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Repeated oestrus synchronisation of beef cows with progesterone implants and the effects of a gonadotrophin-releasing hormone agonist at implant insertion
  1. C. D. Penny, BVM&S, MRCVS1,
  2. P. R. Scott, DVM&S, FRCVS1,
  3. B. G. Lowman, BSc, PhD2 and
  4. N. A. Scott, NDA2
  1. 1 Department of Veterinary Clinical Studies, Royal (Dick) School of Veterinary Studies, Easter Bush Veterinary Centre, Roslin, Midlothian EH25 9RG
  2. 2 Scottish Agricultural College, Animal Biology Division, Bush Estate, Penicuik, Midlothian EH26 OPH


A group of 97 spring-calving beef cows were initially oestrus synchronised with controlled internal drug release (CIDR) intravaginal progesterone implants inserted for nine days and a prostaglandin injection on day 7. Approximately half the cows were given 10 μg buserelin when the implants were inserted, and they all received a single fixed-time artificial insemination (Al) 56 hours after the withdrawal of the implants. The overall pregnancy rate to the first synchronised Al was 55 per cent, the buserelin-treated cows having a pregnancy rate of 63 per cent compared with 47 per cent in the untreated cows (P>0.05). Sixteen days after the first synchronised Al all the cows were re-implanted with used CIDR implants which were removed five days later, and the cows received a second synchronised Al on days 23 to 24. Cows which received the second Al were implanted with new CIDR devices 16 days later and these were removed after five days and the non-pregnant cows received a third synchronised Al. The pregnancy rates to the second and third synchronised services were 74 per cent and 75 per cent, respectively.

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