Reaction of cows ovaries to GnRH administration in different estrus cycle stages

Casiana Ciolac Șipețan, Ioan Bencsik, Dorel Dronca, Ioan Peț, Lavinia Ștef, Gabi Dumitrescu, Eliza Simiz, Ion Carabă, Mărioara Nicula, Adela Marcu, Mirela Ahmadi, Tiberiu Iancu, Nicolae Păcală

Abstract


Administration of GnRH in the luteal phase of estrous in dairy cows induces an increase of LH levels, with the modification of the growth waves of the ovarian follicles. GnRH induces ovulation or atresia of the dominant follicle and the recruitment of a new wave of follicular growth. The GnRH administration in the luteal phase of the estrous cycle induces growth waves synchronization of ovarian follicles, so that, a new wave of follicles started to grow at 5-6 days after administration. In our experiments, we administered 2ml Ovarelin (100 mcg GnRH), to three groups of cows (116 cows): in early luteal phase of the estrous cycle (days 4-5), in the middle of luteal phase (days 9-12), and late luteal phase (days 15-16). The rates of cows standing heat were 91.66% when GnRH was administered in early luteal phase, 95.22% when was administrated in the middle of luteal phase, and 73.68% in late luteal phase GnRH administration. After artificial insemination, the conception rates were 48.48% in early luteal phase, 52.5% at middle luteal phase and 46.42% in the late luteal phase of the estrous cycle.

Keywords


cow; estrous cycle; GnRH; luteal phase

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LUCRARI STIINTIFICE ZOOTEHNIE SI BIOTEHNOLOGII (SCIENTIFIC PAPERS ANIMAL SCIENCE AND BIOTECHNOLOGIES)

ISSN print 1841 - 9364
ISSN online 2344 - 4576
ISSN-L  1841 - 9364
(former ISSN 1221-5287, E-ISSN 1841-9364)

PUBLISHER: AGROPRINT Timisoara, Romania
PAPER ACCESS: Full text articles available for free
FREQUENCY: Semiannual
PUBLICATION LANGUAGE: English
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Banat´s University of Agricultural Sciences and Veterinary Medicine "King Michael I of Romania" from Timisoara
Faculty of Animal Science and Biotechnologies
300645, Timişoara, Calea Aradului 119, Romania

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