| On July 9th,2019,the Ministry of Agriculture and Rural Affairs issued a notice No.194 to prohibit the addition of antibiotics in feed.It is urgent to find a safe and harmless substitute for antibiotics.Lactobacillus is a functional additive,which is universally recognized as food-grade probiotics.It has many advantages,such as wide source,high safety,non-toxic and so on.The metabolites of Lactobacillus also have similar biological activities with Lactobacillus,such as antioxidant,antitumor,immunity regulation and so on.Therefore,in this study we compared and analyzed the differences among Lactobacillus and its live bacteria,metabolites on production performance,antioxidant capacity,immunity,intestinal permeability and fecal microbial community of weaned piglets,which can provide more information for the application of Lactobacillus and its metabolites in weaned piglets.Experiment 1:Identification of Lactobacillus cqf-43,extraction of its metabolites and analysis of antioxidant activity in vitro.In this study,the strain of Lactobacillus cqf-43 preserved in our laboratory was identified by 16s r RNA gene sequencing.After that,crude extracellular polysaccharide（c-EPS）was extracted from the bacterial liquid.The scavenging rate of c-EPS on DPPH free radical,hydroxyl free radical and the reducing power of c-EPS were measured.The results showed that the strain was Lactobacillus plantarum cqf-43.The scavenging rate of c-EPS for DPPH free radical and hydroxyl free radical increased gradually with the increase of its concentration.When the c-EPS was 10 mg/m L,the scavenging rate of DPPH free radical and hydroxyl free radical reached 67%and 44%respectively.Moreover,the reducing power of c-EPS increased with its concentration.In conclusion,the results indicated that c-EPS has a good antioxidant capacity in vitro.Experiment 2:Effects of Lactobacillus cqf-43 and its metabolites on production performance,antioxidant capacity,immunity,intestinal permeability and fecal microbiota of weaned piglets.120 healthy 28-day-old Duroc×Landrace×Large weaned piglets with the body weight of 8.20±0.81kg were randomly divided into 4 groups with 6 replicates per group and 5 pigs per replicate.Weaned piglets in the control group（CON）were fed with basal diet,and the weaned piglets in bacterial liquid group（BL）were fed the basal diet supplemented with 1%Lactobacillus cqf-43 bacterial liquid,the weaned piglets in bacterial body group（BB）were fed the basal diet supplemented with 1%Lactobacillus cqf-43 bacterial body,the weaned piglets in metabolites group（ME）were fed the basal diet supplemented with 1%Lactobacillus cqf-43 metabolites.The pre-feeding period of this experiment was 3 days,and the trial period was 42 days.All weaned piglets were fed at 08:00,13:00 and 19:00,and the feed consumption was recorded.During the experiment period,all weaned piglets were weighed before feeding at 09:00 AM on the first day and on the 43rd day,respectively.Diarrhea of piglets was recorded at 09:30 AM and 14:30 PM every day.From the 40th to 42nd day,200 g feces of piglets were collected and were fully mixed,which was used to determine the apparent digestibility and microbial composition of feces.Piglets were fasted at 12:00 PM On the 42nd day,and blood samples were collected from the anterior vena cava on the 43rd day,to detect the serum biochemical,antioxidant,immunity and intestinal permeability indicators.The results showed as follows:（1）There was no significant difference in feed intake among the three supplementation groups compared with the CON group（P>0.05）,the BB group increased the daily weight gain of weaned piglets（P<0.05）;There was no significant difference in daily gain among each supplementation group.Compared with the CON group,the ratio of feed to gain of weaned piglets was significantly increased in the supplementation groups（P<0.01）,and there was no significant difference in the ratio of feed to gain in each supplementation group.（2）All supplementation groups significantly reduced the diarrhea index（P<0.01）and diarrhea rate（P<0.01）of weaned piglets compared with the CON group,while there was no significant differences in diarrhea index and diarrhea rate in each supplementation group.（3）There was no significant difference in the apparent digestibility of ASH,EE,Ca,TP,and CP among the three supplementation groups compared with the CON group（P>0.05）.（4）There was no significant differences in the serum ALT,AST,ALP,AST/ALT,TP,ALB,GLO,A/G,BUN,CREA,TC,TG,HDL,and LDL among the three supplementation groups compared with the CON group（P>0.05）;（5）There was no significant difference in serum T-AOC and MDA among the three supplementation groups compared with the CON group（P>0.05）.The BL group significant increased the SOD content in weaned piglet serum（P<0.01）,and the SOD content in the BL group was significant higher than BB group and ME group（P<0.01）.Compared with the control group,the BB group and ME group significant increased the serum GSH-Px content of weaned piglet（P<0.01）,and the GSH-Px content in the BB group and ME group was significant higher than BL group（P<0.01）.（6）There was no significant difference in serum Ig A,Ig G,Ig M,IL-6,and IL-10 among the three supplementation groups compared with the CON group（P>0.05）.Both the BL group and ME group significant increased the IL-2 content in the serum of weaned piglet（P<0.01）,and the IL-2 content in the BL group and ME group was significant higher than BB group（P<0.01）.Compared with the CON group,the BL group increased the TNF-αcontent in the serum of weaned piglet（P<0.05）,and the TNF-αcontent in BL group and ME group was higher than BB group（P<0.05）.（7）There was no significant difference in serum D-LA among the three supplementation groups compared with the CON group（P>0.05）.The BL group and ME group significant reduced the DAO content in the serum of weaned piglet（P<0.01）,and the DAO content in the BL group was significant lower than BB group（P<0.01）.（8）Compared with the CON group,the BB group and ME group significant increased the abundance of Clostridiaceae in the fecal microbial community（P<0.01）,and the abundance of Clostridiaceae in the ME group was significant higher than BL group（P<0.01）.All supplementation groups significant reduced the abundance of Oscillospiraceae in the fecal microbial community compared with the CON group（P<0.01）,and there was no significant difference in the abundance of Oscillospiraceae in each supplementation group.Compared with the CON group,the BB group and ME group significant increased the abundance of Clostridium＿sensu＿stricto＿1 in the fecal microbial community（P<0.01）,and the abundance of Clostridium＿sensu＿stricto＿1 in the ME group was significant higher than BL group（P<0.01）.（9）Compared with the CON group,there was no significant differences in the concentrations of propionic acid,valeric acid,and isovaleric acid in the feces among the three supplementation groups（P>0.05）.The BL group increased the concentration of acetic acid in the feces（P<0.05）,and the concentration of acetic acid in the BL group was higher than ME group（P<0.05）.Compared with the CON group,both the BL group and BB group increased the concentration of butyric acid in the feces of weaned piglets（P<0.05）,and there was no significant differences in butyric acid concentration in each supplementation group.In conclusion,c-EPS of Lactobacillus cqf-43 has antioxidant activity in vitro,and Lactobacillus cqf-43 bacterial liquid,bacterial body and its metabolites can reduce the ratio of feed to gain,alleviate diarrhea,improve antioxidant capacity,and change fecal microbial flora structure in the feces of weaned piglets.Lactobacillus cqf-43 bacterial liquid and its metabolites can improve the immunity of weanling piglets,Lactobacillus cqf-43 bacterial liquid and bacterial body can increase the content of short-chain fatty acids in the feces of weaned piglets.Lactobacillus cqf-43bacterial liquid,bacterial body and its metabolites have positive effects on the production performance of weaned piglets,and have different improvement functions,which can be used as a safe and effective additive for further study. |
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