Abstract

Recent studies with Trichostrongylus colubriformis have provided some direct evidence to support the view that the major contributor to reduced production in gastrointestinal nematode infections is the host immune response, rather than damage from the parasite per se. However, it is unknown if this is also true for abomasal infections. Parasite naïve lambs were either trickle infected with Teladorsagia circumcincta L3 larvae; similarly infected and concurrently immuno-suppressed with the corticosteroid methylprednisolone acetate; immuno-suppressed only; or remained as controls. Immuno-suppression abrogated the reduction in intake and subsequent production losses and reduction in feed conversion efficiency associated with infection suggesting the damage caused by this abomasal parasite per se may have little detrimental effect on lamb productivity. These findings add weight to the view that components of the developing immune response are generally the cause of reduced productivity in infected lambs. They may have ramifications for the genetic selection of animals that are predisposed to mount a strong immune response. KEYWORDS: immuno-suppression; nematodes; intake; feed conversion efficiency; sheep.

AW, Greer, RW McAnulty, M Stankiewicz, and AR Sykes

Proceedings of the New Zealand Society of Animal Production, Volume 65, Christchurch, 9-12, 2005