Effects of gonadotropin-releasing hormone administration or a controlled internal drug-releasing insert after timed artificial insemination on pregnancy rates of dairy cows.
10.4142/jvs.2016.17.4.577
- Author:
Jae Kwan JEONG
1
;
In Soo CHOI
;
Hyun Gu KANG
;
Tai Young HUR
;
Ill Hwa KIM
Author Information
1. Veterinary Medical Center and College of Veterinary Medicine, Chungbuk National University, Cheongju 28644, Korea. illhwa@cbu.ac.kr
- Publication Type:Original Article
- Keywords:
dairy cow;
post-insemination;
pregnancy rate;
progesterone concentration
- MeSH:
Female;
Gonadotropin-Releasing Hormone*;
Insemination, Artificial*;
Pregnancy Outcome;
Pregnancy Rate*;
Pregnancy*
- From:Journal of Veterinary Science
2016;17(4):577-582
- CountryRepublic of Korea
- Language:English
-
Abstract:
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 F(2α) 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.
