Dinâmica folicular por ultra-sonografía em novilhas pré-púberes da raça Gir

Abstract

The objective of this research was contribute to knowledge of reproduction physiology in the Gir breed, by ultrasound study of follicular dynamic in prepubertal heifers. Follicular growth was monitored in 13 heifers during 42 consecutively days. A process of successive anovulatory follicular waves was identiffied, with each wave showing a dominant follicle and a variable number of other smaller in size (subordinates). The waves were variables in length, for purposes of analysis, they were classified in three categories as follows: waves of class 1 length (CO1: ≤12 days), class 2 (CO2: 13-16 days) and class 3 (CO3: ≥17 days). Forty-nine waves were thus analyzed: 6 CO1 (12.2%), 31 CO2 (63.3%) and 12 CO3 (24.5%). Differences among length of waves were observed, even between those from the same female. In the CO1 class the mean maximum diameter of the dominant follicle was (P<0.05) shorter (9.4±0.3 mm) than CO2 (10.4±0.2 mm) and CO3 (11.6±0.4 mm). The plateau and rates of growing and atresia of follicles were not different (P>0.05) between CO classes. Similar characteristics on subordinate follicles were not different (P>0.05) among CO classes.