A moderately common problem seen in budgerigars and some other species of birds is calcium deposition in the kidney resulting in kidney failure. The cause of this disease has been hypothesized to be either excess calcium or vitamin D₃ in the diet. To determine the cause of this disease, groups of budgerigars were fed diets containing various concentrations of calcium and vitamin D₃ and allowed to breed.  Results of this study showed that budgerigars need less dietary calcium (0.3%) than most other species for growth and egg laying.  When dietary calcium concentrations reached 0.7%, mild calcium deposition occurred in nestlings and adults.  When calcium concentrations reached 1.5%, death occurred in chicks and adult birds.  All seed diets containing less than 0.3% calcium resulted in weak bones in laying hens and their eggs did not hatch.  Vitamin D₃ concentrations ranging from 500 to 3,300 International Units of vitamin D₃ per kilogram of diet did not cause calcium deposition in the kidney as long as diet did not contain more than 0.3% calcium.

This research is important because it shows that budgerigars can only tolerate a narrow range of calcium in their diet.  Calcium concentrations in seeds are insufficient, but calcium concentrations found in most pelleted diets will be too high and could be toxic.  Therefore, it is necessary to supplement seed diets with some form of calcium, e.g., cuttlebone and if you are going to feed pellets, they should be no more than 25% of what a budgerigar eats.  This research also shows that budgerigars can tolerate a wide range of vitamin D₃ concentrations in the diet without problems.

 Progress in the Study of Macrorhabdus ornithogaster (Formally Megabacteria).

Work at Texas A&M University has shown that the organism formally known as megabacteria is not a bacterium, but is a yeast.  The name of this yeast is now officially, Macrorhabdus ornithogaster (MO). MO commonly infects budgerigars. It grows locally in a narrow zone of the stomach. Infections are very common in nestling birds, but most nestlings self cure as they become young adults. Most infections do not result in disease. However, some 2-4 year old budgerigars with MO infections will have a decreased appetite, will lose weight and die. Research into the treatment for this organism has been hampered because it could not be grown outside of the bird. Recently, investigators at Texas A&M University have grown MO.  Key to its growth is the fact that it can only grow in a very narrow pH range and it requires reduced oxygen environment.  Treatment studies in birds show the only effective treatment is to dose by mouth each bird twice a day with a drug known as amphotericin B and to treat for up to 1 month.  Water soluble amphotericin (Fungilin; Vetafarm, Wagga Wagga, Australia) did not result in cure when provided to infected birds for 1 week.  Whether this product would work in budgerigars with different strains of MO or if used for a longer period of time is not known.  Tests done on organisms growing in culture suggested that low toxic anti-fungal chemicals like sodium benzoate (concentration range 0.5 to 25 mg/ml) may be useful in treating MO in budgerigars.  It should be noted, that the low toxic anti-fungal chemicals have not been used in budgerigars and the safety of these chemicals in these birds is not known.  Treatment of any bird with these chemicals is not recommended until additional research has been done.

Acknowledgement

This article by Dr. David N. Phalen is supplied by the World Budgerigar Organisation (www.world-budgerigar.org), as part of their encouraged exchange of research information, and supplied to the WBO with kind permission by the Budgerigar Association of America.

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