An energy shortage is most unlikely to occur in the captive parrot unless the owner fails to provide sufficient seed. Most owners, particularly of the single pet bird, have a tendency to over feed with the result that birds store excess subcutaneous and intra-abdominal fat. This may ultimately lead to deposition of fat in the liver resulting in liver failure. Arteriosclerosis is also very common in psittacines, particularly ageing birds, but whether arterial disease can be directly linked to a high energy content of the diet has not been proven. Diets high in fat, in our experience, also led to fatty infiltration of the cardiac muscle with resultant heart failure and, while these problems are most commonly seen in show budgerigars, they do occur in other members of the psittacine family.
Stored foods are likely to have a low vitamin content.
Although some fresh green foods may contain adequate levels of vitamins A and C, it is always wise to supplement the diet with a comprehensive vitamin supplement, either by using one of the prepared pelleted foods mentioned at the end of the paper or by using one of the well known paediatric drops obtainable for your local veterinary practice or chemist. The most common lesion caused by this deficiency in parrots is a hyperkeratosis of the oral mucous membrane which is often accompanied by oral candidiasis and secondary bacterial infections, sometimes extending down into the oesophagus. These birds are usually in poor condition. Owing to the lack of research work carried out on parrots almost nothing is known about their susceptibility to other diseases which might be related to nutritional deficiencies. Iodine deficiency has been well documented in the budgerigar and thyroid lesions associated with lack of dietary iodine have been seen in other species of small parrakeets.