Proceedings of the 5th International Symposium on EQUINE ...

Havemeyer Foundation Monograph Series No. 3TABLE 1: Embryo recovery rates and recipients pregnancy rates at Day 14 and 30 in TY and in MAHaflinger maresEmbryo recovery rate Recipient pregnancy rate Recipient pregnancy rate(Day 14) (Day 30)Two years 74/85(87%) 8/16(50%) 8/16 (50%)mature 22/26(84.6%) 6/11(54.5%) 5/11(45.4%)TABLE 2: Embryo recovery rates in <strong>the</strong> different years <strong>of</strong> <strong>the</strong> study in <strong>the</strong> TY donors1991 1992 1993 1994 1995 1996 1997 Total10/13 4/6 17/18 6/6 17/20 12/12 8/10 74/85(77%) (67%) (94%) (100%) (85%) (100%) (80%) (87%)TABLE 3: Outcome <strong>of</strong> consecutive embryo recovery attempts in <strong>the</strong> same mares in <strong>the</strong> TY donors1st cycle 2nd cycle 3rd cycle 4th cycle <strong>5th</strong> cycle 6th cycle Total44/51 20/24 6/6 2/2 1/1 1/1 74/85(86%) (83%) (100%) - - - (87%)MA mares (Table 1). Recipients ovulated betweenone day before and 4 days after <strong>the</strong> donors.Embryo quality was excellent or good in 71/74(95.9%) and in 22/22 embryos derived from <strong>the</strong>TY and <strong>the</strong> MA mares, respectively.Embryo recovery rates in <strong>the</strong> TY donors weresimilar both in <strong>the</strong> different years <strong>of</strong> <strong>the</strong> study(Table 2) and in consecutive oestrous cycles <strong>of</strong> <strong>the</strong>same year (Table 3).TY donors and control mares, when bred,produced live foals in 42/49 (85.7%) and in 38/43(88.4%) <strong>of</strong> <strong>the</strong> occasions, respectively.DISCUSSION AND CONCLUSIONSIn this study <strong>the</strong> use TY Haflinger mares asembryo donors resulted in a high embryo recoveryrate throughout <strong>the</strong> years and in a pregnancy rateafter non surgical transfer in <strong>the</strong> normal range(Squires et al. 1999). Both embryo recovery ratesand recipient pregnancy rates were similar in TYand in MA mares.These results are in agreement with whatfound by Savage et al. (1989) and Fleury et al.(1985), which reported an embryo recovery rate <strong>of</strong>80.6% in 2 years old Arabian fillies and <strong>of</strong> 85% inunder 3 years old Mangalarga mares, respectively.On <strong>the</strong> contrary, Iuliano and Squires (1985)obtained an embryo recovery rate <strong>of</strong> only 36.3% in2-year-old Arabian fillies and Steiner and Jordan(1988) reported a lower embryo recovery rate inthree 2-year-old than in 3 mature Hanoverianmares. Breed and seasonal effects could haveaccounted for <strong>the</strong>se differing results.Although in our study most fillies wereemployed as embryo donors only once or twice,some mares provided embryos in 3 and 6consecutive oestrus cycles suggesting that shorttime fertility <strong>of</strong> <strong>the</strong>se young donors was notaffected by embryo recovery procedures aspreviously reported for mature mares (McKinnonand Squires 1988). The foaling rates for marespreviously used as embryo donors and for controlswas similar, confirming that early use as donorsdid not affect fertility in <strong>the</strong> following years(Savage et al. 1989).In conclusion, this study indicate that 2-yearoldmares can be successfully used as embryodonors, as a method to anticipate foals productionfrom valuable mares, with no negative effects on<strong>the</strong>ir future reproductive efficiency.ACKNOWLEDGEMENTSWe thank <strong>the</strong> Stud <strong>of</strong> Corpo Forestale dello Stato<strong>of</strong> Pieve S. Stefano (AR) which provided <strong>the</strong>horses, and <strong>the</strong> former undergraduate students <strong>of</strong>Faculty <strong>of</strong> Veterinary Medicine <strong>of</strong> University <strong>of</strong>87