A study on the function of foam from the proctodeal gland of the male Japanese quail (Coturnix coturnix japonica) with respect to its effects on sperm competition

The effect of foam from the male Japanese quail on sperm competition was investigated by comparing fertility and mating behaviour of foam-producing (sham-operated) and foamless (foam gland cauterized) males in two male / five female mating group situations. In vitro examinations of sperm behaviour in foam were also carried out. Over an eight-week experimental period, foam-producing males sired more than 90% of the progeny produced when in competition with a foamless male. Pens in which two foamless males were competing had significantly lowered fertility and hatchability of eggs, while pens with two foam-producing males had the highest fertility. Foamless males attempted and completed copulations as often or more often than foam-producing males and examinations of females post-copula revealed that sperm transfer was occurring during copulations by both types of males. Results indicate that foam allows a male to copulate less frequently and yet maintain good fertility levels. Foam significantly hindered the penetrating ability of quail sperm in thin albumin-filled capillary tubes (75 mm long x 1.2 inner diameter). On the other hand, foam significantly prolonged quail sperm motility. The behaviour of quail sperm when mixed with foam from the same or from a different male, was indistinguishable when examined on microscope slides at 400x magnification. I found that during copulation by quail, sperm and foam are mixed and deposited into the female's coprodeum, rather than in the oviduct as with most other birds examined. In conclusion, because the temporal pattern of egg laying in the Japanese quail (late in the day) precludes a peak in copulations at the optimum time for fertilization (within an hour post-oviposition), foam may aid a male's reproductive success by suspending and sustaining his sperm in the female's coprodeum, thus avoiding excessive loss of sperm via oviposition. These experiments also suggest a hypothesis about a role for foam in sperm competition: its physical presence fills space which may preclude normal foam and semen deposition by subsequent copulations and thus increase the chances of the foam/sperm mass from subsequent copulations being excreted by the female.Land and Food Systems, Faculty ofGraduat