Turkish Journal of Veterinary & Animal Sciences




Variations in estrous and ovulation times occur because of follicle diameter during PGF2a injection, in mares. The purpose of this study was to see the effect of follicle diameter on estrous and ovulation. Therefore 43 estrous cycles were evaluated in 32 Thoroughbred mares. Ten mg PGF2a (Dinoprost Tromethamine, Dinolytic) was injected intramuscularly in diestrous period for synchronization. Follicle diameters were measured and divided into groups in centimeters as follows ² 1 cm, 1-2 cm, 2-3 cm, 3-4 cm ve > 4 cm, during PGF2a injection. Result of daily teasing and rectal palpation every other day and daily rectal palpation during estrous period revealed that post injection-estrous, estrous period, post injection-ovulation, and estrous-ovulation times were in group ² 1 cm 5.91±2.71, 7.25±1.43, 11.75±2.23 and 6.16±1.95 days, in group 1-2 cm 4.81±2.84, 6.56±1.94, 10.68±2.95 and 5.87±2.85 days, in group 2-3 cm 3.90±1.44, 5.10±1.57, 8.00±1.78 ad 4.20±1.53 days and in group 3-4 cm 3.00±1.41, 4.60±1.35, 6.20±2.31 and 3.60±1.01 days, respectively. There was no follicle > 4 cm during PGF2a injection. As a result, reduced estrous and ovulation times occured because of enlarged follicle diameters during PGF2a injection. Therefore it was concluded that evaluation of ovaries for follicle structurs before PGF2a injection would be beneficial.


Mare, PGF2a, follicle diameter, estrous and ovulation

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