Effects Of Dietary Starch Types And Carbohydrate Levels On The Growth, Flesh Quality And Mucosal Non-specific Immunity In Juvenile Blunt Snout Bream (Megalobrama Amblycephala)

This study was focus on the effects of dietary carbohydrates types and levels on growth,meat quality,intestines and liver health in juvenile blunt snout bream(Megalobrama amblycephala).The main results are as follows:1 Effects of dietary starch sources on growth,digestibility and flesh quality in juvenile blunt snout breamThe purpose of this experiment was to investigate the effects of wheat,corn,sorghum,and cassava starch feed materials and their different ratios in the feed on nutritional metabolism,health and meat quality of blunt snout bream.Ten groups of iso-nitrogen and iso-lipid basic diets were set up,including wheat group(WS),corn group(CS),sorghum group(BS),cassava group(MS),wheat:maize(2:1)group(WC),wheat:maize(1:2)group(CW),wheat:sorghum(2:1)group(WB),wheat:sorghum(1:2)group(BW),wheat:cassava(2:1)group(WM)and wheat:cassava(1:2)group(MW).450 blunt snout bream with the initial average weight of 45.93 ± 0.13 g were selected and randomly divided into 10 groups.Each group consisted of three replicates and 15 fish per replicate.The 60-days culture experiment was carried out in 30 cages(1m×1m×2m).The results are as follows:1.The weight gain rate of the two starch raw materials groups were higher than that of the single starch group,and the weight gain rate of WC group was significantly higher than that of MS group.2.The apparent digestibility of protein in BS group,WC group,WB group,BW group,WM group and MW group was significantly higher than that in WS group,while the apparent digestibility of fat in CS group,CW group,WB group,BW group,and WM group was significantly higher than that in WS group.The content of crude fat was the lowest and significantly lower in CS group than in CS group.3.The content of flesh crude protein in the CW group was the highest and significantly higher than that in the CS group,while the content of crude fat were the lowest and significantly lower than that in the CS group.4.Flesh pH in WC group was the highest and significantly higher than BS,MS and WB group.5.The yellowness of meat color in CW group was the lowest,and there was no significant difference with WS group.The redness of meat color in MW group was the highest and significantly higher than that in WS group,while the brightness of meat color was the lowest and significantly higher than that in WS group.6.The water holding capacity in CS group was the lowest and was significantly lower than other groups;There was no significant difference between WM group,MW group and MS group in the water holding capacity(P>0.05),but all of them were significantly lower than the WS group;7.The expression of AMPD1 in BW group was significantly higher than WS,WB and BS group;The expression of MyoD in WC group was the highest,and significantly higher than that in other groups,the expression of MyoD in WM group was significantly higher than that in WS group and MS group,but there was no significant difference with that in MW group;The expression of Myf5 in WB group was significantly higher than that in WS group and BS group,but there was no significant difference with that in BW group;The expression of MRF4 in WB group was significantly higher than that in WS group,but there was no significant difference with that in BW group and BS group;Compared with the control group,the expression of Leptin-R in CW group,BW group and MW group were significantly decreased.The results showed that when wheat starch and corn(sorghum or cassava)starch were added in a ratio of 2:1 in the feed,the maximum weight gain rate was obtained,and the digestibility of protein and fat and meat quality were improved.2 Effects of dietary glucose and starch levels on the growth,digestibility,and skin-associated mucosal non-specific immunity in juvenile blunt snout bream.A 10-week feeding trial was performed to evaluate the effects of different types and levels of carbohydrates in growth performance,apparent digestibility coefficients and skin-associated mucosal non-specific immune parameters in blunt snout bream(Megalobrama amblycephala).Fish were randomly fed four diets containing two carbohydrates(glucose and starch)diets and two carbohydrates levels(330 and 440 g kg-1).High carbohydrate levels remarkably increased the weight gain rate(WGR),apparent digestibility of dry matters,protein and carbohydrates,body crude protein content,plasma levels of aspartate transaminase(AST),and skin-associated mucosal levels of immunoglobulin M(IgM),HDL,cholesterol,lysozyme(LZM),advanced the transcriptions of mucin 2(Muc2),mucin 5b(Muc5b)and apolipoprotein A-I(apoA-I),whereas the opposite was true for feed conversion ratio(FCR),plasma levels of IgM,skin-associated mucosal levels of major histocompatibility complex(MHC)and ?-Defensins,and the transcriptions of heat shock protein 70(Hsp70).In addition,carbohydrate types of glucose remarkably increased the survival rate,apparent digestibility of dry matters,protein and carbohydrates,body crude ash,plasma levels of total protein(TP),globulin(GLB),immunoglobulin M(IgM),complement 3 and complement 4 and the transcriptions of Muc5b.Whereas the carbohydrate types of starch remarkably increased viscero somatic index(VSI),hepatosomatic index(HSI),condition factor(CF),abdominal fat percentage(AFP),apparent digestibility of lipid,advanced the transcriptions of Muc2,apoA-1,and heat shock protein 70(Hsp70).Significant interactions between different types and levels of dietary carbohydrates were also observed in WGR,apparent digestibility of dry matters,protein and lipid,body crud ash,plasma levels of TP,albumin(ALB)and AST,skin-associated mucosal levels of major histocompatibility complex(MHC)and?