Abstract

One alternative to control of gastrointestinal nematode parasitism with anthelmintics may lie in genetic selection for resistance to infection and/or disease. Heritabilities for faecal egg count suggest that good selection responses can be achieved with Romney sires. Research must now identify markers that will accurately predict resistant and susceptible animals. To do this successfully, mechanisms associated with immune-competence, - tolerance and -expulsion and host resistance to these nematodes must be elucidated more fully. This review examines local and systemic humoral and cell-mediated immunities to some of the GI nematode parasites infecting sheep, goats and cattle, with emphasis to sheep. Additional literature is presented identifying some of the factors that may modify any responses; factors such as host nutrition, hormonal and reproductive status and genetics. The overwhelming conclusion must be that significant large voids exist in our understanding of the processes of immunity exerted by domestic stock to combat infection with nematode helminths. Furthermore much latitude has been taken describing and interpreting observations since many are postulated from studies involving laboratory host parasite models.

AR, Sykes

Proceedings of the New Zealand Society of Animal Production, Volume 46, , 1-4, 1986