Common laying hen disorders Prolapse in laying hens
The average hen lays about 300 to 325 eggs per year. Once hens reach
reproductive age, most will lay an egg almost every day without any
During oviposition (the process of laying an egg) the shell gland (the lower part of
the hen’s reproductive tract where the egg shell is formed) is temporarily everted
(turned inside out) along with the egg. This allows the hen to lay a very clean
egg. Sometimes the oviduct will not immediately retract once the egg has been
laid. This condition is known as prolapse. If not noticed immediately, other birds
will pick at the protruding material, often causing hemorrhage, infection, and
death if quick action is not taken.
What causes prolapse?
Management of laying hens during the rearing and laying period can play a
significant role in prolapse problems. Some laying hen strains are more prone to
pecking, which can increase the damage to the bird, but this is generally not
considered a major cause of prolapse. Following is a summary of conditions
where prolapse related problems are more likely to occur.
Over or underweight Birds
Overweight birds are more prone to prolapse due to general muscle
weakness and a tendency to lay larger eggs. Too much fat around the
reproductive organs can also lead to prolapse.
Birds that are underweight (according to management guide
recommendations) when the birds begin lay are more likely to suffer
prolapse because they may begin laying before the reproductive tract has
Early Photostimulation –(increasing day length to stimulate sexual
Birds that are exposed to increasing day length before the reproductive
tract has fully matured are more likely to prolapse, because the
reproductive tract may not be fully matured when they begin lay.
Unbalanced feed rations
Insufficient calcium in the diet will cause problems with eggshell formation
but can also result in poor muscle tone. Poor muscle tone may cause
problems with oviduct retraction once the egg has been laid. The longer
the oviduct remains outside the body, the greater the chance other birds
will peck at the material, which could cause irreversible damage.
Reproductive age of the flock
Prolapse is more likely to occur at peak production and peak egg mass,
simply because of the large demand placed on the birds metabolism.
Laying double yolked eggs
The excessive size of these eggs will stretch and possibly weaken cloacal
muscles. Weakened cloacal muscles will lead to an increase in the
amount of time the oviduct is outside the body.
High light intensity
Under high light intensity conditions, birds are more likely to see and be
attracted to the everted oviduct—and thus more likely to peck at it and
One of the first signs of a prolapse problem is the presence of blood-streaked
eggs. As always, careful and vigilant management will lower the rate of prolapse
as well as most other flock health problems. If possible, isolate affected birds to
prevent further damage. Some reminders:
Photostimulation should occur when the birds reach the weight and age
recommended by the breeder.
Balanced feed rations are required to sustain egg production and maintain
body weight at recommended levels. Consult with a feed provider if you are
Ensure that the light intensity in the barn is at the breeder recommended
level. Consider reducing the light intensity by covering windows, or replacing
bulbs with lower wattage bulbs.
If the flock is laying a lot (more than 4%) double-yolked eggs, gently restrict
feed intake (about 5-10% less than they eat ad libitum).
Spend time with your birds to observe vent-pecking behaviour, and isolate
them from the flock.
Last resort only: consider a very low wattage red-colored bulb. If birds can not
distinguish the color of the everted shell gland from the background of colors,
they may not be as prone to cause damage.
This information is maintained by
Last Revised/Reviewed July 18, 2002