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The diversity of the microbial community of the udders of sheep

Microbial communities are multi-species groups of diverse organisms which live and interact in a shared environment.

Two known examples of a microbial community in humans are in the gastro-intestinal tract and lungs. An example of a microbial community in animals is the natural colonisation of bacteria in the alimentary system (gut).

Changes in the balance of bacteria in the communities that exist in such locations can lead to infections such as gastroenteritis and pneumonia.

The development and composition of colonising bacteria within a microbial community is therefore an important determinant of the health of all higher-order organisms. Improving our understanding of animal-associated microbiomes is essential to identify strategies to maximise health and productivity and minimise disease.

Intramammary infections (IMI) in sheep present as a range of scenarios from acute severe systemic clinical mastitis to subclinical infection detectable by a raised somatic cell count (SCC). IMI have major economic impact through reduced milk production, premature culling and even death of ewes.

It is therefore important to find ways of managing and treating IMI because it reduces the health and productivity of sheep. It is also frustrating for farmers to try and manage as detection is difficult and treatment is often of limited success.

Over 130 species of bacteria have been linked to intramammary infections in cattle. There is no reason to suggest that a similar number of bacteria cannot infect the sheep mammary gland. Hence, this research hypothesizes that the sheep udder is a site where bacteria live in a microbial community.

Consequently, the hypotheses of this research were:

1. A natural microbial community forms in the sheep udder

2. Changes in the community composition result in disease

The project has used molecular-based whole community approaches including:

  • DNA extraction from sheep milk
  • Polymerase Chain Reaction (PCR) to amplify bacterial DNA in milk
  • Denaturing Gradient Gel Electrophoresis (DGGE) to compare the bacterial diversity between milk samples
  • High-throughput Illumina MiSeq platform
  • Mixed effects modelling of milk bacteria and DGGE data

SheepPCR MachineDGGE machines

The combination of the aforementioned techniques will allow the first comprehensive investigation of the development and composition of bacterial species in the sheep udder.

This research aims to provide a fresh insight into intramammary bacterial colonisation in sheep to generate novel approaches to disease management.

For further details on my research please visit:

A poster summarising some of this research can be found here.

AHDB Beef and Lamb logoKTNBBSRCQMMS Warwick logo

Project researcher: EMonaghan
Emma Monaghan

e dot m dot monaghan at warwick dot ac dot uk

Project Supervisors:


Laura Green

Professor Laura Green

Laura dot Green at warwick dot ac dot uk

Kevin Purdy

Dr Kevin Purdy

K dot Purdy at warwick dot ac dot uk