Comparison of Gonadotropin-Releasing Hormone versus Estrogen-Based Fixed-Time Artificial Insemination Protocols in Grazing IBos taurus/I Suckled Beef Cows

The use of estrogens in food animals is banned in several countries, but fixed-timed artificial insemination protocols (without the necessity of estrus detection) for beef cattle in South America are primarily based on estrogen. This study determined the optimal non-estrogen-based protocol in grazin...

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Bibliographic Details
Published in:Animals (Basel) 2023-09, Vol.13 (17)
Main Authors: Ferré, Luis B, Jaeschke, Julian, Gatti, Juliana, Baladón, Gerardo, Bellocq, Ezequiel, Fernández, Gustavo, Rearte, Ramiro, Kjelland, Michael E, Colazo, Marcos G, Thomas, Jordan M
Format: Article
Language:English
Subjects:
Beef
Beef industry
Chorionic gonadotropin
Comparative analysis
Estradiol
Ethylenediaminetetraacetic acid
Hormones
International economic relations
Phenols
Progesterone
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Summary:The use of estrogens in food animals is banned in several countries, but fixed-timed artificial insemination protocols (without the necessity of estrus detection) for beef cattle in South America are primarily based on estrogen. This study determined the optimal non-estrogen-based protocol in grazing Bos taurus suckling beef cows maintained under typical pasture conditions in Argentina. A total of 697 cows were enrolled in two experiments and the gonadotrophin-releasing hormone-based fixed-timed artificial insemination protocols resulted in similar or greater fertility compared to estrogen-based protocols in Bos taurus suckled beef cows. The greatest fertility was attained with the 7 & 7 protocol, which includes gonadotrophin-releasing hormone, prostaglandin and an intravaginal progesterone device. This study shows that non-estrogen-based fixed-timed artificial insemination protocols can successfully synchronize Bos taurus suckled beef cows under grazing conditions. Hence, beef cattle producers in South America could use the 7 & 7 fixed-timed artificial insemination protocol in order to meet those requirements imposed by countries that do not allow the use of estrogen in food animals. Fixed-timed artificial insemination (FTAI) protocols for beef cattle in South America are primarily based on estradiol esters and intravaginal progesterone-releasing devices (IVPD). The objective of this study was to determine the optimal gonadotropin-releasing hormone (GnRH)-based protocol as an alternative to the use of estrogen-based protocols in grazing Bos taurus suckling beef cows. All cows received an IVPD on the day of protocol initiation and prostaglandin F[sub.2α] (PG) plus equine chorionic gonadotropin (eCG) treatments at the time of IVPD removal. In Experiment 1, cows (n = 235) were randomly assigned to one of four treatments: (i) 7-day estradiol = 2 mg of estradiol benzoate (EB) at IVPD insertion on Day 9 and 1 mg of estradiol cypionate (ECP) at IVPD removal on Day 2; (ii) 7-day GnRH = 10 µg of GnRH at IVPD insertion on Day 10, IVPD removal on Day 3 and GnRH at FTAI; (iii) 7 & 7 estradiol = PG at IVPD insertion on Day 16, EB on Day 9 and ECP at IVPD removal on Day 2; (iv) 7 & 7 GnRH = PG at IVPD insertion on Day 17, GnRH on Day 10, IVPD removal on Day 3 and GnRH at FTAI. In Experiment 2, cows (n = 462) were randomly assigned to one of four treatments: (i) 6-day estradiol = EB at IVPD insertion on Day 9, IVPD removal on Day 3 and GnRH at FTAI; (ii) 7-day estradiol
ISSN:2076-2615
2076-2615
DOI:10.3390/ani13172803