Egg yolk formation and deposition are quite vital for oocyte maturation and egg production in hens. There are great differences in egg production and number of preovulatory follicles among individuals in Guangxi Ma chickens at the same or various ages, however, the causes of this phenomenon remain unclear. This study aimed to elucidate the differences in yolk precursors formation among Guangxi Ma hens at the same or various ages with dissimilar egg laying rate via comparing the synthesis and transportation of yolk precursors, serum estradiol (E