Table 2.
Results from a multivariate proportional hazards model of mortality in calves during the first 28 d of life 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 | 1.02 | 0.52 | 1.98 | 0.96 |
| PS | 0.86 | 0.44 | 1.69 | 0.72 | |
| UC | Reference | — | — | — | |
| Weight category3 | |||||
| Low | 0.96 | 0.44 | 2.07 | 0.93 | |
| Mid | 0.71 | 0.33 | 1.52 | 0.46 | |
| High | Reference | — | — | — | |
| Serum IgG status4 | |||||
| FPT | 26.22 | 7.60 | 90.38 | <0.01 | |
| PFPT | 5.88 | 1.68 | 20.52 | 0.02 | |
| APT | Reference | — | — | — | |
| Calf ranch | |||||
| A | 0.29 | 0.14 | 0.60 | <0.01 | |
| B | 0.44 | 0.21 | 0.95 | 0.08 | |
| 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.