Efficacy of timed embryo transfer with fresh and frozen in vitro produced embryos to increase pregnancy rates in heat-stressed dairy cattle

J Dairy Sci. 1999 Nov;82(11):2369-76. doi: 10.3168/jds.S0022-0302(99)75487-1.

Abstract

Our objective was to determine whether pregnancy rates in heat-stressed dairy cattle could be enhanced by timed embryo transfer of fresh (nonfrozen) or frozen-thawed in vitro-derived embryos compared to timed insemination. Ovulation in Holstein cows was synchronized by a GnRH injection followed 7 d later by PGF2 alpha and a second treatment with GnRH 48 h later. Control cows (n = 129) were inseminated 16 h (d 0) after the second GnRH injection. On d 7, a fresh (n = 133) or frozen-thawed (n = 142) in vitro-derived embryo was transferred to cows assigned for timed embryo transfer after categorizing the corpus luteum by palpation per rectum as 3 (excellent), 2 (good or fair), 1 (poor), and 0 (nonpalpable). Response to the synchronization treatment, determined by plasma progesterone concentration (ng/ml) < or = 1.5 on d 0 and > or = 2.0 on d 7, was 76.2%. Mean plasma progesterone concentration on d 7 increased as the quality of corpus luteum improved from category 0 to 3. Concentrations of progesterone in plasma were elevated (> or = 2.0 ng/ml) at 21 d in 64.7 (fresh embryo), 40.3 (frozen embryo), and 41.4 +/- 0.1% (timed insemination) of cows, respectively. Cows that received a fresh embryo had a greater pregnancy rate at 45 to 52 d than did cows that received a frozen-thawed embryo or timed insemination (14.3 > 4.8, 4.9 +/- 2.3%). Body condition (d 0) of cows influenced the pregnancy rate and plasma progesterone concentrations. In summary, timed embryo transfer with fresh in vitro-produced embryos in heat-stressed dairy cattle improved pregnancy rate relative to timed insemination.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Body Composition
  • Cattle / physiology*
  • Corpus Luteum / physiology
  • Cryopreservation*
  • Embryo Transfer*
  • Female
  • Hot Temperature*
  • Insemination, Artificial / veterinary
  • Pregnancy
  • Progesterone / blood
  • Stress, Physiological*
  • Time Factors

Substances

  • Progesterone