The Dietary Appropriate Lipid Sources And Carbohydrate To Lipid Level Of Juvenile Hybrid Sturgeon,Acipenser Baerii♀× A. Schrenckii♂

This study was designed to explore the effects of different lipid sources and Carbohydrate to lipid level(CHO:L)on the growth performance,body composition and physiological and biochemical parameters of juvenile hybrid sturgeon.The results may provide theoretical basis for optimizing the formula feed for juvenile hybrid sturgeon.This experiment mainly includes the following four parts as follows:1.Effects of different lipid sources on growth performance and body composition of juvenile hybrid sturgeonAn 8-week feeding trial was conducted on juvenile hybrid sturgeon(A.baerii♀×A.schrenckii ♂)to evaluate the effects of different dietary lipid sources on growth performance,body composition,lipid metabolism enzymes and serum biochemical indexes.Five practical diets,which had fish oil,soybean oil,linseed oil,rapeseed oil and palm oil respectively,were fed to five groups of 300 hybrid sturgeon(mean initial body weight 76.59±1.16 g).The results showed that:(1)The weight gain rate(WGR)of experimental fish in soybean oil group were the highest,and the WGR was significantly higher than that of other groups(P<0.05).The feed conversion rate(FCR)of palm oil group was significantly higher than that of soybean oil(P<0.05).(2)Dietary different lipid sources had no significant effects on condition factor(CF)and visceral somatic index(VSI)of hybrid sturgeon(P>0.05).However,the liver somatic index(HSI)of linseed oil group was significantly higher than that of fish oil and palm oil(P<0.05).(3)The apparent digestibility of dry matter and crude lipid of experimental fish were significantly affected by different lipid sources(P<0.05).and soybean oil group was the highest.The highest crude lipid content was observed in whole fish and liver of hybrid sturgeon fed linseed oil(P<0.05).The lowest crude lipid content was observed in musle of hybrid sturgeon fed fish oil.The crude protein content of liver in linseed oil group was significantly higher than that other groups(P<0.05).4)The content of eicosapentaenoic acid(EPA)and docosahexaenoic acid(DHA)in fish oil group was significantly higher than that in other groups(P<0.05).The content of polyunsaturated fatty acids in soybean oil group was significantly higher than that in other groups.In summary,soybean oil has better growth effect on hybrid sturgeon.2.Effects of different lipid sources on physiological and biochemical parameters of juvenile hybrid sturgeonThe experimental design was the same as experiment 1.The results showed that:(1)The content of polyunsaturated fatty acids in soybean oil group was significantly higher than that in other groups.In addition,the liver lipase(LPS)activity of fish oil group and soybean oil group was significantly higher than that in other three groups(P<0.05).Liver lipoprotein lipase(LPL)activity in linseed oil group was significantly higher than that in palm oil group(P<0.05),however,different lipid sources had no significant effect on liver lipase(HL)of hybrid sturgeon(P>0.05).(2)The pepsin activity in stomach of fish oil group and soybean oil group was significantly higher than that of other groups(P<0.05).The pepsin activity in intestinal of fish oil group was significantly higher than that of linseed oil group,rapeseed oil group and palm oil group(P<0.05).The amylase activity in stomach and intestine of fish oil group,rapeseed oil group and palm oil group were significantly higher than that of linseed oil group(P<0.05).(3)The content of serum low-density lipoprotein cholesterol(LDLC)in rapeseed oil group was significantly higher than that in soybean oil group(P<0.05).The content of total cholesterol(TC)in soybean oil group was the lowest.The content of serum triglyceride(TG)in palm oil group was significantly higher than that in rapeseed oil group(P<0.05).(4)The total antioxidant capacity of serum in fish oil group was significantly higher than that in linseed oil group,rapeseed oil group and palm oil group(P<0.05).Serum malondialdehyde content in palm oil group was significantly higher than that in fish oil group and soybean oil group(P<0.05).Serum superoxide dismutase activity in soybean oil group was significantly higher than that in other groups(P<0.05).The results showed that soybean oil was the most suitable fat source for juvenile hybrid sturgeon to maintain the healthy state.3.Effects of different CHO:L on growth performance and body composition of juvenile hybrid sturgeonAn 8-week feeding trial was conducted on juvenile hybrid sturgeon to evaluate the effects of different CHO:L on growth performance,body composition.Six practical diets,which had 0.21,0.68,1.42,2.82,5.87.0.46 CHO:L respectively,were fed to six groups of 450 hybrid sturgeon(mean initial body weight 9.30±0.12 g).The results showed that:(1)The final average weight,weight gain rate and specific growth rate all reached the maximum when the CHO:L was 5.87.(2)Condition factor(CF)and visceral somatic index(VSI)increased first and then decreased with the increase of CHO:L,while liver somatic index(HSI)increased significantly with the increase of CHO:L(P<0.05).(3)When the CHO:L was 5.87,the apparent digestibility of dry matter was significantly higher than that of CHO:L of 0.21(P<0.05),while the apparent digestibility of crude lipid decreased significantly with the increase of CHO:L(P<0.05).(4)The crude lipid of whole fish and muscle increased with the increase of CHO:L.The glycogen in muscle and liver increased significantly with the increase of CHO:L(P<0.05).Regression analysis of weight gain rate showed that the optimum CHO:L of juvenile hybrid sturgeon was 1.37,the utilization ability of carbohydrate in juvenile hybrid sturgeon was higher than that of lipid.4.Effects of different CHO:L on physiological and biochemical parameters of juvenile hybrid sturgeonThe experimental design was the same as experiment 3.The results showed that:(1)The amylase activity in stomach and intestine increased significantly with the increase of CHO:L(P<0.05),while the lipase activity in intestine and liver decreased significantly with the increase of CHO:L(P<0.05).The activity of pepsin in stomach increased first and then decreased with the increase of CHO:L,and the activity of pepsin in stomach reached the maximum when the CHO:L was 5.87,which was significantly higher than that in group 0.21(P<0.05).(2)Liver lipoprotein lipase,liver lipase and total esterase decreased significantly with the increase of CHO:L(P<0.05).(3)The contents and activities of serum glucose,alkaline phosphatase,total cholesterol and triglyceride in juvenile hybrid sturgeon were significantly different(P<0.05).Serum glucose increased significantly with the increase of CHO:L(P<0.05).The content and activity of serum alkaline phosphatase,total cholesterol and triglyceride decreased significantly with the increase of CHO:L(P<0.05).(4)In addition,the CHO:L of 0.68 was the highest in CAT activity and SOD activity.