A cross-sectional study of 329 farms in England to identify risk factors for ovine clinical mastitis

Abstract

The aims of this study were to estimate the incidence rate of clinical mastitis (IRCM) and identify risk factors for clinical mastitis in suckler ewes to generate hypotheses for future study. A postal questionnaire was sent to 999 randomly selected English sheep farmers in 2010 to gather data on farmer reported IRCM and flock management practices for the calendar year 2009, of which 329 provided usable information. The mean IRCM per flock was 1.2/100 ewes/year (CI:1.10:1.35). The IRCM was 2.0, 0.9 and 1.3/100 ewes/year for flocks that lambed indoors, outdoors and a combination of both, respectively.Farmers ran a variety of managements before, during and after lambing that were not comparable within one model, therefore six mixed effects over-dispersed Poisson regression models were developed.Factors significantly associated with increased IRCM were increasing percentage of the flock with poor udder conformation, increasing mean number of lambs reared/ewe and when some or all ewes lambed in barns compared with outdoors (Model 1).For ewes housed in barns before lambing (Model 2), concrete, earth and other materials were associated with an increase in IRCM compared with hardcore floors (an aggregate of broken bricks and stones). For ewes in barns during lambing (Model 3), an increase in IRCM was associated with concrete compared with hardcore flooring and where bedding was stored covered outdoors or in a building compared with bedding stored outdoors uncovered. For ewes in barns after lambing (Model 4), increased IRCM was associated with earth compared with hardcore floors, and when fresh bedding was added once per week compared with at a frequency of ≤2 days or twice/week.The IRCM was lower for flocks where some or all ewes remained in the same fields before, during and after lambing compared with flocks that did not (Model 5). Where ewes and lambs were turned outdoors after lambing (Model 6), the IRCM increased as the age of the oldest lambs at turnout increased.We conclude that the reported IRCM is low but highly variable and that the complexity of management of sheep around lambing limits the insight into generating hypotheses at flock level for risks for clinical mastitis across the whole industry. Whilst indoor production was generally associated with an increased IRCM, for ewes with large litter size indoor lambing was protective, we hypothesise that this is possibly because of better nutrition or reduced exposure to poor weather and factors associated with hygiene.

Predisposing factors for bacterial mastitis in ewes

“…Indrebø () has studied specific sheep housing features related to mastitis prevalence and reported higher prevalence rates in sheep houses with slatted floors. However, Cooper, Huntley, Crump, Lovatt, and Green () have reported that concrete and soil were associated with higher incidence rates of clinical mastitis.…”

Factors affecting ewe somatic cell count and its relationship with lamb weaning weight in extensively managed flocks1

“…Mastitis, an inflammation of the mammary gland caused by bacterial infection, is characterized by palpable lumps in the udder, abnormal milk, and tissue discoloration in its clinical state ( Menzies and Ramanoon, 2001 ). The average incidence of clinical mastitis ( CM ) is relatively low (1.2% to 3%) across flocks sampled around the world ( Quinlivan, 1968 ; Arsenault et al, 2008 ; Cooper et al, 2016 ), but can have large variation within flocks (0–37%; Grant et al, 2016 ). Nevertheless, CM was the primary reason for culling 6.7% of ewes in the United States in 2011 ( USDA APHIS, 2012 ).…”

Assessment of Subclinical Mastitis Effects on Live Weight, Body Condition Score (Bcs) and External Udder Measurements of Dorper Sheep

“…The present study means that good udder conformation or live weight or BCS are not associated with the increase risk of mastitis in Dorper sheep. In contrast, the previous study by [37] indicated that the risk of mastitis infection is associated with udder conformation where the pendulous udder with the extreme teat position and greater cross-sectional area of the teats in dairy ewes resulted increase the risk of mastitis infection in ewes compared to the normal udder conformation [28] also stated that the pendulous udder will make the lamb difficult to suckle effectively and did not feed sufficiently which may trigger the lamb attempt to repeated suckling that could lead to teat lesions or intramammary infection. Moreover, the adjusted R 2 is important value that used in the model for checking their quality of prediction [38].…”