Evidence of sperm storage in the female ostrich

Objective To determine the length of time following mating that fertile egg s can be laid by an ostrich (Struthio camelus). Design A clinical reproductive problem in a pair of breeding ostriches prov ided the opportunity to mate the birds at intervals of 5 to 8 days and asse ss the fertility of the eggs laid. Procedure Following prolapse of the phallus of the male ostrich during the breeding season, the pair were immediately separated. The hen was reintrodu ced to the cock at intervals of 5 to 8 days over a 6 week period for superv ised mating. Records were kept of dates of mating and laying, number of egg s laid, egg weights, and fertility determined by candling after 2 weeks inc ubation. Results Over the 6 week period, 10 eggs were laid, of which 8 were fertile and 2 infertile. Fertile eggs weighed 1020 to 1285 g (mean 1143). The two i nfertile eggs weighed 1160 and 925 g. Six fertile eggs were laid 2 to 7 day s after mating. The remaining two fertile eggs were laid the same days that mating occurred, suggesting that fertilisation resulted from the last mati ngs 5 and 8 days previously, or from earlier matings. Conclusion Sperm storage occurs in ostrich hens and fertile eggs can be lai d for at least 5 to 8 days after copulation. Further studies are required t o demonstrate the maximum period during which stored sperm are capable of s uccessful fertilisation.