Table 2.

Cox proportional hazards model evaluating first antibiotic treatment for diarrhea over the 77-d experimental period in 320 calves randomly assigned to receive 1 of 3 milk replacers¹

Variable	Hazard ratio	P-value	95% CI
Treatment group
CON	Referent
P5	1.28	0.30	0.80 to 2.05
P10	1.42	0.14	0.89 to 2.26
BW at arrival
<44.5 kg	Referent
44.5 to 47.6 kg	0.62	0.07	0.37 to 1.03
47.6 to 50.8 kg	0.72	0.35	0.43 to 1.22
>50.8 kg	0.57	0.04	0.33 to 0.98
Source
Local dairy farms	Referent
Order buyer	2.17	0.002	1.34 to 3.53
Auction	1.31	0.25	0.83 to 2.06

¹Treatments: CON = all-milk-protein MR; P5 = 15% of CP replaced with spray-dried porcine plasma included at 5% of the absolute formula; P10 = 30% of CP replaced with spray-dried porcine plasma included at 10% of the absolute formula.