Structural characteristics of the sheepbreeding industry and implications for genetic and reproductive technologies

摘要

The structure of the sheep breeding industry needs to be understood and documented in order to assess the possible gains resulting from the implementation of genetic and reproductive technologies. This paper reports a structural description of the sheep industry, which apart from census information obtained every 5 years has received little attention since 1948. The proportion of the national flock represented by the minor and 'unspecified' category of the breed census has increased from 1.7% (1979)to 18.4% (1989), suggesting the questionnaire format may be incapable of soliciting reliable responses from farmers utilising crossbreeding or developing composite breeds. The size of the national registered flock has been relatively stable, however there have been major changes in its composition. The Romney, although having sustained a 12,5% decrease in ewe and flock numbers over the last 5 years, is still the most popular registered breed. Somewhat greater reductions in ewe and flock numbers have occurred in the Coopworth, Border Leicester, and Perendale breeds. The Texel has proved to be the most influential of the recently imported exotic breeds and despite a relatively small number of registered ewes (4,745 compared with 130,937 registered Romneyewes), has the third largest number of flocks and second highest number of rams presented for registration. A comprehensive analysis of the Registered Romney breed indicates that only 32 studs (of 624) supply 78% of the sires used by other breeders. Another 31 studs use exclusively homebred sires and sell the remaining rams to unregistered breeders. These results indicate the cost-effective application of technologies for the improvement of genetic gain would be best focused on a subset of the ram breeding flocks, Benefits from the development of new technologies are reliant upon their cost-effective adoption by industry and their implementation by that subset of the sheep breeding industry achieving genetic progress.