Effects Of Dietary Protein And Lipid Levels On The Growth,Immunity And Amino Acid Composition Of Portunus Trituberculatus

Portunus trituberculatus is an important breeding species in the coastal areas of my country.Portunus trituberculatus not only cannibalize each other,but also rely on fresh feed during the breeding process.This results in poor breeding quality,stability and burden on marine resources of Portunus trituberculatus.Therefore,it is imperative to found a compound feed with equal energy and lipid and a breeding method suitable for Portunus trituberculatus.A new hanging cage culture method was used to study the effects of the interaction of different lipid levels and protein levels on the growth,immunity and muscle amino acid composition of Portunus trituberculatus.The research and development of feed provides a theoretical basis.The main research is divided into three parts:1.The effects of the lipid levels and protein levels on the growth and the body shape of Portunus trituberculatusUsing 3×2 two-factor design,one hundred and five crabs with initial weight of63.85±1.19 g were randomly divided into 7 groups,each group had 3 repetitions.The feeding trial lasted for 56 days.six diets were formulated with three protein levels of 40%,38%,36%and two lipid levels of 5%.10%,and fresh bait(Philippine clams)as the control group.The results showed that dietary protein and lipid level and the interaction of the two significantly affected the growth performance of portunus trituberculatus.The weight gain rate(WGR),specific growth rate(SGR),and protein efficiency(PER)at 38% protein level were significantly higher than other groups,the feed conversion rate(FCR)was the lowest(p<0.05),WGR and SGR in the 5% lipid level group were significantly higher than 10% group(p<0.05),while PER was the opposite.The growth performance of crab fed diets containing 38%protein and 5% lipid were not significantly different from the control group(p>0.05).The carapace length increased(CLG)and the carapace height increased(CHG)of Portunus trituberculatus at 5% lipid level were significantly higher than those at 10% level group(p<0.05),and the hepatopancreas index(HI)was the opposite.Carapace width increased(CWG),CLG,CHG at 36% protein level were significantly higher than 40% group,and the hepatopancreas index(HI)at 38% protein level was significantly lower than 36% and 40%groups(p<0.05).In summary,under the experimental conditions,the growth performance and PER of Portunus trituberculatus in the 38% protein and 5% lipid level group have advantages than the live group.2.The effect of feed protein and lipid level on immunity,antioxidant,hepatopancreas function and lipoprotein deposition of Portunus trituberculatusThrough the above experiments,the results showed that dietary protein and lipid level and the interaction of the two significantly affected the immune index,antioxidant index,liver function and lipoprotein deposition of Portunus trituberculatus.The acid phosphatase(ACP),alkaline phosphatase(AKP)activities in the blood and the aspartate aminotransferase(GOT)and alanine aminotransferase(GPT)activities in the hepatopancreas at 36% protein level were significantly higher than others(p<0.05).Superoxide dismutase(SOD)and catalase(CAT)activity in the blood at 36% and 38% protein levels were significantly higher than 40%groups.The HDL-C content in the blood and hepatopancreas and GOT activity in the blood at38% protein levels were significantly higher than 36% levels(p<0.05).The LDL-C content in the hepatopancreas and blood at 40% protein level was significantly lower than other protein levels(p<0.05),and the hepatopancreas SOD activity reached the maximum.The CAT,GOT activities,malondialdehyde(MDA),high-density lipoprotein cholesterol(HDL-C)content in the blood and GOT,GPT activity,HDL-C,cholesterol content(T-CHO),triglyceride(TC)content in the hepatopancreas at 10% lipid levels is significantly higher than 5% levels(p<0.05),GPT activity in the blood and low-density lipoprotein cholesterol(LDL-C)content in the hepatopancreas is the opposite.In summary,under the experimental conditions,feeding the compound feed significantly improved the immunity and antioxidant level of Portunus trituberculatus,and the hepatopancreas function level of Portunus trituberculatus at 10%lipid levels were most similar to the fresh feed group.3.The effect of feed protein and lipid level on muscle nutrition of Portunus trituberculatusThrough the above experiments,the results showed that dietary protein and lipid level and the interaction of the two significantly affected the muscle body composition and amino acids of Portunus trituberculatus.Crude lipid,crude protein,and crude ash of muscle at 38%protein levels were significantly higher than 36% levels(p<0.05),and crude protein at 10%lipid level group were significantly higher than 5% groups(p<0.05).In terms of amino acid composition,essential amino acids(EAA)content in the fresh group was the highest and was significantly higher than 40% protein and 10% lipid level group(p<0.05),and there was no significant difference between the other treatment groups(p>0.05).Non-essential amino acids(NEAA)at 36% protein and 5% lipid level group reached the highest value and was significantly higher than the fresh group(p<0.05).The ratio of essential amino acids to total amino acids(EAA/TAA)was the highest in the fresh group and was significantly higher than each feed group(p<0.05).In summary,under the experimental conditions,excessive protein and lipid levels affect the composition of amino acids.The body composition and amino acid deposits at 36% protein and 5% lipid level groups of Portunus trituberculatus are similar to the fresh feed group,and the body composition at 38% protein and 5% lipid level group was the most similar to the fresh feed group.The results of the above growth indicators,biochemical indicators and amino acid composition show that under the experimental conditions,the growth,feed conversion rate and body composition at 38% protein and 5% lipid level group of Portunus trituberculatus have advantages over the fresh group.The amino acid deposition at 36% protein level and 5%fat level was similar to the fresh group,and the immunity of Portunus trituberculatus in the fresh group was worse than the feed group,And the survival rate of tricwart spindle crab under suspension breeding conditions is greatly improved.