K. Maijala 1/
Genetic variation in animals has developed during millions of years. In the course of time the usefulness of different genes and gene combinations has been under severe tests, especially concerning adaptability to different conditions and resistance to diseases and parasites.
During the last ten thousand years man has partly influenced this evolution, and many breeds adapted to local needs and environments have been developed. The possibilities of making changes in the genetic make-up of farm animals and of concentrating on the utilization of the breeds considered to be the best, have increased in recent decades, thanks to the availability of modern reproduction, computer and communication techniques.
The increased rate of changes and parallelization of breeding goals have awakened concerns about losses of genetic variation both within and between breeds. Many breeds have disappeared or are threatened. A recent survey showed that 81, 51, 67 and 12 European breeds of cattle horses, sheep and goats, respectively, were considered endangered (Maijala et al., 1984).
Activities for preventing gene and breed losses have been started in different parts of the world (FAO, 1981), in order to maintain the possibility of adjusting animals to future, unpredictable needs. In many countries the emphasis is on conserving breeds, and hence it is topical to discuss whether this could be done economically, when the current competing ability of the breed is unsatisfactory and the population is small.
Before discussing the possibilities and ways of maintaining small populations or so-called rare breeds it is important to make clear why they should be conserved. in Europe, the reasons for conserving genetic variation have been discussed among others by Maijala (1970), Mason (1974), Simon (1984) and Maijala et al. (1984). On the basis of these and other papers, the following list of arguments for conservation can be made:
A. Economic-biological reasons
B. Scientific reasons
C. Cultural-historical reasons
In many points (e.g. A.1, 2, 4) it is a question of maintaining the possibility of changing breeding objectives according to unpredictable changes in needs. Even negative changes in the production conditions of ruminants are possible, if grains are needed directly for human consumption or for fuel. In Italy it has already been necessary to return to the original local breeds in utilization of dry mountain pastures (Rognoni, 1980).
The arguments A.3, B.1-4 and C.1-3 require conservation of entire breeds. Availability of distinct and different kinds of breeds or lines makes the utilization of conserved variation more rapid and effective in the case of need, both in pure- and crossbreeding. Gene combinations are conserved besides genes, and both the cultural-historical and emotional interest are satisfied, which is not the case in storing material in frozen form or as gene pools. On the other hand, both the initial and maintenance costs are high, and there are risks for diseases, accidents, genetic drift, inbreeding and contamination from other breeds. Because of the smallness of population, genetic improvement by selection is slow, and hence the gap in current breeds or selection lines increases (Maijala et al., 1984).
These disadvantages can be considerably lessened with the aid of simultaneous conservation of frozen semen and embryos, which also makes it possible to manage with rather small numbers of live animals (e.g. 20-300 females). These are needed for evaluation purposes as well as for cultural-historical reasons even if frozen semen and embryos were satisfactory for the conservation of the genetic variation itself. It is also very probable that the frozen material would be forgotten in store by our descendants, if no live animals could be seen and studied.
Additional arguments for maintaining many breeds as pure were given by Land (1981), who suggested a planned development of strains with divergent biological traits, since some old local breeds have proved themselves useful in many countries, because of their special traits for the modern market (e.g. lean carcasses, double-muscling, high fertility). Their maintenance would increase genetic flexibility and the rate of progress and ensure the availability of desired genetic variation at the time of need.
Bowman (1981) considered that "the conservation of a wide range of genetic variation coupled with the development of a capability to reproduce and multiply quickly and cheaply desirable types of animals, are far more important to the future of animal production than the development of over sophisticated forms of within-population selection".
An idea of the relative costs for maintaining purebred populations for the purpose of genetic conservation can be obtained from Table 1, based on the studies by Brem et al. (1984) and by Smith (1984).
In both calculations, maintenance of live animals as pure breeds was many times as expensive as frozen semen, even though the number of animals was assumed to be very low, allowing no selection in the population during storage and not even in the first years after starting its reuse. In the study by Brem et al. (1984) the conservation as frozen embryos was also considerably cheaper than as live animals, while there were very little differences in the study by Smith (1984). in the latter study, conservation of sheep breeds was not essentially cheaper than that of cattle breeds.
Availability of many-sided semen stores makes it possible to conserve a breed without big risks for genetic drift and inbreeding depression. Frozen embryos offer the additional advantage that the breed can be regenerated and used for crossbreeding within a generation, even if the number of live animals of the breed is zero or minimized to show only its type and colours to our descendants. In addition, frozen embryos conserve better than frozen semen gene combinations and frequencies. It is likely that the costs of preparing embryos for frozen stores will decrease, especially if it becomes possible to make embryos by taking ova from the ovaries of slaughtered females and by using in vitro culture and fertilization.
Table 1 ESTIMATED ANNUAL COSTS FOR CONSERVING CATTLE AND SHEEP BREEDS IN THREE DIFFERENT WAYS, WHEN STORAGE TIME IS 20 YEARS AND INVESTMENT COSTS AND INTERESTS ARE NOT CONSIDERED
|Species||Author||Live animals||Frozen semen 1/||Frozen embryos 2/|
|Cattle||B 3/||4 860 £5/||
|25f x 4e|
|Cattle||S 4/||5 000 £||10m,26f||600 £||25mx50d||4 250 £||25f x 25e|
|Sheep||S 4/||3 000 £||22m,60f||635 £||25mx30d||3 000 £||25f x 25e|
1/ Requires at least 10 additional years to regenerate the breed.
2/ Requires about one generation (3 yrs in cattle) to regenerate the breed
3/ Brem et al., (1984)
4/ Smith (1984)
5/ 1 £ = 3.6 DM
m = males, f = females, d = doses, e = embryos
The returns from breed maintenance are still more difficult to estimate than the costs, because of the difficulties in predicting the future. However, Smith (1984) tried to calculate the probabilities of future uses of stocks to justify conservation from the national viewpoint. He based his calculations on the following factors: (1) total value of market, (2) cost of conservation, (3) proportion of the stock used in future commercial production, (4) proportional gain in economic efficiency over current stocks, (5) number of years until commercial use, and (6) length of the utilization period. Table 2 shows the estimated probabilities for the market volume in the U.K.
The general conclusion of Smith (1984) from the probability-values was that even small gains in efficiency and low proportions of the genes from a conserved stock would bring profit for the nation. Thus, it would be worthwhile to maintain a stock, even if there is a very small chance that the stock would be useful in the future. The costs of conservation appear to be small relative to possible future gains in national production. The required probabilities were the lowest for frozen semen, while those for live purebred animals and for frozen embryos were 5 to 10 times higher. In small countries with a limited market the probabilities required are, of course, higher. It has to be stressed also that the profits can be harvested only on the national level, not by individual enterprises.
In his extended studies Smith (1985) calculated the reduction in uncertainty about the permanence of breeding objectives by selecting alternative stocks for different sets of objectives. The size of each line was 5 males and 150 females, of which 50 were selected per year. The national return/cost ratio (in U.K.) in one year of one year's genetic improvement was 1900 in dairy cattle, 940 in beef cattle, 500 for meat production traits in sheep, and 200 for sex-limited traits in sheep. Even if these values might not be entirely realized in practice, there appears to be sense in developing alternative selection stocks for reducing the uncertainty with regard to the future needs and breeding objectives. The longer the time horizon, the higher number of stocks one could develop profitably. The high R/C values can be applied on the national level, while smaller investors have to apply lower values (e.g. 10), where the maximum benefit is sensitive to the number of stocks selected.
