Influence of donor parity and age on the success of commercial equine embryo transfer

Abstract

Summary Data were compiled regarding the success of commercial embryo recovery rate, transfer pregnancy rate, and embryonic loss in recipients, with respect to influence of donor parity and age, between 1985 and 1988. There were significant differences between maiden and subfertile mares for embryo recovery rate (40/66 versus 81/282), transfer pregnancy rate (34/49 versus 38/78), and embryonic loss in recipients (4/34 versus 13/38). There were also significant differences between recently foaling and subfertile mares (146/276 versus 81/282) and for younger mares (two to eight and nine to 17‐year‐old) compared with older mares (18 to 28‐year‐old) for embryo recovery rates (80/132, 94/183 and 93/309, respectively). Transfer pregnancy rates differed signifiantly between mares aged two to eight‐years‐old compared with those aged nine to 17 and 18 to 28‐years‐old (59/84, 50/97 and 50/90 respectively). No differences were observed among any of the age groups regarding embryonic loss in recipients. There was an effect of year on embryo transfer pregnancy rate in 1985 compared with subsequent years that could have been attributed to any of a wide variety of external factors.

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

“…In contrast with previous reports, the present results showed no significant differences in PR 15 days after ET between aged and younger mares (Pickett et al, 1987;Vogelsang and Vogelsang, 1989;Squires et al, 1999Squires et al, , 2003Stout, 2006;Losinno et al, 2008;Mortensen et al, 2009;Atwood and Bowen, 2011;Pessoa et al, 2011). This could be explained, at least in part, because of a vast majority of equine embryos recovered in the present study were of good morphological quality (>90% grade 1 or 2).…”

Effects of Repeated Embryo Collection on Embryo Recovery Rate in Fertile Mares

“…Squires et al. 1982; Vogelsang and Vogelsang 1989; Carnevale and Ginther 1995). In contrast to those studies, our animals were research mares chosen because of their good fertility.…”

Equine embryo transfer: review of developing potential

“…In the case of young fertile mares inseminated with fresh semen from fertile stallions, more than 70% of flushes should yield an embryo (Losinno et al 2001). However, embryo recovery rates drop substantially when aged mares (>14 years) or those with a history of subfertility are used as donors (Squires et al 1982;Vogelsang andVogelsang 1989: Meadows et al 2000), or when chilled transported or, in particular, frozen-thawed semen is used (Meadows et al 2000;Stout 2003). In sport-horse practice in Europe and the USA, embryo recovery rates typically range between 30 and 50%, largely because owners often wish to recover embryos from aged donor mares inseminated with chilled or frozen semen (Squires et al 2003).…”