Table 3.

Effect of arrival bovine viral diarrhea virus (BVDV) infection on subsequent pen-level morbidity and mortality in a study to investigate the effect of BVDV infections on the overall health and performance of feedlot cattle

Variable	Relative riska	95% CIc	P-value
Initial UF treatmentb
Evidence of type I BVDV — Yes vs. No	1.40	0.84–2.35	0.195
Evidence of type II BVDV — Yes vs. No	0.82	0.56–1.20	0.314
Initial NF treatmentb
Evidence of type I BVDV — Yes vs. No	1.51	1.14–2.00	0.004
Evidence of type II BVDV — Yes vs. No	0.69	0.49–0.98	0.036
Overall mortality
Evidence of type I BVDV — Yes vs. No	2.01	1.26–3.21	0.003
Evidence of type II BVDV — Yes vs. No	0.58	0.35–0.96	0.034
Infectious mortality
Evidence of type I BVDV — Yes vs. No	2.83	1.64–4.88	< 0.001
Evidence of type II BVDV — Yes vs. No	0.52	0.26–1.03	0.061

^aRelative risk — the ratio of the rate of disease in pens with evidence of type-specific BVDV infection on arrival divided by the rate of disease in pens with no evidence of type-specific BVDV viraemia on arrival

^bUF — undifferentiated fever and NF is no fever

^c95% CI — the 95% confidence interval calculated for each relative risk, corrected for feedlot and initial weight effects and intra-pen clustering of animal health events using generalized linear modeling techniques. The partially maximized likelihood function was used to calculate the confidence intervals. When convergence of the confidence interval could not be attained using the maximized likelihood function, asymptotic normality was used to calculate the confidence intervals