Table 2 PROBABILITIES NEEDED FOR THE USE OF CONSERVED CATTLE AND SHEEP STOCKS IN U.K. TO JUSTIFY THEIR CONSERVATION, ACCORDING TO SMITH (1984). USE MADE AFTER 20 YEARS FOR 20 FURTHER YEARS. REQUIRED ECONOMIC EFFICIENCY OVER THEN CURRENT STOCKS 5%
|Species||Products||Method of conserv.||Probability (%) needed with different degrees of substitution|
100% = complete substitution
50% = 2-breed cross or synthetic
10% = specialized use
1/ Total annual value of production in U.K. 1900 mill. £.
2/ Total annual value of production in U.K. 1500 mill. £.
3/ Total annual value of production in U.K. 400 mill. £.
Smith concluded from his calculations that there is scope and many benefits from creating and manipulating genetic diversity to maximize the future economic efficiency of our livestock.
In spite of the many motives for maintaining several breeds and of the obvious national economic profitability of their maintenance in the long term it may not be possible or realistic to maintain all breeds. A choice is often made necessary by the fact that the number of people understanding the motives is limited, and hence also the resources available are limited. The criteria for choosing breeds for maintenance have been discussed by many authors (e.g. Mason, 1974, Simon and Schulte-Coern, 1979, Simon, 1934, Maijala et al., 1984, Bodó et al., 1984). They are closely connected with the motives and partly with the methods of conservation.
An important question is whether there is time to evaluate a breed before deciding to conserve it. Provisional maintenance may often be well-founded. Evaluation is even impossible for unknown traits, which may-became important in future. Compromises are needed between ideals and possibilities, between motives and methods and among different objectives. Both practical experience and theoretical knowledge from different sectors are important in the decision making, which thus may sometimes become complicated. The main viewpoints to be considered can be listed as follows:
- performance (overall or in some special trait)
- adaptation (climate, feed, management system, local tastes)
- resistance (infection, parasites)
- special characteristics (major genes, biochemical traits)
- heterosis or complementarity expectations in crosses
- history and age as a separate breed
- breed purity and relationships within breed
- relationships to other breeds and evolutional origin
- population size and its trends (vulnerability)
It is important to consider whether the breed should be preserved without selection or maintained with simultaneous selection. For some breeds which occur in several countries, international cooperation is desirable in both decision making and action.
The economic-biological reasons mentioned above for maintaining minority populations referred to possible future needs. However, changes in needs and production conditions do not vary only with time but also with geographical and agricultural location within a certain era. Considering the whole world, some places are now living the stage of development which in some other places occurred hundreds of years ago. An interesting feature of history is that it often repeats itself even at the same location. Taking into account the wide spectrum of environmental and economic circumstances and the versatility of many farm animal species, it should be possible to find good economic niches for many minority breeds. Examples of special uses for cattle, goats, horses and sheep are listed in Table 3.
There are several alternative uses for each species, and it is likely that different breeds suit differently for them. It is also probable that some minority breeds can be utilized many-sidedly, while the popular majority breeds often are specialized to just one or two tasks. An idea of the many-sided uses and of special qualifications of farm animal breeds can be obtained from a recent working party report (Maijala et al. , 1985). An effective utilization of the many-sidedness may be the key to the profitability. The production conditions may vary even in the same village or community, and in the era of A.I. it is possible to use males of different breeds within the village, even within a farm. For some products, marketing may cause problems, if all neighbouring farmers do not produce the same product, but for some' products it is advantageous to be the only producer in the community. A creative imagination has often given good results in finding new ways for production and marketing, and its importance is obviously increasing in the era of surpluses concerning conventional products.
Table 3 POSSIBLE SPECIAL USES IN ECONOMIC PRODUCTION FOR BREEDS OF SOME FARM ANIMAL SPECIES
|Possible in breeds of|
|Tractive power in difficult conditions||X||X|
|Production of "biological" food||X||X||X|
|Production in prison farms||X||X||X||X|
|Production at school farms||X||X||X||X|
|Pasture and lawn management||X||X||X|
|Forest management, underbrush-clearing||X|
|Production of sera for research & health||X||X|
|Production of unallergenic milk|
|Production of other medicines||X||X|
|Dam line in crossbreeding for meat||X||X||X||X|
|Utilization of harsh environments||X||X|
|Utilization of marginal areas||X||X||X|
|Experimental animals in research||X||X||X|
|Production of luxury furs||X||X||X||X|
|Production of wool for handicraft||X|
|Animals in part-time farming||X||X||X|
Utilization of marginal areas or otherwise harsh environments deserves special attention, since ruminants do not have competitors in that field, the importance of which may increase. It is important that some breeds are continuously kept and selected in those conditions, in order to have suitable animals available at the time of need. Especially beef cattle, whose feed efficiency is poor, should be kept under extensive conditions, in order to minimize the costs of calf production. The adaptation and hardiness of local breeds can be exploited now by using them in commercial crossing for meat production with specialized meat breeds. Mason (1989) considered that a commercial crossbreeding system serves breed conservation because of the need of continuous supply of local adapted breed as foundation stock, giving financial inducement for maintaining such breeds.
The utilization of prison farms for breed conservation turned out to be possible in Finland, when it was realized that animals on these farms serve largely the psychological care and employment of prisoners so that top yields are not necessary and not even possible.
Animals are part of nature, and hence native breeds of farm animals are often kept in natural parks. In France, at least two breeds of cattle, two breeds of 'sheep and one goat breed are kept in that way (Mason, 1982). The Rove goats graze the fire-breaks and keep them clear of scrub. In Hungary, flocks of indigenous breeds of cattle (Hungarian Grey) and of sheep (Racka and Cigaya) are kept in two big national parks (Hortobágy, Kiskunság), which were established in 1972 and 1974 (Salamon, 1982, Szabo, 1982). Bodó et al. (1984) considered that "the costs in maintenance of cattle can be minimized by keeping them in national parks, where they can also help to maintain the biological balance by grazing the tail grasses".
Small numbers of indigenous farm animals are also kept in ecological museums in different countries.
An important way of decreasing the costs for conservation of breeds is to use them for leisure time activities, the demand for which is increasing with shortening working time and increasing standard of living. Examples of such activities are given in Table 4.
Table 4 POSSIBLE USES OF FARM ANIMAL BREEDS FOR PLEASURE AND RECREATION
|Kind of use||
Possible in breeds of
|Animals in national parks||X||X|
|Farm animal parks and museums||X||X||X||X|
|Riding for hobby and racing||X|
|Agricultural and native place museums||X||X||X||X|
|Social company of humans, pet-keeping||X||X||X|
|Aid in bringing up children, 4 H-farms||X||X||X||X|
|Maintenance of local culture & tradition||X||X||X||X|
|Exhibition in zoos||X||X||X||X|
The use for pleasure has been especially important for horses, where trotting and riding competitions bring in considerable amounts of money, not only to the successful enterprises but also to the states, which thus can support maintenance of working horses, too. At least in fir land it has been compulsory to arrange a certain proportion of starts in trotting matches for Finnhorses, and so the decrease in the number of Finnhorses has stopped many years ago, and the number of foals has been increasing in the 1980s. A working party set up by the Ministry of Agriculture and Forestry suggested in 1982 that the prize level of Finnhorses should be developed in proportion to that of warm-blooded trotters, in order to safeguard the continuation of the positive development in numbers. Whether this secures the maintenance of the right horse type for working is another question.
