Genetic selection increases parthenogenesis in Chinese painted quail (Coturnix chinensis)

Parthenogenesis, embryonic development of an unfertilized egg, occurs naturally in turkey, chicken, and quail species. In fact, parthenogenesis in turkeys and chickens can be increased by genetic selection. However, it is unknown if genetic selection for parthenogenesis is effective in quail or if selection for parthenogenesis affects egg production. Therefore, the objectives of this study were to determine if the incidence of parthenogenesis in quail could be increased by genetic selection and if selection for this trait affects egg production. To prevent fertilization, 1,090 females were caged separately from males at 4 wk of age and then caged individually at 6 wk of age to monitor egg production. Eggs were collected daily, labeled, and stored for 0 to 3 d. After 10 d of incubation, 20 unfertilized eggs from each hen were examined for the occurrence of parthenogenesis and embryonic growth. In the parent (P) generation and subsequent generations (1 to 4), hens laying eggs containing parthenogenetic development and males whose sisters or mothers exhibited parthenogenesis were used for breeding. There was a linear increase in the percentage of hens exhibiting parthenogenesis as generation of selection increased. With each successive generation, there was a quadratic response in the percentage of eggs positive for parthenogenesis. When compared with the P generation, parthenogenesis was almost 3 times greater for eggs laid by the fourth generation (4.6 to 12.5%, respectively). Even when only hens exhibiting parthenogenesis were examined, the percentage of eggs demonstrating embryonic development responded quadratically with generation of selection. The embryonic size at 10 d of incubation was greater for each subsequent generation when compared with the P generation. There was a linear decrease in both egg production and the average position of an egg in a clutch as generation of selection increased. In conclusion, genetic selection for parthenogenesis increased the incidence of parthenogenesis and embryonic size but decreased egg production and average position of an egg in a clutch as generations of selection increased.