Apparent selenium toxicity in emus (Dromaius novaehollandiae).

A commercial emu breeder experienced high embryonic mortality during the 1992-93 breeding season, apparently associated with high levels of selenium. The feed was a mixture of catfish food supplemented with a vitamin E and selenium premix. The mixture contained an average of 1.4 ppm selenium. Selenium analysis was conducted on eggs from several hens laid during the period of vitamin and selenium supplementation and after the supplementation was withdrawn. Initial egg selenium levels ranged from 1.2 to 7.1 ppm, with a mean value of 4.2 +/- 0.7 ppm (n = 9). Eggs collected over a 2-month period post-withdrawal contained 2.1 +/- 0.2 ppm selenium (n = 6). Eggs sampled between 2 and 3 months post-withdrawal contained 1.1 +/- 0.1 ppm selenium (n = 4). Egg selenium levels decreased significantly over the 3-month period (P < 0.05) for each individual sample.