I. Bodó1
1 Introduction
Recommendations for a minimum population size for use in preservation programmes throughout the world are important for the following reasons:
The minimum number is an important parameter for planning both the preservation of isolated non-commercial populations for possible use in the long term future and also for conserving populations which, though having current economic value, are threatened. Conservation by cryogenic storage of genetic material and the maintenance of breeding herds or flocks involve different problems and issues; therefore the problems of ex situ and in situ preservation must be treated separately. Identification of the different types of populations such as breeds, strains, lines etc. for a preservation programme is an associated topic, related to the minimum number question, but it is not appropriate to consider it in detail here.
Many factors influence the recommendations for a minimum number for threatened populations which should be considered when deciding upon recommendations. The danger of extinction is a function of genetic drift and the fixation of homozygous loci relative to the size, dynamics and structure of a population. Some important factors influencing this situation are:
1 Department of Animal Breeding, University of Veterinary Science, Budapest, Hungary.
When all these aspects are taken into consideration the inevitable conclusion is that a defined minimum number must be worked out for each individual case. Nevertheless a general framework can be given which then needs to be elaborated in each case. The idea of a World Watch List for threatened breeds, strains and populations needs definition of the minimum numbers for each level of threat. These guidelines must be sensitive to the species, regional and national aspects of programmes.
2 Scientific and experimental calculations and systems
Classical and current calculations of minimum populations size use the concept of effective population size, Ne, which adjusts the actual number of active breeding animals to a sex ratio of 1:1 (Wright 1921, Fisher 1946, Falconer 1964, Fewson 1966, Pirchner 1968, Dohy 1989). With random mating the level of inbreeding increases as the population size decreases. Wright (1931) and Lush (1945) indicate that this effect is very small when the Ne is more than 200. Smith (1982, 1984) calculated the drift of haploid and diploid genes and concluded that 25 non-related animals are theoretically enough for the long term storage of a population. For safety reasons it is often recommended that this figure should be doubled. This figure of 25 is widely cited in the literature in connection with artificial insemination and embryo transfer systems. Wu (1990) calculated that, if the inbreeding coefficient is to increase by no more then 0.1 per 100 years, then a minimum Ne of 100 is needed for horses and cows having a generation interval of five years, whereas for sheep and pigs with a generation interval of two and a half years the Ne would be 200. Brem et al. (1990) are of the opinion that a population is not threatened when the effective population number is over 50 and where there is a minimum of 10 males. For effective selection an Ne of at least 100 is necessary.
Table 1. Population size proposed for preservation (populations size)
| Maijala (1982) | Alderson (1981) | |||
| male | Stable female | Decreasing female | ||
| Cattle | 20 | 1,000 | 5,000 | 750 |
| Sheep | 20 | 500 | 1,000 | 1,500 |
| Goat | 20 | 500 | 1,000 | 500 |
| Pig | 20 | 200 | 500 | 500 |
| Horse | 1,000 | |||
Rasch and Herrendorfer (1990) based on a literature survey, recommended an Ne of 200 for maintaining a genetically constant population over 50 generations. Based on the results of Latter (1959) and Hill (1972), Rochambeau and Chevalet (1990) offer a new and more sophisticated method for the calculation of the effective population size. Thus, theoretical approaches can be summarized as giving an Ne in the range of 25 to 400 depending upon circumstances. Some authors calculate specific figures for several species, while others do not make distinctions between them and use a single figure for all. For everyday practice, some authors prefer to give simpler population figures rather than Ne for the maintenance of populations. The most frequently cited authors in this respect are Maijala (1982) and Alderson (1981). Their recommendations are summarized in Table 1.
The Rare Breeds Survival Trust considers that when the number of male lines decreases below 4 the population is threatened (Alderson 1980). Draganescu (1975) used different criteria for the domestic animal species and also took into consideration the costs (Table 2).
Table 2. Minimum numbers for different species (Draganescu, 1975)
| Pigs: | 25 boars + 100 sows |
| Sheep: | 10–12 rams + 100–250 ewes |
| Cattle: | 10 bulls + 50–60 cows |
| Poultry: | 50 cocks + 250 hens |
Chen Ruihe (1990) gives a Chinese view of the minimum number as follows: “..it is well known, according to theoretical calculations, that the minimum number must be 12–15 rams and 100–250 ewes, but a better alternative is to extend and enlarge the flock”. Smith (1984) suggests the following minimum numbers (male/female) for several species: cattle 10/26; sheep 32/60; pigs 44/44; chickens 72/72. This recommendation is a synthesis of genetic and financial aspects. Beilharz (1983) recommended 25 males and 25 females per generation each giving one progeny to the next generation. According to Sheldon (1984), 400 animals are necessary in a 1:1 sex ratio. Simon (1991) proposes a breed be regarded as threatened when the effective population size (Ne) is less than 50 and when there are other conditions affecting the populations. The effective population size of 50 can be derived from a variety of sex ratios. For example it can result from the following ratios of males and females - 25/25; 20/35; 15/180; 13/300. Simon adds that the associated conditions which would cause the population to be regarded as threatened include a decrease in the number of breeding animals by more than ten percent per year, the number of herds being less than ten and matings with other breed(s) being greater than ten percent or other economic conditions causing rapid changes in the population.
