饲料蛋白质水平对匙吻鲟生长、体组成及健康状况的影响

为探讨饲料蛋白质水平对匙吻鲟生长、体组成、消化酶活性、血清生化指标、抗氧化性能的影响。配制了5个不同蛋白质水平(35.44%、37.20%、39.19%、42.05%和45.30%)的等脂饲料,将初始体质量为(158.00±0.29) g的匙吻鲟在室外养殖系统中进行56d的饲养。结果显示:①随着饲料蛋白质水平的提高,实验鱼的增重率(WGR)和特定生长率(SGR)呈先上升后下降的趋势,其中39.19%、42.05%组的WGR和SGR显著高于35.44%、45.30%组;45.30%饲料组的蛋白质效率(PER)显著低于其他各组。以WGR和SGR为参考指标,回归分析结果表明,匙吻鲟获得最佳生长时对饲料中蛋白质水平的要求分别为40.67%和40.84%。②随饲料蛋白质水平的提高,实验鱼体成分没有显著性变化。③39.19%组蛋白质表观消化率显著高于其他组,45.30%组脂肪表观消化率和干物质表观消化率显著高于39.19%组和42.05%组;42.05%组肠蛋白酶活性和肝脏脂肪酶活性显著高于其他组;42.05%组肝脏淀粉酶活性略高于其他组;肝脏蛋白酶活性没有明显变化趋势。④饲料蛋白质水平对匙吻鲟血清生化指标有显著影响。39.19%、42.05%组实验鱼的谷丙转氨酶(ALT)显著低于其余各组;37.20%、39.19%组的球蛋白(GLOB)含量显著高于其他组,35.44%组白蛋白(ALB)含量显著低于其他组;总蛋白(TP)含量39.19%、42.05%和45.30%组之间无显著性差异。⑤饲料蛋白质水平为39.19%以上时,血清过氧化氢酶(CAT)活性显著高于低蛋白质水平组;除37.20%组,其余各组间超氧化物歧化酶(SOD)活性差异不显著;丙二醛(MDA)含量各组之间没有显著性差异。研究表明,在本实验条件下,匙吻鲟适宜饲料蛋白质水平为40%～41%。

Effects of dietary protein levels on growth, body composition and health status of paddlefish (Polyodon spathula)

An 8-week growth trial was conducted to determine the effects of dietary protein levels on growth, body composition and health status of paddlefish (Polyodon spathula). Five experimental diets were formulated to contain 35.44%, 37.20%, 39.19%, 42.05% and 45.30% dietary crude protein (CP) with 5% lipid levels, respectively. At the end of the experiment, fish fed 35.44% to 42.05% CP diet resulted in significantly higher weight gain rate and specific growth rate, and both decreased at 45.30% CP level. The protein efficiency rate did not change significantly when the dietary CP increased from 35.44% to 42.05%; however, it significantly decreased when protein level reached 45.30%. The body composition of the experimental fish did not change significantly with the increase of dietary protein levels. The protein apparent digestibility coefficients (ADC) of 39.19% CP level is significant higher compared with other groups, which was contrary to lipid ADC and dry matter ADC. Liver lipase activity of P. Spathula peaked with the fish fed 42.05% CP level. The highest superoxide dismutase activity of the P. spathula was observed in the 37.20% treatment, and the activity of catalase significantly increased when CP level reached 39.19% compared to the 35.44% treatment. Based on second-order polynomial regression analysis of weight gain rate and specific growth rate, the recommended dietary protein level for P. spathula diet is 40%-41%.