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Commercial application of the follicular ablation technique in mares
Two experiments were conducted to determine the practicality of utilizing ultrasound-guided follicular ablation in a commercial setting. The objective of the initial experiment was to investigate the efficacy of follicular ablation as a technique for ovulation synchronization when compared to a standard progesterone and estrogen (P&E) protocol. Twenty nonpregnant mares were assigned to an ablation (AB) or P&E group. Briefly, AB mares (n=10) were subjected to ablation for removal of all follicles larger than 10 mm on d0 and administered PGF2α twice on d5. Mares were administered hCG d11 and subjected to ultrasound 2x/d until ovulation was detected. Mares in the P&E group (n=10) were scanned at initiation of the protocol and received P&E IM 1x/d for 10 d. On d10, mares received PGF2α and ultrasound monitoring began on d15. On d18 mares were administered hCG and evaluated 2x/d until ovulation was detected. The interval from initiation of synchronization to ovulation (10.4 vs 19.1 d, P<0.0001) and the interval from hCG administration (1.2 vs. 2.3, P<0.0001) was shortened in the AB group. Ablation may be an acceptable non-steroidal alternative to the conventional P&E protocol.
The objective of the second experiment was to determine if ablation could lengthen the postpartum interval to ovulation to increase the chance of conception post-foaling. Eighteen postpartum mares were assigned to an AB or control (CON) group. On d6 postpartum, AB mares (n=9) were subjected to follicular ablation for removal of all follicles larger than 10 mm. Mares were administered PGF2α twice on D11 and monitored via ultrasound 1x/d until a follicle ≥35 mm was detected at which time they received hCG. Following hCG, mares were monitored 2x/d until ovulation was detected. The CON mares were evaluated using ultrasound beginning d4 postpartum continuing every other d until a follicle ≥30 mm was detected and scanning frequency increased to 1x/d. When a follicle ≥35 mm was identified, mares were administered hCG and monitored 2x/d until ovulation was detected. Ablation lengthened the interval from foaling to ovulation (15.9 vs. 10.0, P=0.003). Increasing the interval from foaling to ovulation is known to increase conception rates; therefore, the application of this procedure could be utilized to optimize the timing of breeding to improve conception outcomes. These experiments demonstrate commercial application of follicular ablation and are evidence for incorporating this procedure in a commercial setting.
Keywords: mares, follicle ablation, postpartum ovulation