In France in 1980, breeds numbering no more than a few thousand were considered to be threatened with extinction (Devillard 1981). A general recommendation for the first monitoring in developing countries is a total population size of less than 10,000 animals (Hodges 1989). Ngere (1989) thinks, based upon west African experience, that 7,000 is an appropriate level for action to start. The FAO Committee on Agriculture in 1989 accepted the notion of total population size of 10,000 or the number of females in the population as 5,000 as levels for action to be initiated (reported in FAO, 1990). Another possible approach is to use not only the minimum variable population size (MVP) but also its relationship to the effective population size, Ne (Foose 1988). This relationship is expressed by MVP/Ne. In extreme cases of very small populations, Yamada and Kimura (1984) consider that a founder stock with less than 5 individuals cannot survive when such parameters as fecundity, viability, sex ratio, and their correlation to inbreeding depression are taken into consideration.
A common idea for specifying the minimum number is the creation of categories which largely depend on population size and which indicate differing levels of threat. Rognoni (1981) proposed the categories in Table 3.
Table 3. Different levels of endangering of animal populations (Rognoni, 1981)
| Relic populations | less than 100 individuals per breed |
| Semi-relic populations | 100–4,000 individuals per breed and seriously threatened by extinction |
| Small populations | 5,000–15,000 individuals per breed and expected to reach an equilibrium |
| Large but declining | 12,000–500,000 individuals per breed |
| Populations in equilibrium | 17,000–110,000 individuals per breed |
The system of American Minor Breeds Conservancy (1990) is very practical and has been in use for a decade (Table 4):
Table 4. The American Minor Breeds System, (1990)
| Category | Mammals | Poultry |
| Watch | breeds whose registration over a 25 year period have shown a steady decline or where registrations are less than 5,000 per year | 2,000–20,000 females and less than 10 male lines, decreasing tendency |
| Minor | Cattle, sheep, goat, horse, breeds with less than 1,000 registrations per year. Pig breeds with less than 200 registrations per year. | Females less than 2,000, male lines 5 or less. Less than 3 male lines. |
| Rare | Cattle and horse breeds with less than 200 registrations per year. Sheep, goat and pig breeds with less than 200 registrations per year. | females less than 500, male lines less than 3. |
| Feral | Stocks known to have been running wild for at least 100 years with no known introduction of outside blood. | |
Another classification is used by the World Conservation Union (IUCN) for wild animals. It is not possible to use it as a normal standard for domestic animals but it has some useful aspects shown in Table 5. (Thornback, 1983).
Table 5. Status of populations according to the Red Data Book System
| Out of danger | effective conservation measures have been taken and the population is considered relatively secure |
| Indeterminate | lack of enough information to say which category is appropriate |
| Rare | taxa with small world populations that are not at present threatened or vulnerable, but are at risk |
| Vulnerable | taxa believed likely to move into the threatened category in the near future if the causal factors continue operating |
| Endangered | taxa in danger of extinction and whose survival is unlikely if the causal factors continue operating. Included are taxa whose numbers have been reduced to a critical level or whose habitat have been so drastically reduced that they are deemed to be in immediate danger of extinction. Also included are taxa that are possibly already extinct but have definitely been seen in the past 50 years. |
| Extinct | species not definitely located in the wild during the past 50 years (criterion used by CITES) |
Results of two trials to make an acceptable system for the categories of risk status of farm animals were published in 1989 simultaneously by Maijala (1990) and Bodó (1990a) in FAO (1990). Maijala (1990) feels it is appropriate to apply the terms endangered, vulnerable and rare from the IUCN classification to domesticated animals; and perhaps in some cases also extinct, indeterminate and insufficiently known might be useful. The recommended categories are in Table 6.
Table 6. Categories based on Ne
| developed countries | developing countries | ||
| Endangered | Ne | >50 | >100 |
| Vulnerable | Ne | 50 – 100 | 100 – 500 |
| Rare | Ne | 100 – 500 | 500 – 2,000 |
Bodó (1990a) used the number of breeding females in several categories (normal, insecure, vulnerable, endangered, critical) and also took possible sex ratios into consideration. The comparison of the IUCN system for wild animals and a possible solution to farm animals was published by Bodó (1990b) at the 4th World Conference of Genetics applied to Livestock Production. Other publications touching the same topic are Maijala 1974, Crawford 1981, Campo and Orozco 1982, Sirkkomma 1983.
3 Some examples of the history of preserved small populations
The theoretical considerations and classification systems can be illustrated with some practical examples of animal breeding.
Emperor Napoleon received a flock of Merino sheep from Spain as a gift about 185 years ago. This flock is the famous Rambouillet Merino and it was kept without addition with not more than 100 – 120 ewes from the beginning (Perret 1985).
As a consequence of the activity of Rare Breeds Survival Trust in Great Britain the number of Portland females grew from 85 to 341 and the number of cows and heifers of White Park cattle from 65 to 138 between 1974 and 1986 (Alderson 1989). The stock of Soay sheep which consisted of 20 rams 44 ewes, 22 male lambs and 21 female lambs was left on an uninhabited island in the UK, (Alderson 1989).
The most interesting population of the world from the preservation aspect is the Chillingham cattle in the UK. It has been an inbred population of some dozen head since 1270. After the severe winter of 1974 the herd consisted of 8 cows and 5 bulls without young animals. During the subsequent ten years the population increased to 8 bulls 29 cows and 7 calves. The extreme homogeneity of this herd can be well understood and is demonstrated by biochemical polymorphisms (Wallis 1986).
In Switzerland a small swine population (Wollhaarige Weideschwein) is registered as having only six ancestors of which two were boars and four sows (Marx 1990); the group is however experiencing some reproduction problems.
In the former USSR, as described by Dmitriev and Ernst (1989), five cattle breeds, six chicken breeds, eight goose breeds, seven turkey breeds and one guinea fowl breed did not exceed 1,000 head in population size.
The Murnau-Werdenfelser cattle are preserved in Bavaria with 17 bulls and 250 cows.
