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

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

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

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

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

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

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

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

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.

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.

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.

Injection Methods

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

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

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

Results Under Construction

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

Results – Trial 2 Effect of injection on hatched chick weight

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

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

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

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)

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)

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