Finnhorse has also been found to be a suitable riding horse for beginners. Here the working type suits the purpose rather well. In order to increase this type of use of Finnhorses, the working party suggested that opportunities to participate in horse-racing should be arranged for Finnhorses in their own classes.
In some countries, there are farm animal parks, which have importance in creating interest in the old breeds among people and help in getting money for conservation activities through tourism. The best examples can be found in the United Kingdom, where Cotswold Farm Park has representatives of 22 old breeds and attracts over 100 000 visitors per year (Henson & Henson, 1982). A Finnish animal park also has a farm animal section, and Norway has plans to establish such a farm for conservation purposes. The numbers of animals per breed in those farms are small, and hence one should have animals also elsewhere, in order to conserve enough variation and to avoid inbreeding.
The latter concerns also zoos, in which representatives of old farm animal breeds are sometimes kept. It is generally thought among animal geneticists that the role of zoos is to maintain wild ancestors of domestic breeds. The wild types would be valuable sources of genes and should thus be conserved. In 1975 there were altogether 244 Przewalski horses in 58 zoos in the world (Mason, 1980).
Mason (1980) considered pet keeping important in the sense that the close relationship between human and animal gives a motive for breeding rare or disappearing breeds. On this basis large groups of people become interested in visiting animal parks and in supporting conservation activities. Private societies for conservation purposes have been established among others in France in 1971, in the United Kingdom in 1973, in the Netherlands and in North America in 1977, in Denmark in 1981, in Austria, FRG and Swizerland in 1982. These have already increased the interest in conservation in their countries and in many cases prevented endangered breeds from disappearing.
Besides the direct economic problems, for which finding other uses for the breeds is important, there are genetic, hygienic, organizational and safety problems making the conservation of breeds more difficult.
The genetic ones are mainly of two kinds:
The hygienic problems are also of two kinds:
An appropriate organization is needed for collecting and disseminating information, preparing mating plans, exchanging animals, etc.
In order to avoid risks of accidents (e.g. fires) the stored material should be placed in several locations.
These different kinds of problems are inclined to increase the costs of conservation. In addition, investments have to be made much before the returns, which for their part are uncertain and may be harvested by another group of people than by those who made the investment. Therefore, it is important to find and utilize various alternatives for getting immediate incomes for the material and that the society (state) takes at least partial responsibility for the costs as a national insurance fee.
The possibilities of conserving breeds of cattle, horses, sheep and goats for future needs were discussed, especially from the economic viewpoint. At first, several economic-biological, scientific and cultural-historical motives for conservation were presented. Many of them spoke in favour of conserving entire breeds, but it was realized that simultaneous conservation of frozen semen and embryos makes the conservation cheaper or better.
Referring to the calculations by Smith (1984, 1985) it was stated that even small gains in efficiency and low proportions of the genes from a conserved stock would bring profit for the nation and that it pays to create genetic diversity to maximize the future economic efficiency of livestock.
The main viewpoints to be considered in choosing breeds for conservation were presented.
Several alternative ways for utilizing rare breeds in economic production were listed. Special attention was directed to the utilization of marginal feed resources and of local breeds as dam lines in commercial crossing-for meat production. Keeping indigenous breeds as a part of the natural environment in natural parks was also noted, as well as utilizing them for leisure time activities. These have been especially important in horses, which are used for riding and trotting. Attention was paid also to tourism, farm animal parks, zoos and hobby organizations. In spite of these possibilities, the state has to assume a partial responsibility for the costs of conservation, since the main returns from it can only be harvested in the future and not by those who invested the money.
|1984||Bodó I., Buvanendran V. & Hodges J. Manual for training courses on the animal genetic resources conservation and management. Vol. I. Budapest. 68 pp.|
|1981||Bowman J.C. Breeding livestock for the future. FAO Anim. Prod. & Health Paper 24: 178-189.|
|1984||Brem G., Graf F. and Kräusslich H. 1984. Genetic and economic differences among methods of gene conservation in farm animals. Livest. Prod. Sci. 11: 65-68.|
|1981||FAO. Animal Genetic Resources, Conservation and Management. FAO Anim. Prod. and Health Paper 24: 388 pp.|
|1982||Henson J.L. and Henson F.L. The role of tourism in conserving rare breeds of farm livestock in Great Britain. Intern. Conf. on Gene Reserves, Debrecen, Hungary. 4pp.|
|1981||Land R. An alternative philosophy for livestock breeding. Livest. Prod. Sci. 8: 95-99.|
|1970||Maijala K. Need and methods of gene conservation in animal breeding. Ann. Génét. Sel. Anim. 2: 403-415.|
|1984||Maijala K., Cherekaev A.V., Devillard J-M., Reklewski Z., Rognoni G., Simon D.L. and Steane, D.E. Conservation of animal genetic resources in Europe. Final report of an EAAP working party. Livest. Prod. Sci. 11: 3-22.|
|1985||Maijala K., Simon D.L. and Stean D.E. Report by the working party on animal genetic resources. EAAP Commission on Animal Genetics. Greece. 6 pp.|
|1974||Mason I.L. The conservation of animal genetic resources: Introduction. 1st World. Congr. Genet. appl. Livest. Prod. Madrid. Vol. II: 13-21.|
|1980||Mason I.L. Methods of breed conservation. In animal genetic resources care and use. National Research Council (Italy). Rep: 171-184.|
|1982||Mason I.L. The role of protected areas in the in-situ conservation of animal genetic resources. Intern. Conf. on Gene Reserves. Debrecen, Hungary. 11 pp.|
|1980||Rognoni G. Preliminary results of the research project "Defense of animal genetic resources". In: Animal Genetic Resources Care and Use. National Research Council (Italy). Rep.: 55-75.|
|1982||Salamon F. Nature protection and animal keeping in the Hortobágy national park. Intern. Conf. on Gene Reserves, Debrecen, Hungary. 7 pp.|
|1984||Simon D.L. Conservation of animal genetic resources - reviewing the prob lent. Livest. Prod. Sci. 11: 23-35.|
Simon D.L. and Schulte-Coern H. Verlust genetischer Alternativen in der Tierzucht - notwendige Konsequenzen. Zühtungskunde 51: 332-342.
|1984||Smith C. Estimated costs of genetic conservation in farm animals. FAO Anim. Prod. & Health Paper 44/1: 21-30.|
|1985||Smith C. Scope for selecting many breeding stocks of possible economic value in the future. Anim. Prod. 41: 403-412.|
|1982||Szabo T. Protecting indigenous domestic animal breeds in the Kiskunság national park. Intern. Conf. on Gene Reserves, Debrecen, Hungary. 4 PP.|
C. Matzon 1/
As a result of the improvement in and intensification of agricultural production in Sweden, the acreage of natural grazing land decreased from nearly 1 million ha to 200 000 ha from the time between the two world wars up to today.
