Real-time ultrasound evaluation of follicular development in superovulated cows

THERIOGENOLOGY REAL-TIME ULTRASOUND EVALUATION OF FOLLICULAR DEVELOPMENT IN SUPEROVULATED COWS K.M. Thayer, D.W. Forrest and T.H. Welsh, Jr. Department of Animal Science Texas A&M University College Station, Texas 77843 USA Methods to assess follicular development during superovulation treatment regimens have been limited. This study evaluated the use of real-time ultrasound to monitor follicular development and time of ovulation in superovulated cows. Six mature Jersey cows were injected (i.m.) with FSH-P (Burns-Biotec) twice daily for 4 days (28 mg total) beginning on day 9 of the estrous cycle. Prostaglandin F, ( PGFz Lutalyse@)was injected (35mg) at 0800 hr onaday 3 of thg'treatment. Ovarian examination was performed with a real-time linear-array ultrasound system (Technicare 210DX) equipped with a 5 mHz intrarectal transducer on the mornings of days 1,3 and 4 of the treatment and then every 4 hr for 48 hr beginning at standing estrus or at 2000 hr on day 5. Ovulation was determined by acute disappearance of individual follicles between ultrasound examinations. Ovulation was confirmed by palpation per rectum of all cows between 4 and 10 days after PGF,= and by laparoscopy of 3 cowsto estimate number of corpora lutea (CL) on day 7 after PGF,%. Number of Size (mm) ---.. Interval (hr) from PGFZm to: Ovulation Mean ovulation Ovulations ovulatory Ist Last time follicles estts cow L R 1 y* -%-- 76.7 +3w5 ::*: 5.2 ; Z: 2 7" ;z*; Is-; % > ;: 9:8 *0:5 5" ;: >lOO 81:3 +_1:4 67 43 11.3 50.8 g: 45: 68 11.9 to.6 83.4 t2.8 > 96 5 2 _ _* 68 * indicates ovary with CL prior to PGF,= Large (7-10 mm) antral follicles were present in all cows by day 3. Cow number 6 failed to ovulate even though large follicles were present. The appearance of these follicles differed from that of follicles that subsequently ovulated. Ovulatory follicles were non-echogenic with well-defined borders, whereas the follicles of the anovulatory cow were echogenic (gray appearance). Of the 9 antral follicles (12-20 mm) present at treatment initiation, 2 underwent atresia (~3 mm at treatment end), 2 maintained a consistent diameter but did not ovulate, and 3 increased 8-10 mm and ovulated 72-80 hours after PGF2,. The fate of the other 2 follicles could not be determined. Real-time ultrasound can be used to monitor follicular size and time of ovulation in superovulated cows.

JANUARY

1985VOL.23NO.l

233