A longitudinal study of factors associated with acute and chronic mastitis and their impact on lamb growth rate on 10 suckler sheep flocks in Great Britain

摘要

Acute mastitis (AM) in ewes can lead to sudden death, loss of an affected udder half, chronic intra-mammary infection detected as intra-mammary masses (IMM), raised somatic cell count or full recovery. AM has economic costs for farmers in treatment costs, costs of replacement ewes and reduced income from loss of lambs or poor growing lambs. AM is also a significant welfare concern as it is a painful disease. Studies in suckler sheep have reported larger litter size and previous mastitis among the risk factors for AM (Waage and Vatn, 2008) while work in dairy sheep has included looking at udder conformation in relation to udder health (Casu et al., 2010). A common practice among suckler sheep farmers is to check the udder of each ewe at the end of lactation or before the start of the breeding season and ewes with IMM may be culled. The impact of this practice is unknown; possible hypotheses include that it reduces onward transmission of bacterial strains causing mastitis and reduces the number of slow growing lambs in a flock The aim of this study was to investigate ewe risks for and inter-relationships between AM, IMM and udder conformation and their impact on lamb growth rate.