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THE
CONTINUOUS GROWTH IN EGG SIZE
J.
Gregersen, LINCO Set & Hatch
It
is common knowledge that broiler-hatching
eggs, due to ongoing genetic improvement
have in the past and continue to increase in
size, and leading broiler breeding companies
predict a further increase in size in the
coming years. But what is not common
knowledge is how much this will affect your
hatching results. Why? Because larger
hatching eggs in existing trays means closer
contact, cracks and ultimately lower
hatching rates.
 During
my visits to hatcheries all over the world,
I have seen as many as 14% visibly cracked
eggs in a tray. I do not even dare to think
about how many hairline cracks I could have
added to this figure.
Visual
cracks usually mean that the eggs will never
hatch and hairline cracks mean that the eggs
might not hatch. These cracks usually occur
from insufficient space in the setter trays.
If two eggs have physical contact “shell
to shell”, one of them will most probably
crack in handling and/or turning.
The
“improved” large eggs do not fit most
existing setter trays on the market today
and the result is more cracked eggs,
especially towards the end of the production
period. Also many setter trays hold 150 +
eggs and are too heavy. When handled they
will twist and cause cracked eggs.
Eggs
with visible cracks are easy to identify and
remove whereas hairline cracks are mostly
not recognised at all and will consequently
remain on setter trays and be incubated as a
first quality egg. Hairline cracks can only
be identified by carefully candling.
A
research group from the University of
Alberta has recently analysed what happens
to an egg with a hairline crack when
incubated, and these are the results:
Hatchability % will decrease
significantly: 0 - 25%
Fertility % will decrease
significantly: 0 - 25%
Relative
egg weight will decrease significantly: 0
- 2,5%
Mortality will increase
significantly: 0 - 5,5%
Egg weight loss in setter will
increase significantly: 0 - 3,5%
Embryonic mortality mid and late term
as well as cull %
will increase significantly:
•
Mid (8-14 days) 6%
•
Late (15-21 days) 2,9%
•
Cull (10,9%)
Contamination will increase
significantly: 0 - 4%
At
LINCO Set&Hatch we have been conducting
trials with different egg sizes and setter
tray types. In the first trial we selected
hatching eggs in the weight range between 60
and 70 grammes. We measured diameter and
recorded the weight of each individual egg
and exactly the same eggs were placed at the
same position on each tray used in this
trial.
LINCO
Set & Hatch tray 60-70gr.
The
trial was repeated with new batches of eggs
weighing 70-80 grammes and +80 grammes. The
pictures below show the results where those
in red indicate those eggs, which are
touching the other eggs. Some of these eggs
surely will crack before they are hatched.
Only with the two options of LINCO
Set&Hatch and Classic trays, there is
still plenty of space around the eggs in all
trials, ensuring best possible airflow and
thereby heat transportation (transmission).
The more space between eggs also eliminates
hairline cracks and when LINCO setter trays
are used for on farm traying (less handling)
cracked eggs are reduced to an absolute
minimum.
LINCO
Set & Hatch tray 80+gr.
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