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1
The Need to Conserve
Livestock Genetic Resources
Selected varieties of plants and animals form the foundation of
agriculture. Domesticated animals have provided people with
food, fiber, transport, and-draft power for thousands of years,
and during the past 200 years, they have been modified by selective
breeding to serve better the changing needs of humanity. Genetic
diversity within agricultural species is important as expanding hu-
man populations seek to improve their standards of living and place
greater demands on natural resources. New technologies that ma-
nipulate animal physiology and environment have substantially en-
hanced livestock production, particularly in the latter half of this
century, to meet food and other economic demands.
As a result of modern changes and improvements, however, the
genetic diversity of some species may be declining. Symptomatic of
that decline is the increased reliance on animals of a single breed or
type for commercial production at the expense of other recognized
types. If genetic diversity is significantly reduced, it may limit future
options for improving livestock populations or for modifying them
to meet unforeseeable needs.
THE DEVELOPMENT OF ANIMAL AGRICULTURE
Domestication of livestock began about 11,000 years ago, follow-
ing the rise of grain cultivation (Hodges, 1990a; Willham, 1982~. As
the security of plant-based food supplies increased, people adopted a
more settled life-style in small communities. However, decreased
21
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22 / Livestock
mobility intensified hunting around the settlements and nearby ani-
mals became scarce. Domesticated animals offered a dependable source
of meat, skins, and bones; later, their value for other products and
uses was recognized. Ruminants, such as cattle, goats, and sheep,
were particularly beneficial because they ate forage plants that were
unsuitable for human consumption.
Goats and sheep were the first species to be domesticated for
food, beginning about 11,000 years ago. Domestication of pigs and
cattle followed and was complete by about 8,000 years ago. The
earliest archeological traces of these domesticates are found in the
Fertile Crescent, an area of southwest Asia between the Mediterra-
nean Sea and the Persian Gulf. Horses were probably tamed about
6,400 years ago in central Eurasia; chickens were domesticated about
5,000 years ago in Southeast Asia; and buffalo were domesticated
about 4,000 years ago in India and Southwest Asia. In the Americas,
there is evidence of the taming of alpacas and llamas in the Andes
Mountains up to 6,000 years ago and the domestication of turkeys
in Central and South America about 2,000 years ago. (Reviews of
the domestication of these and other animal species can be found in
Clutton-Brock [1981i, Epstein [1969, 1971], Mason [1984], and Zeuner
[1963~.)
About 40 domesticated mammalian and avian species are widely
recognized (Table 1-1~. However, only 6 mammalian species (buffalo,
cattle, goats, horses, pigs, and sheep) and 4 avian species (chickens,
ducks, geese, and turkeys3 are used extensively throughout the world
because cultural preferences and use for them have developed. These
species are classified as the major domesticates. (See Appendix A for
an overview of the status of these species.)
Although the other minor species are numerically less abundant
on a global scale, they are nevertheless critically important to the
people whose livelihoods are built around them (National Research
Council, 1991~. The uses of the minor species depend primarily on
their abilities to produce valued products in specific environmental
niches and on the traditional or cultural patterns of use for their
products in some societies. Species have developed marked physi-
ological distinctions under different environmental conditions, and
accordingly, some breeds are far better suited than others for produc-
tion under specific conditions. Examples are guinea pigs, alpacas,
llamas, and yaks in high altitudes; camels in desert regions; and musk
oxen and reindeer in arctic tundra.
In addition to genetic variation among species, genetic differ-
ences are also found between types and breeds of a single species.
For example, hair sheep are recognized for their superior ability to
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The Need to Conserve Livestock Genetic Resources / 23
TABLE 1-1 Generic Distribution of Important Domesticated and
Semidomesticated Mammals and Birds, by Order, Family, and Species
Mammals
Birds
Lagomorpha
Leporidae
Rodentia
Carnivora
Oryctlagus cuniculus (rabbit)
Muridae
Rattus norvegicus (rat)
Mus musculus (mouse)
Caviidae
Cavia porcellus (guinea pig)
Canidae
Canisfamiliaris (dog)
Felidae
Felis catus (cat)
Proboscidae
Elephantidae
Elephas maximus (Asiatic elephant)
Perissodactyla
Equidae
Equus caballus (horse)
E. asinus (ass or donkey)
Suidae
Sus domesticus (swine)
Camelidae
Camelus bactrianus (Bactrian camel)
C. dromedarius (Arabian camel)
Lama pacos (alpaca)
L. glama (llama)
Cervidae
Rangifer tarandus (reindeer)
Bovidae
Bos taurus (humpless, primarily
temperate zones)
B. indicus (humped, primarily
tropical zones)
B. grunr~iens (yak)
Bibos sondaicus (banteng)
B. frontalis (gayal)
Bubalus bubalis (water buffalo)
Ovibos moschatus (musk ox)
Ovis aries (sheep)
Capra hircus (goat)
An s e riform es
Anatidae
Anas platyrhynchos (duck)
Cairina moschata (muscovy duck)
Anser anser (goose)
Branta canadensis (Canada
goose)
Galliformes
Phasianidae
Gallus gallus (chicken)
Coturnix coturnix (Japanese
quail)
Phasianus colchicus (ring-necked
pheasant)
Pavo cristatus (peafowl)
Numididae
Numida meleagris (guinea fowl)
Meleagrididae
Meleagris gallopavo (turkey)
Columbiformes
Columbidae
Columba livia (pigeon)
NOTE: Not covered in this report but also of value are certain reptiles (for example,
crocodiles, turtles), insects (for example, silkworms, honeybees), fish and shellfish (for
example, carp, salmon, crayfish), doves, red deer, and fur-bearing mammals.
