2. Materials and methods
2.1. Animals
All procedures involving animals were approved by the Animal Care and Use Committee of Anhui Agricultural Uni- versity and the study was conducted at the Luan Wanxi white goose farm. Thirty female Wanxi white geese dur- ing reproductive cycle (ten in laying period, ten in broody stage and ten in laying cessation period after incubation, respectively), aged 2 years old, were used in the study.