The figures concerning the European Braunvieh (without American Brown Swiss) are 11 and 500 respectively. 7,000 doses of semen from 23 bulls are also available. An effective population size of 51 can be calculated, but the situation will become less favourable because of the old age of the cows (Hirsch et al 1990).
Crawford (1989) reported, that he had maintained poultry populations with 18 males and 50 females for many decades.
The number of Hungarian Grey cows was less than 200 before the preservation programme began in the 1960s (Bodó 1985). The Hungarian Cikta breed has been kept in a flock of 250 ewes for 25 years without any problems. The population size of the different Lippizan studs in the neighbouring Danubian countries has not been more than some dozens each and the use of the males from the other countries began only some years ago (Bodó and Pataki 1984).
Ryder (1985) says that all the captive Przewalski Horses trace their ancestry to 13 founder animals. The average of their inbreeding coefficients is about 0.23 (maximum individual value: 0.597).
4 Discussion
When summarizing the data from the literature and from the practice, some contradiction can be observed and it is difficult to make a simple general conclusion on the minimum number to indicate the threatened status of different farms animal populations. From the theoretical statements and estimations, an Ne of between 50 and 200 seems generally to indicate threatened status. Above an Ne of 200 there is generally no danger of genetic drift and below an Ne of 50, the driftless reproduction and even the survival of the population is uncertain. There are some theoretical and practical considerations which leave some uncertainty when using the effective population size (Ne) to define level of threat for use in the World Watch List. The major aspects are now given.
Effective population size is based on the actual number of breeding females and males without taking into account the initial situation (founder effect, bottle neck syndrome). The increased inbreeding coefficient is then uncertain, if Ne alone is used.
The existence or lack of recessive, (damaging or lethal) factors is unknown and can not be estimated in Ne calculation.
The different characteristics of various species are disregarded.
In theoretical calculations the assumption of random mating is made, whereas in practice sophisticated mating systems are sometimes used.
Some practical aspects like the reproduction rate, the generation interval, the different expenses and the maintenance requirements are also important.
The number of males is sometimes unknown due to the unrecorded use of young males.
As a consequence of these aspects it is not realistic to state simply a single figure of effective populations size and to rely solely upon that for decision making. The most appropriate solution, depending upon the various factors for a given population, is to interpret the effective population size according to the particular situation. A general recommendation which will offer commonly accepted limits is needed, however, for use on a large scale approach to preservation programmes as, for example, in the development of the World Watch List using data banks information. Thus, a published category system should be very carefully elaborated for this purpose, within which the special distinctions and circumstances applying to an individual population can be presented.
5 The proposal
Four different levels of risk are proposed plus normality and extinction in Table 7.
5.1 Normal status
This category applies to populations of more than 10,000 females. It seems to pose no genetic problems. However it must be recognized that, even in this status of risk, the effective number can fall below the level needed due, for example, to sex ratio or rapid decreases of the population due to crossbreeding. Some interventions are then required. Generally in the normal status it is obvious when the population is not in danger of extinction, it can reproduce without genetic loss and there are no visible changes in the population size. In the literature the total populations size is used for this category (ie not effective population size). Here however, it is proposed that the number of females is used since this often fluctuates due to the seasonality of birth and disposal. Other factors can also be misleading, for example when oxen are used for draught, when the generation interval and or reproduction rates are deliberately controlled or changed by adverse environmental factors.
Table 7. Risk categories for domestic animals
| Status | Number of breeding females | Approximate effective population size when the sex ratio is: | |||
| 5:1 | 10:1 | 30:1 | 50:1 | ||
| Normal | > 10,000 | 6,666 | 3,636 | 1,289 | 784 |
| Insecure | 5,000–10,000 | 3,333–6,665 | 1,818–3,635 | 645–1,288 | 392–783 |
| Vulnerable | 1,000–5,000 | 667–3,332 | 364–1,817 | 129–644 | 78–391 |
| Endangered | 100–1,000 | 67–667 | 36–363 | 13–128 | 8–77 |
| Critical | <100 | <67 | <36 | <13 | <8 |
| Extinct. The resuscitation of the population is impossible, even if after a bottle neck syndrome other genetic variance comes into being. | |||||
5.2 Insecure status
With a population size of 5,000 to 10,000 females, some disadvantageous effects can affect the existence of the population. Crossbreeding and the use of semen of exotic males under the pressure of sales promotion organizations can cause large changes in a short time. That is why some preventive measures must be taken into consideration. In developing countries, in transhumance situations for example, risks are even more evident though are usually not predictable or avoidable. In these cases the obligatory activities of the next status level should be introduced.
5.3 Vulnerable status
The population number is typically 1,000 to 5,000 females. Here the level of threat is increasing. Measures for well-directed programmes should be set up for example, the establishment or renewal of breeders associations, publicity, the subsidy of preserved animals and regulation of marketing etc.
5.4 Endangered status
The population size is between 100 and 1,000 females which implies that the breed is in danger of extinction. Without action its effective population size is inadequate in most cases to prevent continuing genetic loss in future generations. An increase in the degree of inbreeding is unavoidable and threatens the vitality of animals. There is a real danger either of spontaneous loss for example by sudden disease, or due to neglect by man. Methods of preservation must be started to save the population in question, for example by cryogenic storage, management of a narrow sex ratio, sophisticated mating system, measurement of biochemical polymorphisms etc, using RLFP, VNTR and finger-print techniques when available. However these electrophoretic studies often show a surprisingly small amount of genetic variability at gene level (Cunningham, 1990). The level of danger is not the same for a populations with 100 and 1,000 breeding females. Therefore the minimum population size must be chosen on an individual basis within the framework of the financial support system made available for example by government or other local or international organizations. Then, the aspects of reproduction, sex ratio, generation interval, system of management, the possible presence of defect genes, mating system used, possible financing etc. should be taken into consideration.
