ESTRADIOL E GNRH NA SINCRONIZAÇÃO DO ESTRO E INDUÇÃO DA OVULAÇÃO DE VACAS MESTIÇAS

Palavras-chave: Benzoato de estradiol (EB). Biotecnologia. Cipionato de estradiol (EC). Reprodução.

Resumo

Benzoato de estradiol (EB), cipionato de estradiol (EC) e hormônio liberador de gonadotrofinas (GnRH) foram avaliados como indutores da ovulação na IATF em vacas mestiças em lactação. No experimento I (n=45) a dinâmica folicular foi avaliada, enquanto no experimento II (n=171) a eficiência reprodutiva foi avaliada. Todas as fêmeas foram submetidas a um protocolo de sincronização: inserção no dia 0 (D0) de dispositivo intravaginal de liberação de progesterona (PRID; 1g) mais administração de EB 2mg; D8, remoção de PRID, administração de 0,150mg de PGF2α e 400 UI de eCG, e as vacas foram alocadas em três tratamentos: 1) TEB9 - administração IM de 1mg EB em D9 e AI realizada 52 horas após a remoção PRID; 2) TEC - administração IM de 1mg EC em D8 e AI realizada 48 horas após a remoção de PRID; e 3) TGnRH - administração de 100µg GnRH em D10 e AI realizada 52 horas após a remoção de PRID. A taxa de crescimento folicular foi menor no grupo EC (p <0,05). Não houve efeito dos tratamentos nas taxas de ovulação e prenhez (p >0,05). O uso de EB, EC e GnRH como indutores de ovulação em protocolos de IATF não mostrou diferenças marcantes nos padrões avaliados de dinâmica folicular e prenhez.

Referências

ALMEIDA, I. C. et al. Pregnancy rates in dairy cows after the use of hormonal protocols of timed artificial insemination. Revista Brasileira de Ciências Veterinárias, 23: 99-103, 2016a.

ALMEIDA, I. C. et al. Pre-synchronization protocol in crossbred cows in the postpartum period. Revista Brasileira de Medicina Veterinária, 38: 353-357, 2016b.

AYRES, H. et al. Effect of timing of estradiol benzoate administration upon synchronization of ovulation in suckling Nelore cows (Bos indicus) treated with a progesterone-releasing intravaginal device. Animal Reproduction Science, 109: 77-87, 2008.

BANDAI, K. et al. A simple and practical short-term timed artificial insemination protocol using estradiol benzoate with prostaglandin F2α in lactating dairy cows. Theriogenology, 141: 197-201, 2020.

BARBOSA, C. F. et al. Inseminação artificial em tempo fixo e diagnóstico precoce de gestação em vacas leiteiras mestiças. Revista Brasileira de Zootecnia, 40: 79-84, 2011.

BARUSELLI, P. S. et al. The use of hormonal treatments to improve reproductive performance of anestrous beef cattle in tropical climates. Animal Reproduction Science, 82: 479-486, 2004.

BÓ, G. A. et al. Technologies for fixed-time artificial insemination and their influence on reproductive performance of Bos indicus cattle. Society for Reproduction and Fertility, 64: 223-236, 2007.

BÓ, G. A. et al. Alternative programs for synchronizing and resynchronizing ovulation in beef cattle. Theriogenology, 86: 388-396, 2016.

CERRI, R. L. A. et al. Progesterone concentration, follicular development and induction of cyclicity in dairy cows receiving intravaginal progesterone inserts. Animal Reproduction Science, 110: 56-70, 2009.

COLAZO, M. G.; AMBROSEA, D. J. Neither duration of progesterone insert nor initial GnRH treatment affected pregnancy per timed-insemination in dairy heifers subjected to a Co-synch protocol. Theriogenology, 76: 578-588, 2011.

COLAZO, M. G. et al. Progesterone supplementation before timed AI increased ovulation synchrony and pregnancy per AI, and supplementation after timed AI reduced pregnancy losses in lactating dairy cows. Theriogenology, 79: 833-841, 2013.

FERREIRA, R. M. et al. Inducing ovulation with estradiol cypionate allows flexibility in the timing of insemination and removes the need for gonadotrophin-releasing hormone in the timed AI protocols for dairy cows. Reproduction, Fertility and Development, 29: 468-475, 2017.

GOTTSCHALL, C. S. et al. Avaliação do desempenho reprodutivo de vacas de corte lactantes submetidas à IATF apartir da aplicação do GnRH, da manifestação estral, da reutilização de dispositivos. Acta Scientiae Veterinariae, 40: 1-10, 2012.

KAPSE, S. et al. Dominant follicle diameter at insemination is related to positive pregnancy outcome in dairy cattle. Indian Journal of Animal Reproduction, 38: 56-57, 2017.

MADALENA, F. E.; PEIXOTO, M. G. C. D.; GIBSON, J. Dairy cattle genetics and its applications in Brazil. Livestock Research for Rural Development, 24: 1-49, 2012.

