Making Good Decisions on Dry Cow Management to Improve Udder Health - Synthesising Evidence in a Bayesian Framework.

The dry period is now recognised as a critical time for the control of clinical and sub-clinical mastitis in dairy cattle. Infections that occur, or that are not cured, during the dry period often result in clinical mastitis or raised somatic cell counts in early lactation. There is known to be large variability between herds in the patterns of dry period intramammary infections (IMI) and yet, until recently, there has been no information on farm determinants of the risk of IMI, other than in relation to dry cow treatments. In this paper we consider new research on cow characteristics, farm facilities and herd management strategies during the dry period in relation to clinical mastitis and raised somatic cell counts (SCC) in early lactation. We then describe, within a Bayesian framework, the concept of synthesising existing knowledge with new data to facilitate decision-making on dry cow management for individual farms.