Serum Biochemistry of Greater Rhea (Rhea americana) in Captivity in the Northeast of Brazil

SIMPLE SUMMARY: The greater rhea (Rhea americana) is the largest endemic bird species in the central and northeastern regions of Brazil. It has economic importance due to its meat, leather, and feathers being appreciated, but its hunting is only allowed in registered commercial breeding grounds because of its threat of extinction. In Brazil, these animals are found mainly in captivity, thus facing different management and nutrition than free-living animals, a fact that can affect health problems identified only through laboratory tests. This study carried out an analysis of the serum biochemistry of greater rhea raised in captivity in the northeast of the country and identified that the values of calcium, cholesterol, and uric acid were higher in females than in males, allowing the result to be attributed to diet or stress at the time of collection. Our study is the first report on the biochemical profile of greater rheas in captivity in Brazil, and the data showed broad-spectrum results which contribute to the diagnosis of diseases through the analysis and interpretation of the biochemical profile of these animals in the practice of the veterinary clinic. ABSTRACT: 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.