Study On Follicular Development And Changes Of Reproductive Hormones In Binhu Buffalo In Hunan

In order to improve the reproductive rate of the Binhu buffalo, follicle development and changes of the reproductive hormones were studied in this present experiment through estrous synchronization technology and B ultrasonography. 1 Dynamic changes of follicle development in Binhu buffalo of Hunan provinceIn the present study, dynamic changes of follicular development of Binhu buffaloes were explored by estrus synchronization and B ultrasonography. The results showed that:（1） About emergence time of the follicular wave, the first and second wave occurred on 1.5d and 8.2d for the two-follicular-wave heifers of buffaloes during a whole estrous cycle, which were occurred on day 1.0 and day 12.3 in the multiparous buffaloes, and there was no significant difference between the heifers and the multiparous buffaloes （P>0.05）. For the three-follicular-wave heifers, the first, second and third wave emerged on day 1.0,7.5 and 15.0, respectively. （2） Duration of the follicular wave for the heifers of the two-wave buffaloes was 7.16 days （for the first wave） and 10.33 days （for the second wave） respectively, and it was 9.33 days （for the first wave） and 11.13 days （for the second wave） of the multiparous buffaloes. However, duration of the three-wave buffaloes was 6.5days, 8.0 days and 9.0days, respectively. Difference between the two-wave buffaloes and the three-wave ones was not obvious （P>0.05）. （3） The number of the recruited follicles was 16.46 for the multiparous buffaloes in a whole estrous cycle, which was larger （P<0.05） than that of the heifers （12.48）. （4） The total number of follicles in the multiparous buffaloes （7.97） was higher （P<0.05） than that in heifers during a whole estrous cycle. （4） The number of the selected follicles was 7.96 （in the multiparous buffaloes） and 7.30 （in the heifers）, but no difference was between them （P<0.05）. （5） The maximum diameter of the dominant follicles was 8.22mm （for the first wave） and 9.81mm（for the second wave） in heifers, which was 7.85mm and 7.54mm in the multiparous buffaloes, respectively. There was no significant difference between that in the heifers and the multiparous buffaloes. In addition, the maximum diameter of the dominant follicles in the first, second and third wave was 7.54mm,10.33mm and 8.32mm for the heifers during a whole estrous cycle. （6） There was no difference between the heifers and the multiparous buffaloes about the number of different sizes of follicles on both sides of the ovaries （.P>0.05）。 2 Studies on changes of reproductive hormones in Binhu buffaloesChanges of the reproductive hormones were studied by RIA technology. The results showed:（1） The concentration of FSH was continuously increased from 2 days before onset of estrus to the day when estrus was initiated, which reached a peak （3.5mIU/mL） on the first day after estrus, then continuously decreased. （2） The concentration of LH was increased before estrus and then gradually increased on the 3rd （22.13IU/mL） after estrus, then decreased （reaching 16.12mIU/mL） on day 6 of estrous cycle, after another increase and decrease the level of LH reached a threshold （15.17mIU/ml） on the 10th day of estrous cycle. Later, there were two releasing surges on day 14 （20.71mIU/mL） and 16 （22.17mIU/mL）, reaching a peak （23.24mIU/mL） on day 18 of the estrous cycle. The LH concentrations of proestrus, oestrus, metaestrus were 20.65mIU/mL,20.02mIU/mL,23.24mIU/mL, there was no significant difference among the three groups （P>0.05）, but the concentration of the three were all significantly higher than those of the diestrus period （17.24mIU/mL） （P<0.05）. （3） The concentration of E2 was the lowest （20.43mIU/mL） 2 days before onset of estrus, following a continuous increase and reaching a releasing surge （72.88pg/ml） on day 6 of estrous cycle, after that it decreased slowly and reached a minimum （39.90pg/mL） on day 15 of estrous cycle. Then E2 release increased quickly and reached a peak （118.32pg/mL） on day 19 of estrous cycle, but the concentration of LH dropped rapidly to below 40pg/mL, which was 67.83pg/mLduring the proestrus period, significantly higher than that of oestrus （51.01pg/mL）, metaestrus （56.33pg/mL） and diestrus （53.74pg/ml） （P<0.05）, but here was no significant difference among the different stages of estrous cycle （P>0.05）. （4） The concentration of P₄ dropped rapidly, reaching a threshold （0.37pg/mL） on the day when estrus initiated. Afterwards, it was increased and followed by emergence of three releasing surges （6.79pg/mL on day 7,8.96pg/mL on day 10 and 7.77pg/mL on day 14）, and then the concentration of P₄ was decreased rapidly till estrus point. Difference between the oestrus （1.87pg/mL） and mataestrus （2.62pg/mL） was not remarkable （P>0.05）, but.significantly lower than that of proestrus （4.13pg/mL） and diestus （5.71pg/mL） （P<0.05）. Besides, the P₄ concentration of diestrus was significantly higher than that of proestrus （P<0.05）.