Study On The Effects Of A Novel Protease In Soybean Meal And Rapeseed Meal Diets For Piglets

Proteases improve animal growth performance and promote intestinal health by hydrolyzing proteins into small molecule peptides and amino acids,and promoting the digestion and absorption of proteins and amino acids.A novel protease with high stability,high acid resistance and multiple enzymatic cleavage sites has been developed.In order to apply it to industry better,this study firstly investigated the appropriate dosage of the novel protease in weaned piglets,and then evaluated the effect of the novel protease in different types of diet,so as to provide scientific basis and data reference for its application in pig diets.Experiment 1,Study on the appropriate dosage of a novel protease in weaned piglet diet.The aim of this experiment was to evaluate the effects of the novel protease on productive performance,diarrhea rate,nutrient digestibility,serum biochemistry,digestive enzyme activity,and intestinal health of weaned piglets,in order to obtain the appropriate dosage of the novel protease.A total of 96 DLY weaned piglets(28 d of age)with an average weight of 6.55 ± 0.17 kg were divided into four groups(4 pigs/pen and 6 replicates/group)according to a completely random block design.The piglets were fed corn-soybean meal type diets supplemented with 0(control),150,300 or 600 mg/kg of protease,respectively.The trial lasted 28 d.The results showed that:(1)Compared with the control group,the addition of protease had no significant effect on the growth performance and diarrhea rate of weaned piglets(P > 0.05),and the addition of 300 mg/kg protease significantly increased the apparent total intestinal digestibility of dry matter,organic matter and total energy of weaned piglets(P < 0.05),and its digestibility was quadratic with the dosage of protease(P < 0.01).Addition of 150 mg/kg of protease significantly improved the apparent ileal digestibility of Thr,His,Tyr,and Pro(P < 0.05),and the addition of 300 mg/kg of protease significantly improved the apparent ileal digestibility of Thr,Phe,Ala,His,Ser,Tyr,Pro,and Cys(P < 0.05),and the addition of 600mg/kg of protease on significantly improved the apparent ileal digestibility of Cys(P < 0.05).(2)The addition of protease significantly increased jejunal trypsin and chymotrypsin activities in weaned piglets(P < 0.01),with the highest activity of endogenous digestive enzymes shown in the pigs fed the diet with 300 mg/kg of protease.(3)The addition of protease significantly increased serum globulin(GLB)levels(P <0.05)and significantly decreased the albumin/globulin(A/G)ratio(P < 0.05).(4)The addition of protease significantly decreased duodenal chyme p H(P < 0.05)and significantly increased duodenal villus height(P < 0.05),and the addition of 600 mg/kg protease significantly increased duodenal crypt depth(P < 0.05).The mRNA expression levels of ZO-1(P < 0.01)and CLAUDIN-1(P < 0.05)in the duodenal mucosa together with ZO-1(P < 0.05)and OCCLUDIN(P < 0.01)in the jejunal mucosa of weaned piglets were significantly up-regulated by the addition of protease,but there was no significant effect on the expression levels of tight junction protein-related genes in the ileal mucosa(P > 0.05).In conclusion,the novel protease can improve the digestive enzyme activity of weaned piglets,and promote nutrient absorption and improve the morphology of small intestine.The appropriate dosage in the diet of weaned piglets is 300 mg/kg.Experiment 2,Study on the effectiveness of the novel protease in diets with different protein sources.This experiment was conducted to investigate the effects of different protein ingredient diets supplemented with the novel protease on growth performance,nutrients digestibility,and serum biochemical parameters of piglets.Thirty-two DLY pigs with an initial body weight of 21.40 ± 1.59 kg were used in a 2×2 factorial design,with the experimental factors were diet types(corn-soybean meal type and corn-soybean meal-rapeseed meal type)and protease levels(0 and 300 mg/kg),and the piglets were randomly divided into 4 groups with8 replicates per group and 1 pig per replicate.The trial lasted for 21 days.The results showed as follows:(1)Diet type and protease level had no effect on growth performance of piglets(P >0.05).(2)Compared with soybean meal type diet,the rapeseed meal type diet significantly decreased the digestibility of organic matter,crude fiber and crude protein of piglets(P <0.05).(3)Dietary supplementation of 300 mg/kg protease significantly increased the digestibility of organic matter,dry matter,crude fat,crude protein,crude fiber and gross energy of piglets(P < 0.05).(4)Compared with soybean meal type diet,the rapeseed meal type diet significantly decreased the serum urea nitrogen content of piglets(P < 0.05).(5)Diet type and protease level had no significant interaction effects on growth performance,nutrient digestibility and serum biochemical indices(P > 0.05).In conclusion,the rapeseed meal diet did not affect the growth performance of pigs,but reduced nutrient digestibility as well as serum urea nitrogen levels.The novel protease improved the nutrient digestibility reduction caused by rapeseed meal diets.In conclusion,the novel protease had no significant effect on the growth performance of weaned piglets,but improved the digestibility of amino acids and the activity of endogenous digestive enzymes,and reduced intestinal p H,improved intestinal morphology and intestinal barrier function.The addition of the novel protease to rapeseed meal diet improved nutrient digestibility and reduced pig weight gain costs.The appropriate dosage of the novel protease in piglet diets was 300 mg/kg.