Ovarian follicular dynamics during the estrous cycle in locally adapted Curraleiro Pé-Duro cows

This study aimed to characterize the ovarian follicular dynamics in locally adapted Curraleiro Pé-Duro cows and heifers. Cyclic heifers (n =12) and non-lactating, multiparous cows (n = 11) were examined daily by ultrasonography for two consecutive ovulations (an estrous cycle). Follicles > 3 mm and corpus luteum (CL) were measured and followed until they disappeared. Follicular and luteal characteristics were not different between heifers and cows. Consequently, data on cows and heifers were combined according to the number of follicular waves. Follicular dynamics was characterized by the predominance of two (36.8%) and three (63.2%) follicular waves. No difference in estrous cycle length between these follicular wave patterns was observed. The number of recruited follicles was smaller in the second follicular wave. The ovulatory follicle (OF) growth rate (mm/d) and maximum diameter were greater (P < 0.05) in females, showing three waves. The ovulatory wave was shorter (P < 0.05) than the preceding waves regardless of the wave pattern. No difference was found in CL development between females with two and three follicular wave patterns. Some follicular dynamics characteristics were similar to Bos taurus and others similar to Bos indicus, confirming the crosses made throughout the years. The data from this study will be useful to better estrous cycle manipulation aiming for good results in artificial insemination (AI), fixed-time AI (FTAI), and multiple ovulation and embryo transfer (MOET) programs.