Young growing birds are more susceptible than older birds to vitamin D toxicity. With phosphorus we often find it is more common to be oversupplied with this mineral than for a deficiency to occur. However, a deficiency may cause weight problems, joint stiffness, weakness, trembling, and appetite loss. If your bird's diet contains excess phosphorus, this would inhibit the uptake of calcium. A deficiency in magnesium can develop if not supplied in your Grey's diet.
Insufficient intake affects all tissues, particularly the heart, nerves and kidney.
These would include loss of appetite, growth failure, lack of coordination, GIT disorders, hypertension, or depression. In addition weakness, muscle tremors, weight loss, nervousness, and feather loss may result. Toxicity is rare, but would cause weakness, sleepiness, and breathing difficulties. If any of the above signs are noticed in your bird it would be of value to have the blood levels checked for the vitamins and the minerals described. The most important thing to remember is that the function of calcium, magnesium, phosphorus, and vitamin D, in their proper ratios, are all closely dependent on one another.