Species diversity in gastrointestinal nematode communities of dairy goats: species-area and species-climate relationships.

Abstract

Gastrointestinal nematode communities (12 species) of dairy goats were studied in four regions located in the centre of the western part of France. These regions had very similar annual mean temperatures (11 to 12.5 degrees C) but had rainfall accumulations ranging from 600 to 1330 mm per year. Breeding management (area of pastures, number of goats in the flock, the age of the farm, and the size of the initial goat population) was investigated only in the driest region. The number of helminth species and Shannon diversity index were positively correlated to the permanent pasture area and negatively to the age of the farm. Evenness was negatively correlated to the age of the farm and increased with the increasing levels of rainfall. The results are interpreted in the following terms: i) large areas of permanent pasture include a large array of environments favourable to the development of the free-living stages of various species of nematodes; ii) age of the farm is unfavourable to the maintenance of all introduced species as the farms are helminth-isolated and infestation can only occur during the grazing season thus imposing the necessity of successive annual recolonization of the pastures; and iii) free-living stages are very susceptible to dryness and survive better in areas with heavy rainfall.