| The Onychostoma macrolepis is a small indigenous fish with high economic value.And the wild population has been listed in the national secondary protected animals list,but except for artificial breeding in many places in China.It is reported that some research has been done on the biological characteristics,artificial breeding technology,muscle quality and other aspects of the O.macrolepis,but few research on nutrition.Therefore,we developed the carbohydrate requirements and types of requirements on juvenile O.macrolepis.Experiment 1: Study on dietary carbohydrate requirement of juvenile O.macrolepis.Using dextrin as carbohydrate source,the diets with equal nitrogen and equal fat content of14.7%,20.7%,26.7%,32.7% and 38.7% five carbohydrate levels were prepared and used for 56-day culture experiment.The results were as follows:(1)With the increase of dietary carbohydrate level,the final body mass(FBM),weight gain(WG)and protein efficiency rate(PER)of fish significantly increased to 26.7% and then decreased(P<0.05),while the feed conversion ratio(FCR)showed the opposite trend(P<0.05);(2)The hepatopancreas trypsin activity of 32.7% group was significantly lower than that of other groups(P<0.05),and the lipase activities of 14.7%,20.7% and 26.7% groups were significantly higher than those of the latter two levels groups(P<0.05).(3)The whole fish crude protein content in the 14.7%group was the lowest(P<0.05),while the hepatopancreas and muscle glycogen in the 26.7%group were significantly highest(P<0.05).(4)The principal component analysis showed that among the fatty acids that played the main roles,the proportions of PUFA in hepatopancreas,MUFA in muscle and adipose tissue,and PUFA were not significantly different between groups(P>0.05).The systematic clustering average method found that the proportion of PUFA in hepatopancreas,n-6PUFA and MUFA in muscle and MUFA in abdominal fat decreased with the increase of dietary carbohydrate level.R-value analysis showed that treatments with different carbohydrate levels exhibited similar volatility in the same tissue.The correlation analysis showed that the correlation between muscle and dietary fatty acid composition was the highest in the 20.7% group(P<0.05),and the correlation between abdominal fat and muscle tissue and dietary fatty acid composition was significantly higher than that of hepatopancreas(P<0.05).(5)The hepatopancreas glutathione peroxidase(GSH-Px)of the 32.7% group was significantly lower than that of the other groups(P<0.05),the total superoxide dismutase(T-SOD)levels of the 14.7%,20.7% and 26.7% groups were significantly higher(P<0.05),the catalase(CAT)level of the 20.7% group was the highest,and the malondialdehyde(MDA)level of the 38.7% group was the highest(P<0.05).(6)When the amount of carbohydrate in the diet reached 32.7%,severe vacuolation occurred in the hepatopancreas,and the intestinal villi in the 26.7% group were the longest(P<0.05).The results showed that the optimum range of dietary carbohydrate was 20.7%–26.7% and the optimum dietary carbohydrate content was 25.67% by specific growth rate(SGR).Experiment 2: Study on the best carbohydrate addition type in the diet of juvenile O.macrolepis.On the basis of the results of experiment 1,five diets were prepared with glucose,maltose,dextrin,corn starch and cellulose as carbohydrate sources for a 56-day culture of juvenile O.macrolepis.The results were as follows:(1)The maltose group had the best FBM,SGR,FCR and PER(P<0.05),while the cellulose group was the worst(P<0.05).(2)The crude fat content of whole fish was the least in the cellulose group(P<0.05),while the crude ash content was significantly higher than that in the maltose group(P<0.05).The muscle glycogen of maltose and cellulose groups was the lowest(P<0.05).Hepatopancreas glycogen in dextrin group was the lowest(P<0.05).(3)The principal component analysis showed that among the fatty acids that played the main role,the proportion of SFA in the maltose group was significantly increased in the hepatopancreas(P<0.05),the MUFA in the dextrin group was significantly increased(P<0.05),and the PUFA in the cellulose group was significantly increased(P<0.05).In muscle and adipose tissue,the proportion of MUFA in maltose group was significantly increased(P<0.05).The result of systematic clustering average method showed that maltose in hepatopancreas significantly increased that proportion of SFA and MUFA,while cellulose was the proportion of PUFA(P<0.05).In muscle,glucose and maltose significantly increased the proportion of MUFA,corn starch and cellulose increased the proportion of SFA and PUFA(P<0.05).In adipose tissues,maltose and corn starch significantly increased the proportion of MUFA(P<0.05),glucose increased the proportion of SFA(P<0.05).Cellulose and dextrin increased the proportion of PUFA(P<0.05).R-value analysis showed that the diets with different sugar sources exhibited similar volatility in the same tissue,and PUFA was accumulated in the hepatopancreas of the cellulose group.Correlation analysis showed that fatty acid composition of hepatopancreas,muscle and adipose tissue had the highest correlation with cellulose,glucose and cellulose,respectively(P<0.05).(4)The corn starch group could significantly reduce the alanine aminotransferase(ALT),aspartate aminotransferase(AST),and alkaline phosphatase(ALP)(P<0.05).The total protein(TP),albumin(ALB)and globulin(GLB)were the highest in the glucose group(P<0.05).The total cholesterol(TC)and high density cholesterol(HDL-c)in the glucose,maltose and dextrin group were the highest(P<0.05).The low density cholesterol(LDL-c)was the highest in the glucose group(P<0.05),and the triglyceride(TG)was the highest in the dextrin group(P<0.05).(5)Hepatopancreas CAT,T-SOD and GSH-Px contents in the maltose group were the highest(P<0.05),while MDA content in the cellulose group was the highest(P<0.05).(6)Dietary carbohydrate types had no significant effects on the adipocytes and intestinal structure(P>0.05).Studies showed that maltose performed best overall,while dextrin and corn starch were slightly inferior to maltose,and cellulose and glucose were not suitable carbohydrate sources for the fish.The results showed that juvenile O.macrolepis had certain utilization of carbohydrate,and that appropriate amount of carbohydrate in the diet was 20.7%–26.7%,and the most appropriate amount was 25.67%;Maltose was used as the source of dietary carbohydrate,and the growth and health status of O.macrolepis were good.In actual production,corn starch could be considered as the source of dietary carbohydrate for O.macrolepis. |
PDF Full Text Request