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Best practice to minimise mastitis in sheep (PhD)
Summary
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.
Based on the results from a 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. 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 normal. 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. 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, suggesting 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.
Finally, 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 play a role in the development of acute mastitis.
Sector:
Beef & Lamb
Project code:
61110035
Date:
01 October 2015 - 30 June 2019
Funders:
AHDB Beef & Lamb
Project leader:
University of Warwick
About this project
The Challenge
Mastitis is defined as an inflammation of the mammary gland, usually caused by bacterial infection. It is an endemic disease, with impacts on farm sustainability and livestock health and welfare. Estimates suggest mastitis costs the UK sheep industry in excess of £120 M / annum in direct and indirect costs; and this has contributed to it being ranked as the most important disease affecting suckler ewes.
Studies in sheep have identified some of the bacteria associated with disease and some of the risk factors for mastitis. However further work is required on within flock transmission routes and effective managements to control mastitis.
The Project
Objectives:
- Complete a systematic review of the risk factors for mastitis in sheep and possibly cattle
- Conduct at least one within-flock clinical trial to test an intervention to reduce the incidence of mastitis
- Analyse milk and environmental samples collected during the clinical trial to investigate putative within-flock transmission routes
The systematic review will be based on the techniques and principles set out by the Cochrane collaboration and will use structured search terms to provide a transparent, repeatable process of identifying relevant literature and reduce sources of bias. This will provide a detailed review of risks factors for mastitis.
The clinical trial will test an intervention identified from the systematic review.
Ultimately, the aim is to improve management of mastitis and so improve sustainability through reduced economic impact of disease and improved ewe health and welfare.
The Student
Louise Whatford
Results
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.
Based on the results from a 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. 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 normal. 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. 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, suggesting 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.
Finally, 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 play a role in the development of acute mastitis.