A study of 234 Holstein cows was conducted to determine if hormonal
treatments of gonadotropin-releasing hormone (GnRH or Cystorelin®) and(or)
prostaglandin F2a (PGF or Lutalyse®) given early after calving would improve
subsequent fertility of dairy cows. Treatment of cows having abnormal conditions
associated with calving (puerperal problems) reduced interval from calving to
conception by 43 to 48 days when GnRH was given once between days 10 and 14
postpartum or when PGF was administered once between 20 and 24 days after
calving compared with cows given only saline (controls). The reduction in days
open was 27 to 29 days overall for all cows (normal and abnormal) treated with
either hormone compared with controls. Cows (normal and abnormal) given either
hormone required 26 to 41 % fewer inseminations per conception than controls.
Reasons for improved fertility are discussed. We conclude that early postpartum
treatments with GnRH or PGF improved fertility of dairy cows, especially those
that experienced puerperal problems.
