The effect of Gn-RH on the pregnancy rate of artificially inseminated cows.

One hundred and nine pure bred Holstein Friesians were injected intramuscularly with 0.125 mg of a synthetic Gn-RH analogue at the time of the first service to study the effect of Gn-RH on the fertility of inseminated cows. Sixty-four cows or 58.7 per cent were diagnosed as pregnant after one insemination compared to 54 animals or 49.5 per cent in the untreated control group. Total pregnancy rate of 81.65 per cent was 8.3 per cent higher than in the controls, while the services per conception rate improved from 1.49 to 1.39. Gn-RH administration at the time of oestrus could improve herd fertility through its including effect on follicular rupture and regulatory influence on ovarian function.