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24 / Livestock
produce meat and milk in tropical and subtropical climates, while
wool sheep are more suited to producing fiber needed by people in
cooler regions. In cattle, the Bos indices breeds from the Indian sub-
continent are generally better adapted to hot, humid climates than
are the European Bos Taurus breeds, which, although genetically su
A PROBLEM OF NOMENCLATURE
Carolus Linnaeus, a Swedish botanist during the 1700s, developed a
system of naming and classifying plants and animals. According to his
system, cattle belong to the order Artiodactyla or even-toed hoofed
mammals (ungulates), the family Bovidae, and the genus Bos. Domes-
ticated cattle are usually classified into either the humped (Bos indicus)
or humpless (Bos taurus) types. Most of the humpless cattle include
ancestors of the European cattle and the majority of the cattle, which
came from Europe, found in the temperate regions of North and South
America. The humped cattle, usually called zebu, originated in Paki
N'dama cattle (left page) are a humpless breed, Bos taurus, noted for
relatively high production of meat and milk per unit body weight and its
resistance to trypanosomiasis and other endemic diseases of West Africa.
Credit: International Livestock Centerfor Africa. Zebu (right page)from
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The Need to Conserve Livestock Genetic Resources / 25
perior for milk production and growth rate under temperate condi-
tions, usually fail to produce adequately or to survive under tropical
conditions (Cunningham and Syrstad, 1987~. However, some Bos taurus
breeds that were established in West Africa and Latin America before
the introduction of the Bos indices have successfully adapted.
Stan and India and later spread into the tropical zones of Asia, Africa,
Australia, Central and South America, the Caribbean, and the southern
United States.
The designation of cattle as two species appears to be inappropriate
because B. indicus and B. taurus have the same chromosome number
and interbreed readily; the crosses between them are fertile. However,
because of historic origins, the types continue to be distinguished by
their original species names. They also represent types that are widely
divergent in their adaptation to various environments. The informa-
tion that will come from genetic maps of B. indicus and B. taurus may
one day help determine how closely related the various breeds are
within these species.
-
_5
.
it_ 1
I:
lo. _
B~s
Chad in equatorial Africa are Bos indicus cattle with pronounced humps
and fleshy dewlaps that aid heat regulation in hot, humid climates. Credit:
Food and Agriculture Organization of the United Nations.
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26 / Livestock
THE EFFECTS OF TECHNOLOGY ON GENETIC DIVERSITY
Technological advances, such as artificial ~nsemmation, and changing
practices, such as better disease control, in all areas of animal hus-
bandry, including breeding and genetics, reproductive physiology,
and nutrition, are contributing to the improved production capacities
of modern livestock. However, these and other techniques have the
potential to affect negatively the number and diversity of breeds and
types in both developing and developed regions. Such techniques
include in vitro fertilization and cryopreservation of semen (storage
typically in liquid nitrogen at a temperature of -196°C).
Many livestock species traditionally have been raised under ex-
tensive farming conditions, that is, on the range or in fenced areas,
often with minimal inputs for housing, labor, nutritional supplements,
and veterinary care. Their survival has been challenged by diseases,
parasites, and nutritional and climatic stresses over many centuries,
allowing time for natural selection to create populations genetically
adapted to local conditions.
In developing countries, where livestock management practices
and inputs have changed little, adaptation to the environment re
_~
_:.~23~
...
Many village families in Botswana keep free-ranging pigs and poultry. These
animals do not receive veterinary care and are fed only household scraps,
but they provide meat and other products for the family and cash from sales.
Credit: Elizabeth Henson, Cotswold Farm Park.
