The Curves Fitting for Laying Rate and Cumulative Egg Production, and the Correlation Analysis for Laying Performance of Jiuyuan Black Chickens

• Jia LIU, 
• Xiaomeng MIAO, 
• Fugui LI, 
• Qing ZHU, 
• Yan WANG, 
• Huadong YIN, 
• Gang SHU, 
• Lin YE, 
• Xiaoling ZHAO