The Effect of Selective Dry Cow Therapy on Subsequent Lactation Milk Yield

Abstract

Mastitis is the most common and costly disease in dairy herds around the world. Antibiotic treatment of all quarters of all cows at the end of lactation (dry cow therapy, DCT) is a common mastitis control procedure in US dairy herds to eliminate existing and to prevent new intramammary infections (IMI) during the dry period. However, due to growing concerns about antimicrobial resistance, selective DCT (SDCT) has received increasing attention in the past years; selectively treating only infected cows would offer the opportunity to reduce use of antimicrobials in dairy operations. SDCT is successfully practiced in some parts of the world, but there are no recent studies evaluating the effects of SDCT on udder health or milk production in the US dairies. For a switch from total to selective DCT to be feasible, the new alternative needs to maintain similar udder health and production level as the current practice of treating all quarters of all cows. The objective of the present study was to evaluate the effect of SDCT on daily milk yield during the subsequent lactation in US dairy herds.