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
12
85
10
80
8
75
6
70
4
65
2
60
0
55
1985
1990
1995
2000
% Hatchability
Billions of Eggs
Background
Eggs Set
Hatchability
2005
Year
Schaal and Cherian, 2005
Hatchability resulted in 500 million dollar
loss to the US poultry industry in 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
48
(gm)
46
44
42
40
38
Control
Palmitate
Non-Inj
Results - Trial 2
Effect of injection on hatched chick heart weight
0.72
Body weight (%)
0.7
0.68
0.66
0.64
0.62
0.6
Control
Palmitate
Non-Inj
Results – Trial 2
Effect of injection on hatched chick yolk sac weight
18.00
Body weight (%)
16.00
14.00
12.00
10.00
8.00
6.00
4.00
2.00
0.00
Control
Palmitate
Non-Inj
Results – Trial 2
Effect of injection on hatched chick liver weight
2.40
Body weight (%)
2.30
2.20
2.10
2.00
1.90
1.80
Control
Palmitate
Non-Inj
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