5.5 Critical status
Populations of less than 100 females are an extreme case of the previous level of threat. The population is close to extinction. The first action must be to increase the population size. At this level of threat, the genetic variability is often already reduced so that the population cannot be considered the same as the ancient breed. In spite of this likelihood, there are some exceptional populations which have been maintained at this populations size for many years, as shown by some examples given earlier. However, groups of formerly populous breeds which arrive at this small size should not be maintained at this level of threat and efforts should be made to enlarge the population size.
A domestic animal population should be considered extinct, when resuscitation is impossible. If, after a crucial bottle neck syndrome, another genetic variety comes into being a new name must be given to it.
6 Pros and cons
Some questions must now be faced concerning the system which has been proposed above. It can be argued that in this system the issues of generation interval, reproduction rate, specific characteristics of the species, mating system, sex ratio etc. are not sufficiently involved. It seems probable, that the majority of preserved populations will be kept in at an threatened level as a result of the need to balance between the ideal genetic benefits and available finances. When activities cannot be undertaken for all cases, populations with numbers of females between 100 and 1,000 should be afforded some special consideration for attention. On the effect of inbreeding, some geneticists have recently concluded that there are some mechanisms, such as the phenomenon of non-nuclear inheritance, which act against the depletion of genetic variance and the damage of increasing homozygosity (Cunningham 1990, Ron et al. 1990). Nevertheless, it would not be prudent or useful to recommend lower minimum population size limits for preservation on the basis of these new possibilities until they are fully demonstrated by scientific evidence or by some successful practical examples from the history of animal breeding. The threat of a permanently changed situation through failure to act indicates that the figures proposed in Table 7, which are based upon current proven genetic knowledge, should be the basis of action programmes. These threat categories are proposed for developed country conditions to make doubly sure that extinction does not happen; and for developing country conditions, where control is less certain, the figures could be increased with advantage.
7 Recommendation for A.I. and E.T.
In the literature the generally accepted theoretical basis for the storage of genetic material is a stock of non related 25 individuals (Smith 1982). The collection and storage of semen is not too difficult and that is why storage of some hundreds of doses is recommended as a first step for all cattle breeds (Alderson 1989). For the creation of gene banks of embryos many breeding animals are needed (Springmann et al., 1987), when the following aspects are considered:
Cooperation of owners;
Ratio of possible donors animals to recipients;
Response rate to super-ovulation;
Proportion of embryos suitable to deep freezing;
Deep freezing loss;
Storage loss;
Pregnancy rate after thawing;
Loss during pregnancy;
Perinatal loss;
Losses during the growing period;
Sex ratio;
Intensity of selection of breeding females;
Security.
Number of embryos needed for a founder stock of 25 heifers is shown in Table 8.
Table 8. Number of embryos needed for preservation (Brem et al., 1990)
| Embryo survival (%) | pregnancy rate (%) | ||||
| 20 | 30 | 40 | 50 | 60 | |
| 50 | 616 | 411 | 308 | 247 | 206 |
| 60 | 513 | 342 | 257 | 206 | 171 |
| 70 | 440 | 293 | 220 | 176 | 147 |
| 80 | 385 | 257 | 193 | 154 | 129 |
| 90 | 342 | 228 | 171 | 137 | 114 |
The criterium of “non related 25 individuals” means that the same animal must not appear again up to the third generation in 25 pedigrees. Therefore embryo collection involves a male population of 175 head (although not at the same time) and a female population of many thousands. It is generally agreed that at least two embryo or semen banks are necessary for safety reasons (Beilharz 1983). Renard (1982) proposed 130 embryos from 30 donors as a basis for the cryogenetic storage of a population. The situation is more complicated when, in addition to the cryogenic storage there is also a preserved breeding population. Published recommendations indicate the following figures as desirable:
8 Summary
An authoritative programme should be established by FAO which addresses national and regional preservation programmes for domestic animal breeds and which includes the creation and publication of a World Watch List. Associated with this should be a recommended system of risk assessment which is capable of being used in individual cases and adapted to the specific characteristics and problems. Instead of using only the scientifically valuable concept of effective population size it seems more suitable to propose a category system for the different risk-levels of different situations.
The proposed categories are:
Normal status (over 10,000 females); no danger
Insecure status (5,000–10,000 females); a possible danger in the near future
Vulnerable status (1,000–5,000); the problems can be solved by usual measures
Endangered status (100–1,000 females); special methods of needed
Critical status (below 100 females); exceptional methods needed quickly.
Extinct (no animals); too late.
Using these categories it is possible to create the special minimum number for each individual case. This means that within the given category the specificity of the population, the generation interval, the reproduction rate of the species or breed, the mating system used and the management etc. can be taken into consideration when deciding on the minimum number. It is meaningful to study the genetic structure of a population using blood groups and other polymorphisms.
For cryogenic storage of breeding material minimum numbers of doses of semen and of embryos are recommended. The minimum number for ex situ and in situ methods can be combined.
9 References
Alderson, G.L.H. (1981): The conservation of animal genetic resources in the U.K. FAO. An. Prod. and Health Paper No. 24. Rome, 53–76.p.
Alderson, G.L.H. (1989): The chance to survive. A.H. Jolly Ltd Yelvertoft Manor, Northamptonshire. 143.p.
AMBC (1990): The American Minor Breeds Conservancy 1990. Breeders Directory Pittsboro NC USA. 48.
Beilharz, R.G. (1983): Conservation of animal Genetic Resources. In.: World Animal Science 1. Domestication, conservation and use of animal resources. Ed. Peel and Tribe. 93–105.p.
