Effects Of Protease On Growth Performance,Ileal Amino Acids Digestibility And Gut Health In Weaned Piglets

For the better application of protease,two experiments have been included in the study.First,the effect of protease on ileal amino acid digestibility in weaned pigs was investigated.Based on the results of experiment 1,protease was supplemented to corn-soybean meal diets with different levels of soybean meal,to explore the impact on growth performance,nutrient digestibility and gut health.This study provided scientific basis and reference data for protease application in low protein corn-soybean meal diets.Experiment 1.effect of protease on ileal digestibility of amino acids in weaned pigletThe objective of this study was to determine the effect of a protease on apparent(AID)and standardized(SID)ileal digestibility of crude protein(CP)and amino acids(AA)in weaned piglets.Eighteen barrows with initial body weight(BW)of 13.5±0.2 kg were randomly allotted to 3 diets(control,protease diet,and nitrogen-free diet)with 6 piglets per diet after fitting with a T-cannula in the distal ileum.Control and protease diets were corn-soybean meal based diet supplemented with or without 200 mg/kg of protease.The nitrogen-free diet was used to measure basal endogenous losses of AA.The experiment lasted 7 d,and ileal digesta were collected on d 6 and 7.Results showed that the coefficients of AID and SID of CP and total AA were increased by protease supplementation(P<0.05).For indispensable AA,the coefficients of AID of Ile,Lys,Met and Thr,and the coefficients of SID of Ile,Lys,Met,Thr and Trp were increased by protease(P<0.05).For dispensable AA,both the coefficients of AID and SID of Ala,Asp,Cys,Gly and Ser were increased by protease(P<0.05).Experiment 2.effect of protease on growth performance,nutrient digestibility and gut health in weaned piglets fed diets with different levels of soybean meal.One hundred and twenty 28-day-old piglets with BW of 7.49±0.51 kg were used in a 2X3 factorial experiment for 42-d to evaluate the effect of protease in diets with different levels of soybean meal(SBM)on growth performance,nutrient digestibility and gut health.The factors were soybean meal levels(control vs low SBM level)and protease levels(0,150 or 300 mg/kg).Pigs were randomly allotted to 6 treatments with 5 replicate pens and 4 pigs per pen according to their initial BW.Parts of samples were taken on d 14 when pigs euthanized,and fecal samples were taken at the digestion test from d 38 to 41 using endogenous indicator.Results showed:1.The low SBM level diets reduced ADFI(P<0.01),ADG(P<0.01),and G:F(P<0.01)throughout the experiment,except the G:F from 29 to 42 d(P>0.05).Protease improved ADG(P<0.05)and G:F(P<0.01)from 1 to 14 d and G:F from 1-42 d(P<0.05),there were interactions between SBM level and protease in ADFI and ADG from 29-42d(P<0.01),ADG from 15-42d(P<0.05).2.Low SBM level diets decreased diarrhea incidence from 1-14d,15-42d,1-42d(P<0.05).Protease decreased the diarrhea ratio from 1-42d(P<0.05).There was no SBM level×protease interaction in diarrhea incidence(P>0.05).3.Low SBM level diets lowered the digestibility of DM,CP,ash,OM and GE(P<0.01),protease supplemented to different SBM level diets increased the digestibility of these nutrients(P<0.05),and their interactions had significant influence on nutrient digestibility(P<0.05).4.Protease significantly reduced serum urea nitrogen(P<0.05),and increased IGF-1(P<0.05).5.Control SBM level diets had greater organ index(P<0.05)compared with low SBM level diets,protease promoted pancreas and small intestine index(P<0.05),there was an interaction between SBM level and protease in pancreas index(P<0.05).6.Low SBM level diets was significantly decreased duodenum villus height(P<0.01),the ratio of villus to crypt(P<0.01),also reduced villus height and crypt depth in ileum(P<0.01),protease supplemented to control and low SBM diets significantly reduced crypt depth in duodenum(P<0.05),the ratio of the ratio of villus to crypt(P<0.01),and the ratio of villus to crypt of jejunum and ileum were also significantly improved(P<0.01),there was an significant interaction between SBM level and protease in ileum villus height(P<0.01).7.Low SBM level diets lowered the activity of chymotrypsin in ileal digesta(P<0.05),protease increased the activities of trypsin and chymotrypsin(P<0.01),and there was an interaction between SBM level and protease in both enzyme activity(P<0.01).8.Low SBM level diets increased total bacterial in cecum(P<0.05),Bacillus and total bacterial in colon(P<0.01).Protease had no effect on microflora(P>0.05),and there was no interaction in gut microflora(P>0.05).9.Low SBM level diets greatly reduced acetic acid,butyrate acid,total VFA and VBN in cecum(P<0.01),protease significantly improved acetic acid,propionic acid,butyrate acid and total VFA in cecum(P<0.01),acetic acid,butyrate acid and total VFA in colon(P<0.01),there was an interaction between SBM level and protease in acetic acid,propionic acid,butyrate acid and total VFA of cecum and butyrate acid in colon(P<0.05).Low SBM level diets lowered VBN content in cecum and colon(P<0.01),while no significant influence was found on VBN(P>0.05),there was no interaction between SBM level and protease(P>0.05).Protease supplemented to different SBM level diets increased growth performance,nutrient digestibility,gut growth and health in weaned piglets.In summary,protease increases the digestibility of CP and most amino acids in weaned pigs,and protease in normal SBM level and low SBM level diets improves growth performance,decreases the diarrhea incidence,improves intestinal development and health.