Table 5.
Results from a multivariate proportional hazards model of the days to first antimicrobial treatment from 3 field trials (ranches A, B, and C) evaluating the efficacy of feeding a colostrum supplement in milk replacer for 14 d to preweaned calves
| Variable | Level | Hazard ratio | 90% CI1 |
Wald's P-value | |
|---|---|---|---|---|---|
| Lower | Upper | ||||
| Treatment group2 | CS | 0.57 | 0.38 | 0.87 | 0.03 |
| PS | 1.10 | 0.77 | 1.58 | 0.67 | |
| UC | Reference | — | — | — | |
| Weight category3 | Low | 2.17 | 1.35 | 3.48 | 0.01 |
| Mid | 1.60 | 1.03 | 2.48 | 0.08 | |
| High | Reference | — | — | — | |
| Serum IgG status4 | FPT | 3.73 | 2.37 | 5.87 | <0.01 |
| PFPT | 1.89 | 1.26 | 2.82 | 0.01 | |
| APT | Reference | — | — | — | |
| Calf ranch | A | 0.97 | 0.66 | 1.43 | 0.9 |
| B | 1.24 | 0.81 | 1.91 | 0.4 | |
| C | Reference | — | — | — | |
1
CI = confidence interval.
2
CS = colostrum supplement (70 g of dried colostrum powder) added to milk replacer; PS = placebo supplement (70 g of nutritionally matched supplement without IgG) added to milk replacer; UC = unsupplemented control.
3
Low: ≤38.5 kg; mid: between 38.6 and 45 kg; high: ≥45 kg.
4
FPT = failure of passive transfer: IgG ≤350 mg/dL; PFPT = partial failure of passive transfer: IgG between (and including) 351 and 999 mg/dL; and APT = adequate passive transfer: IgG ≥1,000 mg/dL.