Pregnancy rates at Days 2 and 14 and estimated embryonic loss rates prior to day 14 in normal and subfertile mares

B. A. Ball, T. V. Little, R. B. Hillman, G. L. Woods

Research output: Contribution to journalArticlepeer-review

82 Scopus citations


Pregnancy rates at Days 2 and 14 postovulation were determined for 15 normal mares and 15 subfertile mares. Embryonic loss rates were estimated by the difference in the Day 2 and Day 14 pregnancy rates. Mares were artificially inseminated with the pooled ejaculates from three stallions, and the embryonic vesicle was detected with ultrasonography at Days 9, 10, 12 and 14. Mares were short-cycled with prostaglandin F2 alpha (PGF) and rebred to the same stallions, and the Day 2 pregnancy rates were determined by recovery of cleaved ova (embryos) from the surgically excised oviducts. Significantly more (P < 0.01) normal versus subfertile mares were pregnant at Day 14 ( 12 15 vs 3 15). There was no significant difference in the Day 2 pregnancy rate for normal versus subfertile mares ( 10 14 vs 11 14). There were no significant differences (P > 0.5) in the mean number of blastomeres per embryo or in the mean diameter of embryos recovered at Day 2 from normal or subfertile mares. The estimated embryonic loss rate was significantly lower (P < 0.01) for normal verusus subfertile mares ( 0 10 vs 8 11). Fertilization rates were similar for normal and subfertile mares; however, subfertile mares had a higher embryonic loss rate prior to Day 14 postovulation.

Original languageEnglish
Pages (from-to)611-619
Number of pages9
Issue number5
StatePublished - Nov 1986


  • embryonic loss
  • fertilization rate
  • mares
  • oviduct

ASJC Scopus subject areas

  • Small Animals
  • Food Animals
  • Animal Science and Zoology
  • Equine


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