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Carney NJ, Squires EL, Cook VM, et al. Comparison of pregnancy rates from transfer of fresh versus cooled, transported equine embryos. Theriogenology. 1991;36(1):23-32doi: 10.1016/0093-691x(91)90430-l.
Carney, N. J., Squires, E. L., Cook, V. M., Seidel, G. E., & Jasko, D. J. (1991). Comparison of pregnancy rates from transfer of fresh versus cooled, transported equine embryos. Theriogenology, 36(1), 23-32. https://doi.org/10.1016/0093-691x(91)90430-l
Carney, N J, et al. "Comparison of pregnancy rates from transfer of fresh versus cooled, transported equine embryos." Theriogenology vol. 36,1 (1991): 23-32. doi: https://doi.org/10.1016/0093-691x(91)90430-l
Carney NJ, Squires EL, Cook VM, Seidel GE, Jasko DJ. Comparison of pregnancy rates from transfer of fresh versus cooled, transported equine embryos. Theriogenology. 1991 Jul;36(1):23-32. doi: 10.1016/0093-691x(91)90430-l. PMID: 16726974.
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Theriogenology. 1991 Jul;36(1):23-32. doi: 10.1016/0093-691x(91)90430-l.

Comparison of pregnancy rates from transfer of fresh versus cooled, transported equine embryos.

Theriogenology

N J Carney, E L Squires, V M Cook, G E Seidel, D J Jasko

Affiliations

  1. Animal Reproduction and Biotechnology Laboratory, Colorado State University, Fort Collins, CO 80523, USA.

PMID: 16726974 DOI: 10.1016/0093-691x(91)90430-l

Abstract

Donor mares of mixed, light-horse breeds, maintained at Colorado State University, provided 104 embryos for immediate transfer (fresh embryos). One hundred and thirty-six additional embryos were collected on various breeding farms in the United States and were shipped to Colorado State University via commercial airlines (cooled embryos). Embryos were harvested 7 d after ovulation, graded, and either transferred into a mare immediately (<1 h) or placed in Ham's F-10 medium plus 10% fetal calf serum in an atmosphere of 5% CO2, 5% O2, 90% N2 and packaged in a passive cooling unit (Equitainer) for shipment to our laboratory. All embryos were measured and graded just prior to surgical transfer via flank incision into synchronized mares. Recipients had ovulated 1 or 2 d before (+1, +2), on the same day as (0), or 1, 2 or 3 d after (-1, -2, -3) the donor mare. Pregnancy of recipients was determined by ultrasonography on 12, 35, and 50 d after ovulation of the donor. Pregnancy rates at 12, 35, and 50 d were similar for fresh (74, 64, 61%) and cooled embryos (80, 67, 66%), respectively. Overall, embryo size affected (P<0.05) pregnancy rates at 12, 35 and 50 d. Embryos of Grade 1 (excellent) or 2 resulted in more pregnancies than those of Grade 3 or 4 (poor) embryos. Embryonic losses between 12 and 35 d or between 35 and 50 d were not altered (P>0.05) by treatment (fresh or cooled) nor by age of the donor mare (P>0.05), but embryonic losses between 12 and 35 d were greater (P<0.06) for embryos stored for >12 h (25%) versus those stored for <12 h (10%). The duration needed for shipment (<12 h or >12 h) of cooled embryos did not alter pregnancy rates at 12 d (P>0.05). Age of donor mare had no effect (P>0.05) upon pregnancy rates of cooled or fresh embryos transferred nor on embryo quality. In summary, equine embryos can be cooled to 5 degrees C and maintained in storage for up to 24 h without decreased fertility, compared with those of embryos transferred in <1 hour.

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