ABSTRACT
Gastrointestinal nematode infestations comprise the most important group of conditions limiting intensive sheep production worldwide. Infestations range from acute disease with profuse diarrhoea and possible death (Fig. 15.1) to chronic disease with reduced performance (Fig. 15.2), extending to weight loss and emaciation. Nematode infestations raise concerns because of their prevalence, effects on production, very considerable control costs with reliance upon chemical control and animal welfare consequences. In many developed countries the growth of the organic food sector has highlighted the need for more integrated approaches to parasite control.
