Evidence of sperm storage in the female ostrich

To determine the length of time following mating that fertile eggs can be laid by an ostrich (Struthio camelus).

A clinical reproductive problem in a pair of breeding ostriches provided the opportunity to mate the birds at intervals of 5 to 8 days and assess the fertility of the eggs laid.

Following prolapse of the phallus of the male ostrich during the breeding season, the pair were immediately separated. The hen was reintroduced to the cock at intervals of 5 to 8 days over a 6 week period for supervised mating. Records were kept of dates of mating and laying, number of eggs laid, egg weights, and fertility determined by candling after 2 weeks incubation.

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 infertile eggs weighed 1160 and 925 g. Six fertile eggs were laid 2 to 7 days after mating. The remaining two fertile eggs were laid the same days that mating occurred, suggesting that fertilization resulted from the last matings 5 and 8 days previously, or from earlier matings.

Sperm storage occurs in ostrich hens and fertile eggs can be laid for at least 5 to 8 days after copulation. Further studies are required to demonstrate the maximum period during which stored sperm are capable of successful fertilization.