Cage Layer Fatigue, Osteoporosis in ...

Cage Layer Fatigue, Osteoporosis in Laying Hens

Cage Layer Fatigue, Osteoporosis in Laying Hens

Osteoporosis more severe between 25 and 50 weeks of age. (1, 2, 3, 4)

Marginal calcium deficiency has often been found to be triggering agent in cage layer fatigue. (1, 2, 3, 4)

Clinical signs of Cage Layer Fatigue are exclusively seen in layers housed in cages. The flock has reached or passed their peak production and egg size is at its maximum.  The rate of lay in affected hens is above the average production of the flock. The hens appear normal but are unable to stand up and are reluctant to reach feed and water. In affected hens, egg production remains normal, with little or no deterioration of shell quality. Permanent paralysis may result from the fracture of spinal vertebrae, causing pressure on the spinal column. Death occurs in the absence of corrective measures. (1, 2, 3, 4)

Osteoporosis normally consists of loss in bone quality which predisposes the birds to fractures in a rage of bones of the body, ischium, humerus, and keel bones show the highest incidence of fractures, followed by fractures of pubis, ulna, coracoid and femur.

Osteoporosis was first described in the cage laying hens that had brittle bones and were unable to stand, but willing to eat and drink. The condition was then called "cage layer fatigue". They often are alert, but later become depressed and die from dehydration. Osteoporosis is more severe between 25 and 50 weeks of age. (1, 2, 3, 4)

Bone fragility is responsible for up to 30% of fractures of commercial flocks during their life, and its incidence may reach 90% during catching, transporting, and processing. (1, 2, 3, 4)

Nutritional methods of preventing osteoporosis have not been successful. However poor nutrition may exacerbate the problem. Increasing calcium in ration prior to egg production may be necessary, but, but it has been suggested that increased calcium is fed too long before egg production, the parathyroid gland may be suppressed. Feeding calcium in particulates either as oyster shell or limestone granules may extend the period of calcium absorption during the night, which reduces the depletion of medullary bone and benefits the eggshell quality. (1, 2, 3, 4)

Observed Clinical Signs happenings

Visibly sick birds

  • Birds are unable to stand, but willing to eat and drink
  • Hens with cage layer fatigue have trouble standing and typically crouch or lie at the back of the cage.
  • Birds often are alert
  • Paralysis in severe cases

Lameness or unusual movement incoordination ataxia

  • Paralysis due to the collapse of spinal bone (severe cases)

Body Parts (Neck wings breast abdomen shanks legs hocks feet joints vent skin)

  • Bone become so thin that spontaneous fractures may occur, especially in the vertebrae, tibia and femur
  • Fractures of ischium, humerus, and keel bones show the highest incidence, followed by fractures of pubis, ulna, coracoid and femur
  • Bone fragility is responsible for up to 30%  of fractures in commercial flocks during their life


  • Low mortality or increases gradually
  • Some birds have an egg in the oviduct and have to die acutely

Dead birds

  • Poor bodily fleshing condition
  • Dead birds may be dehydrated or emaciated, simply due to a failure of these birds to eat or drink
  • Some birds have an egg in the oviduct and die acutely (good body fleshing condition)

Egg quality

  • May increase the incidence of thin-shelled eggs
  • Thin-shelled and soft-shelled or porous eggs
  • Calcium and phosphorus deficiency results in reduced egg production and thin-shelled eggs
  • Poor shell quality occurs most commonly in older flocks
  • Eggshell weakness leads to loss of income due to egg cracks and breakage.
  • Hairline cracks (Blind checks) increased
  • Ungraded or second's eggs increased
  • Egg specific gravity score lower (should be above 1.080 (1.068 thin shells)

Diet or Feed Changes

  • Recent Feed delivery
  • Recent formulation / diet

Cage Layer Fatigue, Osteoporosis in Laying Hens DOES NOT exhibit or manifest any of the following clinical signs happenings:

  • Egg drop
  • High mortality or increases rapidly
  • Many visibly sick birds
  • Flock behaviour activity change
  • Droppings abnormalities
  • Respiratory abnormalities
  • Neurological Nervous
  • Head, Comb, Wattles, Face, Nostrils, Sinuses, Mount, Beak, Earlobes, abnormalities (except eyes)
  • Feathers abnormalities
  • Feed Consumption Changes
  • Internal Egg defects
Causing Agents
Calcium (Ca) and Phosphorous (P) deficiency or imbalance in the diet. The utilization of calcium and phosphorous depends on the presence of adequate amount of vitamin D in the diet It is defined as a decrease of normal mineralization of structural bone, resulting in increased fragility and susceptibility to fracture. Confinement of laying hens in cages has been showing to reduce bone strength significantly. The "Cage Layer Fatigue" syndrome apparently is not due to a simple deficiency of calcium but involves other etiologic factors not yet identified. Feed formulated to meet the calcium requirements of average production but not the maximum production.
Affected Systems/Organs
Reproductive, locomotor systems and liveability.
Mainly Affects
Egg production and egg quality
Supplementation of vitamin D and implementation of proper Ca and P levels and ratio in the diet. The availability of phosphorous can be increased by inclusion in the diet of phytase of microbial or plant origin.
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


  1. Y.M. Saif. 2008. Disease of Poultry. 12th Edition. page 1137,1157
  2. David E. Swayne. 2013.  Diseases of Poultry 13th Edition. page 1222,1240
  3. Paul McMullin. 2004. A pocket Guide to Poultry Health and Disease. First Edition. page 484
  4. Steven Leeson, John D. Summers. 2008. Commercial Poultry Nutrition. Third Edition. page 218


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