Mineral deficiency in pet birds

Mineral deficiencies present one of the most frequent problems in pet bird nutrition. Calcium deficiency during reproduction leads to disturbances of egg production (thin-shelled eggs, egg binding) or a demineralization of th e skeleton. During the growth of chickens calcium and phosphorus are requir ed in a ratio of 1.6:1, whereas some rearing feeds as well as commercial se ed mixtures contain extremely Low calcium levels and more phosphorus than c alcium. Without an adequate calcium supply, the growing birds rapidly devel op rickets and adults will in the long term show osteomalacia. Furthermore a sodium deficiency (with disturbances of egg production or feather picking ) occurs, if pet bird fanciers offer seed mixtures without mineral suppleme nts. A low zinc content results in disturbances of the mucous membrane of t he crop which causes an inflammation. Signs of insufficient copper content are decreased feed intake, poor quality of eggshells or eventually fading f eathers. Muscle dystrophy may be related to a selenium deficit in birds fed exclusively on cereals. In addition the calcium-phosphorus ratio is often imbalanced. This imbalance is made worse (up to 0.03:1) by the dehusking an d shelling of seeds and is tolerated in adults for a long time (even if ind ividual birds show osteomalacia on Xray), although clinical signs will even tually develop, particularly in the presence of high amounts of phytate. In this connection the ability of phytin to cause secondary deficiencies by f orming complexes with other minerals such as zinc should be considered. In general, the diagnosis of mineral disturbances is very complex and difficul t. The assessment of mineral contents in plasma is possible, but not easy d ue to high variations and the lack of reference data. In addition to X-rays (mineralization of the skeleton!), analyses of feathers are made, but thei r value is doubtful given the present state of knowledge of normal values. The most helpful information is given by nutritional anamnesis and feed ana lysis. Although it is very difficult to quantify the mineral requirements o f per birds in different stages of life (maintenance, growth, moult etc.), first estimates as well as recommendations exist and allow a rough evaluati on of mineral supply provided under the specific feeding conditions reporte d by bird fanciers.