Tŷ Coch Project Introduction: How to identify, control and eradicate iceberg diseases in sheep.
Site: Tŷ Coch
Address: Llanbadoc, Usk, Monmouthshire
Technical Officer: Elan Davies
Project Title: How to identify, control and eradicate iceberg diseases in sheep.
Introduction to project:
Iceberg diseases, such as OPA (ovine pulmonary adenocarcinoma), Johne’s, MV (Maedi Visna), CLA (caseous lymphadenitis) and Border disease, are of great significance to the UK sheep industry. These are diseases which are present as a small number of clinically affected cases with a larger number of sub-clinical cases in the rest of the flock.
These diseases are of great significance due to the following:
- Animal welfare – these diseases once contracted are ultimately fatal, for example OPA results in overproduction of lung fluid.
- Effects on productivity due to poor mothering, poor lamb growth and lower birthweights of lambs.
- Inappropriate use of antibiotics – often thin ewes are assumed to be suffering from chronic bacterial pneumonia and treated with antibiotics
There have been several studies into the prevalence of these iceberg diseases but there is little published data into the cost-benefits of identifying and eradicating these diseases on commercial farms.
In addition, EID tags and electronic software to allow useful data to be recorded and used to make ongoing breeding decisions is a tool that is underused. In this project, we hope to showcase the real benefits of using this technology for the farm through aiding in breeding decisions and monitoring productivity.
Over several years there has been an increased ewe death rate which was attributed to Maedi Visna (MV). However, in summer 2020, there was a high number of cases of mastitis and a number of ewes developing an unusual gait whilst wasting in condition. As a result, the culling rate was high and there was an overall high cost to the business in terms of a high replacement rate and an inability to cull for reasons other than MV (for example poor foot conformation, prolapses, age and poor mothering ability).
A “thin ewe” screen of six cull ewes picked up three cases of Maedi Visna disease in the Mule flock comprising 140 ewes. Further testing of a six thinner ewes in the Aberfield flock comprising 130 ewes revealed no infected sheep. The source of infection is unknown and there is a desire to find out how far the infection has spread and whether it is present in the Aberfield flock, which has been managed separately for the past four years.
Project Objectives:
The aim of this part of the project is to establish how many ewes in the Mule flock are infected with MV and whether it is present in the Aberfield flock, and if so, at what level. This would be achieved initially with a blood test on all of the ewes (270). Depending on how many positive sheep are identified, the positive cases would be culled immediately, or managed as a separate group to minimise further spread. A second blood test of all the sheep in the infected part of the flock and cull ewe screening of the uninfected flock six month later would be also desirable.
The ultimate aim of the project is to discover whether MV can be eradicated by the careful separation of groups and blood testing. If MV is removed from the flock then culling can be based on age, prolapses, poor mothering and lameness and the overall health and productivity of the flock would improve. The true extent of iceberg diseases and their prevalence in Wales is very much unknown, therefore this project offers great potential in terms of knowledge transfer to increase farmers’ understanding of the various diseases, how to identify, control and eradicate them.
Key Performance Indicators Set:
Due to the nature of this project, identifying short-term, specific key performance indicators is difficult. The long-term benefits of undertaking work to identify, control and eradicate iceberg diseases from the flock would mainly be improved productivity and longevity, however, it might not be seen for many years following this work.
Timeline and Milestones:
