Effective estrus-ovulation synchronization of recipients for embryo transfer in Holstein heifers
2006
Ushijima, H.(Chiba-ken. Animal Experimental Station, Ichihara (Japan)) | Mori, T. | Ohno, K. | Mihara, N.
This paper presents the effects on estrus-ovulation synchronization of Holstein heifer recipients for embryo transfer (ET) by control of follicular wave dynamics, i.e., by Ovsynch or Heatsynch treatment. At a random stage of the estrus cycle, all heifers were given an intramuscular (i.m.) injection of 50/mug GnRH analog, being followed 7 d later by two i.m. injections of 7.5mg PGF2alpha analog. For the Ovsynch group, another i.m. injection of 50/mug GnRH was given 48h later, whereas for the Heatsynch group an i.m. injection of 0.75 mg estradiol benzoate was given 24h later. Each method causes estrus-ovulation synchronization. Effect of estrus-ovulation synchronization was markedly better (P0.001) for the Heatsynch vs. Ovsynch group, i.e., estrus synchronization rate 24-72 h after PGF2alpha injection of 96% vs. 76%, estrus detection rate of 93% vs. 62%, and rate of acceptable recipients with a palpable functional corpus luteum on rectal examination 7d after estrus of 92% vs. 63%. The pregnancy rates (62 and 51%) of ET were the same between Heatsynch and Ovsynch groups. These results clearly indicate that the Heatsynch protocol is more feasible for estrus-ovulation synchronization of ET recipients in Holstein heifers.
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