Table 1.

Effect of milk replacer medication, breed, gender, week, and the interaction of milk replacer with these on abundance of selected antibiotic resistance genes in the feces of dairy calves.

	Log gene copies per gram wet feces			SE4	P <
	Control1	Subtherapeutic2	Therapeutic3		Trt	Breed	Gender	Day	Interactions5
n	12	7	9
tetG	7.40	7.29	7.17	0.18	NS	NS	NS	0.06	Trt*gender; breed*gender
tetO	9.18	9.10	9.13	0.34	NS	NS	NS	NS	NS
tetW	8.89	8.80	8.43	0.28	NS	NS	NS	0.07	NS
tetX	7.47	7.70	6.99	0.34	NS	NS	NS	NS	NS
sul1	6.29	5.88	6.34	0.28	NS	0.10	NS	NS	Trt*gender; gender*week
sul2	6.78	6.64	6.61	0.23	NS	NS	NS	NS	NS
ermB	7.20	7.31	6.82	0.37	NS	NS	NS	NS	NS
ermF	7.91	7.36	6.95	0.32	0.04	NS	NS	0.003	NS

¹Control milk replacer containing no antibiotics fed from day 2 to weaning (59 ± 2 day).

²Medicated milk replacer containing 10 mg/calf/day of tetracycline and neomycin fed from day 2 to weaning.

³Medicated milk replacer containing 1000 mg/calf/day of tetracycline and neomycin fed from day 36 to weaning.

⁴SE for treatment LS means.

⁵Significant (P < 0.10) two and three way interactions of treatment, breed, gender, and week.