The objective of the present study was to compare the effect of different dosages of equine chorionic gonadotrophin (eCG) on the follicular dynamics and hormonal concentrations in Alpine goats. During the breeding season, the goats were submitted to estrous and ovulation synchronization with a device containing progesterone for 14 days. Female goats (n=24) were divided at random into four groups of 6 animals each. On the day of dispositive removal, the animals received 0 (Control), 200, 300 and 400 UI of eCG. Follicular development was observed by ultrasonography one day prior to administration of eCG until next ovulation. The plasma estradiol (E2) and progesterone (P4) concentrations were daily determined using RIA. All treated animals showed estrous. Estrous cycle with three and four waves of follicular growth were observed. Size of the largest follicle was smaller in control group animals of the third wave (5.5 ± 0.50 mm) when compared to those treated with 300 UI of eCG (7.17 ± 0.35 mm). Gonadotrophin increased the number of small and medium follicles considering the control group because the average number of corpora lutea were higher in 400 UI (4.27 ± 0.23) females than those treated with 200 UI (1.95 ± 0.19). Plasma concentrations of progesterone and stradiol showed differences among experimental groups. Combinations among progesterones and eCG is an adequate alternative for estrus synchronization and support the development of new protocols for reproduction techniques as superovulation and embryo transfer in goats.
follicular dynamics; goats; estrous synchronization; ultrassonography
