FEMALE-FEMALE INFLUENCES ON THE DURATION OF THE POSTPARTUM ANESTROUS PERIOD IN BEEF-COWS

Two experiments were conducted to determine whether female to female i nfluences could reduce the duration of the post-partum anoestrous peri od in beef cows. In experiment 1, cows were housed from calving, eithe r in individual stalls, which precluded physical contact with other co ws (treatment I, no. = 19) or as a group, with a cow in oestrus introd uced to the group twice per week (treatment G; no. = 18). The percenta ge of cows cycling by day 50 post partum was similar for both treatmen ts, but at 91 days post partum was significantly higher (P < 0.05) in the G than in the I cows (89% v. 58%). In experiment 2, cows were hous ed in individual stalls from calving and exposed twice per week to eit her cervical mucus collected from cows in oestrus (treatment M; no. = 21) or distilled water (treatment W; no. = 24). The percentage of cows cycling by 70 days post partum was similar in both treatments but by 130 days there were significantly more (P < 0.05) M cows cycling (86% v. 58%). In neither experiment were LH profiles at 22, 43 or 64 days i nfluenced by treatment. The results indicate that cervical mucus of co ws in oestrus contains pheromone(s) which can reduce the post-partum a noestrous period in beef cows with extended anoestrous periods.