Pedigree Dorset Horn sheep in Australia. 1. Breed expansion and other vital statistics

Abstract

The Dorset Horn in Australia is maintained almost exclusively for producing rams for crossbreeding in the prime lamb industry. Flock Book records have been used to assess the expansion and other statistics of the breed. Dorset Horn sheep were first imported in 1895 with the first flock registered in 1920. The number of pedigree flocks increased to 1298 in 1958 and total ewes to 11 3,762 in 1968. Flocks declined to 61 4 and ewes to 60,801 in 1973, during which there was a rapid expansion in Poll Dorset flocks and ewes. Early expansion of the Dorset Horn occurred in South Australia and Victoria but over 85 per cent of flocks and ewes were located in New South Wales and Victoria in 1973. In 1973,40 per cent of flocks contained less than 51 ewes with only 2.8 per cent having more than 400 ewes. The mean age of studs in 1973 was 15.3 years, with 22 per cent established for 0 to 5 years, compared with 7.1 years and 62 per cent respectively in 1958. Stud dispersals have increased dramatically in recent years to 19.7 per cent of extant studs in 1973. Examination of flocks present in 1969 but dispersed prior to 1974, showed the proportion of dispersed flocks decreased with increasing flock size and increasing stud age, up to 40 years. Migration of sires between all regions was low, but of the migrant sires, South Australia supplied 76 per cent in 1954 and the central western region of New South Wales 57 per cent in 1974. Approximately half of the rams sampled had sires bred in the same stud.