Animal genetic resources exist in the form of a vast array of breeds and livestock populations which have evolved and adapted over many centuries, to the range of environmental conditions encountered throughout the world. The pressure of selection imposed by climate, soil type, altitude, available food supply, endemic diseases and parasites, management techniques and market demands have resulted in thousands of breeds, types and strains, each with their own genetic make-up, and each adapted to its own specific niche.
The future improvement and development of livestock for agriculture is dependent upon the availability of this genetic variation, which is its principal resource. The requirements for genetically controlled variation are constantly changing over time and are unpredictable. They are influenced by environmental and climatic changes, by changes in market demands, and by the effects of new breeding technologies and DNA manipulation techniques.
The animal genetic resources available throughout the world are in a dramatic state of decline. The development of artificial insemination and other techniques that facilitate easy transfer of breeding material from one geographical region to another, have resulted in widespread cross breeding and the replacement of local stocks through prolonged dilution. In many cases this has been carried out without initial characterization or evaluation of indigenous breeds and with no effort to conserve local strains. It has resulted in the disappearance of a substantial number of local populations, with the consequent loss of their inherent genetic adaptation to their local environments. This increasing loss of identifiable diversity in animal genetic resources has been recognized for many years. Particular concern has been growing with respect to the speed at which uncharacterized breeds are disappearing in some rapidly developing regions of the world where climatic, parasitic or disease pressures could have produced important genetically adapted breeds. (Hodges, 1990c; Office of Technology Assessment, 1987; Weiner, 1989)
There are already compelling examples from cereal and crop production, where industrialized hybrids, selected for greatly increased production, were found to be susceptible to new viral, fungal or insect parasites, which are constantly evolving, and which resulted in dramatic crop failures. Unimproved indigenous landrace stocks were found to contain genetic variation which often included resistance to such parasites. The potential and actual use of these genes for resistance, for incorporation into the production stocks was soon realized. The discovery that unimproved landrace plants had valuable genetic characteristics resulted in the establishment of large scale collections of landrace seed and plant materials for inclusion in national, regional and global germplasm banks (Fowler, 1990; National Academy of Science, 1991a; National Academy of Science, 1991b; Office of Technology Assessment, 1987).
The need for parallel conservation of animal genetic resources, as raw material for future animal breeding programmes, is also recognized and is becoming an important issue in international, regional and national agricultural planning. Conservation is of particular concern in regions of rapid agricultural change, where indigenous stocks and farming methods are being replaced. Areas where climatic extremes or particular parasitic conditions have resulted in genetically modified and unique local stocks which are able to survive under extreme conditions are also a high priority. Such conservation efforts are particularly important in the light of predicted global climate change, and the ability of microbial and insect parasites to evolve and adapt to modern chemical control methods.
Since its inception, the Food and Agriculture Organization of the United Nations (FAO) has been concerned with the conservation, evaluation and use of animal genetic resources. In 1980 a joint Technical Consultation with the United Nations Environment Project (UNEP) developed a technical programme which called for global census information of all those breeds still in existence, and a listing of those in danger of extinction. Considerable work was then done to gather and make this information available (Brook, 1978; Dmitriev, 1987; Hasnain, 1985; FAO, 1977a; FAO, 1977b; FAO, 1980a; FAO, 1980b; FAO, 1981; FAO, 1982; FAO, 1986d; FAO, 1989a; Maijala et al 1984; Peilieu, 1984; Yalcin, 1986) (See Appendix 1).
It was soon realized that breed information needed to include details concerning the population characteristics, details of the local environment, management and production parameters. In 1986, the FAO developed generalized descriptors, in association with the European Association of Animal Production (EAAP), for use in breed identification and characterization (FAO, 1986b; FAO, 1986c) linked to a proposed database system (FAO, 1986a)
During 1987, an International Genetic Resource Data Bank was established at the Institute for Animal Breeding and Genetics in Hanover, Germany, and became a joint EAAP/FAO venture (Simon, 1989). It is intended that this database will eventually be moved to FAO headquarters in Rome and will act as a global information centre for populations of livestock and their environmental niches throughout the world. Access to this data will be available to all United Nations member countries.
It was clear that description and characterization of breeds would take a considerable length of time and that urgent action was needed to prevent the imminent extinction of many populations. Ad hoc conservation programmes were begun in many countries during the 1970's and 80's, concerned with specific breeds or groups of breeds. However, this action was independent, largely uncoordinated and usually centered on national breeds. There was no global attempt to identify populations in most immediate danger or those of greatest potential genetic value.
In 1990, the FAO helped to establish the basis for three regional genebanks, each with two centres, to act as global depositories for frozen animal genetic material (Hodges, 1989). Full details of the aims and objectives, mechanisms for deposition and access, and protocols for disease control and legal ownership have been developed for these centres (Hodges, 1990a). These genebanks are designed to act as long term stores for the preservation of genetic material which might otherwise be lost. They are an insurance policy for farmers and future livestock breeders throughout the world.
By the end of 1990 all the technical recommendations of the 1980 FAO/UNEP Expert Consultation on Genetic Resources had been initiated (Hodges, 1990b).
There are three methods for the conservation of animal genetic resources. The first involves the conservation of animal genetic material in the form of living ova, embryos or semen stored cryogenically in liquid nitrogen (-196 degrees centigrade). The second is the preservation of genetic information as DNA, stored in frozen samples of blood or other animal tissue or as DNA segments. The third is the conservation of live populations.
The advantages, disadvantages and potentials for co-ordination of these systems are reviewed in chapter 4 of this manual, but all are valuable tools with a role to play in the conservation of animal genetic resources.
At the 1989 FAO Expert Consultation it was agreed that frozen embryo and semen technology was cost effective for long term genetic preservation. It was also recognized, however, that there is no single method of preservation which is optimal for all situations. The conservation of live populations in situ has a number of advantages, and may be the only option available in some instances. In situ conservation is also very flexible in its application and allows for the development and utilization of breeds (Weiner, 1989).
This manual has been prepared to draw together the information and experience of in situ live animal conservation theory and practice as it is found throughout the world. It has been written in parallel with a similar manual for the ex situ preservation of cryogenic material (Hodges, 1990a) and is designed to assist with the planning, development and implementation of conservation projects and therefore incorporates many ideas and principles already described in previous FAO publications (see Appendix 1).
Chapter 2 reviews the source of animal genetic resources and the many influences which have acted over time to produce the wealth of livestock varieties available today. It explains the processes of genetic change, selection and extinction with respect to species, breeds and genes.
The need for conservation is discussed in chapter 3 with consideration of economic potential, scientific use and cultural importance alongside the need to conserve unique and endangered populations. The size of populations considered to be rare at the species, breed and gene level and the effects of small population size on genetic variation within populations are all discussed.
Chapter 4 outlines the methods of conservation for live populations beginning with a survey of the advantages and disadvantages of in situ and ex situ conservation. The idea of conserving through separate breeds or composite gene pools are considered along with sampling techniques, selection and methods of random or pedigree mating in small populations.
In the final chapter the practical application of in situ conservation programmes are reviewed with examples from throughout the world.
The summary includes a flow chart for the identification of populations in need of conservation, strategies for conservation and suggestions for the implementation of programmes to conserve animal genetic resources in situ.
1. Conservation and improvement of heartwater resistant Tswana sheep in a village based project in Botswana.
2. Locally adapted pigs and poultry require no veterinary or feed inputs while producing meat and eggs. (Gaborone, Botswana)