The utilization and conservation of the world's animal genetic resources

Abstract

The utilization and conservation of animal genetic resources constitute a complex set of problems. Simultaneous consideration must be given to the immediate need for genetic improvement, and to the conservation for future unforeseen needs — as well as for historic and scientific purposes. Because of rapid adoption of intensive selection methods in animal breeding and the introduction of artificial insemination, the genetic composition of the livestock populations of the industrialized countries is currently undergoing very rapid changes. In the Third World, livestock are largely bred and managed in traditional systems, although modern techniques are likely to be introduced at an increasing rate in the decades to come. An account is given of the rapid changes in the cattle breed composition in Europe and the Mediterranean basin. Of the total number of breeds which existed in 1970, 115 indigenous breeds are threatened by extinction and only 30 are holding their own. There has been a change towards Friesian cattle in the lowland areas and towards Simmental cattle in the moderately elevated areas of central and south-eastern Europe. Reasons are discussed why we need to conserve animal genetic resources, e.g. the cultural, historic and scientific interests on the one hand, and the more practical/economic ones on the other. Examples are given of breeds which, for historic reasons, should be conserved. However, to meet practical/economic needs in the future, ought to be the most important reason for conservation, and yet that type of conservation is often most difficult to justify and to arrange in practice. That changes in general economic conditions may completely reverse an earlier decline in numerical strength of animal strains is exemplified by the current use of Cornish chicken in many broiler strains, the present interest in former draught cattle of southern Europe to produce lean carcasses of beef and the use of the Finnish Landrace sheep to boost lambing rates through crossbreeding. Methods for assessing the decay of genetic variation are briefly discussed. Blood groups and other biochemical polymorphisms may be usefully employed as “marker genes” to measure the overall change in genetic variation; examples of such studies of north-west European cattle breeds are reviewed. Many different possibilities of conserving animal genetic material exist. Animal parks are gaining popularity and should be utilized more in the future. In species as cattle, where semen can be kept frozen and used for artificial insemination, storing frozen semen is a relatively cheap way of medium-term conservation. Work is now underway on several species for the storage of frozen embryos. The developing countries require special attention with regard to the utilization and conservation of animal genetic resources. The genetic variation of the animal populations in the developing countries appears to be very large. Local strains are often well adapted to stresses in the environment such as high solar radiation, periodic droughts and various diseases. Large-scale programmes for the evaluation of the animal strains are required. The occurence of cattle strains in West Africa, e.g. Baoulé and N'Dama, which show a high degree of tolerance towards trypanosomiasis is interesting. Their use in heavily tsetse-infested areas as an alternative to bush clearing and spraying with insecticides needs further investigation and/or promotion.