Published online by Cambridge University Press: 20 November 2017
Nematodes are a particular challenge to animal health and productivity in organic sheep systems, where the prophyllactic use of anthelmintic is prohibited. The peri-parturient rise in faecal egg output, a consequence of relaxation of host immunity in late pregnancy and early lactation, is potentially a key factor in the epidemiology of parasitic gastro-enteritis on organic sheep farms. Coop and Kyriazakis (1999) developed a hypothesis to explain the relationship between nutrition and periparturient breakdown of immunity to parasites, and there is now an increasing body of evidence for the involvement of dietary protein (Houdijk et al 2001). The objective of this study was to test this hypothesis in organically managed ewes carrying a mixed, naturally acquired infection, grazing on grass/clover in early lactation, and to examine the potential for a nutritional approach to parasite control in commercial practice.