温度与饲料蛋白质水平对吉富品系尼罗罗非鱼(Oreochromis nilotica)幼鱼生长和血清生长激素水平的影响

采用中心复合试验设计和响应曲面分析方法,在试验室条件下,研究了温度(20～34℃)和饲料蛋白质水平(25％ ～ 50％)对吉富品系尼罗罗非鱼(Oreochromis nilotica)幼鱼生长、饲料效率和血清生长激素(GH)水平的影响.试验期为56 d.随着温度和饲料蛋白质水平的上升,特定生长率、饲料效率和血清GH水平均呈先上升后下降的变化趋势.温度与饲料蛋白质水平的一次效应对特定生长率、饲料效率和血清GH水平有显著影响(P＜0.05)；温度和饲料蛋白质水平的二次效应与互作效应对饲料效率和血清GH水平有显著影响(P＜0.05),温度与蛋白质水平对特定生长率无互作效应(P＞0.05).高温与饲料高蛋白质水平会降低饲料效率和血清GH水平.因子与响应值间二次多项回归方程的决定系数分别达到0.958、0.955和0.875(P ＜0.01),可用于预测.温度/饲料蛋白质水平最优组合为29.9 ℃/40.3％,此时,特定生长率和饲料效率均较高,分别为2.748％/d和77.5％,其可靠性达0.888.温度对特定生长率、饲料效率和血清GH水平影响较饲料蛋白质明显.血清GH水平与特定生长率相关性较低,而与饲料效率呈正相关.因此,建议在罗非鱼幼鱼的培育中,按照上述温度与饲料蛋白质组合安排生产,以提高罗非鱼养殖效益.

Temperature and Dietary Protein Level Affect Growth and Serum Growth Hormone Level in GIFT Nile Tilapia Juvenile(Oreochromis nilotica)

The purpose of this experiment was to examine the effects of temperature(from 20 ℃ to 34 ℃) and dietary protein level(from 25% to 50%) on specific growth rate(SGR),feed efficiency(FE) and serum growth hormone(GH) level in GIFT Nile tilapia juveniles through central composite rotatable experimental design and response surface method under laboratory conditions.The entire experiment lasted for 56 days.Results showed that SGR,FE and serum GH level were increased at the beginning and then decreased with increasing of water temperature and dietary protein level.The linear effects of temperature and dietary protein level on SGR,FE and serum GH level were statistically significant(P<0.05).The quadratic effects of temperature and dietary protein level and reciprocal effects of temperature × dietary protein level on FE and serum GH level were significant(P<0.05);but the reciprocal effects of temperature × dietary protein level on SGR was nonsignificant(P>0.05).High temperature and high dietary protein level inhibited FE and serum GH level.Model equations of the SGR,FE and serum GH level on temperature and dietary protein level were established,with the coefficients of determination being 0.958,0.955 and 0.875,respectively(P<0.01),and could be applied in prediction.The optimal temperature/dietary protein level combination was obtained utilizing statistical optimization approach: 29.9 ℃/40.3%,at which the maximal SGR and FE reached 2.748%/d and 77.5%,respectively,with the reliability being 0.888.The effects of temperature on SGR,FE and serum GH level were more significant than those of dietary protein level.There was weak correlation between serum GH and SGR.However,a positive correlation was found between serum GH and FE.Thus,breeding efficiency of tilapia juvenile can be improved by rearing the species at an optimal combination of temperature and dietary protein level.