不同糖及糖水平对松浦镜鲤GH/IGF-Ⅰ基因表达和鱼体组成的影响

Effects of different dietary carbohydrates and carbohydrate levels on GH / IGF-Ⅰ mRNA expression and the fish body composition of juvenile mirror carp (Cyprinus carpio)

摘要:

旨在探讨不同糖及糖水平对松浦镜鲤GH(growth hormone)/IGF-Ⅰ(Insulin-like growth factor-Ⅰ)基因表达和鱼体组成的影响。选用初始体质量(8.30±0.15) g的松浦镜鲤420尾, 随机分为4组, 每组3个重复, 每个重复35尾鱼。分别饲喂添加25%和50%的淀粉(LS/HS)和葡萄糖(LG/HG)饲料, 实验周期为60 d。实验结果表明:HS组和LS组的GH基因表达量显著低于LG组(P<0.05)。HS组的IGF-Ⅰ基因表达量显著低于LS组和LG组(P<0.05)。各实验组的鱼体粗蛋白含量差异不显著 (P>0.05)。HS 组的水分值显著低于其他实验组(P<0.05), 粗脂肪含量显著高于其他各组(P<0.05)。氨基酸组成结果显示, HS 组的Leu含量和Cys含量显著低于LG组 (P<0.05), Ala含量显著低于LS组和LG组(P<0.05), 其他各组间差异不显著(P>0.05);其他氨基酸含量各组间差异不显著(P>0.05)。必需氨基酸总量、半必需氨基酸总量、非必需氨基酸总量和总氨基酸含量各组间差异不显著(P>0.05)。综上, 饲料中添加高水平的淀粉抑制了GH基因和IGF-Ⅰ基因的表达, 同时增加了全鱼粗脂肪含量、降低了一些氨基酸的含量。

Abstract:

The effects of the different dietary carbohydrates and different carbohydrate levels on GH /IGF-Ⅰ gene expression, body composition and amino acid composition were studied in juvenile mirror carp (Cyprinus carpio). 420 Songpu mirror carp (mean weight=8.30±0.15g) were randomly divided into 4 dietary treatments triplicate groups and 35 fish per triplicate. The fish in 4 groups were fed two carbohydrates (starch and glucose) diets with two levels (250 g/kg and 500 g/kg) (LS/HS/LG/HG) and were reared for 60 days. Results showed that the GH mRNA expression levels of HS and LS groups were significantly lower than that of LG group (P<0.05). The IGF-Ⅰ mRNA expression level of HG group was significantly lower than that of LS and LG groups (P<0.05). The crude protein was not significantly different among groups (P>0.05). The moisture of HS group was significantly lower than that of the other groups (P>0.05). The crude fat of HS group was significantly higher than that of the other groups (P>0.05). The body amino acid composition results showed that Leu and Cys contents of HS group were significantly lower than those of LG group (P<0.05). Ala content of HS group was significantly lower than that of LS and LG groups (P<0.05). The other amino acids contents were not significantly different among groups (P>0.05). The total essential amino acids, semi-essential amino acid, total non-essential amino acids and total amino acids had no significant difference mong groups (P>0.05). In conclusion, high dietary starch could inhibit the expression of GH and IGF-Ⅰ genes, increase body crude fat content and decrease some amino acids contents.