Animal Health: Calves 3

摘要

Bovine respiratory disease (BRD) is a common disease concern in dairycattle that is most commonly initially diagnosed in young dairy heifers.BRD has a negative impact at both the individual animal level and atthe herd level, but this performance loss is highly variable, dependingon disease severity, accuracy and completeness of clinical detection,effectiveness of treatment, and on-farm culling practices. Consequencesinclude decreased rate of weight gain, a higher culling risk either asheifers or as cows, delayed age at first service, delayed age at first calving,and in some cases, lower future milk production. In this data set of104,100 Holstein dairy replacement heifers from across the US, 36.6%had one or more cases diagnosed within the first 120 d of age with thehighest risk of new cases occurring before weaning. Comparison of theraising cost for Holstein heifers with BRD and those without a recordedhistory of BRD resulted in an estimated cost per incident case occurringwithin the first 120 d of age of $252 or $282, depending upon whetheranticipated future milk production differences were considered or not.No additional differences in first lactation performance such as cullingrisk or reproductive performance were evaluated. Current market conditionsas reflected in this model have contributed to a cost estimate that issignificantly higher than previously published estimates, driven in partby the losses associated with selective culling of a subset of heifers thatexperienced BRD. Depending on the available inventory of replacementheifers and the level of BRD within the herd, selective culling based ondisease occurrence may limit a herd’s ability to selectively cull basedupon genetics; however, this financial cost was not considered here.The cost of BRD in dairy replacement heifers presented here is likelyhigher than many realize when all aspects of growth and performanceare considered but may not completely capture the full economic losses.