Follicular dynamics in Anglo-Nubian goats using transrectal and transvaginal ultrasound

Abstract

The objective of the current trial was to characterize the follicular dynamics, the time of ovulation and to determine the efficiency of transrectal linear versus transvaginal microconvex endocavitary ultrasound transducers, under tropical conditions. The estrous cycles of goats were subjected to daily ultrasound evaluation for 2 cycles, alternating linear and microconvex transducers. The pattern of follicular growth was characterized by 3 or 4 follicular waves. Follicular wave emergence occurred at days 1.0 ± 0.0, 5.17 ± 1.06, 10.63 ± 2.01 and 14.5 ± 0.33 during the first estrous cycle, and at days 1.17 ± 0.24, 5.33 ± 0.47, 11.17 ± 1.34 and 16.5 ± 0.99 during the second estrous cycle. Similarly the interval between the follicular waves was 4.17 ± 1.05, 5.67 ± 1.07, 5.33 ± 0.70 and 5.75 ± 0.72 days for the first estrous cycle and 4.17 ± 0.43, 5.83 ± 1.05, 7.17 ± 0.99, 6.75 ± 0.72 days for the second estrous cycle. No difference between cycles regarding the timing of follicular wave emergence and interval between follicular waves was recorded. The diameter of the ovulatory follicle was 5.4 ± 0.46 mm and 5.3 ± 0.23 mm in goats with 3 and 4 follicular waves, respectively. The microconvex transducer caused less animal discomfort, allowed faster visualization of the ovaries and produced higher quality images, compared to the linear transducer. In conclusion, it can be said that follicular growth in Anglo-Nubian goats under tropical conditions was characterized by a wave-like pattern which did not differ between estrous cycles and could facilitate more efficient control of ovulation.