MARTINEZ, M. F. et al. The use of a progesterone-releasing device (CIDR-B) or melengestrol acetate with GnRH, LH, or estradiol benzoate for fixed-time AI in beef heifers. Journal of Animal Science, 80: 1746-1751, 2002.

MARQUES, P. R.; BARCELLOS, J. O. J; McMANUS, C. Competitiveness of beef farming in Rio Grande do Sul State, Brazil. Agricultural Systems, 104: 689-693, 2011.

MELO, L. F. et al. Progesterone-based fixed-time artificial insemination protocols for dairy cows: Gonadotropin-releasing hormone versus estradiol benzoate at initiation and estradiol cypionate versus estradiol benzoate at the end. Journal of Dairy Science, 99: 9227-9237, 2016.

MENEGHETTI, M. et al. Fixed-time artificial insemination with estradiol and progesterone for Bos indicus cows I: Basis for development of protocols. Theriogenology, 72: 179-189, 2009.

NELSON, S. T. et al. Automated activity monitoring and visual observation of estrus in a herd of loose housed Hereford cattle: Diagnostic accuracy and time to ovulation. Theriogenology, 87: 205-211, 2017.

PEREIRA, L. L. et al. Effect of body condition score and reuse of progesterone-releasing intravaginal devices on conception rate following timed artificial insemination in Nelore cows. Reproduction in Domestic Animals, 53: 624-628, 2018.

PINAFFI, F. L. V. et al. Follicle and corpus luteum size and vascularity as predictors of fertility at the time of artificial insemination and embryo transfer in beef cattle. Pesquisa Veterinária Brasileira, 35: 470-476, 2015.

PULLEY, S. L. et al. Ovarian characteristics, serum concentrations of progesterone and estradiol, and fertility in lactating dairy cows in response to equine chorionic gonadotropin. Theriogenology, 79: 127-134, 2013.

RICCI, A. et al. Characterization of luteal dynamics in lactating Holstein cows for 32 days after synchronization of ovulation and timed artificial insemination. Journal of Dairy Science, 100: 9851-9860, 2017.

ROELOFS, J. B. et al. Effects of insemination ovulation interval on fertilization rates and embryo characteristics in dairy cattle. Theriogenology, 66: 2173-2181, 2006.

SÁ FILHO, M. F. et al. Equine chorionic gonadotropin improves the efficacy of a progestin-based fixed-time artificial insemination protocol in Nelore (Bos indicus) heifers. Animal of Reproduction Science, 118: 182-187, 2010.

SÁ FILHO, M. F. et al. Importance of estrus on pregnancy per insemination in suckled Bos indicus cows submitted to estradiol/progesterone-based timed insemination protocols. Theriogenology, 76: 455-463, 2011.

SÁ FILHO, O. G.; DIAS, C. C.; VASCONCELOS, J. L. M. Effect of progesterone or 17β - estradiol on luteal lifespan in anoestrous Nelore cows. Journal Animal Science, 84: 207-207, 2006.

SÁ FILHO, O. G. et al. Fixed-time artificial insemination with estradiol and progesterone for Bos indicus cows II: Strategies and factors affecting fertility. Theriogenology, 72: 210-218, 2009.

SALES, N. S. et al. Effects of two estradiol esters (benzoate and cypionate) on the induction of synchronized ovulations in Bos indicus cows submitted to a timed artificial insemination protocol. Theriogenology, 78: 510-516, 2012.

SALES, J. N. et al. Effects of eCG are more pronounced in primiparous than multiparous Bos indicus cows submitted to a timed artificial insemination protocol. Theriogenology, 86: 2290-2295, 2016.

SARTORI, R. et al. Follicular deviation and acquisition of ovulatory capacity in bovine follicles. Biology of Reproduction, 65: 1403-1409, 2001.

SARTORI, R.; MONTEIRO JR., P. L. J.; WILTBANK, M. C. Endocrine and metabolic differences between Bos taurus and Bos indicus cows and implications for reproductive management. Animal Reproduction Science, 13: 168-181, 2016.

SOBREIRA, R. R. et al. Estradiol cypionate and estradiol benzoate in artificial insemination protocols in fixed time in crossbred heifers. Veterinária e Zootecnia, 24: 581-591, 2017.

SOUZA, A. H. et al. Effects of equine chorionic gonadotropin and type of ovulatory stimulus in a timed-AI protocol on reproductive responses in dairy cows. Theriogenology, 72: 10-21, 2009.

VASCONCELOS, J. L. M. et al. Reduction in size of the ovulatory follicle reduces subsequent luteal size and pregnancy rate. Theriogenology, 15: 307-314, 2011.

VASCONCELOS, J. L. M. et al. Evolution of fixed-time in dairy cattle in Brazil. Animal Reproduction Science, 12: 940-951, 2018.

Publicado
2020-07-31
Seção
Medicina Veterinária