Dr Alastair MacRae

The Royal (Dick) School of Veterinary Studies/The Roslin Institute

Research Interests

Production diseases in cattle and sheep, and links with nutrition. Although the majority of attention for livestock disease research in the UK is focused on Notifiable Diseases such as Tuberculosis, Foot and Mouth Disease and Bluetongue, the majority of the economic losses on most farms occur due to production diseases (or diseases of intensive livestock production). Examples of such production diseases would be mastitis, lameness, reduced fertility and hypocalcaemia in dairy cattle; perinatal mortality in beef calves and lambs. Although such diseases have a multifactorial aetiology, many are highly linked with nutritional management: for example there are well established links between negative energy balance (NEB) and increased disease risk and reduced fertility in dairy cattle. My research seeks to establish the nature of these links, and define the mechanisms by which they operate. For example, previous work in both Canada and the DHHPS has shown that high Non Esterified Fatty Acid levels in late pregnancy lead to an increased risk of the development of Left Displaced Abomasum in dairy cattle; by understanding how energy balance can influence such disease occurrence, we can devise strategies to try and reduce these diseases occurring.

Epidemiology of production diseases in cattle and sheep. The Dairy Herd Health and Productivity Service currently operates the largest database of culling and disease rates in dairy cows in the UK via a simple system of farm recording.  Whilst this information is primarily used to feed information back to farmers and their veterinary surgeons, it also represents the best representation on the main conditions affecting dairy cattle in the UK at the herd level. My research aims to examine the main association and risk factors for these disease conditions; for example, does increasing herd size result in higher disease levels? Analysis of data on individual farms will focus on more specific conditions, such as risk factors for cystic ovarian disease in dairy cattle.

Monitoring and management of diseases in cattle and sheep, including economic costs and benefits of disease control. With the numbers of animals per unit of labour increasing on many UK farms, more remote methods are required to monitor cow health and productivity at the farm level. In particular, economic losses due to subclinical disease mean that productivity is lost even before the clinical disease has become apparent. The early detection and precise identification of subclinical disease enables these losses to be minimised, if intervention can be efficiently targeted. By working with industry partners, this has sought to develop technologies for monitoring, as well as the early detection and diagnosis of disease in dairy cattle. Examples include prediction of calving using automated sensor technologies, and monitoring rumen pH using rumen boluses.

I am also involved in the Paraban and Paraban Reloaded projects, which are collaborative projects with SRUC, University of Glasgow and James Hutton Institute funded by the Scottish Funding Council and QMS, in partnership with Scottish Government. This project is primarily based on Knowledge Exchange of information on paratuberculosis (Johnes disease) control in Scottish dairy and beef herds.

Selected Publications

  • A C Barrier, C Mason, C M Dwyer, M J Haskell, A I Macrae. 2013. Stillbirth in dairy calves is influenced independently by dystocia and body shape. Veterinary Journal Vol: 197 Pages: 220-223. More»
  • A. C. Barrier, M. J. Haskell, S. Birch, A. Bagnall, D. J. Bell, J. Dickinson, A. I. Macrae, C. M. Dwyer. 2013. The impact of dystocia on dairy calf health, welfare, performance and survival. Veterinary Journal Vol: 195 Pages: 86-90. More»