The importance of well managed natural grazing land has been discussed in Sweden especially during the last years. In these areas, there are several endangered species of wild fauna and flora.
Agricultural policy in Sweden today is to reduce the overproduction of agricultural products and this will affect the total number of farmers and acreage of both arable land and grazing land. The number of grazing animals will probably diminish in a radical way.
It is of great importance for Swedish nature conservation to ensure that areas of agricultural land - from the scientific and cultural point of view - will be managed in the right way to conserve fauna and flora. But it is also of vital importance for the understanding of the cultural background to use indigenous, local breeds in the management of the reserves for research and education.
Therefore, the Environment Protection Board already supports and in the future intends to support further the maintenance of native breeds.
Out of a total acreage of well over 1.5 million ha of national parks and nature reserves about 10 000 ha is agricultural land. A great portion of this land is owned by the government but also local communities and individuals are landowners. Restrictions through e.g. management plans makes it possible for the authorities to regulate land use.
The most significant instrument to keep adapted native breeds in reserves is through subsidies to tenants. A tenant can, if he keeps indigenous grazing animals in a traditional way, get support in the form of a lower rent and in some cases, acreage allowances or head payment. Governmental funding can also be done for bushclearing, fencing, transport and support for farm buildings.
Just recently, the Environment Protection Board, in cooperation with local authorities, started a scheme for the management of chalets (mountain pastures) in Dalarna county in Sweden. These chalets are not nature reserves. Chalets are a traditional, very specific type of agricultural system in the mid parts of Sweden. Cattle, sheep and goats are for about 2-3 months taken to grazing areas up in the woodlands far away from the villages in the valleys.
For each dairy cow of local breed (SKB) the farmer gets a yearly subsidy of SKr 500 (about $75.00). If the cow is of lowland type or a crossbreed the subsidy is SKr 300. Subsidies are also available for heifers, goats and sheep.
The main reason for the Board to release funds for these activities is to get the farmers interested in this traditional form of production and by that keep the cultural landscape open. By allowing higher subsidies for native breeds the authorities emphasize the importance to preserve native breeds in the areas from where they originate, not least from the educational point of view.
F. Pirchner and J. Aumann 1/
Population size has received much attention both in population genetics and in applied animal improvement. Official recognition of a group of breeders as a herd book society depends in some countries., e.g. in the Federal Republic of Germany, on the number of animals deemed sufficient to carry on an effective breeding plan. Size of a population can be viewed from the genetic and economic aspects. The genetic aspect concerns prospects of genetic improvement without consideration of costs incurred by the breeding work. On the other hand, population size may reflect on the economy of the breed improvement.
Common sense would lead one to expect more genetic progress in large populations - selection intensity can be greater and outstanding and rare individuals are more likely to be found there than in small populations. However, the reproductive rate is by and large independent of population size which implies that selection differences are roughly equal in populations of different size. High selection intensity in small populations will lead to a high rate of inbreeding in much shorter time than in large populations. It can be shown theoretically .(Robertson, 1960) that long-term selection response will be greater in larger populations simply because they harbour more genetic variability.
In populations with normally distributed traits, selection intensity increases somewhat with size. This increment is relatively modest and may have little impact on breed improvement except in well ' planned and precisely executed breeding schemes. Robertson (1960) has developed a theory which predicts that the total selection gain should be 2 Ne times the genetic improvement of one generation selection. The half-time of the total genetic advance should be reached after roughly 1.4 M generations (Ne = effective population size). However, in practical breed improvement, longterm time scales barely matter apart from the fact that the predictions were only partly substantiated by experiments. In breed immprovement where changing market requirements etc. are important, short term and medium term considerations would appear to be of overriding importance, i.e. selection gain over, say, a dozen or two dozen generations at the most.
The importance of population size on medium and long term genetic progress has been investigated in a number of experiments. Roberts (1966) reports from mouse experiments that the half-life of genetic progress is of the order of N /2 generations. This indicates that genes with large effects are responsible for a large part of the genetic advance. The Australian group (Frankham et al., 1968) reports rather large scale Drosophila experiments. They did find the expected connection between size of the population and selection intensity.
However, there was little change in the magnitude of realized heritability even though it increased slightly with increasing population size. On the long term, i.e. over 40-50 generations, large populations showed more progress but in the short and medium term the advantage of larger populations was rather modest. However, it must be emphasized that mass selection only was employed in the experiments.
An investigation by Hanrahan et al. (1973), employing mice, revealed clear advantages of larger populations. Effective population size was greater and the rate of inbreeding clearly lower in populations with 16 mating pairs than in those with 4 mating pairs. Genetic progress was greater in the larger population which is a consequence of a greater realized heritability. Selection intensity showed little difference which was to be expected due to within family selection.
Summarizing experimental investigations, larger populations permit greater selection gain, even on short term and medium term scale, partly due to greater selection intensity but mainly, however, due to greater realized heritability. The cause of the greater realized heritability in larger populations may be genetic drift which in smaller populations soon leads to increased homozygosity and thus to loss of genetic variability. a number of investigations indicate this in addition to theoretical expectations.
The other aspect of population size and genetic improvement concerns economics. Improvement work in large populations can be much more economi cal if one succeeds in spreading the genes of superior animals widely. Nowadays this may be accomplished by A.I. The advantages of large populations is great in particular if selection is very expensive as it is when progeny testing is used. A number of investigations indicate these advantages (Comberg, 1980).
The experimental investigations were performed with populations of comparatively small numbers. So the next question concerns the size of domestic animal populations and whether these are comparable with those mentioned above. The effective population size in respect -to inbreeding and drift of the latter is surprisingly small and comprises but a fraction of the real numbers.
We have investigated three Bavarian horse populations (Fehlings et al., 1983). The Haflinger has an effective size of about 80, the Bavarian draught horse about 120 and the German trotter a little more. The figures are comparable to Ne's from other horse and cattle populations. The inbreeding increment of U.S. Holsteins indicated, before introduction of A.I., an Ne of about 120 (Lush et al., 1936) and that of the Bavarian Fleckvieh is not very different. Some populations have lower effective numbers and one may pose the question whether breed improvement work can be effective in such populations. However it can be stated that respect to effective population size, smaller breeds have numbers which are not much bigger than those of the largest experimental population investigated by Frankham et al. (1968) and others.
Another question concerns the connection between population size of domestic breeds and their genetic progress. Hintz et al. (1978) have published the estimates of yearly genetic progress of the five major U.S. dairy breeds over a period of about 15 years from the early 1960s to the middle 1970s. A perusal of the figures of Table 1 indicates no connection between size and genetic progress of these five breeds - Brown Swiss have a greater genetic trend than Holstein-Friesians even though their real numbers are but a fraction of the Holsteins and their effective size is also somewhat, though only little, smaller. The conclusion from this comparison must be that genetic progress depends on several things, possibly also on population size but that the latter's effect is overshadowed by other factors and that it is not discernible in the published figures. This may be due to the flattening of the curve relating genetic progress to population size when this curve approaches the asymptote. This flattening appears to occur at relatively low numbers (Ne < 100) and other factors become much more important. At any rate, as can be judged from the figures published by Hintz et al. (1978) under practical circumstances population size appears to be a minor factor with regard to genetic progress.
