The Study On Postpartum Oestrus Inducement And Variations Of 5 Kinds Of Reproductive Endocrine In Small Tail Han Sheep

Postpartum oestrus inducement in milking ewes can shorten the time between yeaning and next pregnancy effectively and use ewes'fertility farthest to enhance economic returns of cultivation. FSH, LH, PRL, P4, E2 concentrations in the serum of small tail han sheep which were within 60 days after parturition in spring and autumn were measured by radioimmunoassay, so that reproductive hormone variation regularity of milking small tail han sheep can be mastered. Then milking small tail han sheep were induced oestrus with with bromocryptine, progestogen and gonadotropic hormone. And FSH, LH, PRL, P4, E2 concentrations in the serum of this period were measured to test the efficacy of this induced oestrus technology and to master reproductive hormone variation regularity of ewes during this period. It can offer theoretical and theoretical foundations of developing oestrus inducement in milking ewes further. The results showed:1. FSH, LF, P4, E2 concentrations in the serum of small tail han sheep which were in the initial stage after parturition in spring and autumn were all in a low level.2. FSH concentrations in the serum of small tail han sheep in the spring and autumn began to increase in the 10th day after parturition, and their average values in the 40th day after parturition were (9.31±3.90) mIU/mL and (10.25±3.96) mIU/mL respectively.3. LH concentrations in the serum of small tail han sheep in the spring and autumn began to increase in the 10th day. In spring the peak was (13.09±5.38) mIU/mL in the 40th day after parturition, and maintained higher than average concentration level until the end of the test. In autumn, LH concentrations in the serum increased slowly and the peak was (14.04±8.51) mIU/mL in the 60th day after parturition.4. The ranges of PRL concentrations in the serum of small tail han sheep in the spring and autumn were (50.14±19.97)～(17.35±5.24) ng/mL and (50.82±13.41)～(20.87±7.38) ng/mL respectively. PRL concentrations in the serum which were highest in the 0th day after parturition declined slowly during the test.5. E2 concentrations in the serum of small tail han sheep in the spring and autumn which the lowest were (26.15±7.74) pg/mL and (20.18±22.94) pg/mL respectively in the 0th day after parturition increased fluctuantly and irregularly, and the peak existed in the 45th day averagely. Then E2 concentrations in the serum maintained in a high level.6. P4 concentrations in the serum of small tail han sheep which maintained in a low level within 10 days after parturition in spring and autumn began to increase in the 15th and 20th day respectively. The peaks that existed in the 45th and 55th day respectively were (0.55±0.31) ng/mL and (0.70±0.43) ng/mL. P4 concentration variations in the serum of milking ewes after parturition showed individual diversities obviously after comparing P4 concentrations in the serum of each milking ewe. All of milking ewes'Ovaries showed activities within 60 days, which the earliest activities existed in the 10th day after parturition and the latest ones existed in the 40th day after parturition.7. In induced oestrus test, the estrus rate of milking ewes in the treatments of vagina administration with bromocryptine, progestogen and gonadotropic hormone(groupⅠ, groupⅡ), treatments of peroral administration with bromocryptine and vagina administration with progestogen and gonadotropic hormone(groupⅢ) were 100%, 71.4%, 57.1% respectively. In groupⅠ, groupⅡ, groupⅢ, the concentration of serum FSH increased slowly and it was higher than that of the control group(groupⅣ, vagina administration with progestogen; group V,without treatments) (p<0.05) in oestrus. In groupⅠ, groupⅡ, groupⅢ, the concentration of serum PRL declined significantly (p<0.05). The concentration of serum E2 didn't change significantly in all groups before oestrus, it increased quickly in groupⅠand groupⅡin oestrus and existed significant change with other three groups. In groupⅠ, groupⅡ, groupⅢand groupⅣ, the concentration of serum P4 declined suddenly to the basal level in oestrus(p<0.05). The concentration of serum LH changed irregularly during the test. The conclusion is that induced oestrus with bromocryptine, progestogen and gonadotropic hormone is effective in milking ewes and the way of vagina administration with bromocryptine is better.