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The Need to Conserve Livestock Genetic Resources / 27
mains critical. The N'Dama cattle of West Africa, for example, have
developed specific resistance to trypanosomiasis, a parasitic disease
spread by tsetse flies (Trail et al., 1989~. The cattle survive in an
environment in which other, more recently introduced, breeds be-
come unproductive and often die. Yet tremendous pressure to in-
crease food production exists in these developing countries, and the
highly productive breeds of livestock developed in the industrialized
world may superficially appear ideal for use. The technology for
sending germplasm to Africa exists, but the capacity to replicate the
improved environmental conditions of the industrialized world does
not. The result can be the introduction of unadapted livestock that
survive poorly and do little to improve food production.
Inputs and management technologies, such as climate control,
are more common in developed countries and reduce the need for
livestock to be adapted to the environment. Yet a breed's capacity to
be adapted to new conditions, which requires genetic diversity, re-
mains critical to meet future needs and to respond to future produc-
tion changes.
For example, beginning in the 1940s in developed countries, cages
were adopted by chicken farmers to have cleaner eggs and to reduce
cannibalism and feather pecking. The cage system was also a better
alternative to land that could harbor the disease organisms contained
in fowl droppings. Production and management advantages, such as
automated feeding, watering, egg collection, and better feed conver-
sion efficiency, led to further adaptation. However, a move to ban
the use of cages in the European egg production industry was begun
in the early 1980s in response to animal welfare concerns. The Coun-
cil of Ministers of the European Community has established space
and other minimum requirements for hens that will apply to all cages
as of January 1, 1995; Switzerland has banned cages; and Sweden and
the Netherlands may also ban cages (U.S. Department of Agriculture,
1991~. These changes may now require the development of poultry
breeds better suited to cageless environments.
Breecting and Improvement Technologies
Increased production of milk, meat, eggs, and animal fiber has
been based on extensive records of pedigree and performance, which
are essential for accurately identifying superior individual animals.
Systematic improvement of livestock. Copulations began in eiabteenth-
century Europe.
~ ~ v v
Livestock were bred, and the best animals were
selected for breeding until a degree of uniformity was attained. Herdbooks
were started to record pedigrees because of the reliance on ancestry.
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28 / Livestock
The science of population genetics, developed in the 1930s and 1940s
by scientists in Europe and North America, has since been effectively
applied to achieve substantial increases in animal production and
productivity, primarily in developed countries. Progress has been
greatest in dairy cattle, pigs, and poultry. Compared with 30 years
ago, the average dairy cow in the United States produces over twice
as much milk (U.S. Department of Agriculture, 1976, 1990), and fat
thickness in Danish pigs had declined by half (Christensen et al.,
19861. Today's broiler chickens mature in 6 weeks instead of 3 months
(Cahaner and Siegel, 1986; Chambers et al., 1981~.
The positive gains achieved through applying genetic theory to
animal improvement do not necessarily reflect a strategy for coping
with different goals that change with time. Instead, the emphasis is
AN EXAMPLE OF BREED UNIQUENESS
.
;_
North Ronaldsay sheep eat seaweed on Linga
Holm, one of the Orkney Islands of Scotland.
The island is owned by the Rare Breeds Survival
Trust and run as a sanctuary for this breed.
Credit: Howard Payton, Cotswold Farm Park.
A much larger vari-
ety of livestock breeds
exists than is used in
commercial agricultur-
al operations. Thou-
sands of years of adap-
tation to region-specific
environmental condi-
tions and more recent
domestication have cre-
ated diverse and unique
traits in many breeds,
which today are rare or
endangered. The poten-
tial loss of rare or en-
dangered breeds is of
concern to livestock
breeders, who may need
their special character-
istics to adapt commer-
cial breeds to unforeseen
needs, and to research-
ers, who could study
them and expand society's understanding of domestication, selection,
genetics, and evolution.
One such rare breed of sheep, indigenous to an island in the Orkney
archipelago off the northeast coast of Scotland, has adapted to a unique
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The Need to Conserve Livestock Genetic Resources / 29
on identifying selection objectives that represent current economic
situations in the industry and on attempting to maximize rates of
genetic change to achieve those objectives.
This approach can also have a negative effect on maintaining
genetic diversity. Superior animals are identified and, through re-
productive technologies, can produce large numbers of progeny. Certain
breeds are recognized for their superior performance and are more
widely used and more rapidly improved. Breeds that are not eco-
nomically competitive, or that are perceived as being less profitable,
are less popular and are not maintained by producers. A 1982 survey
in western Europe identified more than 700 distinct breeds of cattle,
goats, horses, pigs, and sheep, about 240 of which were classified as
endangered (Maijala et al., 1984~.
set of severe environmental conditions and management practices. It
serves as an example of a livestock breed with an exceptional physiolo-
gy that merits preservation because its genetic characteristics cannot be
found elsewhere.
