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Norgestomet implants, plasma progesterone concentrations and embryo transfer pregnancy rates in cattle
  1. A. K. Smith, BVM&S, DBR, MRCVS1,1,
  2. P. J. Broadbent, BSc, PhD, MBiol,CBiol1,
  3. D. F. Dolman1,
  4. S. P. Grimmer1,2,
  5. D. A. R. Davies, BSc, MA2 and
  6. H. Dobson, BSc, PhD, DSc2
  1. 1 Department of Animal and Feed Technology, SAC (Aberdeen), 581 King Street, Aberdeen AB9 IUD
  2. 2 Department of Veterinary Clinical Science and Animal Husbandry, University of Liverpool Veterinary Field Station, Leahurst, Neston, South Wirral L64 7TE

Abstract

A study was undertaken to test the hypothesis that supplementation with exogenous progestagen at the time of embryo transfer would enhance pregnancy rates in recipients. Twohundred- and-seventy-two oestrus-synchronised crossbred heifer and cow recipients received 200 grade 1 and 72 grade 2 Simmental embryos transferred non-surgically. Heparinised blood samples were taken on day 6 and day 7 (oestrus = day 0) for the assessment of the endogenous plasma progesterone concentration. Half the recipients received an ear implant impregnated with 3 mg norgestomet on the day of embryo transfer. The pregnancy rates were 51.9 and 49.6 per cent for the norgestomet-treated and control groups, respectively. The pregnancy rate for grade 1 embryos was 56.0 per cent and for grade 2 embryos 36.1 per cent (P<0.01). The breed of recipient, weekday of transfer, operator and condition score had no effect on pregnancy rate. The maiden heifers had a higher pregnancy rate (54.2 per cent) than the cows (46.2 per cent). The mean plasma progesterone concentrations of the pregnant and non-pregnant groups on day 6 were 6.7 ng/ml and 6.6 ng/ml, respectively, and 7.6 ng/ml in both groups on day 7.

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      Footnotes

      • Mr Smith's present address is Ovaflo Embryo Transfer, Rowanlea, Garlogie, Skene, Aberdeenshire AB32 6RX

      • Miss Grimmer's present address is Ovaflo Embryo Transfer, Rowanlea, Garlogie, Skene, Aberdeenshire AB32 6RX

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