Table 1 GENETIC CHANGE IN YEARLY MILK YIELD OF U.S.
(Hintz et al., 1978)
|Approximate number of yearly herd book registrations|
|A.I. cows||Non-A.I. cows||A.I. bulls|
|Brown Swiss||38||36||35||13 100|
In closed populations increase of the rate of inbreeding is unavoidable. However, the increase can be effectively postponed as has been found by Vangen (1983) in Norwegian horses or by Strom (1982) and Fehlings et al. (1983) who found inbreeding to be less than expected from inter se relationship. However, increase in inbreeding cannot be postponed indefinitely and at a later point inbreeding in such a population will even overshoot the level which would have arisen by continued panmixis (Robertson, 1964). Of course, any immigration will drastically reduce the level of inbreeding.
One must assume that populations of domestic animals are not closed to the same extent as laboratory populations are - in Central Europe herd books were never closed and only recently herd book societies on the continent have started to follow the Anglo-Saxon tradition in this respect.
Another question concerns the maximum intensity of selection compatible with a tolerable rate of inbreeding. The latter may be taken as the rate of inbreeding which is found in successful populations. In Holstein-Friesians this is roughly 0.4 percent F per generation. If one surmises that the inbreeding is largely caused by sires one arrives at a minimum number of about 30 sires per generation. The generation interval in cattle is about 5 years, therefore 6 bulls should be taken in every year, on average. This presupposes random mating after breeding animals have been chosen. If one would take one son from each sire and one daughter from each dam - not a realistic assumption if selection is to succeed - then the effective population size is roughly 16 Nm/3 (Nm = n. sires/generation). Again if 0.4 percent inbreeding increment is tolerated, 23 to 24 bulls should be used per generation, about 5 per year. These numbers are easily met by most breed societies.
The Tyrolean grey cattle number about 30 000 - 35 000 cows of which 4 000 - 5 000 are recorded each in North and South Tyrol. Insemination is Practised on about 40-50 percent but since herd size is small, the use of community bulls is the rule.
The practical genetic improvement via A.I. breeding programmes would appear to be severely hampered in such small populations. In many papers, the size of populations which permits sustained progress is in the order of several 10 000 and to become profitable the numbers should still be larger (Comberg, 1980).
The bottleneck in breed improvement lies in the selection of A.I, bulls which must be progeny tested and which would require testing of some 4 to 5 x as many bulls as are eventually desired. Furthermore, a certain number of selected bulls is required to avoid inbreeding to increase too rapidly.
In conventional A.I. breeding programmes (Comberg, 1980; Schmidt and Van Vleck, 1973) young bulls are testmated to produce 50 - 100 daughters which are tested for dairy performance which provides the criterion for selection of the bulls. About 1/5 to 1/3 of tested bulls are retained for general use while the future bull sires are chosen from the top 1/20 to 1/10 of all tested bulls. A programme such as this supplemented by efficient selection on the female side permits an increase in genetic merit for dairy performance of up to 2 percent of the average per year. However, the realized genetic advance is considerably less, more of the order of 1.0 to 1.5 percent.
The advantage of A.I. over natural service lies in the much greater numbers possible but also in the fact that daughters are distributed over many herds and preferential treatment or the prevalence of single herd effects in the progeny are unlikely.
Therefore, the fairly widespread use of community bulls and the fact that their progeny are distributed over many herds - not unlike the progeny of A.I. bulls - can result in some 15-20 daughters and thus permits a fairly accurate estimation of their breeding values. Naturally, the accuracy will be lower than that of A.I. bulls on account of the smaller number, but apart from this, the accuracy is comparable to that of A.I. progeny.
The bulls can and should be slaughtered after sufficient progeny - some 15-25 recorded heifers - can be expected. Before slaughter sufficient semen must be collected to permit their use as elite sires for producing young bulls. The procedure is fairly economical since it does not involve a waiting period of bulls or the storage of large quantities of semen. Rather the semen is collected after their use for natural service and the additional cost of the programme consists only of collection and storage of fairly limited quantities of semen. Therefore, many bulls can be tested and a fairly intense selection of bull sires is possible.
In Table 2 the theoretical genetic superiority of bulls selected in a conventional A.I. improvement scheme is juxtaposed to that of bulls from a young bull system as outlined. The differences are negligible but the loss of heterozygosity is less in the latter scheme and the costs would be much less than in the aforementioned "classical" A.I. scheme.
This "natural service" progeny testing scheme has been applied in the North Tyrolean Grey population beginning in 1977. In Table 3 bull numbers and selection intensity as well as progeny group size and age of bulls are outlined.
From 31 bulls whose semen was deposited in the 4 years 7 were selected. During this period the scheme had some difficulties as can be seen from Table 3. The numbers of progeny were uneven and the age of bulls at the time of semen collection became progressively older (the trend was reversed meanwhile).
The genetic progress in the North Tyrolean Grey population was estimated for the period 1977 to 1985. All the bulls were included which had progeny in at least 2 years. They numbered 98 with altogether 240 sire year averages (i.e. 2,4 per bull). The genetic progress was estimated via the regression of progeny average on year. The results given in Table 4 indicate considerable genetic improvement in the segment of the population which participated in the programme. In the case of milk fat-kg the genetic change amounts to more than 1.2 percent of the population average.
Table 2 GENETIC SUPERIORITY OF BULLS SELECTED IN A.I. AND IN NATURAL SERVICE IMPROVEMENT SCHEME
|Testbulls||Bull sires||Cow sires||r 1/||n 2/|
|Δ G, kg milk/year||360||205|
|Δ G, kg milk/year||370||260|
1/ Correlation between breeding value and progeny average.
2/ Size of progeny groups.
Table 3 PROGENY TESTING OF NATURAL SERVICE BULLS IN NORTH TYROLEAN GREY CATTLE
Year of semen collection
|Tested/selected||n||Age of bulls in 1983|
|1977||5/2||33 (20-51)||9 ys|
The figures given in Table 4 indicate the natural service - progeny testing scheme was effective. It has been pointed out elsewhere that use of young bulls in A.I. and the use of progeny tested bulls mainly for production of the young bulls should give a high rate of genetic advance (Bar Anan, 1973). However, this was investigated for an A.I. population while the thrust of this paper is the procurement of progeny tests from natural service community bulls and selection of future bull sires from among these; The economy of this approach affords the possibility of progeny testing fairly large numbers of bulls which permits rather intense selection among them. Therefore the deficit in the accuracy due to lower numbers compared to regular A.I. bull selection schemes can be balanced by the greater intensity of selection possible. Therefore genetic progress due to such breeding plans should be competitive. However, in contrast to regular A.I. schemes more bulls participate in the reproduction which should decrease the inbreeding increment and increase the genetic effective population size (N ) thus permitting sustained genetic improvement without the necessity to import genetic material from other services.