The North Ronaldsay sheep survive exclusively on a diet of seaweed
on an island shoreline buffeted by the North Sea's cold winds and
winter storms. They have fine bones, a naturally short tail, and a small
body, one-third the size of sheep in commercial production. Character-
istic of all primitive sheep breeds, the North Ronaldsay displays a wide
range of wool color, from white to grey or blue-grey and occasionally
brown or black.
The islanders of North Ronaldsay erected a protective, circumscrib-
ing seawall 160 years ago to prevent foraging sheep from damaging the
iodine-rich seaweed surrounding the island. When the demand for
cropland increased the sheep were placed outside the seawall, and sea-
weed became their primary source of forage. Then, as now, islanders
harvest the sheep for meat and wool.
Excluded from all sources of grass forage, the North Ronaldsay sheep
developed distinct foraging preference and behavior that set them apart
from other breeds. To obtain all nutritional requirements from limited
fresh water and abundant kelp beds along the shore, they have mas-
tered the physiological challenge of handling elements, like sodium,
present in excess in their environment as well as obtaining important
trace elements, like copper.
The copper concentration present in Laminaria, the most preferred
kelp, is one-third the concentration found in terrestrial herbage. Other
breeds found in Scotland, which normally feed on grass or hay, would
(continued)
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30 / Livestock
Animal breeders have recognized that selection objectives change
over time, but they have always assumed that sufficient genetic di-
~rersity would remain to permit changes In selection objectives. However,
as technological advances improve the ability to select for particular
genetic traits, the potential of losing related, unselected genes in-
creases. Consequently, the capacity for an intensively selected trait
to be further manipulated through selection and improvement may
be compromised.
.
Reproductive Technologies
Reproductive inefficiency, or the inability to produce regularly
the optimum number of offspring, is a costly and economically limit
die from lack of copper if fed Laminaria. However, the North Ronald-
say sheep are so well adapted to the low concentration of copper present
in Laminaria that higher copper levels are toxic to them.
The North Ronaldsay sheep are also very salt tolerant. Foraging on
seaweed directly from the sea subjects the sheep to high concentrations
of sodium and other salts. With no source of fresh water for much of
the year, their capacity to withstand saltwater is unique. The physio-
logical or biochemical mechanism by which this adaptation is possible
has yet to be studied and understood.
These sheep have also adapted to the challenges of living and feed-
ing on rocky island shores where the sea is a constant threat. While
other sheep breeds have a diurnal feeding pattern, the beginning deter-
mined by sunrise and the end sunset, the behavior of the North Ronaldsay
sheep is linked to the tidal cycle. The sheep begin to feed about 3.5
hours after high tide when the beds of Laminaria are exposed. Feeding
ends 4 hours later, shortly after low tide, when the tide begins to ad-
vance and the likelihood of being stranded at sea increases.
Until recently the entire population of North Ronaldsay sheep, about
3,000 individuals, existed exclusively on one island. The entire breed
was at risk. Sudden environmental degradation, like a catastrophic oil
spill in the North Sea, could destroy its food source and habitat. Dis-
ease could decrease its number, thereby reducing the genetic diversity
within the population.
In 1973, a population of 150 North Ronaldsay sheep was established
on the island of Linga Holm by the private, then newly formed Rare
Breeds Survival Trust of Great Britain. This reserve sheep flock has
now grown to 500 individuals. The physical environment of Linga
Holm is similar to North Ronaldsay, but grass forage is available from
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The Need to Conserve Livestock Genetic Resources / 31
ing problem for animal industries (Pond et al., 1980~. Reproduction
is influenced by genetics, nutrition, disease, and environmental fac-
tors, such as temperature arid pholoperiod. Each of these factors can
be modified to enhance productivity and profit, but improvements
can rarely be realized with only one modificahon. For example, highly
prolific breeds of sheep and pigs exist, but their use in commercial
production may be contingent on the ability to provide improved
prenatal nutrition to the dam, increased attention to the offspring at
birth, and supplemental postnatal nutrients to both offspring and
dam. Highly productive dairy cows and layer hens usually require
large amounts of feed to produce high levels of milk or eggs.
Where the production environment is ideal, reproduction is lim-
ited by physiology. The situation is particularly clear in cattle, which
the interior of the island. The sheep still prefer Lamirtaria and other
types of kelp. However, other groups, brought to farms in England
and Scotland, that have less access to kelp may change their forage
preference. Over time, the genotype and phenotype of these splinter
populations may be expected to diverge from that of the original in
response to new environmental conditions and management practices.
Although not of great commercial value, the North Ronaldsay sheep
possess other characteristics that may be of interest to local breeders.
