rickets in poultry

1. RICKETS
DEFINITION
In poultry a deficiency of vitamin
D3, phosphorus or a wide
imbalance in the
calcium: phosphorus ratio of the
diet can
cause rickets. The term
osteomalacia has been used to
denote similar condition in laying
chickens

2. OCCURRENCE
Deficiencies of vitamin D3 and
phosphorus are encountered
most frequently in young chicks or
poults a few weeks old.
Calcium deficiencies usually affect
birds of the same age
or adult layers.

3. ETIOLOGY
1. There are numerous forms of vitamin D,
however only
cholecalciferol or vitamin D3 acts as the
nutritional
precursor of 1,25 dihydroxycholecalciferol, the
hormone that stimulates active transport of
calcium and phosphorus across the intestinal
epithelium, bone and shell formation

4. malabsorption or any intestinal
condition impairing nutrient
absorption,

5. Calcium deficient laying hens may suffer from cage
layer fatigue (up to 30 weeks of age) or
bone breakage (old hens).

6. CLINICAL SIGNS
1. In young growing flocks,
affected birds develop a
lame, stiff-legged gait.
There is retardation of growth.
There may be enlargement of the
ends of long bones,
especially noticeable in the hocks.
Birds often rest in
a squatting position

7. Egg layers can experience
increased number of
thin-shelled and soft-shelled eggs
followed soon by
decreased egg production

8. Laying hens suffering from cage
layer fatigue lie on
their side, with their legs extended
or they crouch in
the corner of their cage.

9. LESIONS
1. In young birds bones, beaks and claws are soft
rubbery and the epiphyses of long bones often are
enlarged

10. There is a characteristic beading of
the ribs, most noticeable at their
junction with the spinal
column.
Ribs are thickened and tend to bend
so that the thorax is flattened
laterally

11. The beak becomes soft
and rubbery and can be bent or
flexed easily Parathyroids often are
markedly enlarged

12. DIAGNOSIS
1. In young birds, their age, signs,
and lesions are all
useful in diagnosis. Softening of
the beak and beading
of the ribs are almost
pathognomonic.

13. Careful calculation of the calcium :phosphorus
ratioand vitamin D3 levels of the ration may reveal
that it is
deficient or imbalanced

14. CONTROL
1. Feed a balanced ration with adequate calcium,
phosphorus, and vitamin D3 levels. Rations should
be carefully compounded to fit the age, purpose, and
production of the flock.

15. TREATMENT
1. Adjust the ration to fit the age
and production level of
the flock. If the ration has been
deficient in vitamin D3
give three times the usual amount
for a period of 2-3
weeks. Then go back to a balanced
ration with the
usual recommended level.