Strategies to maintain genetic diversity in rare breeds of livestock

1. Strategies to maintain genetic diversity in rare breeds of livestock Mark Knauer, PhD North Carolina State University Swine Extension Specialist ALBC 11-8-13

2. Why is genetic diversity important? • Genetic diversity and inbreeding are inversely related • Therefore, we work to keep inbreeding at a minimum • What is inbreeding? • Mating together animals that are related by ancestry

3. Inbreeding is unfavorable Impaired reproduction Adapted from Bereskin et al. (1968)

4. Inbreeding is unfavorable Impaired survival Adapted from Bereskin et al. (1968)

5. Inbreeding is unfavorable Impaired growth performance Adapted from Bereskin et al. (1968)

6. Inbreeding is unfavorable • Largest reproductive issue • Getting females bred & continuing the population

7. Inbreeding is unfavorable • Increased incidence of genetic defects • hermaphrodites

8. Other genetic defects

9. Calculating inbreeding Ft = 1 – (1 - ∆F)t • Where • t = generation and • ∆F = 1/2Ne • Where Ne= the effective population size

10. Maintaining genetic diversity Ft = 1 – (1 - ∆F)t Reduce the rate of inbreeding

11. Avoid mating close relatives • Avoid mating – in order of importance • Parents and offspring • Full siblings - brothers and sisters • ½ siblings – ½ brothers and sisters

12. Increase your population size

13. Increase the number of herd sires used favorable unfavorable Important to use as many males as possible Using a couple or several males, instead of just 1, significantly reduces inbreeding

14. Bring in outside genetics – live animals

15. What if your new boar is too large/too small for your females? • If boar is too small • Collect semen off of the sow in heat • Inseminate sow with collected semen • Use a breeding crate • If boar is too big • Train to mount an AI dummy • Use a breeding crate

16. Train to mount an AI dummy

17. Use a breeding crate

18. Bring in outside genetics – semen

19. Develop a grade up program ½ heritage × 3/4 heritage × 7/8 heritage × ×

20. Maintaining genetic diversity Ft = 1 – (1 - ∆F)t Lengthen the generation interval

21. Generation interval __ L = Lm + Lf ______ 2 Where L = generation interval

22. Lengthen the generation interval • Do not keep offspring out of gilt litters • Keep offspring out of old boars and old sows

23. Keep offspring out of older parents Rate of inbreeding is 3 times less in scenario 2 vs. 1.

24. Strategies to maintain genetic diversity • Avoid mating close relatives • Increase your population size • Increase the number of males used for breeding • Bring in outside genetics • Live animal introductions • Semen • Develop a grade up program • Lengthen the generation interval

25. Thank you all for your hard work! • Maintaining heritage breeds can be challenging • Important to maintain the genetic diversity associated with heritage breeds

26. Thank you for your time Mark Knauer mtknauer@ncsu.edu

28. Strategies to reduce inbreeding • Sample outside genetics • At least once every 3 years • Lengthen your generation interval • Retain old sows • Avoid mating • Brothers and sisters • ½ brothers and sisters • Parents and siblings

29. Strategies to reduce inbreeding • Sample outside genetics • At least once every 3 years • Lengthen your generation interval • Retain old sows • Avoid mating • Brothers and sisters • ½ brothers and sisters • Parents and siblings

30. Strategies to reduce inbreeding • Sample outside genetics • At least once every 3 years • Lengthen your generation interval • Retain old sows • Avoid mating • Brothers and sisters • ½ brothers and sisters • Parents and siblings

31. Other benefits of using AI • Genetic improvement • Only one “best” herd • Genetic cost - may be less expensive to use AI than maintain a boar • How many sows do you have? • Increase number of potential matings • How many of you have had a boar that was too big or too small to breed a desired female?

32. Other benefits of using AI • Genetic improvement • Only one “best” herd • Genetic cost - may be less expensive to use AI than maintain a boar • How many sows do you have? • Increase number of potential matings • How many of you have had a boar that was too big or too small to breed a desired female?

33. Other benefits of using AI • Genetic improvement • Only one “best” herd • Genetic cost - may be less expensive to use AI than maintain a boar • How many sows do you have? • Increase number of potential matings • How many of you have had a boar that was too big or too small to breed a desired female?

34. Summary • Multiple potential benefits to adopting AI • Maintain genetic diversity! • Genetic improvement • Reduce genetic cost • Increase boar usage • You are taking a positive step today towards the benefits of AI technology

35. Why should you use AI? 1# reason – genetic diversity Inbreeding causes inbreeding depression which is characterized by reduced fitness

36. Why should you use AI? Inbreeding - the breeding or mating of related individuals within a closed group animals When is the last time you introduced outside genetics into your herd?