This experiment was carried out with 22 anestrus Gir cows (Bos indicus), with the postpartum follicular growth studied in 15 of these suckling and kept on pasture, while the seven others were used only for hormonal treatments. Daily real time ultrasonography was done from 4th to the 50th day, using B-mode ultrasound scanner equipped with a linear array 5.0MHz probe. No animal showed estrus, ovulation or follicular luteinization during de experimental period. Four to eight follicular waves emerged each six or seven days and maximum diameter of dominant and subordinate follicles were 8.9±0.6mm and 6.3±0.7mm, respectively. On day 56 of postpartum all cows were separated in two groups: 11 cows were treated either with 4.2 mug of buserelin acetate and 11 with 3,000UI of hCG. Ovulation, follicular regression and luteinization were observed in the two treatments animals, and one new follicular wave emerged within two to three days after the hormonal treatments. Small size corpus luteum and progesterone concentrations under 1ng/mL showed lower luteal activity.
bovine; follicular dynamic; postpartum period; ultrasonography; zebu
