The onset of puberty in indigenous male Thai pigs

Knowledge of puberty plays an important role in planning livestock breeding. The objective of this study was to evaluate the age of the first sexual behavior and the first fertile sperm production, and the changes of reproductive structures in male Thai indigenous pigs, by using a completely randomized design. Male indigenous piglets were randomly divided into 9 groups; each group of 5 piglets was separately sacrificed at the age of 0 (birth), 1.0, 2.0, 3.0, 3.5, 4.0, 4.5, 5.0, and 5.5 months to collect data from the carcasses. The other 3 male pigs were used to test the reproductive ability by natural insemination. The results showed that the first sexual behavior occurred at 2.6 + 0.6 months of age, and the first appearance of fertile sperm mass in the cauda epididymis was in the 4-month group. The semen quality standard was discovered in the 5-month group, and the success of insemination with a fertile female pig was found to be at 5.1 + 0.2 months. The changes in the overall size of reproductive tract and testes occurred in 3 stages of development: slight changes were observed in the first 2 months of age; rapid changes were found from 2 to 4.5 months of age; and gradual changes were detected after 4.5 months of age. Upon examination of semen quality and impregnation ability, it can be concluded that male Thai indigenous pigs attained puberty at the age of 5 months after having manifested sexual behavior for a relatively long period.