Effects of dietary supplementation of lactobacillus-based probiotics on growth and gut environment of nursery pigs
Rao, Samwel O.
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Antibiotic resistance as a result of continuous use has been a thorny issue in pig production. Focus has been directed therefore to use of probiotic supplementation as alternative. Probiotic supplementation has been suggested to benefit the host animal by stimulating appetite, improving intestinal microbial population balance, digestion and improvement of growth performance. Furthermore studies have also suggested a role for probiotics in stimulating the immune system. The objective of this study was to determine the effects of dietary supplementation of Lactobacillus-based probiotics on growth and gut health of newly weaned pigs. Twenty nursery pigs weaned at 21-d of age (6.68 ± 0.27 kg BW) were allotted to 2 treatment groups representing: (1) CON (probiotic-free; corn-soy diet) and (2) PB (test group fed a diet containing 0.2% lactobacillus based probiotics). Pigs were housed individually in metabolism crates and fed the diets for 15-d. At d-15, all pigs were euthanized to collect gut tissues and digesta. There were no differences (P > 0.05) in body weight, ADG, ADFI and FE between the treatments during 15-d period. The numbers of E. coli, Bifidobacteria, Lactobacillus spp., and total anaerobics in colon digesta were altered, although not statistically significant (P > 0.05). Major VFAs were acetate, propionate, isobutyrate, butyrate, isovalerate, and valerate. Acetate accounted for more than 60% of the total VFAs in both treatments while isobutyrate accounted for less that 0.5% of the total VFAs in both treatments. There was no difference (P > 0.05) observed in amount of VFAs in both treatments. There was also no difference (P > 0.05) in the apparent ileal digestibility of amino acids in the diets. Villi height was greater (P < 0.05) in the treatment group as compared to control group. A separate study was conducted to investigate the effects dietary supplementation with Lactobacillus-based probiotics elicits on the immune status of the nursery pig. Differential blood counts were determined on whole blood samples collected on d 13 of the study period. Total RNA was isolated from mesenteric lymph nodes. Gene expression was determined using a 12,000+ pig specific custom microarray, results of which were validated with quantitative PCR. For differential blood counts, there were no differences (P > 0.05) in lymphocyte, neutrophil and monocyte, WBC count, RBC count, hematocrit, and hemoglobin among treatment groups. Microarray results identified significant difference in the expression of 80 genes that were altered by lactobacillus-based probiotics supplementation. Of these genes, nine were comparatively induced (> 2.0 fold) and the rest were comparatively repressed (> 2.0 fold). Functional analyses of these genes identified 25 distinctly enriched functional categories. One of the primary functional categories identified showed significant repression of catalytic activity genes, which represented the majority of repressed transcripts (24.4%). Analyses indicated that lactobacillus based probiotics supplementation altered genes responsible for carbohydrate transport activity, cellular physiology process, defense to pathogens and immune response. In addition, genes related to proteolysis including PRSS2 and CTRB and genes involved in lipid metabolism including LIPC and PLA2G1B were also altered by lactobacillus based probiotic supplementation. Collectively, dietary supplementation of Lactobacillus-based probiotics at 0.2% may have beneficial effects by positively interacting with the intestinal mucosa and the microflora if the length of feeding was increased. The results from these studies indicate that dietary supplementation of Lactobacillus-based probiotics to nursery pig diets may be considered as a nutritional strategy for enhancing intestinal health and possibly positive immune response. Nonetheless, further studies are required to confirm and to elucidate the responsible mechanisms. In addition, the extent to which altered gene expression may affect the animal’s response to actual immune challenge conditions should be determined.