Factors affecting pregnancy rate to estrous synchronization and fixed-time artificial insemination in beef cattle1,2
| Autor: | R. M. Thallman, Sherrill E. Echternkamp |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Estrous cycle
endocrine system medicine.medical_specialty business.industry Artificial insemination medicine.medical_treatment media_common.quotation_subject General Medicine Progesterone secretion Beef cattle Pregnancy rate Controlled internal drug release Endocrinology Internal medicine Follicular phase Genetics medicine Animal Science and Zoology business Ovulation hormones hormone substitutes and hormone antagonists Food Science media_common |
| Zdroj: | Journal of Animal Science. 89:3060-3068 |
| ISSN: | 1525-3163 0021-8812 |
| DOI: | 10.2527/jas.2010-3549 |
| Popis: | Application of AI in extensive beef cattle production would be facilitated by protocols that effectively synchronize ovarian follicular development and ovulation to enable fixed-time AI (TAI). The objectives were to determine whether use of a controlled internal drug release (CIDR) device to administer progesterone in a GnRH-based estrous synchronization protocol would optimize blood progesterone concentrations, improve synchronization of follicular development and estrus, and increase pregnancy rates to TAI in beef cows. Beef cows (n = 1,240) in 6 locations within the US Meat Animal Research Center received 1 of 2 treatments: 1) an injection of GnRH [100 µg intramuscularly (i.m.)] followed by PGF(2α) (PGF; 25 mg i.m.) 7 d later (CO-Synch), or 2) CO-Synch plus a CIDR during the 7 d between GnRH and PGF injections (CO-Synch + CIDR). Cows received TAI and GnRH (100 µg i.m.) at 60 h after PGF. Progesterone was measured by RIA in blood samples collected 2 wk before and at initiation of treatment (d 0) and at PGF injection (d 7). Estrous behavior was monitored by Estrotect Heat Detectors. Pregnancy was diagnosed by ultrasonography 72 to 77 d after TAI. Plasma progesterone concentrations did not differ (P > 0.10) between synchronization protocols at first GnRH injection (d 0), but progesterone was greater (P 0.10) between protocols (52.1 ± 2.1 vs. 50.0 ± 2.4%, respectively) when progesterone was >1 ng/mL (treatment × progesterone; P < 0.01). Inclusion of a CIDR in the synchronization protocol increased plasma progesterone concentration, proportion of cows detected in estrus, and pregnancy rate; however, the increase in pregnancy rate from inclusion of the CIDR was primarily in cows with decreasing or low endogenous progesterone secretion during treatment. |
| Databáze: | OpenAIRE |
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