Dietary Lipids Nutritional Physiology In Redclaw Crayfish,Cherax Quadricarinatus

In this study,the lipid nutritional requirements of Cherax quadricarinatus were systematically studied by using traditional nutrition,biochemistry,molecular biology,microscopy and modern omics techniques.The results can provide theoretical guidance for the research and development of special compound feed for C.quadricarinatus.The results are summarized as follows:1 Growth,antioxidant capacity,and lipid metabolism of juvenile red claw crayfish,Cherax quadricarinatus,fed different lipid sourcesJuvenile C.quadricarinatus were used as the research object(initial average weight:5.83 ± 0.29 g).Five dietary lipid sources(fish oil,soybean oil,palm oil rapeseed oil,and linseed oil)were evaluated in juvenile red claw crayfish,C.quadricarinatus based on the response of growth,antioxidant capacity,intestine histology,whole-body composition,fatty acids nutrition,and lipid metabolism.Crayfish were fed in quadruplicate net cages for eight weeks.Crayfish fed diets with fish oil,soybean oil,and linseed oil obtained significantly higher weight gain and specific growth rate than those fed the other two diets.Survival,condition factor,and hepatosomatic index were not significantly affected by lipid sources.Lipid sources also do not affect the whole-body composition of crayfish.Serum SOD,TAOC,and GSH-PX activities of crayfish fed the palm oil and rapeseed oil diets had a significantly lower value than those fed other diets.The minimum concentrations of MDA have been observed in crayfish fed the soybean oil diet.The activity of ACC in the hepatopancreas of crayfish fed the linseed oil diet showed the highest value,and the CPT-1activity was not significantly affected by different lipid sources.Crayfish fed the soybean oil diet showed significantly higher TC and TG contents in the hepatopancreas than those fed other diets.Most of the fatty acid compositions in the hepatopancreas had a close correlation to fatty acid compositions in diets.All findings in this study indicate that soybean oil is the advantage lipid source for juvenile C.quadricarinatus which can reflect satisfactory growth performance and antioxidant capacity.2 Growth,antioxidant capacity,lipid metabolism,and gut health of juvenile red claw crayfish,Cherax quadricarinatus,fed different lipid levelsOn the basis above,soybean oil was selected as the main lipid source.Juvenile C.quadricarinatus were used as the research object(initial average weight: 11.39 ± 0.28 g).C.quadricarinatus were fed in quadruplicate net cages for 8 weeks.This study evaluated the effects of different lipid levels(4.32%,6.30%,8.33%,10.39%,12.23%,and 13.97%)on growth performance,antioxidant capacity,whole-body composition,lipid metabolism,intestinal histology,intestinal digestive enzyme and gut microbiota of juvenile C.quadricarinatus.Results indicated that through the second-order polynomial regression equation analysis of weight gain and specific growth rate,9.70% dietary lipid level proved maximal growth of the C.quadricarinatus.Survival,condition factor,and hepatosomatic index were not significantly affected by lipid levels.Lipid levels also did not affect the whole-body composition of crayfish.With the increase of dietary lipid level,serum T-AOC and GSH-PX were firstly increased and then decreased,and the highest enzyme activities were found in the 10.39% lipid level group,the lowest activity of SOD was found in the4.32% lipid level group,and there was no significant difference in the content of MDA among all treatment groups.The activities of Lipase and Pepsin were the highest in the 10.39%lipid level group,but there was no significant difference in the activities of Amylase.There was no significant difference in ACC and CPT-1 contents among all treatment groups.The gut microbiota in each treatment group was significantly aggregated,and the separation of gut microbiota in the 13.97% lipid level group was more obvious than that in the other two groups.The above results indicate that the dietary lipid level was 9.70%,the best growth performance of C.quadricarinatus was obtained.10.39% dietary lipid level could obtain better antioxidant ability and digestive enzyme activity compared with other lipid levels.Dietary with different lipid levels had no significant effect on lipid metabolism of C.quadricarinatus.The composition,structure,and diversity of the gut microbiota of C.quadricarinatus were changed by a high level of diet.3 Growth,antioxidant capacity,lipid metabolism,and gut health of juvenile red claw crayfish,Cherax quadricarinatus,fed different cholesterol,and lecithin levelsJuvenile C.quadricarinatus were used as the research object(initial average weight:11.39 ± 0.28 g).C.quadricarinatus were fed in quadruplicate net cages for 8 weeks.The experimental diet supplemented with 0 % cholesterol and 0% lecithin was used as the control group.2 × 3 experiments were designed to evaluate the effects of cholesterol levels(0.5%and 1%),lecithin level(1%,2%,and 3%),and their interaction on growth performance,antioxidant capacity,whole-body composition,lipid metabolism,intestine histology,intestinal digestive enzyme and gut microbiota of juvenile C.quadricarinatus.Results indicated that the cholesterol was 0.5% and lecithin was 2%,crayfish had the greatest weight gain and specific growth rate.Survival,condition factor,and hepatosomatic index were not significantly affected by dietary cholesterol and lecithin.Cholesterol and lecithin also do not affect the whole-body composition of crayfish.The cholesterol level was 0.5% and lecithin was 2%,SOD activity and T-AOC were the highest,and MDA content was the lowest.The cholesterol level was 0.5% and the lecithin was 2%,Pepsin had the highest enzyme activity,while Amylase had the highest enzyme activity and interaction when the cholesterol level was 1% and the lecithin was 2%.When cholesterol level was 1% and lecithin was 2%,ACC content was the lowest and interaction existed,but there was no significant difference in CPT-1 content between groups.The above results indicate that the cholesterol level was 0.5%and the lecithin was 2%,the crayfish had better growth performance,antioxidant capacity,and digestive enzyme activity.Dietary cholesterol and lecithin levels had no significant effects on the lipid metabolism of C.quadricarinatus.Proteobacteria,Firmicutes,and Actinobacteria dominate the gut microbiota of C.quadricarinatus,and the composition and structure of gut microbiota were affected by diets with different levels of lecithin,but the metabolic function of gut microbiota was not affected.