Intramammary infections and mastitis in suckler ewes
Mastitis is an inflammation of the mammary gland (udder), usually caused by a bacterial infection. Over 130 bacterial species of bacteria have been associated with intramammary infections in dairy cows and it is probable that a similar number of species could infect the mammary gland of suckler sheep.
In suckler sheep, mastitis can result in loss of function of a gland, culling of affected ewes or death of a ewe. In addition, many ewes are culled at weaning because of chronic infection detected in the udder as hard swellings.
Reduction in the occurrence of mastitis and intramammary infections would benefit the health and welfare of suckler ewes and their lambs. It would increase sustainable production through an increased productive life of ewes and faster growing lambs.
Intramammary infection and its impact on suckler ewes 2008 - 2012
In a recent study funded by AHDB Beef and Lamb, ewes with a high somatic cell count (SCC) in milk (an indication of infection in the udder) reared lambs that grew more slowly than ewes with a lower SCC. Older and thin ewes were more likely to have a high SCC, as were those with poor udder and teat conformation. Low lamb weight was associated with ewe age, SCC, teat position, littersize, and presence of diarrhoea. Lambs were also more likely to grow slowly the week after their ewe (mother ) developed a traumatic teat lesion, probably caused by lambs biting or grazing the teat skin. For full details, click on the link below.
Huntley, S.J., Cooper, S., Bradley, A.J. and Green, L.E. (2012) A cohort study of the associations between udder conformation, milk somatic cell count, and lamb weight in suckler ewes. Journal of Dairy Science, 95: 5001-5010.
Risks for development of teat lesions 2008 - 2010
To investigate why teat lesions arise, a study of 67 ewes and their lambs was carried out on one farm for up to 10 weeks. The incidence of traumatic teat lesions was greatest 3-4 weeks after lambing. Traumatic teat lesions were more likely to occur in 2 year old ewes compared with 6 and 9 year old ewes, with poor udder and teat conformation, heavy total litter weight and body condition score <2.5 compared with 2.5 14 days previously. Ewes that had had an abnormal udder skin condition (excessively waxy or chapped) were also at a greater risk of developing a traumatic teat lesion. This work is submitted for publication.
Good udder and teat conformation 2009 - present
In early 2012 we visited seven performance recorded pedigree Texel flocks ranging in size from 46 - 151 breeding ewes. A total of 645 ewe udders were scored for 11 characteristics using a combination of linear scores, tape measure, manual palpation and visual examination. Traits measured were the length, width and position of teats on the udder, udder width, udder drop (how low the udder hangs) and degree of separation of the two udder halves. Teats were examined for the presence of lesions and udders checked for the presence of intra-mammary masses.
Teat length and width were similar within individual sheep and were correlated to udder width, udder drop and ewe age. The stage of lactation (number of days since lambing) was also linked with the position of teats, the width of the udder and the degree of separation of the two udder halves.
Using information on the relatedness of the ewes examined and historical family pedigree records we made initial estimates of the heritability of these traits (likelihood of being passed on from one generation to the next). Teat length, width and position, udder drop and degree of separation of the udder halves were highly heritable, udder width was less heritable.
More work is needed to confirm these findings in a larger number of sheep, and we hope to continue this work, in partnership with the Texel Society.
Mammary health group
Professor Laura Green Laura dot Green at warwick dot ac dot uk
Dr Kevin Purdy K dot purdy at warwick dot ac dot uk
Dr Emma Monaghan E dot m dot monaghan at warwick dot ac dot uk