The widespread occurrence of anthelmintic resistance in gastrointestinal nematode (GIN) populations affecting sheep and goats is of major concern to these industries, and is responsible for a concerted research effort into alternative control measures (Zajac and Gipson, 2000 ; Terill et al., 2001). The determination of resistance in grazing ruminants is generally based on measurement of faecal egg count (FEC) (Baker et al., 1998) and selection has been generally on this variable. However, a range of alternative phenotypic traits is available (Mandonnet et al., 1996) and may prove superior alone or in combination with FEC. These traits include those associated with the immune response to GIN, such as specific antibody levels (AB) and blood eosinophil counts (EOS), or those associated with the pathological effects of infection such as packed cell volume (PCV) an indicator of anaemia (Sheep, Pernthaner, et al., 1995 ; Goats, Mandonnet et al., 2001). To make use of these variables we need to know their heritabilites and the phenotypic and genetic relationships between them, an area where information on the goat is lacking relative to the sheep. The objective of this study is therefore to characterise the basic genetic parameters for FEC, PCV and EOS in two goat breeds during natural and induced infections with gastrointestinal nematodes. This report is preliminary in nature, representing data from the first of 5 years of data to be collected.
Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 2002. Session 13, , 13.3, 2002
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