The ratio of weight to pelvic dimensions in this breed produces fewer
problems during birthing compared with other breeds. Introduction of
this trait to commercial sheep on the Orkney Islands may decrease ewe
mortality. Commercial sheep introduced on these islands often die
because of a lack of grass forage during winter storms. North Ronald-
say ewes crossbred with commercial meat rams produce lambs that are
able to finish on Laminaria to carcasses of commercial value. These
characteristics may decrease losses and increase productivity for farm-
ers in the Orkney Islands.
The remarkable breed improvements realized in recent years were
possible, in part, because of the enormous genetic variation developed
over centuries of natural selection and husbandry practices. Further
enhancement of commercial livestock may be necessary as environ-
mental conditions change, market demand varies, or production mech-
anisms are modified. Future study of salt tolerance and copper metab-
olism may benefit from examining the rare, physiological model of the
North Ronaldsay sheep. Preserving the unique qualities of this sheep
and other diverse livestock breeds will ensure a wealth of genetic re-
sources for future use in basic scientific research and the advancement
of the agricultural sciences.
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38 / Livestock
rate. Generally, the relative merits of indigenous and imported stocks
are only superficially weighed when crossbreeding or upgrading programs
are being considered. Comparisons of performance should be made
under the conditions in which the animals will be maintained. In
many cases, a mixture of imported and indigenous genes will be
required to produce suitable crossbreeds. However, indigenous stocks
should be protected until the best crossbreeds can be determined.
Until then, breed replacement runs the risk of losing genes for later
adaptation.
RATIONALES FOR CONSERVING LIVESTOCK
GENETIC RESOURCES
To some extent, the loss of less competitive livestock can be con-
sidered a normal part of the livestock improvement process. Natural
selection favors animals that are best suited to a particular environ-
ment. The genetic composition of a species is thereby adjusted to
new requirements over time. Artificial selection simply redirects and
accelerates this process for the presumed benefit of society. Most
dependent on genetic diversity are the ruminants, because they must
adapt to a wide range of climatic conditions and nutrition levels, and
because they must interact closely with their environment to forage
for feed. They have acquired great diversity that could be reduced
through the misapplication of new technologies for propagating and
disseminating germplasm.
A variety of unpredictable factors could change current demand
for animal products and in turn alter animal production systems. For
example, many of today's consumers demand leaner meat and less
fat in their diets. Pigs that are high in fat, once prized for lard pro-
duction, have been replaced by modern breeds and hybrids that meet
current market and price structures based on lean yield (Alderson,
1990a).
The chief reasons for conserving livestock genetic resources have
economic, scientific, and cultural and historical bases. These factors
are discussed below.
Economic Reasons for Conservation
The strongest basis for conservation is inherently practical: pre-
served germplasm may contribute to future increases in the efficiency
of livestock production. Production demands and conditions have
changed in the past 50 years, and the ability of livestock producers to
respond has been due in part to the ready availability of a wide
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The Need to Conserve Livestock Genetic Resources / 39
The Pantenero swamp cattle of the Pantenal in Brazil are adapted to the
extreme heat and humidity of the region. Credit: Elizabeth Henson, Cotswold
Farm Park.
range of genetic variation. In 1940, for example, 25 million cows in
the United States produced 109.4 billion pounds of milk. In 1990, 10
million cows produced 148.3 billion pounds of milk (P. Vitaliano,
National Milk Producers Federation, Arlington, Virginia, personal com-
munication, June 1991~. Greater production efficiency was achieved
mainly through improved feeds and the selection of breeding stock
with higher capacity to produce fluid milk.
The economic benefits of preservation relative to its costs are dif-
ficult to assess without knowing the nature and degree of future change,
which is not easily predicted. The development of pathogen strains
that are resistant to specific antibiotics, for example, could require
access to germplasm not available within a dominant breed. Deci-
sions about what to preserve are difficult because the costs of main-
taining breeding herds or populations are high.
Smith (1984a), however, demonstrated that preservation programs
based on cryopreservation have very low costs relative to the value
of the livestock industry they are designed to protect. He estimated
that the yearly costs for satisfactorily maintaining a breeding stock
range from £3,000 ($4,000) for sheep or chickens to £12,000 ($16,000)
for pigs. Although the costs to collect and place semen or embryos in
cryogenic storage may also be high, they are incurred only once and
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40 / Livestock
yearly storage costs are low (Smith, 1984a,b). Smith (1984a) thus
concludes that the use of cryopreservation is sound because of the
large potential returns relative to the low continuing costs of mainte-
nance.
Insights into the molecular makeup of the genome advanced quickly
in the 1980s. The foundation is being laid for mapping the genomes
of all livestock species and for gaining a better understanding of
gene action. Although an understanding of variation at the genomic
level is only beginning to develop, molecular techniques offer tre-
mendous promise for identifying and manipulating valuable genes
for a marketable trait or a physiological function. Biotechnological
advances may allow identification of individual genes that can have
positive effects on production, adaptation, and disease resistance traits.
