Embryonic development in the ostrich (Struthio camelus) during the first 7 days of artificial incubation

1. Early development of ostrich embryos was investigated in relation to time of egg collection and genotype.2. A total of 321 ostrich eggs were collected during the 2008 and 2009 breeding seasons and the development of the embryo for up to the first 168h of incubation was described and analysed. A sample of the incubated eggs was weighed and opened daily to investigate developmental changes.3. In fresh eggs, the blastoderm contained a round, translucent dark area pellucida (AP) in the centre, with a surrounding thin white ring, likely to be the beginning of the area opaca (AO). Fresh eggs were considered infertile if the blastoderm was absent and instead numerous white droplets were present surrounded by vacuoles.4. The average blastoderm area of a fresh fertile egg was 15.8 mm(2), increasing to 143.3 mm(2) after 2 d of incubation. By 72h of incubation the area vasculosa (AV) was discernible in the posterior half of the blastoderm.5. At 48h of incubation the blastoderm area in eggs from the South African Black genotype (SAB)xZimbabwean Blue genotype (ZB) crosses (104.518.6 mm(2)) was lower than the pure SAB (141.010.5 mm(2)), ZB (161.7 +/- 13.5 mm(2)) and ZBxSAB crosses (166.1 +/- 14.2 mm(2)).6. Embryo length was 5.01 mm after 72h of incubation and 14.5mm after 168h of incubation. At 168h of incubation AV lengths for both ZBxSAB (53.2mm) and SABxZB crosses (54.1mm) were longer than in embryos from the pure breeds.7. Results from this study can be put to practical use when determining whether eggs are infertile or fertile and also in investigating the age of early embryonic mortalities.