Most estrous cycles in cows consist of 2 or 3 waves of follicular activity. Waves of ovarian follicular development comprise the growth of dominant follicles some of which become ovulatory and the others are anovulatory. Ovarian follicular activity in cows during estrous cycle was studied with a special reference to follicular waves and the circulating concentrations of estradiol and progesterone. Transrectal ultrasound examination was carried out during 14 interovulatory intervals in 7 cows. Ovarian follicular activity was recorded together with assessment of serum estradiol and progesterone concentrations. Three-wave versus two-wave interovulatory intervals was observed in 71.4% of cows. The 3-wave interovulatory intervals differed from 2-wave intervals in: 1) earlier emergence of the dominant follicles, 2) longer in length, and 3) shorter interval from emergence to ovulation. There was a progressive increase in follicular size and estradiol production during growth phase of each wave. A drop in estradiol concentration was observed during the static phase of dominant anovulatory follicles. The size of the ovulatory follicle was always greater and produced higher estradiol compared with the anovulatory follicle. In conclusion, there was a predominance of 3-wave follicular activity that was associated with an increase in length of interovulatory intervals. A dominant anovulatory follicle during its static phase may initiate the emergence of a subsequent wave. Follicular size and estradiol concentration may have an important role in controlling follicular development and in determining whether an estrous cycle will have 2 or 3-waves.

GnRH Cystic Ovaries CowsCystic ovarian disease (COD) has been recognized as one of most important problem in dairy farm, it is a managerial and financial problem.120 Holstein cows with average age between 3 to 5 years were used in this study to determine whether giving GnRH at 14 th day and 21 st day after parturition (using two different types of GnRH) has a role in decreasing incidence of cystic ovaries during days open, and is there is any effects of this program on fertility parameters (the interval from calving to conception, number of service per conception, first service conception rate). Also we refered to the season of milking to see how it affects on the incidence of COD. The findings of this study indicate that using two dose of GnRH (Receptal or Cystorlin) at 14 and 21 days after parturition did not give significant difference comparing with the costs of the programs in preventing COD except a moderate result by using Cystrolin especially with cow more than one season which decreased the incidence by 11%. COD may reach to 42% in herd especially the high yielding Holstein cow. No significant effect on fertility parameters positively or negatively by using GnRH in postpartum period.

The current study was carried out on 26 normal cycling buffaloes. Animals were divided into 4 groups according to the hormonal treatment regime. Group 1 included 11 buffaloes without hormonal treatment. Group 2: five buffaloes injected with one dose of 25 mg prostaglandin F2alpha (PGF2α) after ultrasound diagnosis of a mature corpus luteaum in one ovary. Group 3: five buffaloes injected blindly with two doses of 25 mg PGF2α 11-days interval. Group 4: five buffaloes treated with ovsynch protocol. The pattern of follicular growth (FG) and the corpus luteum (CL) regression were monitored by transrectal ultrasound scanning. Estradiol 17β and progesterone profiles were estimated by radioimmunoassay for all groups. Buffaloes in Group 1 showed two (72.7%) or three (27.3%) waves-like patterns of follicular development. The average length of the estrous cycle was 21.75±0.53 and 27.0±0.58 days in 2- and 3- wave cycle respectively. The duration of the CL was 16.63±0.53 and 22.3±0.88 days in 2- and 3- wave cycles. One buffalo in Group 2 did not respond to injection of a single dose of PGF2α, while the other 4 responded. On the day of injection the diameter of the CL was 1.90±0.11 cm and that of dominant follicle was 0.97±0.07 cm. On day 2 after injection the follicle diameter was 1.4±0.09 cm and the preovulatory follicle on days 3-4 was 1.5±0.03 cm. The regressing CL diameter was 1.3±0.07 cm and progesterone level decreased from 6.27±0.82 ng/mL on day 0, to 0.13±0.06 ng/mL on days 3-4 post injection. Estradiol levels were increased from 5.40±1.2 pg/mL on day 0, to 15.09±1.97 pg/mL on day 3-4 post injection. After injection of the first dose of PGF2α, in group 3 the maximum follicle diameter was 1.10±0.04 cm on day 6, then started to regress (0.60±0.04 cm) on days 13-17 after injection. In the 2nd wave, the ovulatory follicle showed marked increase from day 2 (0.34±0.01 cm) till days 13-17 (1.33±0.08 cm). The diameter of CL increased from 1.53±0.03 cm on day 0 of treatment to 1.71±0.04 cm on day 7 of treatment. The second dose of PGF2α resulted in rapid decrease in the diameter of dominant follicle of the first wave from 0.88±0.05 cm on day 11 of treatment to 0.60±0.04 cm on days 13-17 (day of estrus) and rapid increase in the diameter of dominant follicle of the second wave from 0.89±0.08 cm on day 11 to 1.33±0.08 cm on days 13-17. Injection of the second dose of PGF2α on day 11 of treatment caused rapid decline in the progesterone level from 5.62±0.45 ng/mL on day 10, to 1.09±0.34 ng/mL on day 12, and 0.17±0.05 ng/mL on days 13-17. Estradiol levels were 0.76±0.42, 3.97±1.05 and 5.59±1.36 pg/mL on days 10, 12 and days 13-17. In group 4, the diameter of the largest follicle of the four ovulated buffaloes after first gonadotropin-releasing hormone administration was 1.24±0.09 cm, while that of the unovulated buffalo was 0.97 cm. The diameter of the largest follicle of the ovulated buffaloes was 1.03±0.07 and 1.32±0.03 cm on days 7 and 9 of the treatment. The diameter of the CL was 1.6±0.05 and 1.22±0.07 cm on days 7 and 9 of the treatment. The mean concentration of progesterone level was 1.89±0.56 ng/mL on day 6, 0.27±0.12 ng/mL on day 8 and to 0.04±0.01 ng/mL on day 9 of treatment. The mean concentration of estradiol level was 16.07±9.29, 1.11±0.68 and 2.41±0.93 pg/mL on days 6, 8 and 9 of the treatment.

GnRH is currently the treatment of choice for undifferentiated COD. 16,17 PGF 2 α alone is the treatment of choice for luteal cysts. 18 A new protocol GnRH/PGF 2 α GnRH (ovsynch) has also been used to

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