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2 Essential Conservation Considerations
2 Essential Conservation Considerations
Pages 49-62
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From page 49... ...
This chapter examines the technical elements of managing the genetic resources of livestock including preservation criteria, sampling strategies, and preservation methods. CRITERIA FOR CONSERVING POPULATIONS An animal germplasm conservation program will require decisions on the populations, which can be a particular breed or stock, to be preserved and the methods to be used.
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From page 50... ...
In He United States the American Minor Breeds Conservancy (AMBC) uses the categories rare, minor, watch, and feral to classify the status of a livestock breed that may become endangered based on the numbers of individual registrations per year (Henson, 1985~.
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From page 51... ...
The information contained in Tables 2-1 and 2-2 is based on the numbers of breeds in developed countries and reflects subjective judg TABLE 2-2 Categories Used to Classify the Status of Livestock Breeds by the American Minor Breeds Conservancy Maximum Number of Breed Registrations Per Year Status Cattle Horses Sheep GoatsPigs Rare 200 200 500 500500 Minor 1,000 1,000 1,000 1,0002,000 Watcha 5,000 5,000 5,000 5,0005,000 aA breed may also be placed in this category if a steady decline in registrations has occurred over the preceding 25 years. SOURCE: Henson, E
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From page 52... ...
The importance of Ne to livestock is seen in a hypothetical example of world populations of black and white cattle the familiar Holstein (American) and Friesian (Europe)
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From page 53... ...
Goddard notes that the potential exists to manage these cattle as a single global breed. Under this scenario, the Ne for the global population of black and white cattle could be as low as 80, even though the estimated world population would include several million milking cows.
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From page 54... ...
Managing Live Populations For many countries the most practical way to preserve animal germplasm is to mair~tain live breeding animals at as many locations as feasible. The herds and flocks maintained by private owners often suffice, but if a given breed becomes endangered, publicly supported efforts may be necessary to develop breeding programs that will control inbreeding and ensure breed purity.
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From page 55... ...
At the Hortobagy National Park in eastern Hungary, government resources and initiatives ensure preservation of Hungarian Grey Steppe cattle, Mangalica pigs, Racka sheep, and poultry (Alderson, 1990a; Henson, 1990; Wezyk, 1990~. Many individuals and private groups are interested in maintaining and propagating unique types of animals (Alderson, 1990a; Office of Technology Assessment, 1985~.
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From page 56... ...
For example, the regional government of the Province of Quebec, Canada, pays farmers to rear purebred Canadienne cattle (Henson, 1990~. The methods of payment and the amount of the subsidy may be · Per head.
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From page 57... ...
Farmers are paid for rearing males and making them available for semen collection and for use in contract matings. It has been used successfully in Britain for maintaining rare strains within cattle and pig breeds, and it demonstrates the feasibility of close cooperation among individual farmers, breed societies, private conservation groups, and farmerfunded organizations.
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From page 58... ...
For these reasons, genomic libraries may have an important place as a supplement to frozen semen and embryo banks in a long-term strategy for preserving animal genetic resources. The value of genomic libraries will be continually enhanced as more is learned about the molecular physiology of animal species.
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From page 59... ...
This would be facilitated by the existence of genomic libraries. The screening of a genomic library might also provide the basis for a decision to thaw and transfer embryos from a specific population for further study as live animals.
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From page 60... ...
Given that sampling 25 males and 50 females will reduce loss in genetic variation at any one locus to less than 1 percent, the committee concluded that the following standards for population sampling should be adopted: for semen, 25 sires, each sufficient for 200 to 500 inseminations; for embryos, 25 sires and 50 dams, each with 10 to 25 embryos; for live animals, 25 breeding sires and 50 breeding dams. Private efforts to preserve animals in breeding herds should be encour Private individuals and interest groups, typically in developed countries, maintain a wide array of livestock for reasons not necessarily linked to genetic conservation.
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From page 61... ...
Esse~fi~' Co~ser~ffo~ Co~sfJer~ffons / 6I most immediate danger of exOnchon may not be bow widely studied breeds Omened 19907 It may be difficult to save some of these populabons using current cryogenic technology Research and development are also needed to refine held techniques and to evaluate ~ithinand bet~een-breed responses to collection and the viability of semen and embryos after cryogenic storage @
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