饲料蛋白对翘嘴鲌生长和内分泌激素的影响

EFFECT OF DIETARY PROTEIN ON GROWTH AND HORMONE OF CULTER ALBURNUS JUVENILES

选择健康的翘嘴鲌(Culter alburnus)为试验鱼,以红鱼粉为蛋白源,配制5个蛋白水平的等能、等必需氨基酸(EAA)平衡关联度的半精制饲料,又以豆粕替代鱼粉,大豆蛋白分别替代不同水平的鱼粉蛋白,配制5个EAA关联度的等蛋白、等能的半精制饲料,探讨饲料蛋白对鱼类生长和内分泌激素等的影响。结果表明:饲料蛋白水平对翘嘴鲌的特定增重率(SGR)具有显著影响(p<0.05),40.89%饲料蛋白组的SGR显著高于31.04%、35.51%饲料蛋白组(p<0.05),但与46.62%和50.33%饲料蛋白组没有显著性差异(p>0.05)。血清T3水平与饲料蛋白水平正相关(p<0.05)。血清GH水平与饲料蛋白水平和生长负相关(p<0.05),血清IGF-I水平与饲料蛋白水平和生长正相关(p<0.05)。适宜蛋白水平通过提高翘嘴鲌血清T3和IGF-I的水平来调控生长。当大豆蛋白分别替代54.0%的鱼粉蛋白时,翘嘴鲌的SGR与对照组差异显著(p<0.05)。翘嘴鲌血清T3与饲料大豆蛋白对鱼粉蛋白的替代量负相关(p<0.05)。40.5%和54.0%替代组的血清GH显著高于对照组(p<0.05),且与饲料中豆粕对鱼粉替代水平正相关(p<0.01),与生长负相关(p<0.05)。血清IGF-I与饲料中大豆蛋白对鱼粉蛋白替代量负相关(p<0.05),与生长正相关(p<0.05)。大豆蛋白的替代亦通过对内分泌激素的影响来调控生长。

A series of growth experiments were conducted by using brown fishmeal as the protein source in formulated diets. Culter alburnus with initial weight（ （ 12.84 ± 0.60） g wet weight） were fed with 5 isoenergetic（20MJ/g gross energy） , the same relativity of essential amino acid balance experimental semi-purified diets, containing different protein levels （31.04% ,35.51% ,40.89% ,46.62% and 50. 33% dry matter） in 5% increments,five isonitrigenous （40% protein） and isoenergetic （20 MJ/g gross energy） and different relativity of essential amino acid balance experimental semi-purified diets with soybean protein replacing 0.0% , 13.5% ,27： 0% ,40.5% and 54.0% of fish meal protein,were formulated. After 8-week trial, hormone in serum were measured using radioimmunoassay to examine the effect of dietary protein level and replacement of fish meal by soybean cake on growth and triiodothyronine （ T3 ）, thyroxine （ T4 ）, growth hormone （GH） and insulin-like growth factor-I （IGF-I） of Culter alburnus juveniles. The results showed that SGR was significantly influenced by dietary protein levels （p 〈 0.05 ）. SGR of the fish fed the 40.89% protein diets was significantly higher than that of 31.04% and 35.51% protein diets （p 〈0.05） ,but there was not significantly different from that of 46.62% and 50.33% protein diets （p 〉 0.05）. Serum T3 was a positive correlation with dietary protein level （p 〈 0.05 ） ,which increased with increasing of dietary protein level. Serum GH decreased significantly with increasing dietary protein level,which showed a negative correlation with fish growth. Serum IGF-I showed a positive correlation with dietary protein level and growth （p 〈 0.05 ）. Optimum dietary protein level can regulate growth by increasing serum T3 and IGF-I level. When the replacement level for fish meal protein with soybean protein was 13.5% ,27% and 40.5% ,respectively, there were no significant difference in specific growth rate compared with the control group （p 〉 0.05 ） ,but significantly higher than specific growth rate in fish fed 54% replacement of soybean protein （p 〈 0.05）. Serum T3 decreased with increasing replacement of fish meal by soybean cake. T3 of 27.0% replacement level of fish meal protein by soybean protein were significantly lower than the control group, but there were not significant difference among the replacement groups. Serum T3 was a negative correlation with replacement of fish meal by soybean cake （p 〈 0.05 ）. Serum T4 was higher than T3 but was not influenced by replacement of fish meal by soybean cake. Serum GH of 40.5% and 54.0% replacement level for fish meal protein with soybean protein were significantly higher than the control group, but there were not significant difference among the replacement groups. Serum GH was positive correlation with replacement of fish meal by soybean cake but negative with growth （p 〈 0.05 ） and Serum IGF-I was the opposite （p 〈 0.05 ）. IGF-I of 40.5% and 50.33% treatments were significantly lower than that of 13.5% and 27.0% and the control groups. The replacement for fish meal protein with soybean protein also regulated the growth by changes in the level of hormones.