Table 4 GENETIC PROGRESS IN THE NORTH TYROLEAN GRAUVIEH POPULATION 1977 TO 1985
b daughters/bulls x year
|Daughters of all bulls||Daughters of bulls in Nsprogeny testing programme|
|-.0025||-.0095||-.019 1/||-.01 2/|
1/ p < .05
2/ p < .10
b regression coefficient of daughters of a bull on year.
Δ G/year genetic change per year.
Genetic progress is expected to be greater in larger populations. Experimental investigations bear this out in populations of small size (up to 50 breeding animals). Empirical evidence fails to indicate any connection between numerical size and genetic progress in U.S. dairy cattle populations, also genetic effective size of populations of domestic animals appears to be similar, almost independent of actual size.
The large expense of identification of superior sires in dairy cattle breeding favours large populations. Therefore, low cost methods of identifying superior transmitters are of paramount importance if modern methods of genetic improvement are to be applied in numerically small populations.
It appears that progeny testing of natural service bulls in combination with intense selection permits effective identification of superior sires. Collection of semen from the young bulls as soon as sufficient progeny is assured permits their use as future bull sires. Therefore such a system should be a feasible alternative to the conventional A.I. schemes wherever general A.I. is absent and/or where the populations are too small to sustain large scale progeny testing and selection of A.I. bulls.
|1973||Bar Anan R. The Israeli dairy cattle improvement scheme. Proc. Br. Cattle Breeders Club, Winter Conf. 1972, p. 41-43.|
|1980||Comberg G. Tierziichtungslehre. 3. Aufl.|
|1983||Fehlings R., Grundler C, Wauer A. and Pirchner F. Inbreeding and rela tionship in Bavarian horse breeds. Zeitschrift für Tierziichtung und Züchtungsbiologie 100, 81-87.|
|1968||Frankham R., Jones L.P. and Barker J.S.F. The effects of population size and selection intensity in selection for a quantitative character in Drosophila. I. Short-term response to selection. Genet. Res. 12., 237-248.|
|1973||Hanrahan J.P., Eisen E.J. and Legates J.E. Effects of population size and selection intensity on short-term response to selection for postweaning gain in mice. Genetics 73, 513-530.|
|1978||Hintz R.L., Everett R.W. and Van Vleck L.D. Estimation of genetic trends from cow and sire evaluation. J. Dairy Sci. 61, 607.|
|1936||Lush J.L., Holbert J.C. and Willham O.S. Genetic history of Holstein- Friesian cattle in the U.S. J. Hered. 27, 61-72.|
|1966||Roberts R.C. The limits to artificial selection for body weight in the mouse. I. Genet. Res. 8, 347.|
Robertson A. A theory of limits in artificial selection. Proc. Roy. Soc. London, B 153, 234.
|1964||Robertson A. The effect of non-random mating within inbred lines on the rate of inbreeding. Genet. Res. 5, 164.|
|1973||Schmidt G.H. and Van Vleck L.D. Principles of Dairy Science. W.H. Freeman and Company, San Francisco.|
|1982||Ström H. Changes in inbreeding and relationship within the Swedish stan dard bred trotter. Z. Tierz. Züchtungsbiol. 99, 55-58.|
|1983||Vangen 0. The use of relationship matrixes to avoid inbreeding in small horse populations. Z. Tierz. Züchtungsbiol. 100, 48-54.|
R. Siler, L. Bartos, J. Fiedler 4/ and J. Plesnik 2/
In the opening reports many economically important as well as other aspects were mentioned indicating quite explicitly the necessity of restoring threatened breeds or individual species of farm animals. Thanks to the intensive worldwide movement for conservation of the natural environment, where FAO and UNEP (1980, 1983) play such an important role in the sphere of animal production, practically all countries have gradually become aware of the need to preserve and conserve the diversity of present species as well as to pass on the results as fully as possible to future generations. We therefore appreciate that the present symposium will concentate its attention on major species of farm animals.
We will consider genetic resources primarily in cattle, and contemplate the possibilities of utilizing threatened and disappearing breeds not only in the context of production of milk, beef and veal, but also in the non-economic sphere.
Let us consider individual possibilities of genetic resources preservation in cattle. Taking into account existing experience, present state of knowledge and further development of some biotechnical techniques in reproduction, particularly in cryogenic storage of sex cells and early embryos, the following possibilities of genetic resources preservation are available:
- small populations of living livestock; - preservation of frozen semen; - preservation of frozen embryos; - combination of the above alternatives; - establishment of a so-called gene-pool.
Each of these possibilities has its advantages and disadvantages, both of a biological and economic character.
The first possibility is the breeding of live animals in small populations where it is most important to avoid selection pressure and retain the complex of traits and characters of a corresponding genetic resource, unchanged if possible, from generation to generation. From the genetic point of view it is therefore imperative to choose a constant number of offspring per each sire and dam and through an appropriately controlled plan of mating (rotational system) prevent undesirable effects of inbreeding and random pressure, designated also as genetic drift and/or the effect of Sewal Wright, leading either to full elimination or fixation of some alleles.
The major disadvantage of the second possibility, when the genetic resources are preserved in the form of frozen semen only, i.e. from the sires, is that grading up through repeated matings of each next generation of crossbreds must be done with the semen of genetic resource to develop in such a way the preserved genetic resource in living animals, which must be carried out for five generations at least to achieve the gene proportion of the genetic resource amounting to approximately 97 percent. This accounts for a considerably long period owing to the length of the generation interval in the corresponding animal species. The possibility of practical use of the genetic resource obtained in such a way is therefore remarkably problematic in cattle. Supposing the generation interval is 5 years, 25 years will be needed to obtain living animals of the genetic resource. During this time economic conditions, market demands and technological systems may change so much that the development of the new genetic resource will no longer be desirable.
In terms of time, the third possibility, i.e. preservation of frozen embryos, is the most advantageous. Live animals capable of further reproduction may be obtained during one generation. The present state of development and utilization of this biotechnical method indicates its wide implementation in selection work in the immediate future. However the possible negative influences of those techniques on the transfer of pathogenic microorganisms and/or on future development should also be investigated in detail.
The fourth possibility consists in the combination of the above-mentioned possibilities. For instance, with live animals kept in small populations it is convenient to preserve the desirable number of sires through frozen semen to ensure the necessary rotational matings. The combined preservation of frozen embryos with frozen semen is also advantageous, which substantially extends the blood basis and thus the establishment of genetic resources in living animals. To avoid using grading up, prolonging considerably the "animation" of preserved genetic resources, it is convenient to sustain a certain number of living dams when frozen semen is used.
The fifth case, i.e. the establishment of a so-called gene pool, remains a theoretical possibility for the time being. Its realization is possibile, of course, as evidenced for example by the American experience with the establishment of a gene pool in pigs. Again, generally it concerns the breeding of living animals obtained on the basis of one breed with subsequent inclusion of other breeds. Animals mate with one another which results in a mixture of various hybrids, out of which the animals of desirable type are obtained through strict selection, i.e. not indigenous breeds entering the gene pool. In this case, the aim is not to preserve the breeds as such but their genes.
Therefore, this fifth possibility for back restoration of disappearing breeds is not simple. Desirable animals for such a gene pool may be obtained only through particular and long-term selection on in the course of a number of generations aimed at a desirable productivity type and an increase in the numbers necessary for reproduction.
