Research On The Effects Of Fat Level And Fat Source On The Nutrition Metabolism Of Procambarus Clarkii

OBJECTIVE: To study the effects of different lipid sources and lipid content on the growth and development of Procambarus clarkii prawns during the growth stage.The experiment carried out a comprehensive analysis by determining the growth rate,survival rate,edible part,muscle physical properties analysis,related digestive enzyme activities,serum biochemical indicators and intestinal flora composition of different groups of Procambarus clarkii in order to determine the original The optimal lipid source and fat level of crawfish artificial compound feed provide a theoretical basis.METHODS: mainly composed of two experiments.The first experiment is to determine the optimal lipid nutrition level of Procambarus clarkii.In this stage,additional 0%,2.5%,5%,7.5%,and 10% mixed oils(1: 1 mixture of fish oil and soybean oil)were added to make feed.600 tails of Procambarus clarkii(4.00 ± 1.00 g)from 27 to 32 days old after incubation with relatively uniform specifications were selected and divided into 5 groups of 40 tails in each group,with 3 repetitions.Each group was fed twice a day,and the daily feeding amount was 3% of the total body mass of the shrimp,which was reared for 60 days.Daily mortality was recorded.At the end of the stage,10 shrimp were taken from each repeat group.The growth indexes of the test subjects were recorded and the serum,hepatopancreas,intestine,stomach,and muscle of the test subjects were collected for the determination of related indexes.Through a comprehensive evaluation of the experimental results,the optimum feed crude lipid content of Procambarus clarkii during the growth stage was determined to lay the foundation for second experiment.The purpose of second experiment was to determine the optimal source of feed lipid nutrition for Procambarus clarkii.At this stage,4 different fat sources are used to make artificial compound feed,including lard,soybean oil,fish oil,and mixed oil(1: 1 mixture of fish oil and soybean oil).Use the same experimental method and sampling method as the first stage,and additionally use 16 S DNA high-throughput sequencing to determine the composition of intestinal flora in each experimental group.Through a comprehensive evaluation of the experimental results,the optimal lipid source of Procambarus clarkii during the growth stage was determined.RESULTS:1.Growth index: The level of feed fat has a significant effect on the growth index of Procambarus clarkii(p< 0.05).Each growth index presents a U-shaped change curve between the groups,and the peak values are all T3 groups;The growth indexes of crawfish were not significant(p> 0.05).Comparing the measured values of various indexes,it was found that the mixed oil group had the best growth status and the lard group had the worst growth status.2.Quality of edible parts: The level of feed fat has a significant effect on the quality of edible parts of Procambarus clarkii(p< 0.05).Except for the positive correlation between the hepatopancreas index and the level of feed fat,other indicators are inversely proportional to the level of feed fat The feed fat source had a significant effect on the Gumminess indicator of the edible part of Procambarus clarkii(p< 0.05),but had no significant effect on other indicators(p> 0.05).The edible part of the fish oil group in the four experimental groups had the best quality,and the lard group has the worst quality.3.Nutritional indicators: The level of feed fat has a significant effect on the crude fat content of edible parts of Procambarus clarkii,the ratio of polyunsaturated fatty acids,the proportion of flavored amino acids,and the total free amino acid content(p<0.05).3.The ratio of polyunsaturated fatty acids is inversely proportional to the ratio of flavored amino acids;the effect of different feed fat sources on the general nutritional indicators of Procambarus clarkii is significant in the liver and pancreas,but not in the muscles,and will cause The composition and proportion of edible fatty acids in crawfish tend to be the source of feed fat.4.Digestive enzyme activity and serum biochemical index: The level of feed fat has a significant effect on the digestive enzyme activity and serum biochemical index of Procambarus clarkii(p< 0.05).The content is directly proportional to the activity of pepsin and intestinal amylase;the difference in feed fat sources significantly affects the content of Procambarus clarkii,total cholesterol content and lipase and glutamic transaminase activity,and is the highest in lard group,and There were significant differences between the experimental groups(p< 0.05).5.Histological characteristics of hepatopancreas: The effect of feed fat level on the appearance of hepatopancreas of Procambarus clarkii is shown in its color and fullness,and it has a significant effect on the histological structure of hepatopancreas(p< 0.05),which is It is proportional to the rate of fat vacuoles;the appearance of the hepatopancreas of Procambarus clarkii will be significantly different under the influence of different feed fat sources.The difference in hepatopancreas histological structure is mainly manifested in the hepatopancreas fat empty in the lard group The bubble rate was significantly higher than other experimental groups(p< 0.05).6.Composition of intestinal flora: Different lipid sources significantly affect the relative abundance of the core phylum of Procambarus clarkii,but have no effect on the composition of the core phylum.In different experimental groups,the microbial species abundance and unique bacteria Genus species,relative abundance of common genus are significantly different(p< 0.05),the clustering relationship of intestinal flora in each experimental group is: soybean oil group> mixed oil group> lard group = fish oil group.CONCLUSION: When the feed fat source is mixed oil and the crude fat level is 7.66～ 7.67%(total energy 13179.87 ～ 13181.25 KJ / Kg),the growth index of Procambarus clarkii is the most ideal and the stability of intestinal flora is the strongest It does not significantly affect the quality of its edible parts and the health status of breeding,and the best breeding effect.But the effect of mixed oil is not significantly better than that of soybean oil group and fish oil group.Therefore,in terms of comprehensive feed production technology and raw material cost,soybean oil is the optimal fat source for artificial compound feed of Procambarus clarkii.