Alternatives to the use of antimicrobial feed additives in nursery diets: A pilot study

Darryl Ragland, DVM, PhD; Jessica L. Schneider, RVT; Sandra F. Amass, DVM, PhD, Diplomate ABVP; Michael A. Hill, BVetMed, MS, PhD, MRCVS

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Objective: To evaluate the effect of inorganic minerals and probiotics on pig performance and antimicrobial resistance.

Materials and methods: Ninety-six crossbred pigs 17 to 20 days old were randomly assigned to six experimental diets. A non-medicated basal diet was supplemented with carbadox (55.12 g per tonne), copper sulfate (192.40 g copper per tonne), zinc oxide (2712.68 g zinc per tonne), or the probiotic feed additive BioPlus2B (Chr Hansen Inc, Milwaukee, Wisconsin; 1.1 x 106 or 1.3 x 106 spores per gram of feed). Pigs were weighed weekly and feed consumption was monitored to assess performance. Rectal swabs were collected for isolation of enterococci to evaluate antimicrobial resistance. Isolates were screened for resistance to vancomycin, and the broth microdilution procedure was used to determine minimum inhibitory concentration breakpoints.

Results: The zinc oxide diet promoted the heaviest bodyweights and greatest feed consumption (P < .05). Feed:gain was similar for pigs fed the diets supplemented with carbadox, BioPlus2B at 1.3 x 106 spores per gram, copper sulfate, and zinc oxide. Enterococcal isolates were highly susceptible to vancomycin at the start and end of the study.

Implications: Zinc oxide may sustain acceptable pig performance as the sole growth promotant in nursery diets. BioPlus2B in nursery pig diets did not enhance growth or feed utilization. In this study, the young pig did not represent a significant reservoir of vancomycin-resistant enterococci.

Keywords: inorganic minerals, probiotics, antimicrobial resistance, enterococcus

RIS citationCite as: Ragland D, Schneider JL, Amass SF, et al. Alternatives to the use of antimicrobial feed additives in nursery diets: A pilot study. J Swine Health Prod 2006;14(2):82-88.

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