Gonadotrophin releasing hormone treatment of Holstein cows with follicular cysts monitored by skim milk progesterone determination.

Progesterone was assayed in skim milk fraction of 38 cystic cows, 26 (68.4%) of which had basal ( < 0.5 ng/ml) progesterone concentrations and were diagnosed as having follicular cysts. These cows were allotted at random to one of 3 treatments: (1) a sham injection of sterile water in 7 cows as controls; (2) a single injection (1 mg) of GnRH analog in 8 cows; (3) double injections (1 mg) of GnRH analog at 7-day interval in 11 cows. According to rectal palpation confirmed by skim milk progesterone determination, the double injection group responded well (P < 0.05) compared with the single injection and control groups (81.8% vs 62.5 vs 42.9%). The interval calving to 1st insemination, interval treatment to conception and interval calving to conception were significantly (P < 0.01) shorter in the double injection group than in the other 2 groups. Also, the conception rate to first insemination was significantly (P < 0.05) higher (63.6% vs 37.5% vs 42.9%). The data provide evidence for reduction in infertility and reproductive disorders in cystic cows given double injections of GnRH.