饲料蛋氨酸水平对绿鳍马面鲀幼鱼生长性能的影响

Effects of Dietary Methionine on Growth Performance of Juvenile Green-Finned Filefish(Thamnaconus septentrionalis)

试验旨在研究饲料蛋氨酸水平对绿鳍马面鲀幼鱼生长性能的影响,确定其饲料中蛋氨酸的最适需求量。通过添加不同含量的DL-蛋氨酸(0、0.2%、0.4%、0.6%、0.8%、1.0%)配制出6种等氮、等能的试验饲料,实测饲料蛋氨酸含量分别为0.72%、1.00%、1.12%、1.27%、1.48%、1.67%。每个处理设3个重复,每个重复放养30尾幼鱼[鱼苗初始体重(3.50±0.02)g],养殖试验周期为12周。结果表明:添加0.6%蛋氨酸组鱼的终末均重、增重率和特定生长率显著高于其他各组(P<0.05);添加0.4%和0.6%蛋氨酸组的饲料系数显著低于添加0、0.2%、0.8%和1.0%蛋氨酸组(P<0.05);添加0.6%蛋氨酸组饲料蛋白质效率显著高于其他各组(P<0.05)。添加0.4%和0.6%蛋氨酸组鱼体粗蛋白含量显著高于1.0%蛋氨酸组(P<0.05);添加0.2%、0.4%和0.6%蛋氨酸组鱼体粗脂肪含量显著低于0.8%蛋氨酸组(P<0.05)。添加0.4%蛋氨酸组鱼肌肉的各氨基酸含量均显著高于添加1.0%蛋氨酸组(P<0.05),与添加0、0.2%和0.6%蛋氨酸组相比较差异不显著(P>0.05)。添加0.6%蛋氨酸组鱼血清溶菌酶活力显著高于添加0、0.2%、0.8%和1.0%蛋氨酸组(P<0.05),血清谷草转氨酶和谷丙转氨酶活力显著低于添加0、0.2%和1.0%蛋氨酸组(P<0.05),鱼肝脏过氧化氢酶活力显著高于其余各组(P<0.05)。依据增重率与饲料蛋氨酸水平的折线模型分析,得出绿鳍马面鲀幼鱼饲料中蛋氨酸的最适需求量为1.27%,占饲料粗蛋白含量的2.50%。

This study was conducted to investigate the effects of dietary DL-methionine on the growth per⁃formance of juvenile green-finned filefish(Thamnaconus septentrionalis),and acquire the optimal require⁃ment of methionine in the diet.Six isonitrogenous and isoenergetic experimental diets were formulated by adding different levels of DL-methionine(0,0.2%,0.4%,0.6%,0.8%,1.0%).The measured contents of methionine in the diet were respectively 0.72%,1.00%,1.12%,1.27%,1.48%,1.67%.Each treatment consisted of 3 replicates,with 30 fish[initial weight(3.50±0.02)g]per replicate.The breeding experi⁃ment lasted for 12 weeks.The results showed that the final average weight,weight gain rate and specific growth rate of fish fed the diet added with 0.6%methionine were significantly higher than those of the other groups(P<0.05).The feed conversion rate of 0.4%and 0.6%methionine groups were signifi⁃cantly lower than those of 0,0.2%,0.8%and 1.0%groups(P<0.05).The protein efficiency rate of 0.6%methionine group was significantly higher than those of other groups(P<0.05).The contents of crude protein in whole fish fed the diets added with 0.4%and 0.6%methionine groups were significantly higher than that in the 1.0%methionine group(P<0.05).The contents of crude fat in whole fish of the 0.2%,0.4%and 0.6%methionine groups were significantly lower than that in the 0.8%me⁃thionine group(P<0.05).The content of amino acid in fish muscle in the 0.4%methionine group was sig⁃nificantly higher than that in the 1.0%methionine group(P<0.05),but there was no significant differ⁃ence compared to the 0,0.2%,and 0.6%methionine groups(P>0.05).The activity of lysozyme in serum in the 0.6%methionine group was significantly higher than those in the 0,0.2%,0.8%and 1.0%me⁃thionine groups(P<0.05).The activities of glutathione aminotransferase and alanine aminotransferase in serum in the 0.6%methionine group were significantly lower than those in the 0,0.2%and 1.0%me⁃thionine groups(P<0.05).The activity of catalase in liver in the 0.6%methionine group was signifi⁃cantly higher than those in the other groups(P<0.05).Based on the analysis of the broken-line model between weight gain rate and dietary methionine levels,the optimal requirement of methionine in the diet for juvenile green-finned filefish was 1.27%,accounting for 2.50%of the crude protein content in the diet.