Application Of Insect Protein Powder In Replacement Of Fishmeal With Chitinase On Tilapia

Insect protein powder is a new type of protein source.It has the advantages of high protein content,relatively balanced amino acid content,rich in vitamins and minerals,and good palatability.It also contains immunologically active substances that have antibacterial and antiviral effects.At the same time,insects have the advantages of rapid growth,strong fertility,feeding on biological waste,high feed conversion rate,and easy breeding.However,insect protein powder is rich in chitin and is an anti-nutritional factor in insect protein powder.Chitin is a hardly soluble biopolymer formed by the linking of N-acetylamino monosaccharides via β-1,4-glycosidic bonds,which is second only to cellulose in nature.Chitinase is a type of hydrolase that degrades chitin into low molecular weight by hydrolyzing N-acetylglucosaminide linkages.The exonuclease Chi92 belongs to one of the chitinases,which digests chitin into chitosan.Chi92 has an optimum pH of 6.0,and retains more than 58.1% of its activity at pH 4.0~9.0.The optimum temperature is40°C and it retains more than 48.8% of activity at 20~40°C.To test the effect of the enzyme preparation Chi92,insect protein powders were subjected to in vitro enzymatic hydrolysis tests at 0 U/g,4 U/g,8 U/g,and 16 U/g enzyme amounts,respectively.From the results,it was found that chitinase with different contents had enzymolysis effect on chitin,and the content of reducing sugar increased by 28.6%,40%,and 50% respectively.Therefore,Chi92 is suitable for use in aquafeeds and can effectively degrade chitin to improve the utilization of insect protein powder in feeds,enabling insect protein powders to replace fishmeal,thereby reducing feed costs and improving the production performance of aquaculture animals.To explore the breeding effect of tilapia on insect protein replacement fishmeal formulated feed,the Nile tilapia experiment was divided into 5 groups,each with 3replicates and 30 replicates each(initial weight: 1.74±0.02 g).The control group D1 was a tilapia basal diet.In the principle of equal nitrogen and other energy,the D2 and D4 groups replaced the fish meal with 3% and 6% insect protein powder respectively.The D3 and D5 groups were based on the D2 and D4 groups,respectively.Add 16 U/g of chitinase.Farmed for 56 days.The results are as follows: In terms of growth performance,the weight gain rate and specific growth rate of D3 and D5 were significantly higher than that of the control group;the weight gain rate,specific growth rate,feed coefficient,and protein efficiency of D5 were the best;the food intake of D3 was the best;Body composition,the difference between the experimental group and the control group is not significant;in terms of apparent digestibility,D3,D5 digestibility of dry matter,crude protein,crude fat of feed is significantly higher than the control group,D5 has the best effect;In the intestinal immune and antioxidant capacity,D3,D5 significantly increased GPx,GST,GSH,LZ,ACP,D3 significantly increased CAT,GR and decreased MDA,including D3 MDA,CAT,GR,GST,GSH,LZ,ACP The best effect of D5 was GPx.The serum level of HDL-C,LDL-C,GLU,GSP,TBA,TC,TG,SOD,MDA,and GPx was not significantly different from that of the control group.In general,D3 and D5 are better than D2 and D4.In summary,insect protein powder can increase tilapia growth rate,specific growth rate,food intake,protein efficiency,reduce feed coefficient,improve tilapia nutrient composition,apparent digestibility,immunity and anti-nutrient ability.Chitinase Chi92 is more effective on the basis of insect protein powder,of which d3 is the best.It shows that insect protein powder can promote the growth and health of tilapia,while chitinase Chi92 can effectively degrade chitin and eliminate anti-nutritional factors.The research results laid the foundation for the further study of the mechanism of insect protein powder and chitinase on the physiological and biochemical characteristics of fish,and provided a theoretical basis for the development of high-efficiency formulated aquatic feed based on insect materials.