Reference | Feldpausch2016 (10179)

A total of 480 pigs (PIC 327 × 1050; initially 48.7 ± 2.3 kg) from 2 finishing groups were used for this study. Prior to placement on experimental finisher diets, the pigs did not receive any chlortetracycline in their feed or water to avoid potential confounding study impacts due to disturbances to the intestinal microbiome. All finishing diets were a corn–soybean meal–based diet fed in meal form, which contained a trace mineral premix providing 73 mg/kg Zn and 11 mg/kg Cu to the diet (Table 1). The diets were formulated to be fed in 4 phases (36 to 57 kg, 57 to 79 kg, 79 to 100 kg, and 100 to 132 kg) during the finishing period. Dietary treatments were arranged in a 2 × 2 × 2 factorial with the main effects of added copper sulfate (CuSO4; 0 vs. 125 mg/kg Cu), added zinc oxide (ZnO; 0 vs. 150 mg/kg Zn), and RAC (0 vs. 10 mg/ kg during the last 28 d prior to marketing; Paylean; Elanco Animal Health, Greenfield, IN). The dietary treatments were as follows: 1) a control, 2) the control + 125 mg/kg Cu, 3) the control + 150 mg/kg Zn, 4) the control + 125 mg/kg Cu + 150 mg/kg Zn, 5) the control + 10 mg/kg RAC during only the final 28 d, 6) the control + 125 mg/kg Cu + 10 mg/kg RAC during only the final 28 d, 7) the control + 150 mg/kg Zn + 10 mg/kg RAC during only the final 28 d, and 8) the control + 125 mg/kg Cu + 150 mg/kg Zn + 10 mg/kg RAC during only the final 28 d.

Fecal samples from 5 randomly selected pigs per pen were collected into individual Whirl-Pak bags (Nasco, Ft. Atkinson, WI) on d 0 (baseline) and again on d 90 (before harvest) from the first group of pigs (32 pens). Samples were transported on ice to the Molecular Epidemiology and Microbial Ecology laboratory at Kansas State University (Manhattan, KS) for bacterial isolation and antimicrobial susceptibility analysis.

AST Method: Broth Microdilution

Reference explicitly reports AST breakpoints: True

Reference reports using a MIC table: False