Chicken and Egg Issue 15 - page 50-51

50
Chicken & Egg. Welfare and Food Together.
51
Chicken & Egg. Welfare and Food Together.
Gaynor’s
Tips
Compared to her fancy breed cousins and
broilers bred entirely for meat production,
the commercial layer carries little spare flesh
and concentrates her energy into producing
eggs. In the past all ex-bats would be sent
to slaughter at 18 months of age just before
decline in shell quality and decreased
frequency of laying became apparent.
However, with our help, some hens are now
re-homed into pet homes so they can enjoy
a well-deserved retirement. As a result hens
are unsurprisingly now the sixth most
popular pet in the country.
Hens have only one functional ovary – the
left one. The ovary contains follicles of
differing sizes and maturity. When each
follicle matures, it is called a yolk or vitellus.
The yolk travels from the ovary into the
oviduct. The first part of the oviduct is called
the Infundibulum, this is where the egg stays
for roughly 15 minutes. If the hen has been
mated this is where fertilization takes place.
Beware! If you plan to breed from your girls
it is important to understand that sperm can
survive in the oviduct for as long as 4 weeks,
so if you have a particular cockerel in mind,
keep other cockerels away.
The next part of the oviduct is the Magnum
where the egg remains for roughly 3 hours;
the white albumen is generated here.
Passing down the oviduct the egg reaches
the Isthmus and remains for one hour while
two membranes form around it. Next comes
a 24hour period inside the Uterus – the
shell is formed at this stage. The final stage
A broody hen will take up position in her
favourite nest box and will be agitated if you
try to disturb her. Feathers ruffle and she will
squawk at you in protest if you attempt to
dislodge her, you may even receive a peck
for your efforts.
Even hens that have lived in a colony cage
system and have never had access to their
own eggs before can go broody.
The understandable reaction from many
owners is to seek out fertilized eggs to put
under the broody girl, and whilst this is one
answer, you must be prepared for some
cockerels to hatch.
Hens will go broody regardless of whether
or not a cockerel is present and it can be
upsetting to see your hen sitting in the nest
day after day losing condition. Some hens
will lose feathers and develop a bald patch
on their belly. This broody spot provides
extra warmth for the eggs.
Howdoes my hen produce
an egg every day?
The humble commercial hybrid hen (our lovely ex-bat) has
been designed and modified over the years to ensure peak egg
production and consistency of yield.
Any hen can
go broody.
involves the cloaca and with the help of the
hormone arginine vasotocin, induces uterine
contractions, the egg is laid passing down
through the cloaca.
A hen in her prime laying period between
20 weeks of age (point of lay) and 78 weeks
of age (end of lay) would be expected to
produce around 300 eggs annually (she has
periods of rest in her cycle when laying stops
briefly). Happily the majority of hens continue
to lay after 78 weeks.
(See diagram)
An egg is an ideal incubator and nursery for
a growing chick embryo. The shell is porous
with typically around 7000 pores in the
calcium carbonate shell allowing air into
the embryo. For this reason it is not
recommended that eggs are washed as
bacteria can be introduced via this route.
There are strict regulations governing egg
production within the egg industry and eggs
are not allowed to be sold as first quality if
dirty or damaged in any way.
In such cases it is important to lift your hen
off the nest daily to feed, drink and defecate.
Remove any eggs from the nest and be kind,
but firm with your hen putting her outside to
distract and cool her. You may need to shut
her outside the coop entirely during the day
to avoid her sitting unnecessarily.
How long will this behaviour last? If she were
hatching eggs she would be sitting on the
nest for 3 weeks but may well be broody
up to 6 weeks. Continued cooling of her
underside (lifting her out of the nest) will help
to break the cycle.
Broodiness is a natural tendency that all hens have
to want to sit on and hatch a clutch of eggs.
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