Bodó, I. and Pataki, B. (1984): Special problems in the conservation of traditional horse lines in small herds. 35th Meeting EAAP. The Hague The Netherlands. 3b. 3–5.p.
Bodó, I. (1985): Hungarian activities on the conservation of domestic animal genetic resources, FAO Animal Genetic Resources Information. 4.16–22.p.
Bodó, I. (1990a): Methods and experiences with in situ preservation of farm animals. FAO. An Prod. Health Paper. 80. Rome. 85–102.p.
Bodó, I. (1990b): Special problems of conservation of domestic livestock. Proc. 4th World Conf. Gen. Appl. Liv. Prod., Vol. XIV. 427–433.p.
Brem G., Brening., Muller, M., Springmann, K., Kraüsslich, H. (1990): Genetische Vielfalt von Rinderrassen, historische Entwicklung und modern Moglichkeiten zur Konservierung. Ulmer. Stuttgart, 136.p.
Campo, J.I. and Orozco, F. (1982): Conservation and genetical study of chicken breeds. Proc. 2nd World Cong. on. Gen. Appl. to Livestock Prod. Madrid.
Chen Ruihe (1990): Creation of conservation areas for Hu sheep in Jiangsu province FAO Animal Genetic Resources Information 7. 20–23.p.
Crawford, R.D. (1981): Organizational aspects of animal conservation research-management methods applicable to poultry. An. Prod. Health Paper No 24. FAO Rome. 335–348.p.
Crawford, R.D. (1989): Experience with in situ preservation of poultry breeds. FAO. Expert Consultation Rome. AGR/GL/89/Sept.
Cunningham, E.P. (1990): Quantitative approaches to animal improvement. Proc. of 4th World Cong. Gen. Appl. Liv. Prod. Edinburgh. Vol. XIII. 4–14.p.
Devillard, L.M. (1981): La politique francaise de conservation des races domestiques en peril. FAO An. Prod. Health Papers No. 24. 96–120.p.
Dmitriev, N.G. and Ernst, L.K. (1989): Animal genetic resources of the USSR. FAO Animal Production and Health Paper 65. 571 p.
Dohy, J. (1989): Az allattenyesztes genetikai alapjai. Budapest, Magveto Kiado. 303.p.
Draganescu, C. (1975): Ratiuni si procedee pentur conservarea materialului genetic la animale domestice. Rev. de cresterea animalelor. No. 3. 25–30.p.
Falconer, D.S. (1964): Introduction to Quantitative Genetics. Oliver and Boyd. Edinburgh-London.
FAO (1990). Animal Genetic Resources - a Global Programme for Sustainable Development. Animal Prod. Health Paper 80.
Fewson, D. (1966): Auswahl von Selektionsmerkmalen und Entwicklung von Selektionssysthemen als Forschungsaufgaben der Haustiergenetik. Zuchtungskunde 38. Stuttgart. 115.p.
Fisher, R.A. (1946): Statistical methods for research workers. 10th. ed. London, Oliver and Boyd.
Foose, T.J. (1988): Genetics and demography of small populations FAO. Rome.. The Przewalski horse. An. Prod. Health Paper 61. 93–104.p.
Hill, W.G. (1972): Effective size of populations with overlapping generations. Theor. Pop. Biol. 3. 278–289.p.
Hirsch, M., Kustermann, W., Pirchner, F. (1990): Zuchtverbesserung zahlenmassing kleiner Rinder populationen in Bayern. EAAP, 4th Ann. Meet. Toulouse.
Hodges, J. (1989), Ed.: Manual on establishment and operation of animal gene banks. FAO. Rome.
Latter, B.D.H. (1959): Aust. J. Biol. Sci. 12: 500–505.p.
Lush, J.L.H. (1945): Animal breeding plans. Collegiate Press Ames Iowa USA.
Maijala, K. (1974): Conservation in animal breeds in general. Proc. 1st. Inter. Cong. on Gen. Appl. to Livs. Prod. Madrid. II. 37–46.p.
Maijala, K. (1982): Preliminary report of the working party on animal genetic resources in Europe. EAAP Leningrad G. 1.2.
Maijala, K. (1990). Establishment of a World Watch List for endangered livestock breeds. FAO Rome Animal Genetic Resources. Anim. Prod. Health Paper 80. 167–184.p.
Maijala, K. (1992): Monitoring animal genetic resources and criteria for prioritization of breeds. Expert consultation on the management of global An. Gen. Res. Rome. 7–10 April. 22.p.
Marx, A. (1990): Das Wollhaarige Weidesschwein in der Schweiz. Diplomarbeit Zollikofen. Manuscript. 38.p.
Ngere, L.O. (1989): Endangered livestock breeds in West Africa. Animal genetic Resources. FAO. Rome. Animal Prod. Health Paper 80. 189–196.p.
Perret, G. (1985): Races ovines. ITOVIC. ed 287–290.p.
Pirchner, F. (1968): Populationsgenetik in der Tierzucht. Hamburg Berlin.
Rasch, D., Herrendorfer, G. (1990): Handbuch der Populationsgenetik und Zuchtungsmethodik. Deutscher Landwirtschaftverlag. Berlin. Germany.
Renard, J.P. (1982): Les methodes de conservation des genes. EAAP Leningrad. G. 1.4.
Rochambeau, H. and Chevalet, G. (1990): Genetic principles of conservation. Proc. 4th World Conf. Gen. Appl. Liv. Prod. Edinburgh XIV. vol. 434–442.p.
