رصد ديناميكية الجريبات المبيضية و توصيفها خلال دورة الشبق باستخدام راسم الصدى في بكاكير الأبقار الشامية

Abstract EN

Twelve growing Shami heifers available in Dier-Al-Hajar Station for improving Shami Cattle during 2005-2007 weighing 250±11 kg and 400±21 days old were used to monitore the growth of dynamic of ovarian follicles (daily numbers, size, length and number of waves, rate of growth and regression) and characteristics of estrus cycle (length, time of dominancy, diameter of Graffian follicle and estrus and ovulatory times), length of corpus luteum (CL) during the estrous cycle.

Heifers were maintained under uniform conditions and fed according to their daily growth.

Transrectal Ultrasound Echo System (7.5 MHz probe) was used to study the ovarian structures and to monitor the daily development and regression of ovarian follicles, the formation and regression of corpus luteum in the left and right ovaries during the estrus cycle.

Results indicated that the growth turnover of ovarian follicles was observed and developed in a wave pattern in all Shami heifers and no significant differences in the number and sizes of ovarian follicles were found between right and left ovaries.

A cohort of 5 to 7 small follicles with a diameter 2-5 mm developed together and one of them was selected to continue growing and becomes dominant and later on being regressed or ovulated during the estrus cycle.

One to five follicular waves were observed per cycle and each wave was characterized by the development of one large (dominant) follicle and a variable number of smaller follicles.

The estrus cycle with one follicular wave occurred only in heifers exhibited the first post pubertal cycles with an average length equaled to 8.67±0.33 days.

Frequency of estrus cycle according to the number of follicular waves was 8.4, 25.3, 44.2, 20 and 2.1% in cycles having 1, 2, 3, 4 and 5 follicular waves, respectively.

Furthermore , the length of estrus cycle was also related to the number of follicular waves and it was 21.87±0.62, 22.44±0.74, 26.4±0.72, 26.50±3.50 days in cycles having 2, 3, 4 and 5 follicular waves, respectively with significant differences (P < 0.05) in cycles with 2 or 3 vs.

4 and/or 5 waves.

The functional duration of CL was extended to 9, 12 and 15 days in a short (17-19 days), intermediate (20-24 days) and long estrus cycle (≥ 25 days).

The maximum diameter of dominant follicles in ovulatory waves was significantly larger (P < 0.05) than that of dominant follicles in nonovulatory waves.

In conclusion, this study showed that the development of ovarian follicles in Shami heifers occurs in waves and the most common pattern is three waves per estrous cycle.