Rickets is a common disease found mainly in young meat birds. The main cause of Rickets is inadequate or poor bone mineralisation. A mineral deficiency of either phosphorous or calcium, an incorrect calcium to phosphorus ratio, or a vitamin D3 deficiency in the young growing birds diet may result in abnormal bone development. Generally rickets is caused by a lack of vitamin D3 in the diet, inadequate potency of the D3 supplement or other factors that reduce the absorption of vitamin D3.
At 10-14 days of age young broilers and turkey poults can exhibit lameness as a symptom of rickets and their bones grow rubbery. Another effect seen is a flattening of the ribcage with beading at the attachment of the vertebrae to the ribs and there can also be enlargement of the ends of the long bones. To determine whether the cause of a rickets problem is due to a deficiency of calcium or vitamin D3, or even an excess of calcium, which prevents efficient phosphorous absorption, an analysis of blood levels is needed. Histology can also be performed to confirm rickets.
Although rickets is mainly seen in young growing birds it can also be seen in laying hens which generally results in reduction of shell quality and can lead to osteoporosis. This disorder can also be known as “ cage layer fatigue” and is caused when calcium is taken from the bones to overcome a dietary deficiency resulting in depletion of the bone structure thus the hen is unable to support her own weight.
Providing adequate levels and potency of vitamin D3 supplements and a correct balance of calcium to available phosphorous is necessary to prevent rickets. Due to the young birds limited ability to digest saturated fats (which may lead to an induced deficiency of calcium) a diet should be formulated to ensure optimal utilisation of all fat-soluble compounds.