Mastitis in Sheep
The aim of the mastitis in sheep project is to further our knowledge of the patterns of udder infection in meat sheep during lactation. We are striving to identify what makes some ewes more susceptible to udder infection and udder disease than others. In order to do this we first need to understand what constitutes a healthy udder. By regarding infection and its effects as a spectrum from subclinical to clinical disease we can identify what factors are important, and their relative importance. We have investigated the way in which ewes in a flock are managed and what it is about some ewes and their udders than make them have higher levels of disease. The ultimate goal is to further our understanding such that farmers may be advised by industry on practical steps they may take in order to maximise udder health of their flocks.
The key findings to date are that udder infections of ewes in meat flocks are very common even though signs of mastitis may not be visibly obvious to the farmer. As disease levels in the udder increase, so do the adverse effects on lamb weight, with lambs reared by ewes with udder infection weighing on average 1.5kg less by 8 weeks of age than those reared by ewes with the healthiest udders. Higher levels of infection are seen in old and thin ewes and in those with a large udder drop and large teats. Overall udder health is an important concept, with teat lesions also affecting lamb growth. Position of the teat on the udder is also important and lambs reared by ewes with abnormal teat placement do not grow as well in the first two months of life.
Our findings suggest that flock udder health may be improved by age management and appropriate feeding of ewes. Observing each ewe for teat lesions, particularly around 3-5 weeks in lactation, may identify ewes where feeding is or has been suboptimal. It may be beneficial to consider udder conformation and teat position when making culling or ewe replacement choices.
The project is funded by EBLEX (English Beef and Lamb Executive)
My project has consisted of 3 main parts, using the somatic cell count (the number of white blood cells/ml of milk) as a measure of the level of udder disease.
Part 1: Studies on the longitudinal patterns of somatic cell count and bacterial infection in meat ewes.
Part 2: A cohort study to investigate the association between ewe milk somatic cell count and lamb weight.
Part 3: Intervention studies investigating the effect of the use of a broad spectrum intramammary antibiotic at weaning on subclinical and clinical mastitis in meat ewes in the next lactation. (In progress).
Two other PhD projects are in progress (Emma Monaghan, Selin Cooper) looking more closely at the dynamics of bacteria in the udder.
A research masters on risk factors for teat lesions was completed by my colleague Selin Cooper in 2011. I am indebted to Selin for her detailed observations of teat lesions and udder conformation alongside my cohort study (part 2)
Professor Laura Green
School of Life Sciences
University of Warwick
Gibbet Hilll Rd
Laura dot Green at warwick dot ac dot uk