Comparison of follicular dynamics and hormone profiles in Boer goats examined during the breeding and non-breeding seasons in the tropics of

Abstract. This study aimed to describe ovarian follicular dynamics in Boer goats (n = 14) during the breeding and non-breeding seasons in the tropics of Queensland. Progesterone profiles and follicular dynamics were compared over a 21-day period in the non-breeding season and one oestrous cycle in the breeding season. Between September and October, 100 % of goats were in anoestrus while between April and May they were all undergoing ovulatory cycles. The number of follicular waves during a 3-week period of monitoring was greater during the non-breeding compared to the breeding season (4.8 0.1 vs 4.1 0.1, respectively; P < 0.05), while the number of codominant follicles (5.6 0.3 vs 6.8 0.3, respectively; P < 0.05), growth rate (0.61 0.05 mm/day vs 0.81 0.05 mm/day, respectively; P < 0.05) and the diameter of the largest follicle measured within follicular waves (6.7 0.1 mm vs 7.8 01 mm, respectively; P < 0.05) were less in the non-breeding compared to the breeding season. During the breeding season the interovulatory interval was 19.7 0.2 days. Total number of small follicles (2 to 3 mm) and the total number of follicles ≥3 mm from Days 2 to 14 of the period of examination were greater (P < 0.05) during the non-breeding compared to the breeding season. In the breeding season, 35.7 % of cycling goats showed large anovulatory follicles, which persisted and became luteinized. Ovulatory follicles wer