Table 1.

The number and source location of ewes used in this study.

Breed	Number	Type	District
Small-tailed Han sheep	384	Polytocous and year-round estrus	Shandong Province, China
Hu sheep	83	Polytocous and year-round estrus	Zhejiang Province, China
Cele Black sheep	68	Polytocous and year-round estrus	Cele County, Xinjiang Uygur Autonomous Region, China
Prairie Tibetan sheep	80	Monotocous and seasonal estrus	Danxiong County, Tibet Autonomous Region, China
Sunite sheep	70	Monotocous and seasonal estrus	Inner Mongolia, China
Suffolk sheep	60	Monotocous and seasonal estrus	Beijing, China
Tan sheep	23	Monotocous and seasonal estrus	Ningxia Hui Autonomous Region, China