Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract Only
Publication Acceptance Date: 3/4/2010
Publication Date: 7/1/2010
Citation: Wells, J., Kalchayanand, N., Berry, E.D., Oliver, W.T. 2010. Effects of Dietary Antimicrobials on Fecal Shedding of Campylobacter, Salmonella, and Shiga-toxin Producing Escherichia coli in Production Swine [abstract]. Journal of Animal Science. 88 (E-Supplement 2):616. (Abstract #W102). Interpretive Summary:
Technical Abstract: Antimicrobials are used in swine diet to improve growth and reduce disease. Increasing pressure to remove antimicrobials from swine diets could alter efficiency, but little information is reported on the impact of feeding antimicrobials on zoonotic pathogen shedding. Barrows (n = 160) were sorted by weight into two treatments, and fed growing, grow-finishing, and finishing diets from age 10-14 wk, 14-18 wk, and 18-22 wk, respectively. For each feeding phase, diets were prepared without (A-) and with (A+) dietary antimicrobials (chlortetracycline, 10-18 wk; bacitracin, 18-22 wk). At wk 10, 14, 18, 19, 20, and 22, fecal swabs were collected from each animal for Campylobacter and Salmonella spp. and fecal grabs were collected from one-quarter of the piglets for Shiga-toxigenic Escherichia coli and Shiga-toxin gene analyses. Salmonella was only observed early in the study at low prevalence and was not affected by treatment. Campylobacter was not found in piglets at week 10, but prevalence increased over the study for both treatments. In the growing and grow-finishing phases (wk 14 and 18), Campylobacter was present in 23 and 7 % (P = 0.04) and stx genes were present in 25 and 17 % (P = 0.05) of samples from A- and A+ groups, respectively. In the finishing phase, time was an interaction with treatments. Campylobacter did not differ between treatments for pooled wk 19 and 20 (15 vs 9.4%, A- and A+, P = 0.09) but was different for wk 22 (19 vs 38 %, A- and A+, P = 0.007). The prevalence of stx genes was not different between treatments for wk 19 (39 vs 26 %, A- and A+, P = 0.06), but by wk 20 and 22 stx gene prevalence was different (49 vs 68 %, A- and A+, P = 0.01). Shiga–toxin producing E. coli serogroups O26, O103, and O145 were isolated from 7.2 % of the samples with fewer positives found at end of trial (P > 0.1). Diets with chlortetracycline reduced pathogen shedding, but switching to bacitracin at 18 wk of age increased pathogen shedding with time compared to the A- group.