规格Ⅰ和规格Ⅱ的鱼体粗脂肪含量;(3)2.48%组显著降低了规格Ⅰ和规格Ⅱ的血清谷丙转氨酶活性,显著提高了规格Ⅰ的尿素含量;3.27%组显著提高了规格Ⅱ的血清白蛋白、总蛋白和球蛋白含量;表明适宜水平赖氨酸可能对鱼体肝脏具有保护作用,能够提高其代谢及免疫力;(4)2.48%、2.88%和3.27%组均显著提高了规格Ⅰ和规格Ⅱ的血清赖氨酸含量,显著降低了规格Ⅰ的血清精氨酸和总必需氨基酸含量。以鱼体特定生长率为评价指标,经折线模型回归分析得到规格Ⅰ和规格Ⅱ的最适赖氨酸需要量分别为饲料干重的2.07%和2.19%(饲料粗蛋白含量的6.27%和6.63%)。

Abstract:

A 10-week feeding trial was conducted to investigate the dietary lysine requirement of blunt snout bream (Megalobrama amblycephala) with initial body weight of 52.49±0.18 g (size Ⅰ) and 101.85±1.85 g (size Ⅱ). Six isonitrogenous and isoenergetic semi-purified diets were formulated that containing graded lysine levels (1.29%, 1.71%, 2.09%, 2.48%, 2.88% and 3.27%of dry weight). The results showed thatweight gain rate (WGR), specific growth rate (SGR) and protein efficiency ratio (PER) in fish of size Ⅰ fed with diets containing 2.88% and 3.27% lysine were significantly higher than that of the control group, while the reverse pattern was observed in feed conversion ratio (FCR) and feed intake (FI). The 2.48% lysine diet significantly increased SGR and decreased FCR, meanwhile, 3.27% lysine diet significantly increased SGR and FI in fish of size Ⅱ.The diet with 2.88% and 3.27% lysine significantly increased body fat content in fish of size Ⅰ and size Ⅱ, respectively.Significantly decreased ALT in plasma of size Ⅰ and Ⅱand increased Urea of size Ⅰ were observed fed with 2.48% lysine diet, while increased ALB, TP and GLB in plasma content of size Ⅱ fed with 3.27% lysine diet, which indicate that proper lysine in diet might protect the liver and enhance the metabolism and immunity ability compare with the control group. The 2.48%, 2.88% and 3.27% lysine diet significantly increased the plasma lysine content of size Ⅰ and Ⅱ, and decreased the plasma arginine and total essential amino acids content of size Ⅰ. Based on the broken-line regression analysis of SGR, the optimal dietary lysine requirements of size Ⅰ and Ⅱ were estimated to be 2.07% and 2.19% (6.27% and 6.63% of dietary protein), respectively.