An integral and important aspect in contemplating the choice of a certain possibility of genetic resource preservation is the economy, which plays an important role above all in the cattle, horses, pigs and sheep, while in subtle species of farm animals, particularly in poultry and rabbits, many indigenous breeds are preserved only thanks to enthusiasts.
Work by Brem et al., (1982) provided some initial information. The data indicated that 5reeding live animals in small populations is the most expensive method. The second method is less expensive. However due to the necessity of grading-up for approximately 25 years, the final costs are particularly high. Another adverse feature of this method (when only semen is used) is the loss of resource of extrachromosomal genetic information comprised in the female sex cell.
The most favourable seems to be the use of frozen embryos and semen. Purchase costs are high. However live animals with genetic reserves are available within one generation. Therefore this method of preservation is recommended most frequently and indicative calculations carried out in Czechoslovakia in cooperation with the State Breeding Enterprises, General Management, also confirm this fact.
Detailed model calculations of costs for individual methods of genetic resources preservation in animal production were carried out by Smith in UK (1984a, 1984b).
Based on present current prices in UK the costs of genetic resources preservation in small populations, in the form of frozen semen and finally in the form of frozen embryos were established by Smith (1984c) in cattle, sheep, pigs and poultry, with the similar conclusion as that from Germany (Brem et al., 1982).
Despite the high costs of genetic resources preservation in the form of live animals in small populations, in some cases this method is almost imperative and justified. In the context of general breeders, public, historical and cultural values, therefore also of international importance, it is hardly conceivable to breed a certain breed through a gene bank. However, in such cases too if not embryos, then at least semen of individual sires, participating in the development of a certain population in the course of its genesis, should be preserved, particularly due to possible inbreeding depression.
The review which is presented of costs of individual methods of gene resources preservation indicates equally the desired numbers of animals. These numbers must be minimal. In genetic resources preservation in small populations the ratio of 5 males to 25 females is currently reported, whereas the ratio of 50 to 250 is being recommended in cases with traits of low heritability. With the objective of ensuring consistent rotational matings the more convenient ratio is 1:1. When selecting males to freeze their semen, 25 unrelated animals must be chosen. Twenty-five different matings must be ensured to freeze the embryos.
Apart from their aesthetic and cultural significance, genetic resources preservation and conservation are important in terms of selection and thus are of national economic value.
Economic effects resulting from possible later utilization of the hereditary basis of the preserved genetic resources are given by the difference between the overall increase in performance of animals with the proportion of genes of the breed preserved and the costs for preservation of the breed used. In the model calculations by Smith (1984a) the product of the value expressing the used proportion of genes of the genetic resource and relative profit in economic efficiency, expressing the justification of conservation and preservation of genetic resources, is underlined.
Also in this case we will make use of the model calculations valid for UK. It is surprising how low a proportion of genes of the genetic resource used is sufficient to achieve a great economic effect. This is, by the way, in harmony with the well-known experience that a seemingly high investment used for a relatively small number of selection herds is reflected in tremendous financial gains in commercial herds.
Under UK conditions Smith (1984a) chose the following example. He Presumed a genetic resource preserved for 20 years. After this period it was used again and would be used for another 20 years. A yearly inflation rate of 5 percent was considered. For instance, in dairy cattle, genetic resource preservation is fully justified at only 0.1 percent use of this resource, and at 1 percent profit in economic effectiveness. In the case of frozen semen, the values were even lower.
Thus, on a national-wide scale, the conclusion can be drawn from the above economic considerations that although the envisaged possibility for future use of genetic resources is small, it is worth preserving because the potential economic profitability will greatly exceed the costs for its preservation.
What is as a matter of fact the common feature of all endangered local cattle breeds? First of all it is their extraordinarily good adaptability to local conditions, i.e. relatively better utilization of local feed resources, resistance and longevity. The old proverb is fully true which says that a breed is the product of the soil, i.e. of the natural conditions under which it has originated and has been formed. This outstanding adaptability to extraneous natural environmental conditions can be illustrated by the almost disappearing breeds of the USSR, e.g. Kirgizian breed (Kasachian), Siberian, Petchorian, North Carrelian or Buryatyan (Zebrovskij et al., 1984).
Perfect adaptability is also a prerequisite for a notable heterosis effect in possible commercial crossing of local breeds with improved cultural breeds thus providing better results compared with crossbreeding for improvement or grading up. Another important character, much appreciated by the breeders, is modesty and associated with it hardiness, so that production achieved, however low in comparison with a highly improved but demanding, breed corresponds fully to production conditions of the given region and for this reason is also economically advantageous. Local breeds are also distinguished for their satisfactory diverse, not only one specialized, performance. The quality of consumable products, i.e. milk or meat, of local cattle breeds is better regarding the ratio of their components, particularly protein and fat, and in terms of meat production, better taste and smell, due to a direct effect of free pasture or utilization of animals for draught.
We will now comtemplate the possibilities of using local breeds for milk, beef and veal production. Without going too far for an example, we shall pay our atttention to the characters of Bohemian red cattle formerly kept in our country. This breed of cattle has gradually disappeared and become a component of the Czech Pied cattle (Bílek 1926, 1933; Valenta, 1930; Smerha et al., 1955). Bílek (in Smerha et al., 1955) reports that the Bohemian Red cattle "were good draughters due to their lively temperament and breathing habits, were good dairy cows with yellow, fatty and very tasty milk, and butchers appreciated their good quality meat. Their major disadvantage was relatively late maturity for which they were displaced by earlier maturing, however, more demanding, Simmenthal Bern cattle with no better results in milk yield, ability to draught and longevity at relatively low demands achieved in the poorer mountainous regions along frontiers or in South Bohemia with its primary rocks."
Some concrete data on performance were reviewed by Valenta (1930) demonstrating that, e.g. in the Giant Mountains, the liveweight of Red cattle was higher compared with Bern Bohemian cattle and that with respect to their liveweight (522.2 kg) and low protein consumption (251 kg) they showed the most economic milk production amounting at that time to 2817 kg with 4.1 percent fat, being the highest of all the breeds compared.
The situation was also similar in the country of our hosts with their Polish Red cows always giving a desirable performance due to their advantageous characters and following further improvement by Polish breeders. On this occasion we would like to recall the International Agricultural Congress in Warsaw, 1925, which accentuated local breed maintenance as one of the most attractive items of the working programme in the sphere of animal production (Bílek, 1933).
In Hungary, where Hungarian Gray cattle have been successfully conserved with 187 females and 6 bulls, a number of experiments demonstrated the suitability of these cattle as a component part in maternal lines in the production of beef by crossbreeding (Bodó, 1985).
Similarly we could report on local cattle breeds in other European countries. In this connection as an example we refer to a publication on autochtonous cattle breeds in Spain (Belda, 1981) with 25 breeds recorded.
The situation overseas does not differ, of course. For further illustration only we present some conclusions from the comprehensive study by Wilkins (1984) on Crillo cattle in both Americas, and in various countries of Latin America in particular. This study provides explicit evidence that grading-up of these cattle aimed at obtaining a more cultural breed was a mistake because the purebred Criollo, which is not to be preserved and extended, has a whole number of more favourable characters when compared to both European breeds and zebu.
