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

Equine Embryo TransferTABLE 1: Mean diameters and morphological scores (± sd) by timeEndpoint Treatment Initial Thaw Post thaw Post Post IVCassay IVC assayDiameter (Fm) 1 (n=8) 407 a 294 b 247 b 330 a,b 345 a(±90) (±123) (±80) (±113) (±109)2 (n=5) 410 a 279 b 275 b * 295 b * 302 b *(±97) (±80) (±35) (±64) (±81)3 (n=8) 369 a 303 a,b 250 b,c 216 c 198 c(±49) (±56) (±56) (±27) (±45)Grade(1-4) 1 (n=8) 1.3 a 3.4 b 3.4 b 3.1 b 2.9 b(±.27) (±.23) (±.34) (±.74) (±.88)2 (n=5) 1.2 a 3.6 b 3.5 b * 3.6 b,A * 3.7 b,A *(±.45) (±.42) (±.35) (±.89) (±.67)3 (n=8) 1.4 a 3.3 b 3.8 c 4 c,A 4 c,A(±.35) (±.26) (±.38) (± 0) (± 0)a,b,c Means without common superscript within rows differ (P0.1)Embryos were pooled across treatments intononviable (Grade 3 to 4, 5 to 25% live cells) andviable (Grade 2.5 or better, 90% live cells) groups.There was no significant difference in post-thawmetabolic parameters between viable (n=5) andnonviable (n=16) embryos (Table 3).DISCUSSIONIn <strong>the</strong> current investigation, treatment one (lowmolar ethylene glycol) was more effective incryopreserving large equine embryos thanTreatments 2 (high molar ethylene glycol) and 3(step-down equilibration). Embryos in treatmentone had significantly better final morphologicalgrades and a higher percentage <strong>of</strong> live cells.Additionally, embryos in Treatment 1 had lesschange in metabolic activity pre-freeze to postthawthan embryos in o<strong>the</strong>r treatments, although<strong>the</strong> difference between treatments was notsignificant (P>0.1). Expanded equine blastocystsexposed to 2 M ethylene glycol for 40 minsurvived cryopreservation.Three embryos from Treatment 2 werefractured upon thaw and degenerated in <strong>the</strong> postthaw metabolic assay. Conceivably, embryos58