Heritability of gastrointestinal nematode faecal egg counts in West African village N'Dama cattle and its relation to age.

Abstract Offspring–dam regression was used to estimate the heritability of strongyle faecal egg counts (FEC) of traditionally raised West African N’Dama cattle in the Central River Division in The Gambia. Faecal samples were taken monthly from June–October 1992, and again from July–October 1993, including 179–463 dams and their calves sampled on each occasion. The only proven genetic relationship was the dam–offspring relationship. Gastrointestinal strongyle FEC was expressed as epg (eggs per gram faeces). Regression of offspring FEC on dam FEC, showed a heritability ( h 2 ) of 0.18 (95% Confidence Limits 0.10, 0.25). Heritabilities were higher at the beginning and end of the rainy season than during the months of the peak rainy season. This is in line with earlier suggestions that genetic control of faecal egg counts is most effective during periods of low parasite transmission. There was a significant ( p