The Growth Curve Fitting Of Reproductive Organs In The Chinese Native Pig Breeds

The growth curve of the reproductive organs in the Chinese native pig breeds were analyzed by Logistic, Gompertz and Richards functions.1. The ovary growth process of12Chinese native pig breeds were fitted by using the three nonlinear models of Logistic, Gompertz and Richards functions. The results showed that except Erhualian and Jiangquhai pigs, the goodness of fit reached more than0.92. The optimal models were Gompertz and Richards for Xiang pig as suggested by the highest R2and AR2values (0.9999). Overall, the Logistic and Gompertz models fit the porcine ovary growth curve better. And the Richards function was suitable for Daweizi pig and Xiang pig, indicating that it fitted well both early and late growth process with higher accuracy due to its flexibility. However, the model did not converge and the parameter estimates had little biological significance for poor qualities of the original data of Jiangquhai pig. The earliest inflection point occurred in Erhualian pig but with lower adult ovary weight, indicating the earlier development of sexual maturity. The largest inflection point was found in Jinhua pig, with higher ovary weight and rapid growth rate, showing its relatively late sexual maturity.2. Weight growth of testes, epididymis, seminal vesicle and bulbourethral gland were fitted with the three functions. The determination coefficient of epididymis weight in Daweizi pig was lower, but the fitting effects were good in other breeds. Fitting effects of epididymis weight in Hetao big ear pig, weights of seminal vesicle and urethral ball glands in Erhualian pig, and weight of seminal vesicle in Jiangquhai pig were the best, with determination coefficient of0.999. Under suitable models, age of days at inflection point of growth curves for testicular weight was the shortest indicating its early growth and sexual maturation. Tibet pigs required the longest time to reach the inflection point, showing its slow growth in early testicular development and fast growth in late periods. The earliest inflection point and small adult weight for epididymis in Daweizi pig were observed showing its early growth and maturation. But Hetao big ear pig’s late inflection point and big adult weight for epididymis suggested its slow growth and late maturation.