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breed conservation - discover

This article discusses the steps in breed conservation, focusing on the importance of discovery, definition, population security, and long-term sustainability. It emphasizes the need for accurate identification of breeds and the importance of genetic diversity.

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breed conservation - discover

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  1. breed conservation - discover • D. PHILLIP SPONENBERG, DVM, PHD • VIRGINIA-MARYLAND REGIONAL • COLLEGE OF VETERINARY MEDICINE • VIRGINIA TECH, BLACKSBURG, VA • AND - THE AMERICAN LIVESTOCK • BREEDS CONSERVANCY

  2. steps in conservation • ALBC uses these steps in conservation • discover (encounter and define) • secure the population • sustain for the long term • all three steps are needed to assure success in the survival of breeds

  3. discover • The first step is to discover these rare breeds and populations • the USA has a good informal network with an interest in the conservation of these resources

  4. discover • this network usually indicates the existence of a population that is a candidate for conservation • usually this network commits “errors of inclusion” rather than “errors of exclusion” which helps to alert conservationists • misses relatively few breeds from consideration

  5. discover • always better to commit “errors of inclusion” because this indicates that the network is unlikely to ignore a population that truly merits conservation

  6. define • part of the “discover” step is defining breeds and populations

  7. define • ALBC uses this definition of “breed” • a group of animals with a phenotype that is distinct and recognizable, and that produces this type after being mated within the population • this definition is based in genetics, and establishes the breeds as genetic resources • implies a certain level of genetic uniformity and predictability

  8. define • this definition of breeds ignores populations with high levels of variability, even if some of these do have cultural importance • goal is the conservation of genetic resources that can be predictable as they serve agriculture

  9. classes of breeds • local – landrace – adapted- rustic • standardized • industrial • feral

  10. classes of breeds • each class of breeds needs its own appropriate strategy for effective conservation

  11. industrial • little or nothing possible for their conservation • impossible to duplicate the physical and selection environment in which these animals live • high risk that some will go extinct

  12. standardized breed • standardized breeds have breed associations for their breeders • standardized breeds are usually well defined • conservation of these is easier than the others • important to maintain a high level of genetic variation

  13. feral breeds • few are important to conserve • isolated for long times with distinct foundation and physical type

  14. landrace • usually well adapted • usually poor documentation (history, production) • poor recognition as a true breed in most places

  15. landrace • productive potential is poorly documented • ome do have high production potential and are important to conserve and develop • ost are adapted and resistant

  16. landrace • they do need to be “genetic resources” in the strict sense • need a level of genetic variation that does not prevent prediction of performance

  17. landrace • these need to be defined carefully • important to decide which animals to include and which to exclude • in many cases need to rescue a breed or a bloodline without losing characteristics

  18. landrace • need to develop strategies for long term maintenance

  19. landrace • three steps for effective conservation • Discover/ encounter/ define • secure • sustain • Final success depends on all three steps

  20. discover • for landraces it is necessary to decide if the population is truly a breed in the genetic sense • “breed” in this sense is a group of animals that are similar by origin and type, and that reproduce that type after mating within the group

  21. landrace • To decide if a population is a breed depends on investigations • phenotype (measured or visual inspection) • history • genetic data (bloodtypes, DNA fingerprints)

  22. investigation - history • ideal is long term isolation from other breeds • isolation comes from geography or owner practices

  23. history • some cases will have high levels of isolation • many cases will have doubtful histories, or even more than one version of history • the history and the external phenotype usually agree

  24. investigation - phenotype • in the US few people experienced in zootechnology • rare to measure animals to define breeds • measurements are always more accurate but are not possible in all cases • feral animals, or very extensive systems, present challenges to phenotypic evaluation – especially if measurements are needed

  25. phenotype • look at the animals and compare them to other breeds in the area, looking for evidence of crossbreeding or mixtures with other breeds • this method, even though not exact, works very well in practice

  26. steps one and two • history and phenotype usually agree • most populations either have the uniformity expected of a true breed, or are very variable from crossbreeding

  27. steps one and two • traits such as color or presence/absence of horns are usually not very important • landraces usually vary more in these traits than do standardized or industrial breeds • this variation doesn’t prevent use of these breeds • conservation should include this variability

  28. step three • genetic investigations are more expensive than those for history or phenotype • usually genetic investigations after the other two • after eliminate populations obviously crossbred • include only those that are more uniform

  29. genetic data • genetic data are usually for relative frequencies of alleles • can be analyzed different ways to reveal relationships of populations

  30. branching tree of breed relationships points out breed groups

  31. this type of “tree” also reveals the relative groupings as well as the distance of each population from the others

  32. complicated, but indicates individual animals, and how different they are if the population is split two ways, three, four, or five reveals fundamental points of division

  33. step three • genetic results provide background for deciding appropriate strategies for conservation • can reveal a mixed or uniform population • can indicate animals to include or exclude

  34. step three • DNA results can indicate relationships between breeds, and which are most distinct or distant from others

  35. step three • some individual animals are very important for genetic variation for the future of the breed

  36. Pineywoods cattle • from southeast USA • adapted to a humid subtropical environment • iberian origin

  37. Pineywoods • herds isolated from one another for a century • one breed or many? • all of the cattle are more like one another than any other breed • all of the herds have low numbers. • logical to include them all in a single breed to assure their effective conservation

  38. Pineywoods

  39. bloodlines BARNES HOLT PALMER BOUNDS CONWAY ROBINSON VICE POPPLE O’NEAL GRIFFEN SEAL BAYLIS AGRICOLA KNAPP GARNER ALBANY DIAMOND BEACH CARTER LADNER HICKMAN BROADUS CLARK DEDEAUX EZELL

  40. Pineywoods • each breeder thinks his cattle the most pure of all • need to replace that attitude with more inclusion

  41. Pineywoods • philosophy that works for this breed is to include all of the typical cattle from this region under a single registry and association • cattle are inspected to exclude the herds that have evidence of influence from zebu, Devon, Angus, or Hereford

  42. Pineywoods • these cattle vary more than standardized breeds • important to include this variation • dwarves and polled (hornless) cattle

  43. Pineywoods • another breed is closely related: Florida Cracker • two breeds were separated due to decisions based on regionalism of the breeders • DNA results indicate these two breeds have been separated for more than a century • some distinctions have arisen

  44. Pineywoods • effective to separate the two breeds to conserve

  45. Pineywoods • in the beginning the association encountered resistance from traditional breeders • would not register cattle • change to free registrations worked to increase the numbers of breeders registering cattle

  46. Colonial Spanish Horses • similar to the Pineywoods cattle breed • many herds • each isolated for centuries • one breed or many?

  47. Strains of the breed

  48. Colonial Spanish Horses • some herds have fewer than 30 horses • impossible to maintain these in isolation for the long term, without inbreeding

  49. Colonial Spanish Horses • total population is likely under 3,000 horses

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