Inbreeding in the Dohne Merino breed in South Africa
The actual level of inbreeding and the effect of inbreeding depression on yearling body weight and fleece traits in the South African Dohne Merino population were investigated. All available pedigree data, which comprised of 266 268 records (302 169 animals including base parents) for the period 1975 to 2003 were used for calculating individual inbreeding coefficients. Inbreeding depression was estimated as the regression of performance (corrected for fixed effects) on the individual and dam inbreeding coefficients, fitting an animal model. The rate of inbreeding (ΔF) was estimated as the difference between the individual inbreeding (Ft) and the inbreeding of the parents (Ft-1) divided by (1-Ft-1). The level of inbreeding (F) in the SA Dohne Merino sheep population is very low. The proportion of animals that was inbred to some extent increased from 0.00 (average F = 0) in 1980 to 0.38 in 2003 (average F = 0.012). No significant inbreeding depression on body weight and fleece traits could be found. In general the results suggest that inbreeding at present is not a serious problem in the South African Dohne Merino breed. © South African Society for Animal Science.