Selection Of Potential Probiotic Lactobacillus Strains From Intestinal Tract Of Healthy Piglets And Effect On Feed Efficiency In Weanling Pigs

Total of 231 strains were purified with the MRS plates from different spot ofgastrointestinal tract of a healthy piglets, these spots respectively were stomach, duodenum,jejunum, ileum, cecum, colon and rectum. 26 strains were rapidly selected by examinationof their resistance to PH2.0 for 2 h. Survival rates of most strains after being treated underpH 2.0 were bigger than 80%. These 26 strains have the common biochemical characters,they were identified as belonging to the genus Lactic acid bacteria. Through carbohydratefermentation responses analysis (reagents were provided by our laboratory), preliminaryidentification of the 26 strains at the species level were achieved: 7 isolates were identifiedas belonging to the species L. amylovorus, 3 as L. salivarius, 6 as L. reuteri, 9 as L.Plantarum, 1 as L. acidophilus. By molecular identification via 16S rRNA sequencing,10isolates were confirmed as belonging to L. reuteri and 15 stains as L. johnsonii and 1 asWeissella paremesenteroides. 6 strains ZB3, WN1, SNQ5, WN8, SBZ5 and JJB3 out ofthese 26 strains showed broadly antimicrobial inhibition toward the growth of bothpathogenic Escherichia coli O₈ and Salmonella 339, the diameter of inhibition zone wasbigger than 18 mm, the organic acid which was produced by these strains was the maincause for inhibiting pathogenic bacteria. These 6 strains could be survived under 0.3%-0.9% bile for 2 h and temperature of 50℃for 15 min. Through these tests 2 strains wereselected as potentially probiotic lactobacilli for their good characteristics. Spontaneousrifampin-resistance variants of the 2 trains were isolated and were used in weanling piglets.A total of 28 crossbred (Duroc×Landrace×Yorkshire) piglets were weaned at 28 daysand blocked by sex and weight. Pigs within each block were assigned at random to one oftree treatment groups as follows: group A, control; group B, L. johnsonii SBZ5^-R; group C,L. johnsonii JJB3^-R, each treatment had 3 repetitions. The feeding trial consisted of two consecutive periods: baseline period (7 days) and culture administration period. During theadministration period (21 days), each kg of feeds was added with a total of 1.5×10¹⁰ CFU.The average daily gain of pigs given Lactobacillus JJB3^-R was on 34.93% higher comparedto the control group of pigs (P＜0.05), the average daily gain of pigs given LactobacillusSBZ5^-R was on 21.71% higher compared to the control group of pigs (P＞0.05). It showedthat JJB3^-R and SBZ5^-R could improve growth of weanling pigs. The average daily feedsintake of group JJB3^-R was higher on 28.98% than the control group (P＜0.05), the averagedaily feeds intake of group SBZ5^-R was higher on 15.72% than the control group (P＞0.05).Lactobacillus JJB3^-R significantly decreased ratio of feed and gain (F/G) on 5.59%compared to control group (P＜0.01), Lactobacillus SBZ5^-R significantly decreased F/G on4.97% compared to control group (P＜0.05). Lactobacillus JJB3^-R and SBZ5^-R couldeffectively control piglets' diarrhea, and their diarrhea index was obviously lower thancontrol group (P＜0.05). Fecal Lactobacillus counts and Bifidobacterium counts increasedand Escherichia coli counts were lower in the groups JJB3^-R and SBZ5^-R. During 21 daysadministration period rifampin-resistant Lactobacillus counts on average were2.57%-45.47% of total fecal Lactobacilli in group SBZ5^-R. rifampin-resistant Lactobacilluscounts on average were 12.71%-35.29% of total fecal Lactobacilli in group JJB3^-R.In conclusion Lactobacillus JJB3 and SBZ5 had good antireversion force andantibacterial capacity, they can improve growth of weanling pigs and decrease diarrhea,JJB3 was more effective than SBZ5 in application. These 2 strains could be potentialprobiotics for production of pigs.