The effect of mare's age on multiple ovulation rate, embryo recovery, post-transfer pregnancy rate, and interovulatory interval in a commercial embryo transfer program in Argentina

The period of the follicular phase during which the uterus of mares shows estrus-like echotexture influences the subsequent pregnancy rate

“…Furthermore, the second hypothesis was also accepted: this correlation was significant in both PGF-induced and spontaneous estrous periods. Similarly, the ITO length was also positively correlated with PR, which is in agreement with previous reports [9,10,14]. As seems logical, the ITO had a fairly good correlation with the duration of the follicular phase with estrus-like echotexture.…”

“…The interval from PGF treatment to ovulation (ITO) is also greatly variable, ranging from 2 to 16 days [8][9][10], regardless of the day of the estrous cycle on which treatment is administered [7]. Several reports have analyzed the effect of PGF treatment to induce estrus on pregnancy rates (PRs), and although the overall PR of mares after PGF-induced cycles was not different to that of spontaneous cycles [9][10][11][12][13], when the PR of PGF-induced cycles were analyzed according to the ITO, it was observed that the PR increased as the ITO became longer [9,10,14]. It is likely that the ITO correlates well with the period in which the mare shows estrus-like echotexture.…”

Factors Affecting Recipients' Pregnancy, Pregnancy Loss, and Foaling Rates in a Commercial Equine Embryo Transfer Program

“…Recipient's pregnancy and pregnancy loss rates observed in this study were similar to what commonly reported in literature for surgical or non-surgical equine ET programs: 60-89% at 14 days and 58-70% at 50 days of pregnancy [2][3][4]6,21,33,38,40].…”

Mare and stallion effects on blastocyst production in a commercial equine ovum pick-up–intracytoplasmic sperm injection program

“…natural mating and AI) have been examined in numerous surveys. Among these, it is accepted that the status (maiden, foaling or barren; Squires et al 2006;Allen et al 2007) and age (Vanderwall and Woods 1990;Carnevale and Ginther 1995;Allen et al 2007;Marinone et al 2015) of the mare are major contributors to reproductive success and efficiency. Conversely, the intrinsic fertility of individual mares has not been considered to have a major effect on reproductive efficiency in intensively managed thoroughbred stud farms, not least because mares can only produce a single foal per year whereas over 90% of mares become pregnant by the end of the breeding season (Bosh et al 2009).…”