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Predisposition to repeat breeding in UK cattle and success of artificial insemination alone or in combination with embryo transfer
  1. S. Canu, BVetMED, MSc (Anim Repro), MRCVS1,
  2. M. Boland2,
  3. G. M. Lloyd, BVetMed, DBR, MRCVS3,
  4. M. Newman4,
  5. M. F. Christie, BVM&S, DBR, MRCVS4,
  6. P. J. May, BVM&S, DBR, MRCVS5,
  7. R. M. Christley, BVSc, MVCS, PhD, DipECVPH, MRCVS1,
  8. R. F. Smith, BVSc, BSc, PhD, DipECAR, DipECBHM, MRCVS1 and
  9. H. Dobson, BSc, PhD, DSc, HonAssocRCVS1
  1. 1 Department of Veterinary Clinical Science, University of Liverpool, Leahurst, Neston, Wirral CH64 7TE
  2. 2 Willows Veterinary Group, 267 Chester Road, Hartford, Cheshire CW8 1LP
  3. 3 Camlas Veterinary Practice, Waterloo Place, Salop Road, Welshpool, Powys SY21 7HE
  4. 4 Lambert, Leonard and May, Old Woodhouses, Broughall, Whitchurch, Shropshire SY13 4AQ
  5. 5 Drove Veterinary Hospital, 252 Croft Road, Swindon, Wiltshire SN1 4RW
  1. Correspondence to Hilary Dobson, e-mail: hdobson{at}liverpool.ac.uk

Abstract

To investigate whether there was a subpopulation of repeat breeders (cows or heifers that returned to oestrus after three inseminations) that were less fertile after a fourth artificial insemination (AI) with or without additional embryo transfer, and to estimate the efficacy of AI plus embryo transfer to overcome repeat breeding problems, a two-part investigation was carried out. Part 1 involved 85 repeat breeders and 85 controls subjected to AI alone. In part 2, 128 repeat breeders received AI on day 0 plus an embryo transfer seven days later, while controls received embryo transfer alone on day 7. In repeat breeders, the interval between calving and pregnancy was 80 days longer than in the controls (P=0.01), irrespective of previous fertility treatment which had mainly focused on the ovaries. The incidence of dystocia was similar in repeat breeders and in controls, but repeat breeders had a higher previous incidence of moderate uterine infection compared with controls (P=0.04). In repeat breeder cows, pregnancy rates for AI alone were 30 per cent after the fourth AI (controls: 45 to 64 per cent after one to three inseminations) compared with 52.6 per cent after a fourth AI with embryo transfer (controls with embryo transfer alone: 49 per cent). Successful pregnancies after a fourth AI plus embryo transfer produced a 6.25 per cent incidence of twins.

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