written by: dr. jacquie jacob, university of kentucky
when an egg is being laid, the lower part of the hen’s reproductive tract temporarily turns inside out, allowing the hen to lay a very clean egg with no fecal contamination. (for more information about the hen’s reproductive tract, refer to the article on the avian reproductive system—female). sometimes the oviduct does not return to the proper position after the egg is laid. this condition is known as prolapse. if other hens notice the prolapse, they are attracted to the moist, glistening texture of the oviduct. they will start picking at the material.
prevention of prolapse begins with the way that the pullets are raised. the following problems can lead to prolapse:
- excessive body weight: overweight pullets are prone to prolapse. overweight pullets have a tendency to lay large eggs. too much fat around the oviduct can also increase the incidence of prolapse.
- early photostimulation: photostimulation of the pullets before the reproductive tract has fully matured can lead to prolapse.
- inadequate nutrition: inadequate nutrition, especially a calcium deficiency, can increase the risk of prolapse. calcium is important for proper muscle tone, and weak muscles may make it hard to bring the oviduct into the body, increasing the amount of time the oviduct is exposed.
prolapse can also occur at peak production as a result of the large demand on the hen’s metabolism. the production of large numbers of big eggs, as when a hen is laying double-yolked eggs, weakens the muscles, increasing the amount of time the oviduct is exposed. high-intensity light can make the problem more critical by increasing the visibility of the everted oviduct for other hens in the flock.
the first indication of a prolapse problem is the presence of blood-streaked eggs. early detection of such eggs may help to prevent further damage.
take the following precautions to prevent prolapse:
- monitor the growth of the pullets, and photostimulate only when the birds have reached the right age and body weight.
- feed hens a balanced feed.
- ensure that the light intensity is not too high. if you are having a problem, reducing the light intensity may help.
- if the flock is producing a lot of double-yolked eggs (more than 4% of total production), it may help to slowly reduce the hens’ feed intake to 5% to 10% less than what they were eating when they had feed freely available.
if you have a high incidence of prolapse in the flock, consider using a very low-wattage red bulb. in red light, the birds won’t be as attracted to the everted oviducts, reducing damage to the oviducts that are slow to return to the body.