| The objective of the present study was to characterize follicular waves to determine whether donkey exhibit major and minor wave patterns of follicle development and if the dynamic change existed in ovarian follicule (including recruitment, selection, dominance, atresia and ovulation) during the interovulatory interval (IOI) so that reliable evidence for artificial insemination and multiple ovulation will be provided. The ovaries of Dezhou donkeys with clinically normal estrous cycles were examined daily using transrectal ultrasonography during the breeding season. Profiles of the diameters of all follicles≥8mm and the numbers of follicles≥10 mm were graphed for one IOI. Major waves were defined as those in which one follicle grew to≥25 mm. Minor waves were defined as those in which follicles developed to a diameter of <25 mm. Blood samples were drawn to measure , serum concentrations of estradiol-17β, LH, FSH and IGF-1 by RIA. The follicles at 10d after ovulation were superovulatd with PMSG +PG+LHRH-A3 and FSH-P+PG+LHRH-A3. The results of the research indicated as follows: (1) 2 follicular waves were discovered in one estrous cycle in Dezhou donkey. Dezhou donkeys exhibited major and minor patterns of follicular wave dynamics during the IOI. Four of them shows the major and major follicular waves, six shows the minor and major follicular waves. (2) Minor follicular wave began at the day after ovulation, and its follicle reached the peak at 7 or 8d(7.67±0.24d) after ovulation(89%),11% at 9d,and the mean diameter of the largest follicle was 26.44±2.37mm(19～48.1mm); Wave 2 began at the 10.2d after ovulation ; And the wave 1 neither behavioural oestrus nor ovulation was observed during this period. (3) The diameter of the Major follicular wave ovulatory dominant follicle(>25 mm) increased linearly at 5.22d(3～7d)before ovulation,and reached the plateau 40.7±2.45mm( 30.5mm～54.4mm)at the day before ovulation,whose duration of dominance was 5.3d(3～7d). (4) The diameter of the biggest CL was 37.61±1.58mm(30.4-47mm)and the life length of CL was 17.30±1.62d(12-19d). (5) E2 concentration was related with the duration of dongkey estrus,and it rise from 3d before ovulation to 2d after ovulation. In Dezhou donkey the E2 surge was emerged at 2d before ovulation , which was 62.84±4.89 pg/ml;(6) FSH regulated the recuitment of small follicles, and its concentration declined significantly during the stage of the largest follicle at Wave 1 (7d after ovulation)and Wave 2(23 or 24d after ovulation)with the negative feedback of E2;(7) The increase in LH concentration was correlated with ovulation, In Dezhou donkey the LH surge was emerged at 1d after ovulation , which was 4.69±0.43 mIU/ml;(8) The change in concentration of IGF-1 was similar to E2. In Dezhou donkey the IGF-1 surge was emerged at 1d before ovulation , that was 47.9±3.91 ng/ml;(9) The follicles in Dezhou donkey can not be superovulatd with PMSG +PG+LHRH-A3 , but the Dezhou donkey can be superovulated with FSH-P + PG + LHRH-A3.
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