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KMID : 0893420160170040577
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Journal of Veterinary Science
2016 Volume.17 No. 4 p.577 ~ p.582
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Effects of gonadotropin-releasing hormone administration or a controlled internal drug-releasing insert after timed artificial insemination on pregnancy rates of dairy cows
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Jeong Jae-Kwan
Choi In-Soo
Kang Hyun-Gu
Hur Tai-Young
Kim Ill-Hwa
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Abstract
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This study investigated the effects of gonadotrophin-releasing hormone (GnRH) administration (Experiment 1) and a controlled internal drug-releasing (CIDR) insert (Experiment 2) after timed artificial insemination (TAI) on the pregnancy rates of dairy cows. In Experiment 1, 569 dairy cows that underwent TAI (day 0) following short-term synchronization with prostaglandin F2α were randomly allocated into two groups: no further treatment (control, n = 307) or injection of 100 μg of gonadorelin on day 5 (GnRH, n = 262). In Experiment 2, 279 dairy cows that underwent TAI (day 0) following Ovsynch were randomly allocated into two groups: no further treatment (control, n = 140) or CIDR insert treatment from days 3.5 to 18 (CIDR, n = 139). The probability of pregnancy following TAI did not differ between the GnRH (34.4%) and control (31.6%, p > 0.05) groups. However, the probability of pregnancy following TAI was higher (odds ratio: 1.74, p < 0.05) in the CIDR group (51.1%) than in the control group (39.3%). Overall, CIDR insert treatment at days 3.5 to 18 increased pregnancy rates relative to non-treated controls, whereas a single GnRH administration on day 5 did not affect the pregnancy outcomes of dairy cows.
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KEYWORD
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dairy cow, post-insemination, pregnancy rate, progesterone concentration
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