Feeding Different Dietary Carbohydrate Levels Affected Growth Performance And Physiological Functions Of Channel Catfish(Ictalurus Punctatus)

In the study, taking Channel Catfish (Ictalurus punctatus) as the object of study, researching the growth performance, nutritional composition in muscle, blood indexes, enzyme activity of Channel Catfish by feeding different carbohydrate levels (0%、8%、16%、24%、32%、40%).The study was aimed at determining the appropriate requirements of Channel Catfish feed on carbohydrate levels, and providing theoretical basis for the feed research of Channel Catfish. In the study, using corn starch, bean oil and import fishmeal as protein, lipid and carbohydrate in the feed respectively. Culturing Channel Catfish for3months with the matched pellet feed, the results are listed as follows:1. Different carbohydrate affected the growth performance of Channel Catfish:under the study conditions, specific growth ratio, weight gain ratio and protein efficiency ratio of test fish presented the trend of increased firstly and then decreased with increasing dietary carbohydrate levels。 Among them, the value of fourth group (24%) were maximum. Feed coefficient ratio presented the trend of decreased firstly and then increased. Among them, the value of fourth group (24%) were maximum. According to the regression relationship between weight gain ratio, specific growth ratio, protein efficiency ratio, feed coefficient ratio and carbohydrate levels, in theory, Channel Catfish of weight gain ratio, specific growth rate, protein efficiency ratio are maximum, and feed coefficient ratio is minimum, calculate that carbohydrate level should be17.55%,18%,16.92%,16.04%, respectively.2. The results of this study shows that, dietary carbohydrate levels had little impact on the crude protein, the crude ash and the moisture content of Channel catfish muscle, but it had a significant effect on the fat content of Channel catfish muscle, and shown a positive correlation with the fat content, indicating that the channel catfish has the ability to put feed carbohydrates into body fat.3. Serum glucose concentration, Cholesterol content, Triglyceride content and Total bile acid content shown a positive correlation with dietary carbohydrate levels. According the fitting relationship between blood counts and dietary carbohydrate levels, with the growth of fish, it can be inferred that the third group(16%) and fourth (24%) dietary carbohydrate levels can meet normal cholesterol levels of the experiment fish, while the sixth group (40%) experiment fish may cause liver damage with excessive carbohydrates intake. 4. In this study, the activity of alanine aminotransaminase (ALT) and aspartate aminotransaminase (AST) shown a positive correlation with dietary carbohydrate levels, the fifth group (32%) and sixth (40%) content of ALT and AST were significantly higher than those of other groups. The result shows liver function of the fifth group and sixth experiment fish was damaged with long-term intake of high levels of dietary carbohydrate, so that the content of ALT and AST were significantly increased. However, with increasing dietary carbohydrate levels, the content of alkaline phosphatase(ALP)presented the trend of increased firstly and then decreased. The fourth group (24%) ALP content is the largest, shows that the dietary carbohydrate levels24%were the critical point of Channel Catfish self-decompositionand and utilization on carbohydrate.Based on the above results, it is can inferred that the dietary carbohydrate levels of16%～24%is best on Channel Catfish juvenile under this experimental condition.