Effects Of Dietary Carbohydrate To Lipid Ratios On Feeding, Growth And Carbohydrate/Lipid Metabolism In Chinese Perch, Siniperca Chuasti

As the most economical energy source of fish,sugar can partially replace protein and save feed cost.Excessive carbohydrate addition in dietary is not only cause metabolic burden such as continuous accumulation of postprandial blood glucose and liver glycogen,but also have negative effects on liver tissue and stress response.Lipids provide essential fatty acids for the growth and development of fish.High fat diet can also lead to the excessive addition of fat in fish feed,which can not only lead to abnormal fat deposition of fish,causing fish fat deposition and other health problems,but also have a negative impact on growth performance and feed utilization rate.Therefore,an appropriate carbohydrate to lipid ratios in dietary can provide energy for fish.It also has the function of saving protein.This paper studied the effects of carbohydrate to lipid ratios in the feed of Chinese perch on feeding,growth and metabolism of carbohydrate/lipid,and determines that the Chinese perch had the best growth performance when the carbohydrate to lipid ratios in the feed of Chinese perch fish is in the range of 1.60-1.71.In this study,an 8-week diet feeding experiment was carried out with a mean initial body weight of 12.86 ± 0.10 g.Five isonitrogenous and isoenergetic diets were prepared,and the ratio of glucose to lipid was 0.12,0.86,1.71,3.29 and 7.19,respectively.The results showed that final body weight(FBW),weight gain rate(WGR),specific growth rate(SGR),and protein efficiency ratio(PER)increased with the increase of the carbohydrate-to-lipid ratio ratio from 0.12 to 1.71,and then gradually decreased with the further increase of the carbohydrate to lipid ratios.The double slope regression analysis based on weight gain rate(WGR)showed that the optimal ratio of glucose to lipid in the diet of Siniperca chuatsi was1.60.The content of crude fat and crude protein in liver and glycogen concentration in muscle and liver of Chinese perch were significantly affected by the dietary carbohydrate to lipld ratios(P < 0.05).The content of crude fat in liver was the lowest when the dietary carbohydrate to lipld ratios was 1.71(P < 0.05).The carbohydrate to lipld ratios in dietary significantly increased the concentration of serum glucose(GLU)(P < 0.05).The relative expression levels of lipid metabolism related genes Sterol regulatory element binding protein I(srebp1)and fatty acid synthase(fas)in the liver decreased first and then increased with the increase of the carbohydrate to lipld ratios in the dietary.The appropriate ratio of carbohydrate to lipld ratios in the dietary can effectively reduce the accumulation of liver fat.In addition,we observed that,compared with the control group,the Chinese perch fed a diet with a glycolipid ratio of 1.71 had a higher food intake and the following appetitive genes in the brain: The m RNA expression of neuropeptide Y(npy)and agouti-related neuropeptide(agrp)was significantly up-regulated,and the m RNA expression of the anorexigenic genes cocaine-and amphetamine-regulated transcript(cart)and proopiomelanocortin(pomc)was significantly down-regulated.Therefore,the results of this study provide a theoretical basis for the determination of the appropriate CHO:L ratios for the Chinese perch.