Long-term study of lamb losses

Press, 13 July 1979, Page 9

Long-term study of lamb losses

Lamb losses are one of the more distressing types of loss a farmer can experience, for even if the cause is diagnosed he can do nothing about it. The Ministry of Agriculture and Fisheries is planning a five-year investigation of the problem to assess its economic significance.

Abortions can be caused by the protozoan Toxoplasma gondii, which is thought -to cycle through cats. Sheep are infected by ingesting infected cat faeces. The bacterium Campylobacter (Vibrio) foetus is the other common cause of sheep abortion. It is spread by sheep eating grass contaminated by the discharges of aborting sheep. The losses from abortion on a farm vary from year to year, depending on many factors, particularly the number of susceptible ewes in a flock. The infections that cause abortion may influence the number of deaths due to dystocia (difficult birth), exposure and starvation. A lamb infected with an abortion-causing agent

prior to birth may be born alive but weak and so is more likely to die from a difficult birth, to be too weak to find its monther’s teat and suckle or be too stupid to find shelter in a storm. The Animal Health Division of the Ministry of Agriculture and Fisheries are aware of the problem and are currently establishing a project to investigate the problem over a five-year period. The management of the Belfast slink lamb plant are cooperating to allow the work to be done on lambs after they have been processed.

The project is to run for five years 4 to determine

the incidence of the various types of lamb loss over the economic life of a ewe. The results will show the relative importance of the various causes of lamb abortion and perinatal deaths. This will allow the economics of the losses and possible control programmes to be assessed. Farms selected randomly from an area of North Canterbury will be invited to participate. They will be asked to make all dead lambs available to the Ministry for examination and to mark all slink lambs prior to collection.

Results of the post mortem examinations and the laboratory tests will be available at the end of each season. However, it is the results at the end of the five-year period which are relevant. Participating farmers will need to be prepared to stay in the project for the full fiveyear period. This is possibly the first district survey of lamb losses conducted on a ran-domly-selected population over a long period. If the investigation proves successful farmers may be able to prevent a considerable proportion of their current lamb losses.

The accompanying item on the lamb loss investigation proposed by the Ministry of Agriculture has been contributed by R. C. Gumbfell, veterinary investigation officer with the Animal Health Laboratory of the Ministry of Agriculture and Fisheries at Lincoln.