Calcium (Ca) is an essential mineral that is required for bone growth of chicks, egg shell formation in hens, muscle contraction, transmission of nerve impulses, and blood clotting. Calcium also acts as an important co-factor for several different enzymes and hormones.
There are many causes of hypocalcemia in chickens, even for birds that receive adequate amounts of dietary calcium in their daily diet. Dietary calcium can be reduced in chickens receiving:
- Diets with too much phosphorus, such that it off balances the Ca:P ratio which should be 2:1.
- Foods high in oxalic acid (cassava, spinach, carrots, beet leaves, lettuce, sweet potatoes, turnips) which form insoluble calcium oxalates and decreases calcium availability.
- Excess vitamin C
Several different vitamins and minerals interact with calcium, some act with calcium, and are required in order for the body to absorb it, and others act against it (antagonists).
Calcium Food Sources
|Ingredient||% Ca||% P|
|Defluorinated rock phosphate||34||19|
|Phosphoric acid (75%)||-||25|
Calcium Nutritional Requirements for Chickens
Requirements for calcium in chickens at various life stages are:
|Feed Type||Bird Age||Ca||P||Vitamin D3|
|Chick Starter||Hatch to 6 weeks||0.90%||0.40%||200 ICU|
|Grower||6 to 20 weeks||0.80%||0.30%||250 ICU|
|Layer||20 weeks and older||4%||0.31%||375 IU|
|Breeder||20 weeks and older||3.25%||0.35%||300 IU|
In order for chickens to be able to absorb calcium, they require adequate amounts of phosphorus (P) and vitamin D3.