Udder and teat conformation and chronic mastitis in suckler ewes; 2012 - 2014
The ultimate aim of this project is to provide advice to industry on the impact of ewes with good udder conformation, and removal of ewes with damaged / infected udders, to achieve healthier udders and faster growing lambs.
There is very little information on the distribution, determinants and control of mastitis (infection in the mammary gland) in meat sheep from anywhere in the world. Our group has carried out initial studies of intramammary infection (subclinical mastitis and clinical mastitis) in meat ewes in England, and this project builds on those.
From studies of dairy sheep we know that intramammary infections are the most common cause of involuntary culling of dairy ewes, and represent a major welfare concern. These infections also cause decreased milk production, which is associated with reduced lamb growth rate and lighter lambs at weaning.
Farmers with flocks of sheep rearing lambs for slaughter (meat sheep) report up to 5% of ewes with clinical mastitis per year (Cooper 2011). Affected ewes often die from mastitis or are culled because they lose an udder half, whereas some ewes remain in the flock (potentially still infected) for a subsequent lactation. Anecdotal evidence suggests that 20 – 30% of cull ewes have chronic mastitis with palpable lumps in their udder.
Mastitis is therefore a major cause of economic loss to the sheep industry in England. In meat producing sheep, the financial impacts are due to ewe deaths, carcase disposal, additional labour, treatment and loss of lambs or decreased live-weight gain of lambs reared by affected ewes. Recent estimates suggest that mastitis costs the Texel sheep breed alone £2.7 million per annum in GB.
In effect, the meat sheep industry in England is losing 7 – 12% ewes from the breeding flock per annum and many lambs are growing at a sub-optimal weight because of intramammary infections.
We hypothesise that:
Udder and teat conformation are heritable and that identifying the optimal conformation will reduce levels of intramammary infection, reduce teat damage and increase lamb growth rates.
Ewes retained for breeding with chronic mastitis (defined as palpable masses in the udder) are at greater risk of developing clinical mastitis, and are less productive than ewes with normal udders. In addition, they are a risk for transmitting infection to other ewes.
Upon completion we will have a significantly improved understanding of the impact of chronically infected (lumpy) udders on the lifetime performance of ewes, and the health implications and costs of retaining ewes with lumpy udders in a flock. This information will enable the industry to improve efficiency and animal health and welfare.
Cooper, S. 2011. A study of ovine udder abnormalities: identifying the risk factors for teat lesions. MSc Thesis. School of Life Sciences, University of Warwick.