Effects of Early Versus Mid-diestrus PGF2α Administration in the Mare

In the present study, we hypothesized that serial administration of multiple doses of prostaglandin F2α (PGF2α) to mares during early diestrus (beginning at day 0) will interrupt luteal function and induce a return to estrus similarly to mares treated with a single injection in mid-diestrus (day 10), and fertility of the induced estrus between the two groups will not differ. The specific objectives of the current study were to compare early and mid-diestrus PGF2α treatment as assessed by: 1) determination of the duration of inter-ovulatory and treatment-to-ovulation intervals; 2) comparison of the number of pregnant mares at 14 days post-ovulation. Ten reproductively normal, cycling mares (median age 9 years, range 7-18) were examined daily by serial transrectal ultrasonography. [...]