Effects Of Lactobacillus Delbrueckii On The Digestion And Absorption Of Dietary Nutrients In Growing Pigs

Lactic acid bacteria play an important role in regulating the intestinal microecological balance and the digestion and absorption of pig nutrients.This experiment was conducted to investigate the effects of feeding Lactobacillus delbrueckii on intestinal nutrient digestion and absorption of growing pigs and the potential mechanism of microorganisms.The research results will provide a theoretical basis for the development of Lactobacillus delbrueckii and its application in livestock production.Ten healthy hybrid(Landrace×Yorkshire)growing pigs(male)with an average body weight of 37.29±2.38 kg were randomly divided into 2 groups with 5 replicates per group and 1 pig per replicate,which were control group and Lactobacillus delbrueckii group,respectively.The others in the control group were fed a basal diet without resistance,and the others in the Lactobacillus delbrueckii group were fed the basal diet without resistance with0.1% Lactobacillus delbrueckii preparation.The pre-feeding period was 7 days,and the experiment lasted for 28 days.Feces were collected on days 25-27,and then slaughtered after blood collection in the anterior vena cava on day 28.Intestinal mucosa and contents were collected,and relevant indexes of serum and intestinal mucosa and contents were determined.The test results are as follows:1)Effects of Lactobacillus delbrueckii on growth performance and apparent digestibility of growing pigs.There was no significant difference in growth performance between the control group and the Lactobacillus delbrueckii group(P>0.05);compared with the control group,the apparent digestibility of EE in Lactobacillus delbrueckii group was significantly increased(P<0.05),the apparent digestibility of CP had a tendency to increase(P=0.094);the activity of pepsin in the stomach was significantly increased in Lactobacillus delbrueckii group(P<0.01);In jejunum,the activities of amylase and chymotrypsin were significantly increased in Lactobacillus delbrueckii group(P<0.05),significantly increased the trypsin activity(P<0.01),the lipase activity tended to be enhanced(P=0.053);In ileum,compared with the control group,the activity of lipase was significantly increased in the Lactobacillus delbrueckii group(P<0.05),the amylase activity tended to be enhanced(P=0.074);In pancreas,the activities of lipase and trypsin were significantly increased in the Lactobacillus delbrueckii group(P<0.05),there was no significant difference in the activities of amylase and chymotrypsin(P>0.05).These results indicate that Lactobacillus delbrueckii can improve the digestive enzyme activity in the gastrointestinal tract,thus promoting the digestion and absorption of nutrients.2)The effect of Lactobacillus delbrueckii on nutrient absorption and transport in growing pigs.Compared with the control group,crypt depth of duodenum,jejunum and ileum mucosa in Lactobacillus delbrueckii group was significantly decreased(P<0.01);the ratio of villus height to crypt depth(V/C)in duodenum and ileum was significantly increased(P<0.05),jejunum V/C value was significantly increased(P<0.01);the villus height of jejunum was significantly increased(P<0.05).Amino acid analysis showed that the plasma contents of His,Ala and Ile were significantly decreased in the Lactobacillus delbrueckii group(P<0.05),the contents of Pro and Leu were extremely significantly decreased(P<0.01),and the content of Arg had a decreasing trend(P=0.061).Compared with the control group,the contents of Ser,Arg,Asp,Glu,Ala,Cys,Tyr,Met,Leu and Phe in ileum contents of Lactobacillus delbrueckii group were significantly decreased(P<0.05),and the contents of Arg and Ala were extremely significantly decreased(P<0.01),the contents of Pro(P=0.051)and Lys(P=0.050)had a decreasing trend.The contents of Ser,Gly,Asp,Glu,Ala,Cys,Tyr,Met and Leu in ileal mucosa of Lactobacillus delbrueckii group were significantly increased(P<0.05),the contents of Cys and Tyr were extremely significantly increased(P<0.01),the contents of Thr,Phe and Trp tended to increase(0.05<P<0.10).The m RNA expression levels of SLC7A7,SLC1A5,SLC6A19 and SLC7A9 in ileum mucosa of Lactobacillus delbrueckii group were significantly increased(P<0.05),SLC15A1 m RNA expression had a tendency to increase(P=0.083).This indicates that Lactobacillus delbrueckii can improve the morphology of the small intestinal mucosa,increase the expression level of nutrient transporter genes in the ileal mucosa,and promote the absorption of nutrients.3)Effects of Lactobacillus delbrueckii on ileum microbiota of growing pigs.Lactobacillus delbrueckii significantly increased ileum microbiota Chao1 and ACE index(P<0.05),PD＿Whole＿tree index had a tendency to increase(P=0.098).Lactobacillus delbrueckii increased the abundance of ileal microorganisms such as Proteobacteria,Enterococcus,Lactobacillus,Clostridiales,and Peptostreptococcaceae.Meanwhile,Turicibacter was positively correlated with CP apparent digestibility(P<0.01).Akkermansia was negatively correlated with ileum trypsin and chymotrypsin activity(P<0.05).Clostridium was positively correlated with the activities of ileal lipase and amylase(P<0.05).Enterococcus and Pediococcus were positively correlated with SLC15A1 m RNA expression in ileal mucosa(P<0.05).Enterococcus and Lactobacillus were positively correlated with SLC1A5 m RNA expression in ileal mucosa(P<0.05).Bacteroides and Lachnospiraceae were positively correlated with SLC7A1 m RNA expression in the ileal mucosa(P<0.05).In conclusion,Lactobacillus delbrueckii can improve the digestion and absorption of nutrients by growing pigs by improving the morphology of the intestinal mucosa,increasing the activity of digestive enzymes and the expression level of nutrient transporter genes in the ileal mucosa.The mechanism of action may be related to Lactobacillus delbrueckii’s ability to improve intestinal microecological balance,increase the abundance of lactic acid bacteria and improve intestinal health of growing pigs,as well as the decrease in the abundance of Akkermansia and the increase in the abundance of Turicibacter,Clostridium,Enterococcus,Piococcus and Lachnospiraceae.