Production and incubation in farmed emu (Dromaius novaehollandiae) : a thesis presented in partial fulfilment of the requirements for the degree of Masters [i.e. Master] of Sciences in Ecology at Massey University, Palmerston North, New Zealand
The breeding, egg laying, incubation, chick survival and growth of emu (Dromaius novaehollandiae) were studied in a farmed population. Eggs were laid every 3-5 days between May to October with a peak in July. Birds laid in vegetation, or where absent, near fence lines or by artificial shelters. Clutch size was highly variable (range: 2 - 45) between individuals, and between seasons, and variability increased with the age of the hen. The fate of 578 artificially incubated eggs were recorded. Fertility levels were high (90%) but hatching success was lower. Embryonic mortality was greatest during the first trimester with a second smaller peak at the end of incubation. 434 chicks hatched, representing 68% of all eggs set and 83% of fertile eggs. Weight loss for the entire incubation period was 12.5% and was not correlated with embryo mortality. X-ray and ultrasound equipment were unsuccessful in determining egg fertility. Natural incubation was studied in two emu nests. Egg temperatures averaging 34.1°C and 31.7°C were lower and more variable than those used in artificial incubators. Eggs hatched after 51-54 days. In one nest, deserted eggs cooled to 12.2°C hatched when incubated artificially. Rates of egg turning varied, and two thirds of all egg turns were 90° or less, and only 12% were turned between 158.5° - 202.5°. Water loss during incubation was 10% of the initial egg weight and was greatest at the end of incubation. Males lost up to 30% of body weight during incubation. Survival, sex ratios and growth rates were determined for emu chicks hatching from 637 artificially incubated New Zealand eggs, and 105 eggs imported from Canada for incubation under class 1 quarantine conditions. Survival rates to three months were high (88%). Mortality due to hatch-related problems was restricted to the first week of rearing, and to weeks 8 - 12 when bone deformities became evident. Sex ratios were 50:50. The chicks lost weight after hatching but thereafter grew exponentially. There was no significant difference between male and female hatch weights, or rates of growth, but females grew faster and were heavier up to 18 months. Most birds that grew significantly slower from three weeks of age died within three months. The genetic identity and development of twin emu was described. DNA analysis indicated the twins were identical.