The ability to find useful genes in otherwise undesirable stocks and
to transfer these genes mechanically to improved stocks will aug-
ment genetic diversity. This potential provides a powerful argument
for maintaining currently uncompetitive stocks.
Methodologies for studying the genome at the molecular level
are not, as yet, being routinely applied to livestock populations, even
in developed countries. Nevertheless, rapid progress is being made
in techniques for gene mapping and for identifying associations be-
tween specified segments of the DNA (deoxyribonucleic acid) and
primary production traits.
Application of these techniques to animal species will aid in dis-
cerning and characterizing diversity among various populations, but
it may have both positive and negative effects on maintaining diver-
sity. Marker-assisted selection involves the use of molecular genetic
information to supplement traditional performance information and,
in some cases, can increase rates of genetic improvement. Unfortu-
nately, marker-assisted selection also has the potential to increase
genetic uniformity and could produce an additional decline in ge-
netic diversity in highly selected populations.
Documentation of endangered breeds in some developed coun-
tries has been done by nongovernmental private interest groups, such
as the Rare Breeds Survival Trust (RBST) in England and the Ameri-
can Minor Breeds Conservancy (AMBC) in the United States (Alderson,
1990a). In other developed countries, such as France as well as the
nations of Eastern Europe and the Commonwealth of Independent
States, government programs have been established if. Hodges, con-
sultant, Mittersill, Austria, personal communication, March 1992~.
Generally, endangered breeds have lower profitability under prevail-
ing production and marketing conditions; therefore, substantial in-
vestment in their preservation by commercial interests is unlikely.
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The Need to Conserve Livestock Genetic Resources / 41
Public support to preserve the unique and most endangered of these
breeds may be required. Some breeds in developing countries have
become extinct, but the extent of risk and the rate of decline to other
indigenous breeds are known in only a few developing countries if.
Hodges, consultant, Mittersill, Austria, personal communication, March
1992~. Economic arguments for preservation are more readily justi-
fied for indigenous livestock that are not well characterized because
of specific genes they may carry or their potential genetic contribu-
tions.
Scientific Rationale
Diversity is the base on which genetic research depends. Pre-
served genetic diversity can be of value to many scientific investiga-
tions. Researchers may use genetic variants to clarify mechanisms of
development and physiological controls, patterns of domestication
and migration evolution and speciation, and other biological ques-
tions. For example, the annual number of lambs per ewe vary greatly
among sheep breeds. Certain sheep breeds from countries such as
Australia, Bangladesh, China, Finland, Indonesia, Ireland, Poland, and
the United Kingdom have high lambing rates. Through crossbreed-
ing, they provide the means for genetically transforming ewe prolifi-
cacy. In the Australian Booroola Merino, a single major gene pro-
duces an increase in ovulation rate, but its operation is not completely
understood and requires further study (Bindon and Piper, 1986; Tho-
mas, 1991~.
Special genetic stocks of livestock species are also essential re-
search tools. For example, inbred lines of chickens developed at the
University of California at Davis are used worldwide for research on
immunology and disease resistance of chickens (Office of Technology
Assessment, 1987~. Other beneficial uses of preserved germplasm
will emerge as genome maps are created and as scientists learn to
identify and manipulate specific genes involved in the mechanisms
of growth, reproduction, and disease.
Cultural and Historical Rationale
Preservation programs can provide visual evidence of a nation's
heritage. Just as historical qualities are valued in buildings and geo-
graphic sites, the same regard can be extended to animal populations
that are representative of antique or heirloom breeds or populations.
In restorations of historic villages, for example, old (and often rare)
breeds are desired for authenticity. Farm parks, in which a large
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42 / Livestock
number of endangered and unusual breeds are maintained for the
public, have proved popular in England, where 12 farm parks are
now operating in association with the REST. Similar programs have
begun in other countries (Alderson, 1990a). Furthermore, some ani-
mals are used for recreation and in animal shows, exhibits, and fairs.
One of the poultry stocks identified by the AMBC as being en-
dangered is Dominique chickens, perhaps the oldest of the chicken
breeds in the United States and present as a barnyard chicken since
colonial days. They have black and white feathers and a rose comb
and are featured in American folk art, music, and literature. The few
surviving today in hobbyist exhibition flocks are highly inbred and
not very vigorous.
Some livestock breeds characterize a way of life and provide spe-
cific products in areas around the world. For example, six native
cattle breeds of southern Spain are in serious danger of extinction-
the fighting bull was derived from these cattle. Among the endan-
gered breeds are the dual-purpose Berrenda breeds, used for meat
production and as steers to assist in the handling of fighting bulls
(Rodero et al., 1990~.