Rognoni, G. (1981): Animal genetic resources and their conservation. Defence of animal genetic resources. FAO/UNEP Technical Consultation Rome. FAO. An. Prod. Health Paper 24.pp. 128–130.p.
Ron, M., Genis, I., Eyal, E., Shani, M. (1990): Polymorphism of mitochondrial DNA in Israeli-Holstein cattle. Proc. of the 4th World Congr. on Gen. Appl. to Livestock Prod. Edinburgh. XIV. 255–258.p.
Ryder, O. (1985): Genetics of small populations of Equus Przewalski. FAO. Rome. The Przewalski horse. Animal Prod. Health Paper 61. 127–130 p.
Sheldon, B.I. (1984): Evaluation and conservation of native strains of chicken in SABRAO Region: Animal Genetic Resources Information. 3: 15–18.p.
Simon, D. (1991): Ausschuss der Deutschen Gesellschaft fur Zuchtungskunde zur Erhaltung genetischer Vielfalt bei landwirtschaftlichen Nutztieren. Zuchtungskunde. 426–430.p.
Sirkkomma, S. (1983): Calculations on the decrease of genetic variation due to the founder effect. Hereditas 99. 11–20.
Smith, C. (1982): Genetic aspects of conservation in farm livestock. EAAP Leningrad. G. 1.5.
Smith, C. (1984): Genetic aspects of conservation in farm animals. Livestock Production Science. 11:37–48.p.
Springmann, K., Schutz, W., Krausslich, H. (1987): Factors effecting the utilization of genetic resources 94 tored in an embryo bank. EAAP. Lisbon. G. 1.12.
Thornback, I. (1983): Wild cattle, bison and buffaloes, their status and potential value. IUCN Cambridge. 64.p.
Wallis, D. (1986): The Rare Breeds Handbook. Blandford Press Poole, New York, Sydney 157.p.
Wright, S, (1921): Systems of mating I. II. III. IV. V. Genetics. Princetown Mass. USA 11–178.p.
Wright, S. (1931): Evolution in Mendelian populations. Genetics Princeton Mass. USA.
Wu, Changhsin, (1990): Conservation of animal genetic resources and potential of animal agriculture in China. Proc. of the 4th World Cong. on Genetics Applied to Livestock Prod. Edinburgh. Vol. XIV. 488–491.p.
Yamada and Kimura (1984): Survival probability in small livestock populations. in An. Gen. Res. Cons. by management, data banks and training. FAO. An. Prod. Health Paper 44/1 Rome. 105–110.p.
J. Ruane1
1 Introduction
A data bank is a place where information or data can be stored and managed. In modern times, storage is by electronic means and hence requires the use of computers, be they mainframe or portable. The data that are entered can be instantly recalled, examined, rearranged, edited and printed. In turn, they can then be distributed worldwide in diskette form.
To work for the preservation or promotion of animal genetic resources it is essential that we first know what resources exist. The Global Data Bank for Domestic Livestock aims to document and characterize the different populations of domestic livestock found throughout the world.
2 Current Status
The Global Data Bank is now based in Rome and currently includes 2054 breeds (and varieties of breeds) of ass, buffalo, cattle, goat, horse, pig and sheep. Populations from all areas of the world are covered with the exception of Europe but including the former U.S.S.R. (Table 1). The number of breeds is highest in Asia (43% of total) and, among the seven species, is highest for sheep (29%) and cattle (28%). Most populations (92%) are restricted to a single country while only 8% are found in more than one country.
The list of breeds is still in the development phase and is certain to change as information accumulates concerning populations currently entered in the Global Data Bank that no longer exist and populations that do exist but are not currently included in the data bank. In addition, it is planned that the data already collected on European breeds will be added at a future date.
As of April 1992, the regional data bank for Europe (based in Hannover) contained a total of 707 entries comprising 5 ass, 206 cattle, 54 goat, 110 horse, 92 pig and 240 sheep entries (Maijala, 1992). Note that the numbers in the two data banks are not strictly comparable since in the data bank in Rome there is one entry per breed (even if the breed is found in several countries) whereas in the Hannover data bank there is one entry per breed per country.
The Global Data bank in Rome currently holds information on population size for only 27% of all entries (Table 2). Furthermore, in most cases this information consists of an overall figure for total population size (which may not be up-to-date) or of a description of the breed as rare, disappearing or almost extinct.
1 Animal Production Service, Food and Agriculture Organization, Rome, 00100, Italy.
For 31% of entries in the data bank some information on production characteristics is available (Table 3) while for 20% some information on both population status and production performance is present (Table 4). The production data may consist of data on characteristics such as adult size and weight, milk traits, fleece weight or litter size.
3 Sources of information
The world dictionary of livestock breeds by Mason (1988) was used as the primary source of information on breeds and breed varieties for the data bank. This book provides breed names and synonyms, the geographical location of the population as well as giving a basic description of the origin, physical appearance and main uses of each breed.
Not all entries from Mason (1988) were included in the data bank. For example, those referring to a cross between breeds, a hybrid between two species or to a group or collection of breeds were excluded. On the other hand, all varieties or strains of breeds as well as wild or feral species were included. Of the 2054 entries, 515 (25%) were described by Mason (1988) as a variety, subvariety or strain of a breed and 83 (4%) as wild or primitive
Mason (1988) does not provide estimates of population size (other than to occasionally indicate that a breed is nearly extinct, rare or declining in numbers) or of production performance for the breeds cited. To find this information, a wide range of literature sources in FAO Headquarters were consulted;
Note that at this early stage, greater emphasis was placed on data collection for developing countries. After entering these data it was however obvious that essential information was missing for the majority of breeds (Tables 2 to 4). To rectify this, agreements were made with parties in every part of the world asking them
To confirm that the entries in the data bank relating to their country or region are a true representative of the animal genetic resources in their area.
