بررسی اثرات بالینی نورژستومت کاشتنی و استرادیول والرات بر میزان باروری گاوهای شیری پرتولید کم بارور نژاد هلشتاین

the objective of this study was: the effect of norgestomet implant and estradiol valerate on the conception rate of subfertile high yielding holestein dairy cows. one hundred and six high yielding subfertile dairy cows received norestomet implant contains 3 mg norgestomet subcutaneously in the convex surface of the ear using plunger and simultaneously, 2 ml im injectable solution contains 3mg norgestomet and 5mg estradiol valerate (day 0). the implant was removed 9 days later (day 9). the animals were inseminated artificially at 48, 56 and 72 hours after implant removal. in control group (no: 58), at once they received an incision at the same area with plunger (day 0) and then inseminated artificially at oestrus time. all the cows were examined for pregnancy diagnosis 50-60 days later by rectal palpation. the obtained data analyzed using chi-square statistical method. conception rate in treatment group was significantly more than control group (50.94% vs 20.68%) (p < 0.05). the lactation number, different seasons, the day in milking, and the number of insemination did not affect significantly on conception rate. it is concluded that ovulation synchronization with norestomet implant and estradiol valerate can be useful and valuable approach in improvement of fertility in subfertile high yielding dairy cows