Although the community value of a certain stock for its cultural
heritage role is difficult to assess, its economic value is evident from
the financial support provided by visitors to farm parks. Thus, live-
stock can, arguably, be accorded the same consideration as other en-
dangered reminders of national heritage.
APPROACHES TO LIVESTOCK CONSERVATION
Numerous reports agree on the need to develop national and
international efforts to preserve and manage livestock genetic resources
(Alderson, 1990a; Council for Agricultural Science and Technology,
1984; Food and Agriculture Organization, 1984a,b; Hodges, 1987; Of-
fice of Technology Assessment, 1985, 1987; Smith, 1984b; Wiener, 1990~.
However, the approaches to conservation differ widely within the
livestock community. They hinge on different perspectives about the
importance of traditional livestock breeds, including indigenous breeds,
to long-term genetic improvement programs. These perceptions also
vary between developed and developing countries.
In general terms, these approaches can be divided between two
broad categories: (1) utilizationist, the primary aim being immediate
use of available genetic resources, and (2) preservationist, the pri-
mary goal being long-term preservation of genetic resources for un-
known future use. Proponents of both approaches recognize that
conservation of genetic diversity is economically justified only to the
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The Need to Conserve Livestock Genetic Resources / 43
Oxen are still used today for plowing rice paddies in Bangladesh. Credit:
Steve Raymer, O1992 National Geographic Society.
extent that the preserved germplasm can reasonably be expected to
make a contribution to future livestock improvement programs. Both
also recognize that preserving breeds that are not currently economi-
cally viable has a place in livestock improvement systems. Differ-
ences between the two approaches largely pertain to perspective and
emphasis, but they are real and strongly influence the practices fa-
vored for managing genetic resources. The use and definition of the
terms utilizationist and preservationist are not perfect or exclusive. Rather,
they serve to illustrate the diversity of approaches to genetic conser-
vation of livestock.
The Utilizationist's View
The utilizationist gives the highest priority to using available ge-
netic resources to improve current livestock populations. Increases
in the rate and efficiency of livestock food and fiber production are
paramount. Existing populations are crossbred in carefully planned
programs to achieve new and potentially more valuable gene combi-
nations. The loss of breeds as distinct identities is not generally
viewed as a matter of concern, as long as the genes that make those
breeds potentially useful are retained in commercial stocks.
This approach also recognizes the fallibility of planners, produc
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44 / Livestock
ers, and scientists. Endangered stocks must be preserved during the
period of evaluation, crossing, and progeny assessment, and adequate
genetic diversity must be maintained within commercial stocks to
allow responsiveness to future changes in selection goals. Stocks
with documentable, unique biological characteristics must also be pre-
served for future use. However, the utilizationists place no particu-
lar priority on preserving stocks that have not contributed to improv-
ing current populations or that have no documentable, unique biological
characteristics that they foresee as having potential future importance.
In a report on animal genetic resources conservation in the United
States, the Council for Agricultural Science and Technology clearly
presents the utilizationist's view. It states that two kinds of animal
germplasm merit priority for preservation (Council for Agricultural
Science and Technology, 1984~. They are the following:
· Breeds threatened with deterioration or extinction that have
either known superiority for one or more traits or genetic uniqueness
that could be important in meeting unforeseen needs.
· Stocks that are useful for research or potential commercial ex-
ploitation because of unique genetic traits.
The report further states, "priority in germplasm preservation
should favor stocks of known superiority in specific traits over those
that are merely different from genetic material that is widely accepted"
(1984:29~. It indicates that special efforts to preserve rare livestock
and poultry breeds may not be justified if they do not have identi-
fied, potentially useful biological characters.
The Preservationist's View
The preservationist regards existing breeds as unique genetic en-
tities representing genes and gene combinations that have evolved
over considerable periods of time to fit unique environmental and
production conditions. This approach emphasizes the value of pre-
serving the widest possible spectrum of genetic diversity, because it
is not possible to predict future needs. Breed preservation is re-
garded as the most practical method of gene conservation. The cross-
breeding of endangered breeds with more popular stocks is consid-
ered to be a threat to the survival of endangered stocks. It is acceptable
only when the identity of the original stock as a purebred line has
been preserved. The cultural and historical importance of breeds is
also given high priority.
The preservationist's view recognizes the potential value of breeds
to livestock development, but it places higher priority on preserving
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The Need to Conserve Livestock Genetic Resources / 45
existing breeds. Future use of genetic resources in crossbreeding and
selection programs at the commercial level remains the primary justi-
fication for conservation, but the inability to predict future needs
and, therefore, to choose which breeds are most worthy of preserva-
tion remains central to the rationale for this perspective.