To complete short one-page questionnaires (see Appendix) for those breeds for which there is no information on population size in the data bank and, if possible, to do the same for those breeds for which some information on population size is available. For these questionnaires, it was emphasized that information on population numbers was of primary importance.
4 Information that can be stored
For each entry in the Global Data Bank a wide variety of data can be stored (Table 5) ranging from basic features such as the origin, population size, physical characteristics, uses, production performance and management conditions of each breed to rarer features such as genetic distancing studies, DNA analysis and genetic conservation programmes. To give an idea of the amount of information that can be stored, a print-out for a single breed covers seven pages.
5 Computer software
The programmes for the data bank were written with a standardized software package called dBASE III PLUS. The original programmes were written, as part of an initiative by the European Association of Animal Production (EAAP), at the Institute for Animal Breeding and Genetics in Hannover, Germany with European breeds and conditions in mind. Consequently it was necessary to make some changes to the programmes to make the data bank more suitable for breeds from developing countries. Among the changes made were the simplification of the section on production data and the addition of references for population or production data. These changes were made while ensuring that the data stored in the data banks in Hannover and Rome would remain compatible.
6 Extinct breeds
The 2054 breeds or breed varieties in the Global Data Bank represent populations known or thought to be in existence around the world today. Together with the number of breeds in the European data bank, it can be estimated that at the present time 2500 to 3000 different breeds or breed varieties are found throughout the world. A parallel data bank has also been set up containing information on 208 extinct breeds that Mason (1988) described as being recently extinct or that were important to the origin of certain breeds in the Global Data Bank.
7 Future work
At this stage we have reached the end of the first phase of the project. A first, rough list of animal genetic resources has been drawn up and, following a relatively brief literature survey at FAO Headquarters, information on population numbers and production data has been collected for a small fraction of these genetic resources.
The next phase of the project should have two objectives. Firstly, to update the entries in the data bank, in the sense of confirming the existence of the breeds or breed varieties already in the data bank and the addition of genetic resources not yet documented or included in the data bank. In this way we can work towards producing a final inventory of the populations of domestic animals found throughout the world.
Secondly, population (of primary importance at this early stage) and production data should be collected for those breeds lacking this information and updated for those breeds for which some information already exists. This will then allow us to pinpoint those populations of high merit or production potential that are endangered and/or that should be promoted. The completion of questionnaires described in Section C by individuals throughout the world concerning genetic resources in their own regions will help to fulfil both objectives.
Once the completed questionnaires are received, the data must be thoroughly checked before they can be entered into the data bank. It is especially important that no breed be entered more than once (this is a danger since the same breed may have several names).
Currently, breeds and breed varieties of seven domestic species (ass, buffalo, cattle, goat, horse, pig and sheep) are present in the data bank in Rome. In the future, it is planned to include camelids and poultry as they also represent important animal genetic resources.
8 References
Maijala, K. 1992. Monitoring animal genetic resources and criteria for prioritization of breeds. Proceedings of an expert consultation on the management of global animal genetic resources, 7–10 April, FAO, Rome.
Mason, I.L. 1988. A world dictionary of livestock breeds, types and varieties. Third edition. CAB International, Wallingford, UK.
9 Tables
Table 1. The number of breeds or breed varieties per geographical region in the Global Data Bank.
| Group | Ass | Buffalo | Cattle | Goat | Horse | Pig | Sheep | Total |
| Former USSR | 15 | 1 | 62 | 20 | 59 | 35 | 135 | 327 |
| Africa | 16 | 8 | 173 | 59 | 35 | 8 | 133 | 432 |
| N&C America | 5 | 1 | 67 | 12 | 41 | 35 | 48 | 209 |
| Latin America | 5 | 2 | 45 | 11 | 22 | 17 | 17 | 119 |
| Asia | 22 | 63 | 200 | 147 | 88 | 142 | 231 | 893 |
| Oceania | 0 | 0 | 21 | 6 | 2 | 6 | 39 | 74 |
| Total | 63 | 75 | 568 | 255 | 247 | 243 | 603 | 2054 |
Table 2. The number of breeds or breed varieties for which there is some information on POPULATION SIZE. The figures in brackets represent % of all entries in the data bank (Table 1)
| Ass | Buffalo | Cattle | Goat | Horse | Pig | Sheep | Total | % | |
| Former USSR | 0 | 1 | 43 | 11 | 48 | 22 | 54 | 179 | (55) |
| Africa | 1 | 1 | 50 | 12 | 1 | 1 | 23 | 89 | (21) |
| N&C America | 0 | 0 | 14 | 5 | 9 | 6 | 11 | 45 | (22) |
| Latin America | 0 | 0 | 20 | 2 | 1 | 4 | 6 | 33 | (28) |
| Asia | 4 | 4 | 47 | 27 | 16 | 19 | 84 | 201 | (23) |
| Oceania | 0 | 0 | 1 | 3 | 1 | 1 | 7 | 13 | (18) |
| Total | 5 | 6 | 175 | 60 | 76 | 53 | 185 | 560 | (27) |
| % | (8) | (8) | (31) | (24) | (31) | (22) | (31) |
Table 3. The number of breeds or breed varieties for which there is some information on PRODUCTION. The figures in brackets represent % of all entries in the data bank (Table 1)
| Ass | Buffalo | Cattle | Goat | Horse | Pig | Sheep | Total | % | |
| Former USSR | 0 | 1 | 40 | 9 | 30 | 21 | 53 | 154 | (47) |
| Africa | 0 | 1 | 51 | 21 | 0 | 1 | 46 | 120 | (28) |
| N&C America | 0 | 0 | 3 | 1 | 1 | 1 | 7 | 13 | (6) |
| Latin America | 0 | 0 | 16 | 5 | 0 | 2 | 6 | 29 | (24) |
| Asia | 0 | 24 | 63 | 68 | 12 | 28 | 118 | 313 | (35) |
| Oceania | 0 | 0 | 1 | 2 | 0 | 0 | 2 | 5 | (7) |
| Total | 0 | 26 | 174 | 106 | 43 | 53 | 232 | 634 | (31) |
| % | (0) | (35) | (31) | (42) | (17) | (22) | (38) |
Table 4. The number of breeds or breed varieties for which there is some information on POPULATION SIZE AND PRODUCTION. The figures in brackets represent % of all entries in the data bank (Table 1)
| Ass | Buffalo | Cattle | Goat | Horse | Pig | Sheep | Total | % | |
| Former USSR | 0 | 1 | 38 | 7 | 30 | 21 | 51 | 148 | (45) |
| Africa | 0 | 1 | 38 | 11 | 0 | 1 | 18 | 69 | (16) |
| N&C America | 0 | 0 | 2 | 1 | 0 | 1 | 5 | 9 | (4) |
| Latin America | 0 | 0 | 12 | 2 | 0 | 2 | 5 | 21 | (18) |
| Asia | 0 | 1 | 36 | 25 | 0 | 12 | 80 | 154 | (17) |
| Oceania | 0 | 0 | 0 | 2 | 0 | 0 | 2 | 4 | (5) |
| Total | 0 | 3 | 126 | 48 | 30 | 37 | 161 | 405 | (20) |
| % | (0) | (4) | (22) | (19) | (12) | (15) | (27) |
Table 5. Summary of information that can be stored for each entry in the data bank.
Names of individuals or organizations that provided information on the entry
Degree of usage of artificial insemination and storage of semen and embryos
Genetic characteristics of the breed e.g. marker genes, chromosomal aberrations
Special qualities of breed e.g. disease resistance, adaptability to harsh climate or environment
