Vitamin D Severe Deficiency in Laying Hens
In confined laying hens, signs of deficiency begin to occur as soon as 2 weeks after they are deprived of vitamin D. The first sign is a marked increase in the number of thin-shelled eggs and soft-shelled eggs, followed soon after by a significant decrease in egg production.
Individual hens may show temporary loss of the use of the legs with recovery after laying an egg that usually is shell-less. During periods of extreme leg weakness, hens show a characteristic posture that has been described as a "penguin-type-squat". Later, beak, claws, and keel become very soft and pliable. Vitamin D metabolism has been implicated in problems of eggshell quality.
Observed Clinical Signs Happenings
- Egg production declines rapidly
- Several cycles of decreased egg production and shell strength may each be followed by periods of relatively normal production and shell strength
Visibly sick birds
- Few visibly sick birds
- Hens may show temporary loss of the use of the legs, with recovery after laying an egg that is usually shell-less
- During periods of extreme leg weakness, hens show a characteristic posture that had been described as a “penguin-type squat”
Lameness or unusual movement incoordination ataxia
- Temporary loss of the use of legs
- Extreme leg weakness
Head Comb Wattles Face Nostrils Sinuses Mount Beak Earlobes
- Beak, claws, become very soft and pliable
Body Parts (Neck wings breast abdomen shanks legs hocks feet joints vent skin)
- The sternum usually bend, and the ribs lose their normal rigidity
- keel become very soft and pliable
- Shell-less Soft Shell
- Eggshell strength decreased
- A marked increase in the number of thin-shelled and soft-shelled eggs
Diet or Feed Changes (Recent Feed delivery, Recent formulation /diet, Other silo or improper storage, another feed brand)
- Recent formulation /diet
Vitamin D Severe Deficiency in Laying Hens DOES NOT exhibit or manifest any of the following clinical signs happenings:
- Egg production drops gradually
- Mortality above the standard
- Many visibly sick birds
- Flock behaviour activity change
- Droppings abnormalities
- Respiratory abnormalities
- Neurological Nervous
- Eyes abnormalities
- Feathers abnormalities
- Feed Consumption Changes
- Internal Egg defects
- Causing Agents
- Inadequate dietary vitamin D3
- Affected Systems/Organs
- Reproductive and Locomotion System
- Mainly Affects
- Egg Production and Egg Quality
- Adequate levels of vitamin D3. Calcium and Phosphorous ratio in the diet.
- Suggested Actions
- Can be confirmed with clinical signs and gross lesions
- Technical assistance recommended
- Can be managed with feed additives, off-the-shelf medications
- Diagnosis should be confirmed with rapid assays and/or a certified laboratory
- Veterinary intervention is recommended
Impact on Egg quality
Impact on Liveability
Impact on Production
Overall Economic Impact
- Y.M. Saif. 2008. Disease of Poultry. 12th Edition. page 1126
- David E. Swayne. 2013. Diseases of Poultry 13th Edition. page 1211
- Mark Pattison, Paul F. McMullin, Janet M. Bradbury. Dennis J. Alexander. 2008. Poultry Diseases. 6th Edition.
- Paul McMullin. 2004. A Pocket Guide to Poultry Health and Disease. First Edition.
- Steven Leeson, John D. Summers. 2008. Commercial Poultry Nutrition. Third Edition.
- Donald D. Bell, Williams D. Weaver. 2009. Commercial Chicken Meat and Egg Production. Fifth Edition.
- Gail Damerow 1994. The Chicken Health Handbook.