The Cotswold Farm Park in England gives three reasons for sav-
ing rare breeds that do not appear to meet today's production stan-
dards. First, they are part of society's heritage. Second, their charac-
teristics could make them ideal research subjects. Third, and most
important, they provide livestock breeders with a broad pool of ge-
netic diversity to meet unforeseen needs (Cotswold Farm Park, 1985~.
The Committee's View
The utilizationist emphasizes the characterization of existing breeds
and the evaluation of the most promising as components (either purebreds
or crosses) of current production systems. Only the most promising
breeds or those that represent documentable biological extremes should
be preserved. Improvement of existing populations should meet cur-
rent and perceived future needs. The preservationist's view, by con-
trast, calls for preserving the greatest possible number of breeds as
purebreds. Crossing to form new populations should be accompa-
nied by the protection of breed identity. The preservationist empha-
sizes the inability to predict future needs and, therefore, to create a
priority list of candidate breeds for preservation.
Reconciliation of these two views must begin with the recogni-
tion of their common goal: sustained long-term improvement of live-
stock for use by an expanding global population. The main conflict
is in how each view establishes priorities for conservation and how
each assesses future livestock needs. Current human needs for food
and fiber are pressing and will continue to increase. These needs
must be met. The goal of this report is not to validate one position at
the expense of the other, but to present a position that is acceptable
to these divergent views for building coordinated efforts toward the
common goal of conserving global livestock diversity.
The committee agreed that one goal of genetic resource manage-
ment programs must be to maximize rates of genetic improvement in
commercial stocks. It also endorsed the view that some form of ge-
netic resource conservation is an essential component of long-term
livestock improvement programs. Differences of opinion existed within
the committee on the amount of resources that should be devoted to
breed preservation. It was agreed that preservation should, at a minimum,
address breeds that are of (1) potential economic value, or are (2)
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46 / Livestock
endangered and represent types with documentable, unique biologi-
cal characteristics. For a national program, this approach would en-
courage maintenance of adapted indigenous types as pure lines while
they are being compared with imported stocks and while their opti-
mum role in breeding programs is being determined. It would also
encourage long-term preservation of genetic extremes that could pro-
vide material valuable in future commercial stocks.
The establishment of priorities and the determination of which
breeds or populations are to be preserved will depend on several
considerations, including the resources available, national and inter-
national needs, and the genetic similarity among available breeds
and populations. Development of an understanding of population
structures and genetic relationships among breeds or strains can aid
the setting of priorities.
The committee thus concluded that responsible management of
livestock genetic resources involves aggressive programs of livestock
improvement as well as strategic programs for conservation.
RECOMMENDATIONS
The development of comprehensive national and global strate-
gies for preserving and using animal genetic resources will require
the integration of livestock improvement programs and programs for
conserving livestock genetic resources. To date, improvement pro-
grams have taken precedence over conservation programs, largely
because of the quicker and greater return to investment. Yet, a long-
term approach to increasing global food resources demands that con-
servation become an integral part of programs for animal improve-
ment.
Mechanisms must be put in place to ensure that genetic diversity of the
major livestock species is maintained to support improvements in produc-
tion efficiency and to Accommodate future changes in selection goals.
Global human populations will continue to increase in the fore-
seeable future. Global capacity for food production must, therefore,
also increase. Most major livestock populations of developed coun-
tries have been subject to intensive artificial selection for a period of
less than 50 years. Scientists cannot predict what level of genetic
diversity will be required to support genetic manipulations in live-
stock populations over periods of many hundreds of years. Yet, ac-
tion is required now to maintain genetic diversity, and it must be
undertaken responsibly, regardless of current limitations in under-
standing the basis of genetic diversity. These mechanisms for action
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The Need to Conserve Livestock Genetic Resources / 47
could take many forms, depending on national and international needs
and resources, but their common objective would be to conserve the
livestock genetic resources essential to agriculture and society.
Clear national and international policies are needed to prevent further
losses of potentially important animal generic resources.
Agricultural research policies have focused exclusively on live-
stock improvement programs. They must recognize that conserva-
tion is a vital part of these efforts. In developing countries, the re-
sponsible handling of indigenous breeds must be given a high priority.
Priority for preservation should be given to species, breeds, or popula-
tions that are both at the greatest risk of loss and that appear to have
potentialforfuture use in livestock improvement programs.
In most countries the resources available to preserve animal ge-
netic resources will be limited. In addition, not all animal species or
particular breeds within a species will have a significant economic
role in other countries. Preservation efforts must focus first on those
species and breeds that are at risk and that have potential for contrib-
uting to future economic or social development in the country. A1-
though it may be desirable to save all endangered breeds, limited
resources will necessitate the setting of priorities, based on perceived
future economic contribution and biological uniqueness.
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Representative terms from entire chapter:
genetic diversity
