Hematological and serum biochemical profile of farm emus (Dromaius novaehollandiae) at the onset of their breeding season.

Blood profiling is a helpful tool in detecting the health status, metabolic diseases, nutritional deficiencies, and welfare of animals. Body weights, body temperatures, hematological and serum biochemical parameters, enzymes, and electrolytes in both sexes of farm emus at the beginning of their breeding season (November in Canada), were determined. The reference interval for each analyte was also calculated. Emus have lower body temperatures (37.2 ± 0.2) than other poultry species. There was no significant between-sex difference in BW, body temperature, and all the hematological and enzyme parameters measured. However, females had significantly (P < 0.001) higher serum calcium, phosphorus, albumin, total protein, globulin, and triglyceride levels than males, probably in preparation for egg laying. We also examined our findings in light of their sex-role reversal in incubation and brooding. Contrary to other avian species in which only females incubate and brood, there was no sex difference in the hematological and enzyme parameters measured in emus. We found that emus are similar to other ratite species with respect to the changes in protein, globulin, triglyceride, and calcium levels. The findings from our study contribute to the database for reference emu hematological and serum enzyme, metabolite, and electrolyte values.

Plasma thyroid hormones and growth hormone in embryonic and growing emus (Dromaius novaehollandiae).

Growth hormone (GH), thyroxine (T4) and tri-iodothyronine (T3) are known to be involved in the regulation of growth and development in a variety of avian species. It has been suggested that an absence of GH and thyroid hormones in ostriches is the cause of their neoteny, a phenomenon in which juvenile characteristics are retained into adulthood. Neoteny is typical of all ratites, the single group of flightless birds that includes the ostrich, but similar endocrine studies have not been performed for other members of the group, such as the emu. To test the neoteny hypothesis further, in the present study we measured the plasma concentrations of T4, T3 and GH in emus during embryonic development and from hatching to 1 year of age. Concentrations of T4 and GH increased during the last weeks of incubation, whereas concentrations of T3 were highly variable. After hatching, the concentrations of both thyroid hormones were high during the first 3 days of life and then fell to a constant low level. Plasma concentrations of GH were high at the time of hatching and decreased gradually over the first 22 weeks of age; thereafter, the concentrations of GH were highly variable. No correlation was observed between hormone concentrations and live weight at any time. These results support the hypothesis that thyroid function is abnormally low in ratites, whereas patterns of GH secretion are similar to those observed in other birds. Dysfunction of the thyroid axis could explain, in part, the neotenous physical aspect of adult emus.