Effect of estrus synchronization treatment after luteolysis on Holstein heifers as embryo transfer recipients |
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Authors: | Tatsuyuki YOSHIDA Taro SATO Koji CHIBA Itaru YOSHIMURA Masahiro OSADA Konosuke OKADA Hiroki FURUTA Akihiko OHTA Hitoshi USHIJIMA |
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Institution: | 1. Department of Animal Science, Nippon Veterinary and Life Science University, Musashino;2. Taro Farm‐care Clinic, Sanjo;3. Chiba Prefectural Ichihara Dairy Experimental Station, Ichihara;4. Department of Lifescience, Meiji University, Tama, Kawasaki, Japan |
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Abstract: | This study was designed to evaluate the effect of estrus synchronization treatments on recipient heifers for embryo transfer (ET). Holstein heifers were separated into the following three groups: (i) an administration of 50 µg GnRH (gonadotropin‐releasing hormone) analog was given to heifers at a random stage of the estrus cycle, followed 7 days later by two administrations of 7.5 mg prostaglandin F2 alfa analog (PG) as control; (ii) another administration of 100 µg GnRH was given to the control group at 48 h after the administration of PG as the second GnRH group; and (iii) an administration of 0.75 mg estradiol benzoate (E2) was given to the control group at 24 h after the administration of PG as the E2 group. Each method caused estrus synchronization. Fresh embryos were nonsurgically transferred into the suitable recipients that had a functional corpora lutea (CL) 7 days after estrus. The E2 group showed a significantly higher (P < 0.01) rate of estrus synchronization (98.9%) at 1–3 days after PG administration and the final pregnancy rate of the E2 group (50.6%) was also significantly higher than the other groups (37.1%, P < 0.05 and 30.9%, P < 0.01, respectively). These findings demonstrate that E2 administration 24 h after PG protocol is effective for estrus synchronization of Holstein heifers, thus improving the productivity of ET. |
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Keywords: | embryo transfer estradiol estrus synchronization luteal function recipient heifer |
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