1. Bone Density in Layers and Broiler Breeders D. R. Korver University of Alberta Edmonton, Alberta, Canada

3. Types of Hen Bone Cortical bone – outer structural component ANSC 463 Photo courtesy of Bob Fleming

4. Types of Hen Bone Trabecular bone – inner structural component

5. Types of Laying Hen Bone Medullary bone – Readily mobilized/deposited bone ANSC 463

6. Structural & Medullary Bone in Hens 100  m 94.1456 5x obj Tol. blue 100  m 94.1466 5x obj Tol. blue Slide courtesy Colin Whitehead In LayOut of Lay

7. Laying Hen Bone Health Much more is known about laying hens than breeders

8. Laying Hen Bone Health Much more is known about laying hens than breeders …but many aspects of development are similar

9. Body weight

10. Total Bone Mineral Density

11. Total Bone Area

12. Total Bone Mineral Density (QCT)

13. Total Bone Area (QCT)

14. Estrogen-driven changes in medullary and structural bone Amount 020406080 Age (weeks) Slide courtesy of Bob Fleming Structural bone

15. Estrogen-driven changes in medullary and structural bone Amount 020406080 Age (weeks) Slide courtesy of Bob Fleming Estrogen Structural bone

16. Structural and Medullary Bone Cortical/Trabecular Bone Medullary Bone 16 week pullet

17. Estrogen-driven changes in medullary and structural bone Amount 020406080 Age (weeks) Slide courtesy of Bob Fleming Estrogen Structural bone Medullary bone

18. Structural and Medullary Bone Cortical/Trabecular Bone Medullary Bone 1 st egg hen

19. Estrogen-driven changes in medullary and structural bone Amount 020406080 Age (weeks) Slide courtesy of Bob Fleming Estrogen Structural bone Medullary bone

20. Structural and Medullary Bone Cortical/Trabecular Bone Medullary Bone 60 week hen

21. Calcium Metabolism From Summers and Leeson, 1997 Commercial Poultry Nutrition (2nd ed.) p. 171 Dark Period Hours of Ovulation Cycle Total Shell Ash (g) 8 PM10 AM6 AM10 AM Medullary bone use Medullary bone deposition

22. Bone Ca Moblization MB CB 99.5127 20x obj. TRAP/Tol blue 50µm Photo courtesy of Bob Fleming

23. Welfare: severe bone fractures Osteoporosis – Loss of bone mass – “Caged Layer Fatigue” Loss of cortical bone

25. Calcium Metabolism From Summers and Leeson, 1997 Commercial Poultry Nutrition (2nd ed.) p. 171 Dark Period Hours of Ovulation Cycle Total Shell Ash (g) 8 PM10 AM6 AM10 AM Medullary bone use Medullary bone deposition

26. BW & Bone Breaking Strength Body weight (g) Bone Breaking Strength (kg) Body Weight Bone Breaking Strength

27. Estrogen-driven changes in medullary and structural bone Amount 020406080 Age (weeks) Slide courtesy of Bob Fleming Estrogen Structural bone Medullary bone

29. Layers & Broiler Breeders Low body weight High Ca demand High risk for problems Higher body weight Lower Ca demand Low risk for problems

30. Soluciones

31. Pullet size Increase Ca at the right time: ~5% production – Pre-lay diets PRUDENCIA  from 10-14 days before 1 st egg to 5% Ca particle size – small vs large Increase Ca with age, decrease P Exercise – cages vs floor Genetics Layers & Broiler Breeders

32. Midnight feeding Water Ca supplementation Layers

33. Scatter oystershell in the litter in the afternoon Breeders

34. Conclusions Bone development follows a similar pattern in layers and broiler breeders Layers are more at risk of developing bone problems Proper management can prevent many problems – May be difficult to correct problems once they start

35. Muchas gracias