Parthenogenesis in unfertilized eggs of Coturnix chinensis, the Chinese painted quail, and the effect of egg clutch position on embryonic development.

Parthenogenesis, embryonic development of an unfertilized egg, was studied for many years in turkeys. In fact, as many as 49% of unfertilized Beltsville Small White turkey eggs develop embryos. However, no research exists on parthenogenesis in quail. The Chinese painted quail is a close relative of the more common Japanese quail and, unlike turkeys or chickens, the small Chinese painted quail reaches sexual maturity rapidly, making it a great candidate for further research on parthenogenesis. Obviously, a better understanding of avian parthenogenesis should increase our knowledge of avian fertilization and early embryonic development. Therefore, we determined if unfertilized Chinese painted quail hens produce embryos. Second, we explored the possibility that position of the egg within the clutch influences parthenogenesis. When initial secondary sexual plumage was apparent at 4 wk of age, male chicks were separated from females to prevent fertilization. Hens were placed in individual cages near sexual maturity, at approximately 6 wk of age. Individual eggs were collected daily and labeled with hen number and date. Eggs were stored for 0 to 3 d at 20 degrees C before incubation at 37.5 degrees C. After 10 d of incubation, approximately 4,000 eggs from 300 laying hens were examined for embryonic development under a magnifying lamp. On average, 4.8% of the unfertilized eggs contained an abortive form of embryonic development consisting of undifferentiated cells and unorganized membranes. Approximately 27% of the laying hens produced at least 1 egg with parthenogenic development. However, about 10% (30) of these hens exhibited a predisposition for parthenogenesis by producing 2 or more unfertilized eggs with embryonic development. Twenty percent of the eggs from 2 hens produced embryonic development. Additionally, the first egg laid in a clutch was most likely to produce embryonic development, with a steady decline in the percentage of eggs with embryonic development as position in the clutch increased. In conclusion, the Chinese painted quail does exhibit parthenogenesis and clutch position influences the rate of naturally occurring parthenogenesis.