A Randomized Clinical Trial Evaluating Metabolism of Colostral and Plasma Derived Immunoglobulin G in Jersey Bull Calves

Pipkin, K.M.; Hagey, J.V.; Rayburn, M.C.; Chigerwe, M.

Estimates of the probability of survival as a function of entry into study between the 2 groups were performed using survival analysis. Survival analysis was performed using the Cox proportional hazard model. 13 The proportional hazard assumption was evaluated using log-minus-log plots and the Schoenfield residuals. 14 Entry into the study was considered to be 2 h of age after administration of plasma or colostrum. The specified outcome of interest was death. Survival curves were generated at 1 exit time point (7 d) . At the exit time point calves that did not have the outcome of interest (death) were censored. The Wald-chi square statistic was considered to determine whether group had an effect on survival of the calves at 7 d. 13 The 2 survival distribution curves generated were compared to determine if they were different using the log-rank test. 13 All statistical analyses were performed using commercial statistical software. h,i In all statistical analyses, values of P < .05 were considered significant.