摘要
This experiment was aimed to investigate some changes of ovarian structure in order to confirm the onset of puberty in Thai indigenous gilts. Fifty female animals collected from the North-Eastern area of Thailand were slaughtered in the different age groups as 0, 1, 2, 3, 3.5, 4, 4.5, 5, 5.5 and 6 months of age, respectively （each group = 5 pigs）, for monitoring corpus luteum （CL） occurrence on ovarian surface and some changes of reproductive structure. CL was clearly found for the first time in the 4.5 months age group （P 〈 0.05） which was defined as the first ovulation; nevertheless, group of follicles with 〉 2.0 mm in diameter appeared for the first time in the 3.5 month age group （P 〈 0.05）. For other conformations, size of uterine horns, oviducts or ovaries, including weight of ovaries or whole reproductive tracts, were significantly developed （P 〈 0.05） that was initially taken place in the 3.5 months age group onwards. Thus, it was summarized that the onset of puberty in Thai indigenous gilts, affirmed by CL appearance at the first time, should be happened between 4.0 and 4.5 months of age; however, the development of reproductive structure and follicles to prepare in approaching puberty should be started before 3.5 months of age.
