Partitioning the mortality risk associated with inadequate passive transfer of colostral immunoglobulins in dairy calves

This study developed a method to partition the risk of mortality in dairy c alves in the 1st 16 weeks of life. Observed population mortality and the re lative risk of mortality in each serum protein concentration stratum were u sed to determine the population baseline mortality rate and the mortality r ate due to inadequate passive transfer of colostral immunoglobulin. A total of 3,479 calves were studied, 8.2% of which died before 16 weeks of age. T he population baseline mortality rate was 5.0% and the mortality rare due t o inadequate passive transfer was 3.2%. Thirty-nine percent of the observed mortality was attributed to inadequate passive transfer. This partitioning of risk between passive transfer-related and unrelated sources should prov e useful in conducting investigations of calf mortality problems in dairy h erds.