Normal Fertilization and Factors Influencing the Process of Parthenogenesis in Chinese Painted Quail

In the modern poultry industry, intense genetic selection for meat production has negatively influenced the reproductive performance of commercial birds. Parthenogenesis, embryonic development in unfertilized eggs without any sperm-egg interactions, is known to hinder the normal fertilization process and could be one of the reasons for this reduced reproductive performance in the poultry industry. Therefore, the overall objective of this research was to gain a better understanding of the process of parthenogenesis using Chinese painted quail as the model. Studies on Chinese painted quail reproduction revealed that they are very inefficient in sustained sperm storage and that number of sperm penetrating the egg and subsequent embryonic development potentially alter egg transit time through the oviduct. This poor sperm storage capacity and high sperm-egg interaction requirement might be responsible for the occurrence of parthenogenesis in this species; and in fact, this makes Chinese painted quail an excellent choice for parthenogenesis research. Further, dams selected for parthenogenesis as well as embryonic development, including parthenogen size, alter egg components by possibly delaying the transit time of the egg through the oviduct. Also, both dams and sires selected for the parthenogenesis trait appear to influence their progenies performance, including 1st wk mortality and occurrence of parthenogenesis. Additionally, vaccination of virgin hens with live pigeon pox virus increases parthenogenesis as well as parthenogen size and livability by the direct action of the virus on the embryo. Moreover, live Newcastle disease virus under in vitro conditions was found to have similar effects on the embryo. Because parthenogenesis exists in the modern poultry industry, even the accidental selection of the trait in either males or females could have a negative impact on overall chick production and performance. Also, as vaccination is a routine practice in the industry, it is possible that vaccination of birds that carry the trait will reduce fertility and hatchability due to enhanced parthenogenesis. Overall, currently it appears that, parthenogenesis is adversely affecting the poultry industry; and therefore, additional research on the accurate determination of losses in the poultry industry due to parthenogenesis could further benefit the industry