Relationship between helminth species diversity, intensity of infection and breeding management in dairy goats

Helminth infection, species diversity (proportion of each species in the co mmunity), species number, intensity of infection and anthelmintic resistanc e were investigated in 16 dairy-goat farms of south-western France. The aim of the study was to estimate which breeding management factors may affect diversity and intensity of infection. Anthelmintic resistance was investiga ted because this factor may modify composition of nematode communities. Far m history and breeding management were recorded by means of a questionnaire . Natural and experimental infections were compared to determine which stra tegy was the best to estimate diversity index and number of species from ne matode community of a whole herd. A total of 17 species of helminths, among which 14 nematodes, one cestode (Moniezia spp.) and two trematodes (Paramp histomum daubneyi and Dicrocoelium lanceolatum) were recovered in the 26 ne cropsied culled goats. One culled goat worm burden represented conveniently species number but not species diversity (Shannon index) of parasite commu nity harboured in the whole herd, Experimental sheep infection with larvae from pooled faeces of 15 goats was the best strategy to estimate species di versity in farms. Diversity could be predicted from the number of farms fro m which goats originated at constitution of the herd, the duration of goat winter withdrawal from pastures, and intensity of infection. Anthelmintic r esistance was correlated with the number of farms of origin, area of perman ent pastures and intensity of infection. The strategy adopted for the herd constitution was a critical step as species diversity and risk of anthelmin tic resistance increased with the number of farms of origin. Intensity of i nfection was negatively correlated with species diversity. This suggested t hat more diverse communities were better controlled by the host, in agreeme nt with the widespread statement that diversity would beget stability. (C) 2000 Elsevier Science B.V. All rights reserved.