The genetic structure of the Jersey breed in South Africa

An analysis of the pedigrees of a random sample of 100 South African-bred first-calf Jersey heifers registered in 1985 showed that most breeders have concentrated on a closely interrelated group of Marlu animals and their descendants. Of the 17 young bulls under progeny test during 1985, nine were grandsons of Milestone Generator. The levels of current and long-term inbreeding were only 1% and 4% respectively. In spite of an on-going programme of progeny testing, the generation interval was only 35,3 months in comparison with approximately 50 months at several earlier stages of breed development when pedigree selection and natural service were used.