AVIAN LEUKOCYTE COUNTING USING THE HEMOCYTOMETER

Automated methods for counting leucocytes in avian blood are not avail able because of the presence of nucleated erythrocytes and thrombocyte s. Therefore, total white blood cell counts are performed by hand usin g a hemocytometer. The Natt and Herrick and the Unopette methods are t he most common stain and diluent preparations for this procedure. Repl icate hemocytometer counts using these two methods were performed on b lood from four birds of different species. Cells present in each squar e of the hemocytometer were counted. Counting cells in the corner, sid e, or center hemocytometer squares produced statistically equivalent r esults; counting four squares per chamber provided a result similar to that obtained by counting nine squares; and the Unopette method was m ore precise for hemocytometer counting than was the Natt and Herrick m ethod. The Unopette method is easier to learn and perform but is an in direct process, utilizing the differential count from a stained smear. The Natt and Herrick method is a direct total count, but cell identif ication is more difficult.