Pós-graduação em Ciência Animal - FMVA ; The pet market is developing rapidly and many homes have as a pet the Cockatiel (Nymphicus hollandicus), which are often created and nurtured erroneously, bringing risks to animal health. Most psitacídeos, including the Cockatiels, are preferred by eating mostly sunflower seeds, so the owners ended just providing only sunflower seeds. This lead to the development of malnutrition and changes in bone pattern. In this experiment we analyzed three groups of Cockatiels, each consisting of fifteen birds. Each group received a different kind of food. One was fed with feed (GR), another fed with oats, millet and sunflower (GMIX) and last fed with sunflower (GG). This study aimed to determine the effect of different diets on density of ulna bone of Cockatiels, using as a means to evaluate the Radiographic Densitometry. Statistical analysis demonstrated an increase in consumption of all groups, and the body weight did not change in GG. Bone growth in length was verified in all groups, and no significant difference between them. The thickness was greater in GR and there was no change in the other groups. The serum calcium and alkaline phosphatase did not differ in all groups, and GMIX concentration showed lower serum phosphorus. There was no statistically significant difference in bone density between the groups at the beginning of the experiment. The results obtained in this experiment with the proposed methodology demonstrated that GR had denser bones than the other groups. ; O mercado pet está se desenvolvendo rapidamente e muitos lares possuem como animal de estimação as Calopsitas (Nymphicus hollandicus), que muitas vezes são criadas e alimentadas de forma errônea, trazendo riscos à saúde dos animais. A maioria dos psitacídeos, dentre eles as Calopsitas, têm preferência pela ingestão de sementes principalmente as de girassol, sendo assim, os proprietários passam a fornecer apenas sementes de girassol. Isso pode levar a um quadro de desnutrição e alterações no padrão ósseo. ...