12 December 1984 Research to determine the susceptibility of breeding sheep to roundworm infection

Twelve million ostertagia circumcincta larvae will be used by animal scientists at Lincoln College to try to determine the susceptibility of breeding sheep to roundworm infection.

Lincoln College Council meeting today was told that the college had been given a $27,150 research contract by M.S.D. Agvet (N.Z.) Ltd to carry out the study.

A report from the college research committee said the project was of major significance for understanding integrated methods of controlling parasitism in New Zealand sheep.

Gastro-intestinal parasitism is endemic among sheep, in spite of widespread use of anthelmintics in New Zealand.

Sheep infested with roundworm while lactating show up to 20 per cent reduction in feed intake, milk production and wool growth.

Tensile strength of wool can be reduced by up to 45 per cent when the wool follicle should be able to support rapid fibre growth.

There is this extreme response because not only is a ewe more susceptible to infection while lactating, but also because the effects of parasitism divert nutrients away from wool synthesis.

Some lactating ewes can be expected to show unpredictable responses to anthelmintic treatment, but this has yet to be confirmed.

Even sheep believed to be resistant to infection can suffer reduced wool growth rate of up to 25 per cent.

The breeding ewe has been seen to be of great importance ±n trying to control roundworm infection.

Research at the college will try to understand changes in the susceptibility to infection of breeding ewes during pregnancy, lactation and the dry period.

This should help determine the consequences for wool growth and quality.

Further information from Professor Andrew Sykes, Animal Sciences Group, Lincoln College, Canterbury 8150, New Zealand.