Modulating Fatty Acid Metabolism to Enhance Hatchability of Chicken Eggs

1. Modulating Fatty Acid Metabolism to Enhance Hatchability of Chicken Eggs Travis Schaal Dr. Gita Cherian Department of Animal Sciences

2. Background • Chicken egg incubation lasts 21 days • 12 billion broiler and turkey eggs incubated commercially in US annually • 20% of eggs incubated do not hatch USDA Image Number:95CS1974

3. Background Schaal and Cherian, 2005 Hatchability resulted in 500 million dollar loss to the US poultry industry in 2005

4. Background • Embryos are dependent upon nutrients stored in the egg for sustaining growth and development • An average chicken egg contains 5.5 to 6 g of fat (yolk) • Lipid-rich yolk is the only source of fatty acids available to the developing embryo. USDA Image Number:95cs1973

5. Background • During incubation, over 80% of yolk fatty acids (FA) are absorbed by the developing chick embryo. • In addition, FA are the major fuel and provides over 70 percent of the energy requirements for chick’s heart. USDA Image Number: 97cs0748

6. Hatching A Stressful Act • Hatching is characterized by: The internal pipping by the beak, accompanied by a gradual shift from yolk sac-based respiration to pulmonary respiration

7. Purpose To determine the effect of exogenous supply of fatty acids on chicken embryo health and hatchability.

8. Hypothesis Embryos having an exogenous supply of fatty acids will produce more energy during the stressful process of hatching and will have a higher hatchability rate

9. Methods - In Ovo Injection • Two trials conducted • Practice technique • Trial 1 • A total of 72 eggs were injected in-ovo with fatty acids (0.2 ml) or saline at day 14 of incubation with trans fat, no trans fat, or saline.

10. Methods - Trial 2 • A total of 135 eggs were incubated, 90 eggs were injected in-ovo with fatty acids (Palmitate, 0.2 ml) or carrier at day 15 of incubation.

11. Methods • Eggs set in same tray in the same incubator. • Incubation conditions: 37.5°C dry and 28.3°C wet bulb until hatching when the dry bulb temperature will be reduced to 36.3°C and the wet bulb temperature will be increased to 30.2°C.

14. Injection Methods

21. Methods • Hatched chicks were counted. • Non-hatched eggs were broken open to determine the embryo status (infertile, early or late dead).

22. Methods • Hatched chicks were sacrificed and tissues/blood collected for FA assays. • Heart = oxidation • Liver = synthesis • Brain = tissue with high levels FA • Yolk sac = reservoir

23. Results – Trial 1 • Hatchability • Saline = 80% • Trans fats = 29.6% • No trans fats = 45% • Tissue and blood FA assays pending

24. Results Under Construction

25. Results – Trial 2 • Hatchability Trial 2 • Palmitate = 64% • Carrier = 54% • No injection = 81% • Tissue and blood FA assays pending

26. Results – Trial 2 Effect of injection on hatched chick weight

27. Results - Trial 2 Effect of injection on hatched chick heart weight

28. Results – Trial 2 Effect of injection on hatched chick yolk sac weight

29. Results – Trial 2 Effect of injection on hatched chick liver weight

30. Conclusions • Trial 1 • Optimization of in-ovo injection techniques • In-ovo injection did not affect hatchability • Trans fat reduced hatchability • Trial 2 • Palmitate chick higher body weight (BW) • Injected chicks higher heart weight (% BW) • Injected chicks higher yolk sac weight (% BW) • No effect on liver weight (% BW)

31. So What? • Poultry Production • Hatchability, Body weight • Animal Models • Chick embryo could be used as a model to study fatty acid metabolism during early growth in humans • Link discovered between fatty acid metabolism sudden infant death syndrome (SIDS)

32. Acknowledgements • Howard Hughes Medical Institute • Dr. Gita Cherian • Dr. Kevin Ahern • Mare Goeger