Synchronization of ovulation in beef herds: improved conception rate after and interrupted course of progesterone administration

S Afr J Anim Sci. 1974;4(1):61-5.


PIP: Administration of 50 mg progesterone in 6 im injections every 48 hours was used to synchronize the estrous cycles of 6 herds of cows and/or heifers. Because of a previous finding that cows in the last 3rd of their estrous cycles when progesterone treatment is begun exhibit lower fertility, such cows were excluded by presynchronization of the herd 8 days prior to the start of treatment by 4 48-hourly injections of 50 mg progesterone. 69%-86% of the animals became pregnant in 4 of the 6 herds during the synchronized estrus, which compares favorably with the average 1st insemination conception figure without synchronization (approximately 70%). Previous conception rates observed averaged approximately 47%.

MeSH terms

  • Animals, Laboratory*
  • Biology
  • Endocrine System
  • Hormones
  • Ovulation*
  • Physiology
  • Pregnancy
  • Progesterone*
  • Progestins
  • Reproduction
  • Research


  • Hormones
  • Progestins
  • Progesterone