Effects Of Fermented Feed On Growth Performance,Meat Quality And Colon Microbiota In Finishing Pigs

The fermented feed was used its own characteristics of probiotics that utilizes feed as a fermentation substrate for fermentation in anaerobic or facultative anaerobic environment,resulting in a large amount of lactic acid,volatile fatty acids and other organic acids,and other metabolites.Such fermented feed has good potential in pig breeding.Studies have been mainly focused on the application of weaned piglets,and there are few studies on the effect of fermented feed on the growth performance,carcass traits and the composition of intestinal microbiota in finishing pigs.Therefore,we conducted relevant animal experiments.The study is divided into three parts.1.Effect of compound bacteria fermentation on nutrient content in feedThe study aimed to compare the nutritional composition of the fermentation feed produced by natural fermentation and compound bacteria fermentation.This study prepared the compound bacterial liquid with the ratio of lactobacillus:bacillus:yeast=2:2:1.The complete feed of finishing pig was used as the substrate for fermentation.0.2%of the compound bacterial liquid was added to the TR group,and sterile distilled water was added to the CON group.The feed of two groups were fermented at 37? for 48 hours at constant temperature.After fermentation,the crude nutrients such as crude protein,crude fat and crude fiber were determined.The disappearance rate of dry matter,the content of lactic acid and pH were measured.The results showed that there was no significant difference in the contents of conventional nutrients between between groups(P>0.05),but the number of yeasts significantly increased(P<0.05).The pH in the CON group was significantly lower than the TR group(P<0.05).And concentrations of acetate,butyrate,and TVFA were significantly higher than the TR group(P<0.05).The results showed that microorganisms inoculation had no significant effect on the conventional nutrient content of feeds.However,the number of beneficial bacteria and propionate concentration increased,the butyrate concentration reduced in the fermented feed,the feed quality can be improved.2.Effect of fermented feed on the growth performance,longest muscle quality and blood metabolites of finishing pigsThis study applied metabolomics techniques to study the effects of fermented feeds on the blood metabolites,carcass traits,routine biochemical index and meat quality of finishing pigs.Twenty-four ternary crossbred pigs weighted 60kg were randomly divided into two groups:basal diet group(CON group)and fermented feed group(TR group).Each group had 4 replicates and 3 pigs were repeated.The CON group was fed a full basal diet,and the TR group was fed 80%basal diet and 20%fermented feed(the composition of the fermentation substrate was the same as the basal diet).The pre-feeding period continued for 6 days and the trial period last for 29 days.Combined with the partial least squares-diacriminant analysis(PLS-DA),the major metabolic changes in blood between the pigs of CON group and TR group were detected by UPLC QTof/MS.Using the longissimus dorsi muscle to measure the changes of meat quality.The results showed that there was a significant difference in metabolism between the CON group and the TR group.Major differential metabolites included pyroglutamic acid,xanthine,eugenol,acrylamide and p-coumaric acid which mainly involved in amino acid metabolism and lipid metabolism.Compared with the control group,there was no significant difference on the dressing percentage of finishing pigs(P>0.05),but TR group significantly reduced the backfat thickness and significantly improved the red back muscles,meat color score and tenderness(P<0.05).The results showed that the fermented feed changed the body metabolism,increase the longest muscle color score and tenderness,and improve the meat quality of finishing pigs.3.Effect of fermented feed on colonic fermentation and microbial composition in finishing pigsThis study was carried out to investigate the effect of combined microbial fermented feed on colonic fermentation and microbial composition of colon mucosa and digesta in finishing pigs.The experiment design was the same with the second study,colon mucosa and content samples were collected.The gas chromatography was used to measure volatile fatty acid(VFA)concentration.Illumina MiSeq platform was used to detect community structure and diversity of the microflora of colonic mucosa and digesta.Fermented feed had no significant effect on microbial diversity of colonic mucosa and digesta(P>0.05),while increased the relative abundance of Weissella and Faecalibacterium in colonic mucosa at genus level(P<0.05).The relative abundance of Weissella and Subdoligranulum in TR group were higher in colonic digesta(P<0.05)compared with the control group.No significant difference was observed in pH,lactate,acetate,propionate,isobutyrate,valerate,isovalerate and total VFA concentration between the two groups(P>0.05),while butyrate concentration was greater in TR group(P<0.05).Results showed that fermented feed could affect the composition of colonic microflora and promote the formation of colonic butyric acid in finishing pigs,which improve the intestinal health.