Effects Of NSPs In Rapeseed Meal And Cottonseed Meal On Growth,Intestinal Morphology And Function Of Eriocheir Sinensis

Rapeseed meal and cottonseed meal are two widely available dietary protein sources that can be used to partly replace fish meal in aquatic animal feed.However,the amount of fish meal replacement in diet was restricted because they contain various anti-nutritional factors,in which the non-starch polysaccharides(NSPs)is the highest.Pectin is a high content of NSPs in rapeseed meal,and xylan is a high content of NSPs in cottonseed meal.In this study,we evaluated the effect of pectin in rapeseed meal and xylan in cottonseed meal on growth,digestive physiology,fat synthetical metabolism,intestinal construction and gene expression of peritrophic membrane of Chinese mitten crab(Eriocheir Sinensis).At the same time,the effects of four kinds of NSPs with different viscidity and fermentation on intestinal microflora were investigated by in vitro fermentation.The aim of this study was to assess the anti-nutritional effects of NSPs in rapeseed meal and cottonseed meal,and provide theoretical support for the improvement of feed formulation of Chinese mitten crab.Three experiments were conducted in this study as followed.The aim of the first experiment was to investigate the response of intestinal microflora of Chinese mitten crab to the characteristics of NSPs,i.e.viscosity and fermentation.Four kinds of NSPs,including low fermentation and viscosity of cellulose(CEL),low fermentation and high viscosity of carboxymethylcellulose(CMC),high fermentation and low viscosity of pectin(LP),and high fermentation and high viscosity of pectin(HP),were incorporated into the diet respectively,which then mixed with the intestinal tissue of Chinese mitten crab.After incubating for 24h,the pH value was measured by pH metre,the content of volatile fatty acids was determined by liquid chromatography,and the intestinal microflora was analyzed by selective culture medium.The experimental results showed that:(1)The pH of all groups showed a decreasing trend after 24 h,and the range of change was CEL = CMC<LP = HP.(2)Acetic acid,propionic acid and butyric acid were detected in the fermented production,with the acetic acid was the main volatile fatty acids.No significant difference was observed among groups in content of acetic acid,propionic acid and butyric acid respectively(P>0.05).(3)There was no significant difference in the number of microflora between group of CEL and CMC(P>0.05),however,the lactic acid bacteria and bifidobacteria in the HP group were significantly higher than those in the LP group(P<0.05).These results indicated that intestinal flora of Eriocheir sinensis had different responses to the fermentation of different non-starch polysaccharides.The second experiment was to evaluate the effects of pectin in rapeseed meal on growth performance and digestive function of Chinese mitten crab.Four isonitrogenous and isoenergetic diets named diet of Fish meal,Rapeseed meal,Rapeseed meal +Pectinase and Pectin respectively,were formulated and fed to triplicate groups of Chinese mitten crab[mean initial body weight of(0.44± 0.01)g]for 8 weeks.The results showed that:(1)The weight gain rate and specific growth rate of Fish meal group and Pectin group were significantly higher than those of Rapeseed meal group and Rapeseed meal + Pectinase group(P<0.05),but there was no significant difference between Fish meal group and Pectin group(P>0.05).(2)No significant difference was observed in content of water,crude protein and crude fat among groups(P>0.05).(3)The high density lipoprotein in Rapeseed meal group was significantly lower than other three groups.(4)There was no significant difference in activity of pepsin,amylase and lipase group among groups(P>0.05),but the activity of trypsin and aspartate aminotransferase in Rapeseed meal group were significantly lower than the other three groups(P<0.05).(5)The apparent digestibility coefficient of dry matter of each group was as follows:Rapeseed meal<Rapeseed meal + Pectinase<Pectin<Fish meal(P<0.05),apparent digestibility coefficient of protein in Rapeseed meal group and Rapeseed meal + Pectinase group were significantly lower than the other two groups(P<0.05).(6)The activity of malate dehydrogenase(MDH)in Fish meal group and Pectin group was significantly higher than that in other two groups(P<0.05),content of nicotinamide adenine dinucleotide phosphate(NADPH)in Rapeseed meal group was the lowest(P<0.05),but the activity of lipoprteinlipase(LPL)in all groups showed no significant difference(P>0.05).(7)The fold area in Rapeseed meal group and Pectin group were significantly less than Fish meal group and Rapeseed meal + Pectinase group(P<0.05),but there was no significant difference in the thickness of peritrophic membrane among groups(P>0.05).(8)The gene expression of PM2 in Fish meal group were significantly lower he other two groups(P<0.05).In conclusion,the addition of 40%rapeseed meal significantly affected the digestion and absorption of Chinese mitten crab,which was partly attributed to the pectin in rapeseed meal.The third experiment was to evaluate the effects of xylan in cottonseed meal on growth performance and digestive function of Chinese mitten crab.Four isonitrogenous and isoenergetic diets named Fish meal,Cottonseed meal,Cottonseed meal + Xylanase and Xylan were formulated and fed to triplicate groups of Chinese mitten crabs[mean initial body weight of(0.44±0.01)g]for 8 weeks.The results showed that:(1)No significant difference was observed in survival rate,growth rate,specific growth rate,feed coefficient,fat and protein retention and body composition among groups(P>0.05).(2)The content of serum glucose,high density lipoprotein,low density lipoprotein and cholesterol in blood serum has no significant difference among groups(P>0.05).(3)There was no significant difference in activity of amylase,pepsin,lipase and trypsin(P>0.05),but the activity of aspartate aminotransferase in Cottonseed meal group and Cottonseed meal + Xylanase group were significantly lower than the other two groups(P<0.05).(4)The apparent digestibility coefficient of dry matter of each group was as follows:Cottonseed meal<Cottonseed meal + Xylanase<Xylan<Fish meal(P<0.05),The apparent digestibility coefficient of protein in Cottonseed meal group and Cottonseed meal + Xylanase group were significantly lower than the other two groups(P<0.05).(5)The content of bile acid in the liver of the Cottonseed mea group was significantly lower than that in the Fish meal group(P<0.05),but there was no significant difference in the content of bile acid in the serum and feces among all groups(P>0.05).(6)There were no significant difference(P>0.05)among gtoups in the activity of MDH,NADPH and LPL.(7)The fold area in Xylan group was significantly less than Cottonseed meal + Xylanase group(P<0.05),but there was no significant difference in the thickness of peritrophic membrane among groups(P>0.05);(8)The gene expression of PM2 in Fish meal group were significantly lower than the other three groups(P<0.05).In conclusion,the addition of 40%cottonseed meal significantly reduced the digestion and absorption by Chinese mitten crab,which was partly attributed to the xylan in cottonseed meal.