| By using traditional animal nutrition research methods and molecular biology tools, this study was conducted to investigate the effects of low-ratio or without fish meal diets on feed intake, growth performance, serum biochemical index, immune ability and growth hormone(GH) and insulin-like growth factor-1(IGF-?) gene expression of liver in Yellow River carp(Cyprinus carpio). The objective is to explore the modulation mechanism of growth hormone change which caused by different dietary protein sources, and reduce the feed cost by means of reasonable protein feed formulation.At the beginning of the experiment, 450 fish(initial mean weight 23.58 ± 0.13g) with good health condition were randomly distributed into 15 water-circulated tanks at a stocking density of 30 fish per tank. All fish were divided into 5 treatments with 3 replicates. Using mixed vegetable protein, respectively, replaces the original formula feed fish meal 0%, 25%,50%, 75% and 100%, named F100, F75, F50, F25, F0. The fish were fed in the automatic water-circulated system through the experiment period of 60 days. The results are as follows:1. The growth test results show that the fish meal replacement significantly affected the final weight gain, weight gain rate, specific growth rate, feed convertion rate and protein efficiency rate of Yellow River carp(P<0.05). There are no difference between F100 and F75 groups, and the lowest growth performance was found in F0 group.2. The results of serum biochemical indexes showed that the serum albumin, total cholesterol, blood glucose, alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase were significantly affected by the fish meal replacement(P<0.05). The serum total cholesterol and blood glucose were significantly different(P<0.05), and the content was gradually decreased with the increase of fish meal placement, and the content of F0 group was the lowest. The control group of alanine aminotransferase, aspartate aminotransferase,alkaline phosphatase was significantly lower than other groups(P<0.05), while the control group of alanine aminotransferase and aspartate aminotransferase had significantly different with other groups. There were significant differences of serum uric acid levels between the control group and other groups(P<0.05), and the highest was found in the control group. The highest GH and IGF-? content was found in F75 group, the lowest was found in F0 group.3. The results of whole fish body composition showed that the fish meal replacement did not affect the moisture and crude ash contents of fish(P>0.05). The crude protein and ether extract was not affected by the fish meal replacement(P>0.05), and the ether extract content was improved while the crude protein content was decreased with the increase of fish meal replacement.4. The fish meal replacement did not affect the superoxide dismutase, but sigificantly affect the lysozyme activity, alkaline phosphatase and MDA(P<0.05), the content of F100 group was the lowest, and the content of F0 group was the highest. The lysozyme content of F75 group was the highest.5. The gene expression results showed that the GH and IGF-? m RNA level in liver were affected by the fish meal replacement in carp(P<0.05). The highest m RNA level of IGF-? and GH in liver tissue was found in F75 and the lowest in F0 group.The effect of fish meal replacement on the growth peformance was not significant when the replacement ratio is less than or equal to 25 percent. The fish meal replacement significantly affect the whole fish body composition with the increase of replacement ratio.The GH and IGF-? contents in serum and the gene m RNA level in liver were significantly reduced by the more than 25% ratio. In this study condition, the 25% or less of fish meal replacement ratio could reduce the feed cost, and ensure the rapid growth of fish. |
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