Mljekarstvo (Feb 2008)
Treatment of cystic ovaries with controlled vaginal drug release in combination with gonadotropins and prostaglandins in dairy cows under Egyptian conditions
Abstract
Traditional methods of oestrus synchronization developed over the past 60 years have involved controlling estrous cycle length by luteolytic drugs. The use of controlled internal drug release (CIDR) devices is now well accepted throughout the world to treat some diseases. This study aimed to: a) investigate the ovarian and endocrine responses associated with the treatment of cystic ovarian follicles with gonadotropin (GnRH) and prostaglandin (PGF2α) +/- Progesterone-CIDR placement; b) determine pregnancy establishment following synchronization and timed artificial insemination in cows suffering from cystic ovarian follicles. The ovarian cysts were typed based on the rectal and ultrasonic examination (B-mode System; Pie-Medical Scanner-240 with 6-8 MHz linear probe) into follicular, luteinized and persistent cysts. Two schedules of treatment were designed, in schedule-A, 15 cows with follicular (n=7), luteinized (n=3) and persistent (n=5) cysts were used. The cows received 2 injections of 100 ug GnRH (9 days interval) with 25 mg PGF2α administered 7 days after 1st GnRH dose. In schedule-B, 14 cows with follicular (n=6), luteinized (n=3) and persistent (n=5) cysts were used. The cows administered GnRH and CIDR concurrently, then 25 mg PGF2α 7 days later. The CIDR was removed 2 days after PGF2α. The cows were inseminated 16 hours after 2nd GnRH dose. Blood samples were collected from the jugular vein during the course of 2 schedules to assay the progesterone and estradiol. In schedule-A, 57.1 %, 33.3 % and 40 % of follicular, luteinized and persistent cysts were ovulated after the 1st GnRH injection, while a total of 100 %, 66.7 % and 100 % were ovulated after the 2nd GnRH dose. The cows with follicular cysts appeared the highest rate of pregnancy (57.1 %) followed by the luteinized and persistent cysts (33.3 % and 40 %). Of a total 15 cystictreated cows, 7 were confirmed pregnant (46.7 %). The concentration of progesterone was significantly higher at 1st GnRH injection, then decreased after PGF2α injection and then increased again at 7 day after insemination. In schedule-B, after 1st GnRH dose, 66.7 % of follicular, 0 % of luteinized cysts and 80 % of persistent were ovulated; with a 57.1 % total ovulation rate. Following CIDR removal, 85.7 % (12/14) cows ovulated the recruited follicles and developed a corpus luteum. Of a total 14 cystic-treated cows, 8 were confirmed pregnant (57.1 %). Plasma estradiol declined following intra vaginal placement of CIDR, but markedly increased one day after removal. Plasma progesterone decreased after CIDR removal, but increased again at the presence of palpable corpus luteum. The developed corpus luteum and pregnancy rate were higher in schedule-B (+CIDR) than in schedule-A (-CIDR). In conclusion, treatment of cows with cystic ovarian follicles with GnRH followed by PGF2α 7 days later resulted in recruitment of new healthy follicles, synchronization of ovulation and a marked pregnancy rate (with than without CIDR intra vaginal placement).