Type of management, housing period, feeding
Two ways of describing the performance record are possible a) Giving actual figures for the performance traits described in Table 6 (including reference(s)) or b) comparing the breed to a standard breed (preferably one that is very common) for a range of production traits
Contact address for the conservation programme
10 Appendix. Breed questionnaire - population and performance data
NOTES:
COMPLETE ONE QUESTIONNAIRE PER BREED
QUESTIONS ARE WRITTEN ON BOTH SIDES OF THE PAGE
WHEN GIVING DATA, IF IT IS POSSIBLE, PLEASE INDICATE WHETHER THE DATA SOURCE IS VERY RELIABLE (V), RELIABLE (R) OR NOT RELIABLE (N). e.g. If the population size estimate is 10,000 and the data source is very reliable, write 10,000 (V)
GENERAL INFORMATION
1. Country: ........................................................................................................................................................................................................
2. Species (Buffalo, Cattle, Goat, Sheep, Horse or Pig): .................................................................................................................................
3. Breed name: .................................................................................................................................................................................................
4. Local names or synonyms: ...........................................................................................................................................................................................................................
............................................................................................................................................................................................................................
POPULATION DATA
5. Year of data collection: ..........................................................
6. Total population size: ....................................................................................................................................................................
7. Total number of females being bred: ...........................................................................................................................................
8. % females being bred pure (mated to males of own breed): .......................................................................................................
9. Total number of males used for breeding: ...................................................................................................................................
10. Of the above males, the number in AI-service: ..........................................................................................................................
11. Is the number of females increasing (1), decreasing (2) or stable (3) : ...................................................................................................
12. Additional population information (or any comments on the population data (e.g. source of data)): ........................................................
...........................................................................................................................................................................................................................
...........................................................................................................................................................................................................................
...........................................................................................................................................................................................................................
...........................................................................................................................................................................................................................
...........................................................................................................................................................................................................................
.................................................................................
PERFORMANCE DATA
1. PERFORMANCE
| BUFFALO, CATTLE ASS OR HORSE | GOAT OR SHEEP | PIG | ||||||||||||||
| Milk yield per lactation | (kg) | |||||||||||||||
| Lactation length | (days) | |||||||||||||||
| Milk Fat per cent | (%) | |||||||||||||||
| Milk yield per year | (kg) | |||||||||||||||
| Birth weight (male) | (kg) | |||||||||||||||
| Birth weight (female) | (kg) | |||||||||||||||
| Daily gain (male) | (g) | |||||||||||||||
| Lean meat | (%) | |||||||||||||||
| Litter size | (n) | |||||||||||||||
| Fleece weight (female) | (kg) | |||||||||||||||
| 2. | Adult wither height | (cm) : | Males ...................... | Females ...................... |
| Adult live weight | (kg) : | Males ...................... | Females ...................... |
3. Management conditions under which performance was measured:
a) Type: Stationary (1), Transhumant (2) or Nomadic (3) ........
b) How many months per year were the animals housed ?: ..........
c) Feeding of adults: Total Grazing (1), Grazing + Fodder (2), Grazing + Concentrate (3), Total Concentrate (4), Other (explain) ...................
d) Special conditions, e.g. lack of water supply: ........................
...............................................................................................................................................................................................................................
4. Comments on performance data (e.g. source of data) or additional performance information (e.g. other merits of the breed): ....................
.................................................................................................................................................................................................................................
.................................................................................................................................................................................................................................
.................................................................................................................................................................................................................................
.................................................................................................................................................................................................................................
.................................................................................................................................................................................................................................
.................................................................................................................................................................................................................................
.................................................................................................................................................................................................................................
