Ovarian Dynamics, Plasma Endocrine Profile and Fertility Response Following Synchronization Protocols in Crossbred Cows with Cystic Ovaries

Background: Cystic ovarian degeneration (COD) with prevalence of 10-13% is a common and economically important condition in dairy cattle affecting fertility. Predisposing factors and aetiology of ovarian cysts are multifaceted. The most widely accepted cause is either absent, insufficient or wrong time occurrence of pre-ovulatory LH-surge. The accuracy of differential diagnosis of cyst per rectum can be increased by simultaneous use of USG and/or plasma progesterone assay and therapeutic success depends on type and duration of cystic condition. The literature on these aspects in crossbred cows is meagre, hence was planned to differentially diagnose the ovarian follicular and luteal cysts based on clinical, sonographic and endocrine findings and to study the estrus response and conception rates following different treatment modalities of COD in crossbred cattle. Methods: This study was conducted on greater than 90 days postpartum HF crossbred cows with cystic ovaries (n=58) confirmed by per rectal palpation and ultrasonography. The animals with follicular cysts were randomly treated with either conventional Ovsynch or Ovsynch + CIDR protocol (n=10 each) and those with luteal cysts with either Double PG injections 11 days apart or modified Ovsynch protocol (n=16 each) with fixed time AI. A group of six cystic cows was kept as untreated control. Blood samples were collected in heparinized vacutainers, together with trans-rectal ultrasonography, on day 0 (just before initiation of treatment), on day of last PGF2á injection, on day of induced estrus/FTAI and on day 12 post-AI for determination of plasma progesterone and estradiol-17â by RIA technique. Results: The mean diameters and wall thickness of ovarian cysts regressed significantly (p less than 0.01) among responded cows of all four protocols. The estrus induction response within 48-96 hrs of last PG injection with Ovsynch, Ovsynch + CIDR, Modified Ovsynch and Double PG protocols was 90.00, 100.00, 87.50 and 81.25 %, respectively. The conception rates at induced estrus with FTAI for these protocols were 50.00, 40.00, 50.00 and 43.75 %, respectively and the corresponding overall conception rates for 3 cycles’ post-treatment were 60.00, 70.00, 68.75 and 56.25 %, respectively, compared to zero result of control group. The mean plasma progesterone concentration varied highly significantly (p less than 0.01) between periods of treatment in all protocols, the values were lower (p less than 0.01) on day 0 and on day of FTAI than on the day of last PG injection and on day 12 post-AI. The values on day 12 post-AI were significantly higher in conceived than non-conceived cows. The trend of estradiol-17â profile on day of last PG injection was reversed than on day 0. The higher levels of estradiol-17â on day of FTAI were associated with regression of cystic structures and development of new dominant follicles with estrogenic activity concomitant to induced estrus and ovulatory LH surge in most of the animals as evident from USG monitoring, behavioural signs and conception rates.