Whatford, Louise (2019) Improved understanding of the transmission of mastitis in ewes and strategies for its control. PhD thesis, University of Warwick.

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Abstract

Mastitis in ewes is a painful disease that negatively impacts sheep health and welfare, and farm productivity, through reduced milk yield and quality, premature culling and in some cases death. The aim of this study was to increase our understanding of mastitis in suckler ewes by investigating transmission and persistence of bacteria, and strategies for its control.

A systematic review was developed and conducted to collate all information from peer-reviewed papers on risk factors for mastitis. The results identified that hygiene and nutrition were the two most frequently mentioned risk factors.

Based on the results from the systematic review, an intervention study was conducted to test the impact of an improved hygiene regime during lambing on an indoor lambing flock of suckler ewes. The impact of an improved hygiene protocol from the time a ewe lambed to leaving housing on the prevalence and occurrence of acute and chronic mastitis was investigated. From a flock of ewes, 737 ewes were examined for the presence or absence of intramammary masses (IMM) on five occasions; pregnancy, lambing, early lactation, late lactation and pre-tupping. At first signs of lambing the ewes were alternately allocated to either a control or intervention treatment group. The intervention ewes received additional hygiene protocols and were managed by the researchers, whereas the control ewes were managed by the farm staff as they normally would. There were no significant associations between improved hygiene regimes and the occurrence or prevalence of chronic and acute mastitis in the flock. However, a significant association was identified between chronic and acute mastitis, with the presence of one heavily influencing the presence of the other.

A subset of 10 study ewes from the flock were sampled to investigate transmission and persistence of bacteria, and any influence of the improved hygiene regime using matrix assisted laser desorption/ionisation time of flight mass spectrometry (MALDI-ToF-MS). Strains of bacteria were identified to persist in ewes and possible transmission events were identified particularly involving the lambs. The community of bacteria isolated from the mouths of the lambs were highly similar to the community of bacteria isolated from the milk of the study and mastitic ewes as well as the nose samples from the study ewes. The role of the environment as a reservoir for bacteria and the threat it may pose to the ewe by facilitating the introduction of bacteria into the udder is also discussed. Reduced presence and proportions of overall isolated species, strains and reoccurring strains were reduced when the ewes were housed individually with their lambs and on bedding that was more frequently changed. xvi Having identified that IMM and acute mastitis were significantly associated, any associations between the presence versus absence of IMM on the bacterial communities isolated from mastitic and study ewes were explored. There appears to be a complex relationship between IMM and acute mastitis, and IMM and bacterial diversity. The results support a theory that the presence of IMM is associated with an udder microbiota with lower bacterial diversity and that IMM played a role in the development of acute mastitis.

Item Type:	Thesis (PhD)
Subjects:	S Agriculture > SF Animal culture
Library of Congress Subject Headings (LCSH):	Ewes -- Mastitis, Mastitis -- Prevention, Sheep -- Infections
Official Date:	February 2019
Dates:	Date Event February 2019 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	School of Life Sciences
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Green, Laura E. ; Purdy, Kevin
Sponsors:	Agricultural and Horticultural Development Board
Format of File:	pdf
Extent:	xvii, 167 leaves : illustrations, charts
Language:	eng

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