The Research On The Relationship Between Urinary Gonadal Hormones And Reproductive Behaviors Of Francois Langurs In Captivity

The Francois langur (Trachypithecus francoisi) is listed in the First Category of State Key Protected Wildlife List. In recent years, its population has decreased rapidly because of the habitat degration and illegal catch. Therefore, it is urgent to carry on the protection research on the Francoisi langur. As a manner to protect this species, manual breeding and migration protection are increasingly recognized. And migration protection provides advantages for reproduction research of Francoisi langur. But it is short in reproduction research, especially reproductive physiology research of Francoisi langur. So, basing on the reproduction research of non-human primates at home and abroad, we carry on this research to get more understanding on reproductive physiology of Francoisi langur and then lay the theoretical foundation for manual breeding and expanding species quantity of Francoisi langur. From October 2003 to November 2004, we researched the relationship between the sexual behavior and the urinary gonadal hormone of the adult Francois langur in captivity. We hope that our research could provide science theory for the migration protection, manual breeding and reproductive biology for the Francois langur. The change of reproductive behaviors is the exhibition of the change of reproductive function regulated by gonadal hormones. So measuring the gonadal hormones is a practical method to assess the reprodutive physiological status. In recent years, according to the correlation betwwen the levels of gonadal hormones in urine and in plasma, measuring the levels of gonadal hormones in urine has been applied in many species of non-human primates. Our research applies this method on reproduction study of the Francois langur firstly. We collected the urinary samples of one adult male, three pregnant females and one oestrus female. Then, we measured the levels of testosterone for male, estradiol and progesterone for females by radioimmunoassay. At the same time we recorded the data of reproductive behaviors to find out the possible relationship between the change of the gonadal hormone levels and the reproductive behaviors. Our research showed: 1. In pregnancy, estradiol level ascended gradually. After conceiving 14 days, estradiol concentration was markedly higher than before. But progesterone level had not ascended and kept in a low level until into the middle stage of pregnancy. According to this phenomenan, we could apply estradiol to monitor gestation. 2. In the middle stage of pregnancy, the females behaved sexual solicitations frequently still. Even one female langur's estradiol and progesterone levels showed respectively positive and negative correlations with its sexual solicitations. But gonadal hormones of the other two females didn't showed correlations with their sexual solicitations. So, it was not the gonadal hormones that led to frequently sexual solicitations during pregnancy of females. Females solicit frequently during gestation in order to maintain mating relationship with male and then get protection from male. 3. After parturition, gonadal hormones descended rapidly and maintain very low level until another oestrum. 4. In oestrum,the level of estradiol reached a crest in females before the ovulation. At the same time, the females behaved frequently solicitations that was positively correlated with the change of estradiol level. 5. The level of gonadal hormone has not correlations with the social rank of the females. But the females in higher social rank reproduct earlier. It is to say that there is not evident correlations between reproductive competence and social rank and it is the separation of mating time that reduce the intension of reproductive competence. 6. The estradiol can promote the maternity in females. 7. The abnormal descending of the estradiol level before the parturition for females may indicate the low survivorship of their offspring. 8. Changes of urinary testosterone level in male showed a pulsed trait erratically. 9. After the birth of offspring, the level of testosterone in their fathers'descended evidently. This may be a protection to their babies for males. 10. In captivity, the level of testosterone in male has not correlation with their sexual behaviors but has correlation with their aggression. The social tension can promote the excretion of testosterone. But in our research, the social tension was in so low level that we couldn't find the correlation between testosterone level and aggressive behaviors in male. This research opens out basically the change rules on urinary gonadal hormones and their relationship with reproductive behaviors of Francoisi langur in captivity. But there is only one female's data in oestrum, it needs furthur research on changes of urinary gonadal hormones for Francoisi langur in oestrum. After parturition, the concentration of urinary hormones of females descended to a so low level that couldn't be determined by radioimmunoassay. So it need further improvement for the measurement of urinary gonadal hormones of female Francoisi langur in lactation.