Effect of antibiotics in milk replacer on fecal shedding of Escherichia coli O157:H7 in calves.

摘要: The objective of this study was to compare the concentration and duration fecal shedding Escherichia coli 0157:H7 between calves fed milk replacer with or without antibiotic (oxytetracycline neomycin) supplementation. Eighteen 1-wk-old Holstein were orally inoculated a strain E. (3.6 x 10 8 cfu/calf) made resistant nalidixic acid (NA). Rectal samples obtained three times weekly for wk following oral inoculation. Fecal NA-resistant quantified by direct plating detected selective enrichment procedure. Eight weeks after inoculation, killed, necropsied, tissues (tonsils, retropharyngeal mesenteric lymph nodes, Peyer's patches) gut contents (rumen, omasum, abomasum, ileum, cecum, colon, rectum) sampled quantify detect O157:H7. percentage in feces antibiotic-fed group higher (P < 0.001) early period (d 6 10) compared control no antibiotics. There difference treatment groups 0157 that positive at quantifiable concentrations. A comparison treated untreated showed significant groups. At necropsy, recovered from rumen omasum one calf node patch two group. Supplementation antibiotics may increase probability dairy calves, but effect seems be low magnitude short duration.