Cage layer fatigue is a condition that
is unique to hens that are in a high state of egg production,
primarily caged layer hens. The cause of the condition is thought
to be associated in an imbalance of minerals/electrolytes in the
body.
Rickets and abnormal bones in adult
birds is commonly present. In layers under thirty weeks of age,
the cause is usually a temporary calcium deficiency when egg production
reaches eighty percent or higher. If intake of calcium does not
satisfy the need for egg production, the hen will remove calcium
stored in the bones. Ultimately, osteoporosis develops, bones
become soft and hens are subject to bone fractures. Crippled and
unable to stand, the hen suffers from the caged fatigue symptoms.
Many hens show spontaneous recovery
if removed from the cages and allowed to walk normally on the
floor. This indicates that a lack of exercise may be a partial
cause. Cage layer fatigue is more prevalent in single-hen cages
than in multiple-hen cages. When two or more hens are caged together,
they get more exercise because of competition for feed and water.
Supplementation of the diet with phosphate,
calcium and vitamin D3 is usually helpful. Adding calcium
to young birds by top-dressing the feed with twenty pounds of
oyster shell or limestone per one thousand hens will often help
the condition. In older hens, calcium deficiency is less likely
than phosphorus or vitamin D3 deficiencies. Recommended
treatment in these birds is to remove the hens from cages and
top-dress feed with equivalent level of dicalcium phosphate. Adding
a vitamin/electrolyte supplement to drinking water is recommended
in any age bird suffering from this condition.
Flocks that do not respond to the above
therapy should be submitted to a poultry disease diagnostic laboratory
to determine the cause of the problems. Several diseases can cause
symptoms similar to caged layer fatigue. Flock treatment for the
condition can be prescribed after diagnosis is completed.
Fatty liver syndrome is a condition
that affects only hens. The basic cause is thought to be excessive
dietary energy intake. Hereditary tendencies vary among various
strains of egg production stock, but heredity is not the entire
cause for this malady. Laying hens housed in cages are most often
affected since they are less able to get sufficient exercise and
dispose of the extra dietary energy.
Birds within a flock that are most
often affected are the high producers. This indicates that physiological
energy metabolism and production are closely associated with this
condition. Mortality varies considerably among flocks but can
become excessive in some cases. Lesions include accumulation of
large amount of abdominal fat; enlarged, easily damaged liver
and presence of blood clots that indicate that hemorrhages have
occurred prior to death. Death usually is caused by a fatal internal
hemorrhage originating in a portion of the liver. This hemorrhage
is often caused as the hen is straining to lay her egg and the
enlarged, friable liver is more vulnerable to injury. When a large
blood vessel ruptures, sufficient blood is lost to cause death
of the hen.
The primary treatment for this condition
requires an alteration of the diet or amount of dietary energy
consumed. Replacement of some of the corn in the diet with lower
energy feedstuffs like wheat bran can provide a lower energy diet.
If a complete layer ration is being fed, addition of vitamins
can be of benefit. If grains are the primary feedstuff, it is
suggested that the birds be switched to a complete layer diet.
Control of body fat is the only successful remedy for this condition
and is best accomplished by regulation and reduction of total
energy intake.
Cannibalism is prevalent among chickens
of all ages and can become a serious problem if not corrected
early. The problem is most severe when birds are housed in close
confinement. In most cases it is a vice that progresses from a
minor stimulus and soon becomes a severe problem.
Many causes are thought to initiate
the problem but it is not understood why it is uncontrollable
in some cases but never becomes a problem in other situations.
Cannibalism may start as toe picking in baby chicks; feather picking
in growing birds; or head, tail and vent picking in older birds.
The early symptoms of a cannibalism problem may be difficult to
detect. It is necessary that the poultry man be on constant guard
to detect any aggressive behavior and take necessary management
changes before the problem progresses into a severe case of cannibalism.
Causes that can result in cannibalism
include:
Regardless of the cause, some method of preventing this vice must be used. The most common procedure
to reduce cannibalism is to debeak the birds. Birds grown in houses
with very low light intensity may not require debeaking. Those
grown in houses receiving normal daylight should be debeaked at
the hatchery or within the first two weeks after hatching. This
helps reduce the incidence of feather picking that often develops
into a severe case of cannibalism.
A special method of hot debeaking has
been developed for debeaking broiler chicks at one day of age.
Rather than severing or cutting the beak, a hot blade is used
to burn an area near the tip of the upper beak (egg tooth). The
procedure is designed to leave a thin base to the tip of the upper
beak. This makes it easier for the chick to eat without having
a sensitive, raw beak. The tip of the upper beak gradually drops
off without apparent injury to the chick, thus leaving a shortened
upper beak and a normal lower mandible.
Reducing the mortality is a primary
concern that responds well to adequate floor space. Birds should
not be crowded but instead, provide sufficient room so that weaker
birds can escape from those that are more aggressive. Reducing
the amount of floor space usually results in increased mortality
and reduced growth rate. Not only is there a monetary loss involving
the cost of the chick, but the value of the feed, labor, and other
items necessary to grow a chick until the time of death is a direct
loss. There is also the lost profit that could have been earned
if the dead birds had lived until market or egg production age.