Systematic factors that affect ostrich egg incubation traits
Data obtained from a pair-mated ostrich flock maintained at Oudtshoorn, South Africa, were used to estimate environmental and genetic parameters for egg weight (EWT), water loss of incubated eggs up to 21 days (WL21), water loss up to 35 days (WL35), pipping time (PT) and weight of day-old chicks (CWT). Between 13806 and 19913 artificially incubated ostrich eggs during the 2003 to 2006 production years were used. Systematic factors affecting these traits such as production year, breeding season, female age, incubator type, storage time and ostrich breed, were initially assessed in single-trait-analyses, using ASREML. Eggs and chicks produced by Zimbabwean Blue (ZB) females were 5 and 7% heavier, respectively, than those produced by South African Black (SAB) females. WL21 and WL35 were not significantly different between ZB and SAB birds. There were trends for within-season effects on EWT and CWT, but no general, robust trend applicable to all years could be discerned. Season had a significant effect on WL21, WL35 and PT. An increase was apparent in EWT, CWT and PT with an increase in female age. There was a linear increase in pipping time as egg storage time prior to incubation increased. Incubator type had an effect on WL21 and WL35. Systematic factors affected traits such as WL21, WL35 and PT and should be accounted for before the estimation of genetic parameters. These factors should be considered when planning commercial ostrich husbandry and artificial incubation operations.
Keywords: Embryo development, eggshell, albumen, egg water loss, hatchability
South African Journal of Animal Science Vol. 38 (4) 2008: pp. 315-325