Management practices associated with high mortality among preweaned dairy heifers.

In a national survey of US dairy operations, 1685 dairy operations reported 47,057 new dairy heifers (either births or acquisitions) and 4427 deaths (9.4%) of preweaned dairy heifer calves over a 3 month period. Stepwise logistic regression was used to identify management practices associated with high mortality among preweaned heifers in dairy operations where at least three dairy heifer calves were born alive or moved on to the operation. Analysis was done twice: once by separating all operations by size into high or low mortality; again using only operations with < 2 and > 10% mortality to eliminate dairy operations with intermediate levels of mortality from the comparisons. Results were similar. Dairy operations in the West were more likely to fall in the high mortality category than dairy operations in the rest of the country. In addition, the following dairy operation characteristics were associated with high death levels in both models: rolling herd average milk production < 7710 kg. preweaned heifers placed in groups of seven or more, a male having primary responsibility for the care and feeding of preweaned heifers, calves not receiving hay or other roughages until > 20 d old, calves fed on mastitic or antibiotic milk after colostrum and calves not given whole milk after colostrum.