-Defensins,and the transcriptions of Muc2 and Muc5b.Our results indicate that inclusion of high level of glucose in the diet of blunt snout bream could improve growth performance,nonspecific immunity,and increase the efficiency of protein,which is suggesting that high level of glucose could be used in feed production.3 Effects of dietary glucose and starch levels on the intestinal health in juvenile blunt snout bream.The present study was conducted to evaluate the effect of dietary starch and glucose on the intestinal health of juvenile megalobrama amblycephala.Basic on the Experiment 2,this research measured the intestine of the fish,according to the results of enzyme activity,protease,lipase and amylase activities of megalobrama amblycephala,together with the length of intestinal villi were affected by the carbohydrate types and levels interaction significantly(P<0.05),and the microvilli of length in normal glucose group were significantly less than high glucose group(P<0.05),while in high glucose group,it's significantly higher than high starch group(P<0.05).Light microscope analysis of mucus cells of bream revealed that the highest density of mucous cells was found in the middle intestine of fish.High-throughput sequencing analysis showed that the carbohydrate types and levels significantly affected the intestinal flavor coefficient of fish(P<0.05).The flavor coefficient of the normal-glucose group was significantly lower than that of the high-glucose group(P<0.05).The flavor coefficient of the normal-glucose group was significantly lower than that of the normal-starch group(P<0.05),while that of the high-glucose group was significantly higher than that of the high-starch group(P<0.05).The 16S sequencing analysis of microbial diversity showed that Clostridium and Firmicutes were dominant in the glucose group,while Proteus and Bacteroides were dominant in the starch group.The carbohydrate types and levels significantly affected the expression level of intestinal Muc2 mRNA(P<0.05),the expression level of Muc2 mRNA in the normal starch group was significantly higher than that in the high starch group(<0.05),but the expression level of Muc2 mRNA in the high glucose group was significantly higher than that in the high starch group(P<0.05).To sum up,the high glucose level in feed can promote the digestion level of Megalobrama amblycephala,and improve the intestinal non-specific immunity ability of Megalobrama amblycephala,which is of great significance for reducing cost and improving production efficiency.4 Effects of dietary glucose and starch levels on the liver health in juvenile blunt snout bream.The present study was conducted to evaluate the effect of dietary starch and glucose on liver function of juvenile megalobrama amblycephala.Fish were randomly fed four diets containing two carbohydrates(glucose and starch)diets and two carbohydrates levels(330 and 440 g kg-1).High carbohydrate levels remarkably increased the plasma levels of triglycerides,cholesterol,total protein,activities of ?-amylase and liver mRNA levels of GK,PK and FAS.In addition,it also led to an increase in the number of lipid droplet and heterochromatin in the liver.Carbohydrate types of starch remarkably increased the plasma levels of triglycerides,activities of ?-amylase and liver mRNA levels of FAS.Meanwhile,hepatocyte morphology and the number of lipid droplets and heterochromatin were also significantly affected.Significant interactions between different types and levels of dietary carbohydrates were observed in plasma activities of ?-amylase,liver mRNA levels of GK,PK,FBPase and FAS,hepatocyte morphology and the number of lipid droplets and heterochromatin.Our results indicate that the inclusion of a high level of starch in the diet of blunt snout bream could affect glucose metabolism in the liver.5 Effects of dietary glucose and starch levels on the physiological index and mucosal non-specific immunity in juvenile blunt snout bream under high-temperature stress.This study was aimed to investigate the effects of dietary starch and glucose on M.amblycephala physiological response and immune response in high-temperature stress.At 24h,high-carbohydrate levels resulted in relatively decrease the plasma levels of glucose,cortisol and insulin,and the mRNA levels of Muc2 in the skin,whereas the opposite was true for the mRNA levels of Hsp70,Muc2,Muc5b and Muc5b.Carbohydrate types of starch resulted in relatively decrease the plasma levels of cortisol and the mRNA levels of Muc5b,whereas the opposite was true for the mRNA levels of Muc2 in the gut.Significant interactions between different types and levels of dietary carbohydrates were observed in plasma levels of cortisol and insulin and mRNA levels of Hsp70,Muc5b,Muc2 and Muc5b.At 48h,high-carbohydrate levels resulted in relatively rising the plasma levels of glucose and insulin and the mRNA levels of Muc2 in gut and Muc2 in the skin,whereas the opposite was true for the plasma levels of cortisol and the mRNA levels of Muc5b in the gill.Carbohydrate types of starch resulted in relatively rising the plasma levels of cortisol and insulin and the mRNA levels of Muc5b in gill and Muc2 in the skin,whereas the opposite was true for the mRNA levels of Muc2 in the gut.Significant interactions between different types and levels of dietary carbohydrates were observed in plasma levels of cortisol and insulin and mRNA levels of Hsp70,Muc5b,Muc2 and Muc5b.The results indicated that high-level of carbohydrate diet in the diet of blunt snout bream could strengthen the ability of M.amblycephala against high-temperature stress and enhance the nonspecific immunity ability.