异育银鲫幼鱼对饲料中缬氨酸需求量的研究

通过65d的生长实验, 探讨饲料中不同缬氨酸水平对异育银鲫(Carassius auratus gibelio)幼鱼平均体重(3.17±0.01)g/尾生长性能、饲料利用和蛋白利用的影响, 确定异育银鲫对饲料中缬氨酸的需要量。实验设计由酪蛋白、明胶和晶体氨基酸为蛋白源的8种等氮(蛋白含量:38%)等能(总能:17.0 kJ/g)的半精制饲料, 其缬氨酸水平等梯度逐步升高(0.54、0.79、1.04、1.29、1.54、1.79、2.04、2.29%饲料干物质)。各实验饲料中缬氨酸的实测值分别为:0.66、0.85、1.07、1.22、1.46、1.70、1.86和2.12%饲料干物质。饲料中其他必需氨基酸含量参照异育银鲫肌肉氨基酸模式。每种饲料饲喂3个重复,每个重复30尾鱼,养殖于塑料方箱中(70 cm×55 cm×50 cm;水体容积:150 L), 养殖系统为室内流水系统(500 mL/min流速), 每天两次饱食连续投喂(9:00和16:00)。实验结果表明,饲料中适量的缬氨酸显著提高了异育银鲫的特定生长率、饲料转化效率和蛋白沉积率(P0.05), 但显著影响了血清谷氨酰胺的浓度(P0.05), 但不同的缬氨酸水平显著影响了鱼体灰分含量(P<0.05)。对各处理组异育银鲫特定生长率的结果进行二次回归分析, 结果表明满足异育银鲫最大生长的缬氨酸需求量为饲料干物质的1.72%, 即占饲料蛋白的4.53%。  

DIETARY VALINE REQUIREMENT FOR JUVENILE GIBEL CARP (CARASSIUS AURATUS GIBELIO)

A 65d growth trial was conducted to investigate the effect of different dietary valine levels on the growth performance and feed utilization of juvenile gibel carp (Carassius auratus gibelio) average body weight: (3.17?.01)g, and to determine the dietary valine requirement for gibel carp. Eight isonitrogenous (crude protein content: 38%) and isoenergetic (gross energy: 17.00 kJ/g) semipurified diets were formulated with the graded supplemental levels of crystalline valine (0.54, 0.79, 1.04, 1.29, 1.54, 1.79, 2.04 and 2.29% dry diet, respectively), using casein, gelatin and crystalline amino acids as the main dietary protein sources. The eight experimental diets were determined to contain valine of 0.66, 0.85, 1.07, 1.22, 1.46, 1.70, 1.86 and 2.12% dry diet, respectively. Contents of other essential amino acids in the diets were formulated to simulate the amino acid profile of gibel carp muscle protein. Each diet was fed in triplicate groups and 30 fish each group were stocked in a flow-through system (water flow speed 0.5 L/min) consisting of 24 polyvinyl quadrate tanks (70 cm?5 cm?0 cm; water volume 150 L). Fish were fed to satiation by hand twice a day at 8:00h and 16:00h. Dietary valine levels significantly influenced specific growth rate, feed efficiency and protein retention efficiency (P0.05), but significantly affect the serum glutamine concentration significantly (P0.05), except the body ash contents (P<0.05). Polynomial regression analysis between the specific growth rate and the dietary valine levels indicated that the dietary valine requirement of gibel carp was 1.72% of dietary valine (on a dry matter basis) and 4.53% in terms of dietary protein.