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Embryonic development in the ostrich (Struthio camelus) during the first 7 days of artificial incubation |
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| Authors: | Z Brand SWP Cloete IA Malecki CR Brown |
| Institution: | 1. Department of Animal Sciences, University of Stellenbosch, Matieland, South Africa;2. Directorate: Animal Sciences, Oudtshoorn Department of Agriculture Western Cape, Oudtshoorn, South Africa;3. Directorate: Animal Sciences, Elsenburg Department of Agriculture Western Cape, Elsenburg, South Africa;4. School of Animal Biology, The University of Western Australia, Crawley, WA, Australia;5. UWA Institute of Agriculture, The University of Western Australia, Crawley, WA, Australia;6. Institute of Science and the Environment, University of Worcester, Worcester, UK |
| Abstract: | 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 168 h 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 mm2, increasing to 143.3 mm2 after 2 d of incubation. By 72 h of incubation the area vasculosa (AV) was discernible in the posterior half of the blastoderm. 5. At 48 h of incubation the blastoderm area in eggs from the South African Black genotype (SAB) × Zimbabwean Blue genotype (ZB) crosses (104.5 ± 18.6 mm2) was lower than the pure SAB (141.0 ± 10.5 mm2), ZB (161.7 ± 13.5 mm2) and ZB × SAB crosses (166.1 ± 14.2 mm2). 6. Embryo length was 5.01 mm after 72 h of incubation and 14.5 mm after 168 h of incubation. At 168 h of incubation AV lengths for both ZB × SAB (53.2 mm) and SAB × ZB crosses (54.1 mm) 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. |
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