Prolapse in laying hens is a common multifactorial syndrome that can lead to significant economic losses for producers, and it can even be fatal if not addressed promptly. But what exactly is prolapse, and how can we evaluate the risks?

What is prolapse in layers?

Egg laying usually starts when Pullets are between 17-18 Wks.  During normal oviposition, there is a momentary eversion of the lower part of the oviduct through the cloaca, which quickly reverses. Prolapse occurs when the hen cannot retract the oviduct, and a part of it remains outside the body. Prolapse is also known as vent prolapse, oviduct prolapse, blow-out, cloacal prolapse, or pick out.

The exposed tissues can attract other hens, leading to vent pecking—an abnormal, harmful behavior characterized by pecking damage to the cloaca.  This can lead to further injury to the cloaca. Prolapse, vent pecking, and cannibalism are often interconnected. Prolapse can lead to pecking, and vice versa, as small lesions in the oviduct tissue at the time of oviposition can result in prolapse. The condition might result in death of the affected hens.

Figure 1: Vent prolapse in laying hen.

Figure 2: Bovan hen, 40 weeks presenting vent prolapse. The bird is in pain as it is not able to get rid of the egg, this can result in pecking and cannibalism (photo: UTRIX s.a.l.)

What causes prolapse?

Prolapse is a multifactorial syndrome with no single cause. Both internal and external factors are involved, including farm environment, flock management, animal physiology, health status, and dietary factors. Understanding these elements can help mitigate and prevent the risks.

Environmental and flock management factors:

• Stressors that trigger pecking and cannibalism, such as overcrowding and insufficient feeders and drinkers.
• High temperature and humidity, and poor ventilation, which can favor pecking.
• Improper beak trimming.
• Housing: insufficient number of nests or too brightly lit nests can lead to high number of floor eggs and cloaca exposure to pecking.
• Cage birds are more prone to fat deposition and prolapse, while floor birds are more prone to pecking and cannibalism.
• Lighting: premature light stimulation (before reaching mature body weight), and high light intensity.

Physiological factors:

• Body weight and skeletal development.
• Health status: internal or external parasites.
• Hormonal alterations affecting the function of smooth muscles of the oviduct.
• Double-yolk eggs.
• Reproductive age of the flock, with increased prolapse risk around peak production.

Dietary Factors:

• Calcium deficiency can cause muscle weakness and delay in retraction of the oviduct.
• High energy diets, resulting in fat deposition.
• High protein level/Amino Acids, leading to larger eggs.
• Poor dietary fiber levels can encourage pecking, and lead to poor gut health.

How to detect vent prolapse?

Prolapse is a highly concerning condition, and early detection is crucial to managing and mitigating its impact on flock health and farm revenue. The first sign of a prolapse issue is often blood-stained eggs.

Figure 3: Blood-stained egg, a sign of vent prolapse condition (photo: UTRIX s.a.l.).

How to prevent and control vent prolapse in layer farms?

The major cause of death is not prolapse itself but pecking and cannibalism through blood loss or when the intestines are pecked out. Once pecking and cannibalism occur in a flock, they are very difficult to eradicate.

Observation of flock behavior is key to preventing the issue as early as possible and avoiding its detrimental effects on bird health and survival. Early intervention includes isolating birds with vent-pecking behavior from the flock. Birds with injured vents can be sprayed around the vent with a material of unpleasant taste and smell, such as tar, to prevent pecking by other birds.

As discussed, environmental, flock management, and dietary factors play a role in the syndrome. Good practices that can help prevent prolapse include:

Housing and management

• Minimize the occurrence of floor eggs: ensure the number of nests is adequate and not brightly lit.
• Verify feeders and drinkers numbers are sufficient.
• Perform adequate and uniform beak trimming.
• Use of plastic spectacles, or eye glasses prevent pecking by blocking hens forward vision (figure 4).

Figure 4 : Chicken spectacles or eye glasses help prevent pecking behavior (photo: UTRIX s.a.l.).

Lighting

• Photo-stimulate at the correct flock body weight and uniformity.
• Avoid high-intensity light.
• Avoid more than 16 hours light duration at production (better 15 hours).

Nutrition

It is essential to feed a balanced diet. Key constituents that help prevent prolapse include energy, protein, fiber, calcium, and phosphorus.

• Ensure adequate energy levels: avoid hens being overweight or underweight and check flock uniformity.
• Avoid high levels of crude proteins that encourage larger eggs.
• Ensure high levels of insoluble fiber to control pecking and cannibalism and improve intestinal health.
• Ensure appropriate calcium and phosphorus levels and ratios.

Conclusion

Vent prolapse in laying hens is a complex condition influenced by various environmental, physiological, and dietary factors. Effective management and prevention require a comprehensive approach that includes housing and flock management practices and adapted nutrition, with particular focus on energy, crude protein, insoluble fiber and calcium and phosphorus. By understanding the causes and implementing best practices, producers can significantly reduce the incidence of prolapse. Early detection and intervention are crucial to mitigate the impact of prolapse and associated behaviors such as pecking and cannibalism. With careful observation and proactive measures, laying hens welfare can be protected, ensuring farm productivity.