We investigated the biochemical profile of greater rheas (Rhea americana) in captivity and correlated these values according to the birds’ sex. A total of 69 serum samples were collected from a breeding site in Mossoró, northeastern Brazil, and analyzed to quantify serum biochemical parameters (total protein, albumin, cholesterol, calcium, phosphorus, uric acid, urea, creatinine, ALP, AST, and CK). The birds had levels of urea, creatinine, total cholesterol, aspartate aminotransferase, calcium, and phosphorus similar to the values reported for ratite and ostrich species. By sex, females showed higher values (p < 0.05) of calcium (3.5 mmol/L), total cholesterol (7.5 mmol/L), and uric acid (435.3 μmol/L) than males, which had 3.1 mmol/L, 3.8 mmol/L, and 390.7 μmol/L, respectively. This can be attributed to the difference in diet, the productive phase of females, or stress at the time of sampling. The data present a wide spectrum of biochemical results regarding the health of greater rheas, contributing to the veterinary clinical practice of this species.
