Agriculture Reference
In-Depth Information
to adjust hormone levels. Birds are unable to communicate their problems and the ex-
pense of blood tests to determine irregularities would far exceed the cost of the birds.
In a lifetime of raising poultry, the average person will eventually encounter a bird
that has some hormonal imbalance of some sort. It is only a matter of time before a
dwarflike bird that doesn't grow appears in the flock, or a bird that doesn't seem to be
one sex or the other. Some of these hormonal imbalances can lead to mysterious sud-
den deaths. It is probably best not to become too frantic and panic if an occasional bird
shows up that seems to be different. It is not always a disease; in many cases, it is just a
hormonal imbalance that cannot be helped by ordinary means.
Gonads
The
gonads
(sex organs) of fowl consist of the testes in the male and ovary and oviduct
in the female. Light plays a key role in hormone production in the gonads of both sexes.
Low light usually means low hormonal production, which translates into fewer eggs and
low activity by the males. Low activity by the males means less crowing and less, if any,
breeding.
Male geese will change temperament entirely during breeding season. Mild and pet-
like the rest of the year, they can become extremely aggressive and impossible to be
around during breeding season. All of this is directly related to the increase in the male
hormone.
The male is not the only one with behaviors controlled by hormones. Nesting and
brooding behavior in females is also hormonally controlled and influenced by light.
Light periods of fewer than 12 hours will seriously hamper egg production; 12 to 18
hours of light promotes maximum egg production. Exceptionally long periods of light,
such as continuous daylight, usually reduce egg numbers but increase egg size.
Body Temperature Regulation
Chickens and other poultry species are able to regulate their body temperature differ-
ently than other
homeotherms
. Homeotherms are animals that are able to regulate and
maintain a fairly constant body temperature. Birds do not have sweat glands but are very
efficient at respiratory evaporative cooling. The comb, wattles, shanks, and feet are ex-
posed surfaces where increased blood flow will result in heat loss. This is crucial in both
summer and winter.
In summer, single-combed birds handle heat better than do those with cushion or pea
combs. The large single comb provides an excellent way to lose heat. The reverse is
true in the winter, when large single or rose combs are a hazard in brutally cold weath-
er. Combs and wattles on large single-combed birds can easily get frostbite during cold
snaps.
