A linear-array ultrasound scanner with a 5-MHz transducer was evaluated for the study of
follicular and luteal status in heifers. The ovaries of five heifers were monitored daily until all
heifers were examined for a period from three days before an ovulation to three days after
the next ovulation. There was a significant difference among days for diameter of the largest
follicle and second largest follicle and for the number of follicles 4–6 mm and> 10 mm.
Differences seemed to be caused by the presence of several 4-to 6-mm follicles in early …