Effects Of Single Or Combined Supplementation Of Probiotics And Enzymes In High Protein Diet On Growth Performance,Nutrient Digestibility And Intestinal Health In Weaned Piglets

Protein is an essential nutrient for piglet growth.Early weaned piglets have high protein requirements.However,due to the high cost of high-quality protein sources and possible biosafety issues,it may be necessary to use soybean meal,a common plant protein source,to provide piglets with an appropriate level of intact protein to meet the growth and development needs of piglets.However,excessive undigested proteins in soybean meal can cause intestinal health problems in hindgut fermentation.At present,there is a lack of research on the effects of probiotics and protease alone or in combination on the growth performance,nutrient digestibility and intestinal health of weaned piglets in high protein diets.Therefore,this study evaluated the effects of single or combined supplementation of probiotics and proteases in high-protein diets on growth performance,nutrient digestibility,immune performance,the level of hort-chain fatty acid and intestinal microorganisms of weaned piglets through animal experiments,and sought a high-protein diet regimen for weaned piglets without antibiotics.The experiment adopted randomized block design.A total of 160 weaned piglets(21 ±2 d,initial body weight of 6.12 ± 0.3 kg)were randomly assigned to 4 treatment groups with8 replicates per treatment and 4 piglets per replicate.The experiment lasted for 21 days,plasma samples were collected on d 8 of the experiment,and samples were collected on d22 after fasting weighing.Piglets in each group were fed the following diets: 1)LP: lowprotein diet;(2)HP: high-protein diet;(3)HPPRO: high-protein diet supplemented with 300mg/kg probiotics;(4)HPPRS: high-protein diet supplemented with 300 mg/kg protease;(5)HPPRO+PRS: high-protein diet supplemented with 300 mg/kg probiotics and 300 mg/kg protease.The results showed that compared with LP group,on d 15 and d 22 of the experiment,the body weight of piglets in HPPRO group and HPPRO+PRS group was significantly increased(P < 0.01),and the ADG and ADFI of piglets in HPPRO+PRS group were significantly higher than those in LP group on d 8-14,d 15-21 and the whole period,while the ADG and ADFI of piglets in HPPRO group were significantly higher than those in LP group only during d 8-14 and the whole period.In addition,F:G in HPPRO+PRS group was lower than that in LP group(P = 0.08).Compared with LP group,the diarrhea index of piglets in HP group was significantly increased during d 8-14,d 15-21 and the whole period(P < 0.01),while probiotics or / and protease were added to high protein diet to alleviate diarrhea.Compared with LP group,the apparent digestibility of Thr,Met and Lys in HP group decreased(P < 0.05).Compared with HP group,the apparent digestibility of dry matter,protein,energy and amino acids(Asp,Glu,Gly,Phe,Thr,Ser,Lys)in HPPRO group was significantly increased(P < 0.05),and the apparent digestibility of Ala,Leu,Val and Ile tended to increase(P = 0.05).Compared with LP group,the crypt depth of piglets in HP group and HPPRO group increased significantly(P < 0.05),while the villus length of piglets in HPPRO group increased significantly(P < 0.05).The results of 16 s r RNA highthroughput genome sequencing of colon microbes showed that the relative abundance of Proteobacteria in the colon microbes of HPPRO group was lower than that of LP group(P= 0.06),while Fusobacteriota was higher than LP group and HP group(P = 0.09).At the phylum level,the abundance of Fibrobacterota in the colon of piglets in the HPPRO group was significantly higher than that in the LP group(P < 0.05).At the genus level,compared with the LP group,the abundance of Megasphaera in the colon of piglets in the HP group was significantly increased(P < 0.05);the abundance of Agathobacter,Foumierella,Anaerostipes,Collinsella,Fibrobacter,Lachnospira,Mogibacterium,LachnospiraceaeUCG-009 in the colon of HPPRO group was significantly increased(P < 0.05),and the abundance of Oribacterium tended to increase(P = 0.05).In addition,the abundance of Clostridium＿sensu＿stricto＿1,UCG-005,NK4A214＿group,Christensenellaceae＿R-7＿group and Eubacterium＿ruminantium＿group in the colon of piglets in HPPRO group was significantly higher than that in HP group(P < 0.05).In conclusion,high protein diet can increase the diarrhea index of piglets,which may be related to the damage of intestinal morphology,the decrease of nutrient digestibility and the increase of pathogenic bacteria.The addition of probiotics and protease alone or in combination in high protein diets improved the growth performance of piglets,reduced the diarrhea index of piglets,increased nutrient digestibility,and reduced the number of harmful bacteria.