conserving endangered genetic resources

1. conserving endangered genetic resources • D. PHILLIP SPONENBERG, DVM, PHD • VIRGINIA-MARYLAND REGIONAL • COLLEGE OF VETERINARY MEDICINE • VIRGINIA TECH, BLACKSBURG, VA • AND- THE AMERICAN LIVESTOCK • BREEDS CONSERVANCY

2. current situation • agriculture and animal production have changed more in the last century than in 10,000 years

3. why conserve breeds? • conservation needs to be rational and useful • genetic resources (breeds) have an essential role in agricultural systems

4. current situation • animal production is becoming more industrial • very productive • very narrow and defined • currently very few genetic resources produce the majority of meat and milk

5. current situation • industrial production results in more and more breeds becoming rare or extinct

6. why are breeds important? • breeds • more than a package of genes • a predictable and repeatable genome • need genetic uniformity to serve usefully • available immediately for specific situations

7. reasons to conserve • agricultural security • conserve variations for a future that is secure and comfortable, including ecology • scientific. • genetic variations of interest • animals (diseases, products) • humans (models of disease) • cultural • national or regional heritage

8. agricultural security • short term: meat, milk, wool, services (transport, draft, management of environment) all in the present day • long term: these will all be needed in the future, in a system that provides them over centuries

9. security • need strategies for short and long term • long term survival is impossible without short term survival

10. security • agricultural systems will change in the next years and centuries • details of those changes are unforeseeable • need to conserve the genetic components (breeds) to ensure that future generations can choose the ones they want to use

11. security • local and adapted breeds have high importance • heritability of adaptation is low • heritability of production is medium to high • achieve a population of animals that is productive AND adapted more rapidly if the starting point is with an adapted population rather than a more productive one

12. science • animals provide opportunities to study genetic variation • each breed has its own unique combination of genetic variation • losing breeds means losing this variation

13. cultural heritage • breeds result from interactions between animals and humans • breeds are a living history of this old and important relationship of animals and civilization • tells us who we are and where we have come from

14. cultural heritage • many breeds reveal much about the unique history of different groups of humans

15. cultural heritage • many human groups have their own breeds that are old and central to their cultural identity • if this is the only value of a breed: • the breed can persist in low numbers without much risk of genetic erosion or risk of extinction

16. cultural heritage • population management can be directed at maintaining adequate genetic variation • replacement of breeding animals based on genetic structure of breed rather than improvement • can succeed with small populations (minimum of 100 animals, more is always better!)

17. current production • current production depends on population expressing good characteristics at a high level • requires a high level of genetic variation to maintain production • demands a high population level (thousands) to allow for selection for production

18. current production • production requires selection • selection always selects some and rejects others • rejecting and animal is not only rejecting a few genes, but the entire genome of the animal • it is important to maintain enough variation to assure rugged adaptation and general health, and to avoid inbreeding depression

19. current production • difficult to maintain selection in very small populations without causing problems from inbreeding. Most decision need to be made with regard to genetic structure of the population, leaving few decisions for selection for production.

20. future production • agricultural systems change over time • these changes are difficult to predict • every human generation considers itself wiser than the others, but history indicates that each has a great deal to learn from other generations

21. future • a secure future requires a wide range of breed types • breeds are predictable • can quickly serve their role when needed

22. valuation • the value of a breed is important • the value of individual animals within a breeds is also important

23. value of animals • how to measure the worth of animals and breeds is important • rate of gain? • milk production per year? • milk production over lifetime? • longevity? • individual replacement cost?

24. value of animals • each method results in a different result for genetic selection • short term production usually favors developed or industrial animals • cost of replacement usually favors adapted and resistant animals

25. short term • short term - best to rank breeds by balanced method • animal products do have economic value • replacement costs also have value • both need to be considered • some productive animals have high replacement costs • less productive animals can have much lower replacement costs

26. short term • most adapted animals are smaller than more productive animals • not certain whether animals divide their metabolic resources between production and adaptation • a “total” whether they need to divide them between the two goals • in some cases (Beefmaster catte) it is possible to have both high production and adaptation in benign environments

27. long term • goal is to conserve options for future generations • we have received a complete range of breeds from our ancestors • we need to pass this along to our descendants

28. long term • in an ideal world each breed would have high enough numbers to permit selection • not always possible

29. value • important to include all possible factors to assign worth or value to breeds • document what they offer to production systems • long term usually best to use combination of local adapted breeds with production/industrial ones

30. production systems • breeds can be used in different ways • purebred industrial breeds usually lack adaptation • purebred local adapted breeds usually lack high short term production

31. production systems • the two types can be crossed for productive use • these crossbreeding programs nearly always endanger the local breed • usually the industrial breed gets all the credit for the resulting production of the crossbreds • really both parents are equally important

32. production systems • long term crossbreeding systems depend on pure breeds with good adaptation and production

33. choosing breeds • can select a breed for just about any characteristic • production characteristics have medium or high heritability • adaptation and reproduction characteristics have low heritability

34. choosing breeds • developing a breed that is both productive and adapted is quicker by starting with adapted breed instead of a more productive breed • this idea is usually rejected in favor of a more rapid answer, even though it does not work

35. organization • conservation needs to be effective • with improved communication and transportation, conservation must be organized • isolation that served well in the past to conserve breeds is no longer the situation • without organization many breeds will be lost

36. organization • each country needs its own style of organization • no single model will work in all countries

37. organization in USA • the governmental USDA preserves embryos and semen, has little interest in live animals • non-governmental work is mostly through the American Livestock Breeds Conservancy • conserving breeds for over 30 years

38. ALBC • founded in 1978 by historians to conserve local breeds that were in danger of extinction • grown into a conservation organization that works with breeds of livestock as essential for diverse agricultural systems that function well

39. ALBC • studies breeds and populations to conserve them • has helped some breeds with registry function • helps with genetic management • helps with marketing or products • rescues populations at risk of extinction

40. ALBC • how best to measure populations? • in the North American situation it is logical to use the number of animals registered in each year • this indicates the level of purebred breeding • reveals the activities of the breeders

41. ALBC • annual registrations work poorly for landraces • many of these have no registry • not all breeders will register animals • however it is done, some idea of population size is required to conserve the breed