Compared with zebu, for instance, Criollo cattle have not such a developed herd instinct so that animals are scattered over pastures, which is of considerable advantage under Bolivian conditions. Also the temperament of the Criollo is milder compared with zebu. Zebu is a wilder animal and therefore worse to manage and that is the reason why even hybrids are refused by farmers. However zebu hybrids achieve better meat production and, using the knowledge of genetics of quantitative traits, also show higher fecundity, reduced mortality in calves and a higher growth rate.
Crossbreeding with European dairy breeds is beneficial; the adaptability of the tropical breed with the high milk performance of the European breed is achieved explicitly with the F1 generation, but not in the following generations.
The Criollo, improved by selection for higher milk performance, is very favoured in small isolated farms in the countries of Latin America where its production amounting to over 2000 kg milk for rearing a calf is fully satisfactory for farmers's needs because under such conditions no hybridization scheme can be used (Wilkins et al., 1984).
However here we are in the sphere of ecology, particularly in the sphere of complicated relationships between organisms within pasture chains (Farb, 1977; Odum, 1977). In our case this concerns the so-called pasture chain beginning with green plants, continuing over herbivorous to carnivorous animals; compared with other chains it is relatively simple.
In essence, the effectiveness of pasture depends on two decisive circumstances. First, on their primary productivity and, secondly, on the share of net production which can be annually taken away so that sufficient reserves ensure the future grass stand and plant composition to survive occasional periods of bad weather such as drought etc. (Humphrey, 1949).
When the reasonable utilization of pastures is ensured - and under this precondition only - local cattle breeds, which spread out on pastures, can considerably contribute to better pasture utilization and cultivation, particularly in mountainous regions, so forming a grass stand of good quality and preventing the loss of pasture areas which occur usually on the edges of forests due to natural self-sowing. History speaks mostly of the opposite case when excessive overgrowing of pasture stands has resulted in erosion first and later in complete landscape devastation (Dorst, 1974). Another practical and important characteristic of local cattle breeds in terms of selection is their use as a control population not only with the breeds developed from them through improvement or grading-up but also with imported breeds substituting them gradually. In all cases the technique of frozen semen or early embryos may be used, i.e. the widespread preservation methods used in cattle breeding.
Justification of conservation and preservation of disappearing and endangered local breeds is not based on their economic utilization only There is a whole range of other aspects that should be taken into account in terms of cultural, historical, research, study and other points of view some of them having already been mentioned and referred to so truely by Maijala (1984).
From the cultural and historical aspects, local cattle breeds represent a vivid proof of the creative work of ancient selectioners and breeders establishing many populations through experience and observation and therefore being as valuable a monument as a costly restored and preserved historical construction.
Hence, from the point of view of selection process the endangered and disappearing cattle breeds, as well as all other species of economically significant animals, are extremely valuable material reflecting accurately the goals of past national economies and also the concept of selectioners at that time of animal body conformation. The existence of living animals of these breeds facilitates important comparative studies of anatomical and particularly physiological character, determination of many polymorphous traits enabling evaluation of phylogenetic relations in presently kept breeds, etc.
It is therefore highly desirable to present typical individuals of the endangered and disappearing cattle breeds at agricultural shows for object studies on possible changes in animal performance and breed during the process of improvement. This would be of special value when such breeds are kept in conserved regions, scansens, etc. as already mentioned in the example from Hungary.
In conclusion it can be deduced that the possibilities of utilization of endangered and disappearing local cattle breeds as well as other animal species are indeed versatile. In any case we must not forget our moral and human obligation to preserve these breeds for future generations as a vivid proof of the creative activities of man. If the human community can spend astronomical sums on armaments, construction of spaceships and technical development, then it ought not to hesitate to devote a negligible fraction of these expenses to conserve and preserve natural resources including endangered breeds because they are decisive and necessary for the further existence of man on this planet.
|1981||Belda A.S. Catalogo de razas autoctonas españolas. II. Especie bovina. Ministerio de Agricultura, Dirección General de la Producción Agraria, Madrid. p. 219.|
|1926||Bílek F. Ceská plemena mizející a vymizelá. Ceské hospodárské zvírectvo, X.|
Bílek F. Ucebnice obecné zootechniky. I. Publikace min. zemedelství, 84, Praha.
|1985||Bodó I. Hungarian activities on the conservation of domestic animal genetic resources. Animal Genetic Resources Information, 5: 16-22.|
|1982||Brem G., Graf F. and Kräusslich H. Genetic and economic differences among methods of gene conservation in farm animals. 33rd EAAP meeting Leningrad, USSR.|
|1974||Dorst J. Ohrozená príroda. Orbis, Praha (406 s.)|
|1980||FAO/UNEP Technical consultation on animal genetic resources, conservation and management. FAO, Rome.|
|1983||FAO/UNEP Joint expert panel on animal genetic resources, conservation and management. FAO, Rome.|
|1977||Farb P. Ekologie. Mladá fronta, Praha.|
|1949||Humphrey R.R. Field comments on the range condition method for forage survey. J. Range Mgt. 2: 1-10.|
|1984||Maijala K. Scandinavian activities on the conservation of animal genetic resources. Animal Genetic Resources Information. 1: 20-26.|
|1977||Odum E.P. Základy ekologie. Academia, Praha. p. 733.|
|1984a||Smith C. Economic benefits of conserving animal genetic resources. Animal Genetic Resources Information. 3: 10-14.|
|1984b||Smith C. Estimated costs of genetic conservation in farm animals. (In: Animal genetic resources, conservation and managment, data banks and training). FAO Animal Production and Health Paper No. 44/1: 21-30.|
|1984c||Smith C. Genetic aspects of conservation in farm livestock. (In: Animal genetic resources conservation by management, data banks and training). FAO Animal Production and Health Paper No. 44/1: 31-41.|
|1955||Smerha J. a kol. Speciální zootechnika I. Chov skotu. SZN Praha (899 s.).|
|1930||Valenta F. Ceské cervinky. Sborník vyzkumnych ústavu zemedelskych RCS, sv. 57, MZ CSR, Praha.|
|1984||Wilkins J.V. Criollo cattle of the Americas. Animal Genetic Resources Information. 1: 1-19.|
|1984||Wilkins J.V., Rojas F. and Martinez L. The Criollo cattle project of Santa Cruz, Bolivia. Animal Genetic Resources Information. 3: 19-30.|
|1984||Zebrovksij L.S., Babukov A.V. and Ivanov K.M. Genofond selskochozjajstvennych zivotnych i jevo ispolzovani je ve selekcii. Kolos, Leningradskoje otdelenije, Leningrad (350 s.)|
1/ Agricultural Research Centre, Department of Animal Breeding, 31600 Jokioinen, Finland.
1/ The Swedish Environmental Protection Board, Natural Resources Division, Box 1302, S-17125, Solna, Sweden.
1/ Institute of Animal Science, Technische Universität München, D-8050 Freising, Federal Republic of Germany.
1/ Research Institute of Animal Production, Praha - Uhríneves.
2/ Research Institute of Animal Production, Nitra, Czechoslovakia.