Submitted to: Journal of Applied Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/24/2009
Publication Date: 1/1/2010
Citation: Wells, J., Oliver, W.T., Yen, J. 2010. The Effects of Dietary Additives on Faecal Levels of Lactobacillus spp., Coliforms, and Escherichia coli, and Faecal Prevalence of Salmonella spp. and Campylobacter spp. in U.S. Production Nursery Swine. Journal of Applied Microbiology. 108:306-314. Interpretive Summary: In these trials, we have examined the effects of selected dietary supplements in nursery swine diets. Larch extract supplementation appeared to be most effective in a pelleted feed and increased feed efficiency, but this compound did not decrease fecal shedding of Campylobacter spp. or Salmonella spp. In comparison, carbadox + copper sulfate supplementations increased feed intake and decreased Campylobacter spp. shedding, but this combination in our trials had negligible effects on gain, decreased feed efficiency, and increased fecal coliforms. Supplementation of nonantibiotic compounds to nursery swine can alter animal performances as measured by feed intake, gain, or gain:feed. However, supplementation can alter the fecal flora and pathogens shed, and thus, affect manure management.
Technical Abstract: Larch extract is predominantly a polymer of arabinogalactan containing up to 20% taxifolin, a potential antibacterial. To determine the potential benefit of larch extract in young swine diets, two separate trials were conducted with nursery piglets sorted by weaning weight and age into one of four treatments: 1) basal diet without antimicrobials; 2) basal diet with carbadox + copper sulfate; 3) basal + 1,000 ppm larch extract, or 4) basal + 2,000 ppm larch extract. Diets were fed for a 4-wk period after weaning. In both trials, the carbadox + copper sulfate group consumed more feed over the 4-wk period relative to the other three diet groups (P < 0.05), but did not gain more weight (P > 0.1). In both trials, the G:F ratio was lowest for the carbadox + copper sulfate group relative to other treatments and the differences were (P < 0.05) in comparison to basal or the 1,000 ppm larch extract diets. In fecal samples collected at the end of each trial, Lactobacillus spp. cell counts for the basal, 1,000 ppm larch extract, and 2,000 ppm larch extract diets were nearly 1.0 log10 per g feces greater (P < 0.05) than the carbadox + copper sulfate group, whereas the coliforms and Escherichia coli were nearly 1.0 log10 per g feces lower (P < 0.05). Fecal shedding of Salmonella spp. was not affected by dietary supplement in either trial, but fecal shedding of Campylobacter spp. was not observed for the carbadox + copper sulfate group. In conclusion from this study, larch extract may be a beneficial feed additive to nursery swine at less than 0.2% of diet and this effect is unrelated to microbial counts or pathogen shedding, whereas carbadox + copper sulfate increased feed intake and decreased fecal shedding of Campylobacter spp. Compared to basal fed animals, supplementation with carbadox + copper sulfate significantly altered microbial flora.