Two experiments were conducted to evaluate the efficacy of multi-microbe probiotics (comprising Lactobacillus acidophilus, Bacillus subtilis, Saccharomyces cerevisiae and Aspergillus oryzae) prepared by submerged liquid (LF) and solid substrate fermentation (SF) methods and different antibiotics in weaning pigs [Landrace×(Yorkshire×Duroc)]. In both experiments (Exp.), 288 weaned pigs were randomly allotted to four treatments, on the basis of body weight and sex in a randomized complete block design. There were four replicate pens per treatment and each pen comprised 18 pigs. In Exp. 1, the effects of LF and SF probiotics on performance, apparent total tract digestibility (ATTD) of nutrients and faecal microflora were investigated. The basal diet was prepared without any antimicrobials (negative control, NC), and 100 mg chlortetracycline/kg, 0.30% LF and 0.30% SF probiotics were added to the diets of positive control (PC), LF and SF treatments, respectively. Pigs fed PC and probiotic diets showed improved overall performance compared to pigs fed NC diet. Additionally, the overall gain and ATTD of CP were greater in pigs fed PC and SF diets than in pigs fed LF diet. On d 28, pigs fed PC and SF diets had less faecal Clostridia and coliforms compared with pigs fed NC diet, while pigs fed SF diet had more faecal Lactobacillus than pigs from other treatments. In Exp. 2, a 2×2 factorial arrangement was used to investigate the effects of probiotic products (0.30% LF or SF) and antibiotic (40 mg colistin/kg or 44 mg lincomycin/kg) on growth performance, ATTD of nutrients, small intestinal morphology, and intestinal microflora in pigs. Pigs fed SF probiotics showed improved growth performance, ATTD of DM and CP and had more beneficial intestinal bacteria and less harmful bacteria in the ileum than pigs fed LF probiotics. Antibiotics had no effect on the growth performance and there were no antibiotic×probiotic interaction effect on any of the measured variables. However, pigs fed lincomycin had lower caecal Clostridia counts and greater villus height:crypt depth at jejunum and ileum, whereas pigs fed colistin had lower counts of caecal coliforms and Bifidobacteria. These results indicate multi-microbe probiotics prepared by SF method to be superior to probiotics prepared by LF in improving growth performance and beneficial gut microflora and reducing harmful gut microflora.

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