Data/hora: 22/09/2024 20:01:21

Biblioteca(s): 	Embrapa Rondônia.	
Data corrente: 	31/01/2022	
Data da última atualização: 	31/01/2022	
Autoria: 	BARBOSA, I. P.; CESTARO, J. P.; SILVA, S. A.; NOLETO, G. S.; GONÇALVES, R. L.; SILVA, G. M.; PAES, F. H.; GASPERIN, B. G.; ROVANI, M. T.; PFEIFER, L. F. M.	
Afiliação: 	INGRID P. BARBOSA, Universidade Federal do Acre (Ufac); JAMYLE P. CESTARO, Universidade Federal do Acre (Ufac); SAMIRA A. SILVA, Centro Universitario Aparício Carvalho (FIMCA); GABRIELLY S. NOLETO, Centro Universitario Aparício Carvalho (FIMCA); REUEL L. GONÇALVES, Biogênesis Bago Saúde Animal, Curitiba, PR; GEORGE M. SILVA, Universidade Federal de Rondonia (UNIR); FELIPE H. PAES, Centro Universitario Aparício Carvalho (FIMCA); BERNARDO G. GASPERIN, Universidade Federal de Pelotas (Ufpel); MONIQUE T. ROVANI, Universidade Federal do Rio Grande do Sul (UFRGS); LUIZ FRANCISCO MACHADO PFEIFER, CPAF-RO.	
Título: 	GnRH34: an alternative for increasing pregnancy in timed AI beef cows.	
Ano de publicação: 	2022	
Fonte/Imprenta: 	Theriogenology, v. 179, p. 1-254, Feb. 2022.	
ISSN: 	0093-691X	
DOI: 	https://doi.org/10.1016/j.theriogenology.2021.11.014	
Idioma: 	Inglês	
Conteúdo: 	Two experiments evaluated the effects of gonadotropin releasing hormone (GnRH) treatment on fertility of suckled Nelore beef cows treated with an estradiol/progesterone (P4)-based protocol for timed artificial insemination (TAI). Experiment 1 was designed to determine the effect of GnRH administered 34 h after P4 insert removal (GnRH34) on time of ovulation. Suckled cows (n = 34) were treated with 2 mg estradiol benzoate (EB) and an intravaginal insert containing 1.9 g of P4. Eight days later, P4 inserts were removed, and all cows received 150 ug of d-cloprostenol (prostaglandin F2 alpha analogue), 300 IU of eCG, and 1 mg of estradiol cypionate (ECP). On Day 9 (05:00 p.m.), cows were randomly distributed, according to the diameter of the pre-ovulatory follicle, in two treatments: 1) GnRH (n = 17) cows that received 10.5 ug of buserelin acetate, or 2) no further treatment (control, n = 17). Cows treated with GnRH 34 h after P4 insert removal ovulated earlier (P = 0.02) than control cows (66 ± 0.0 and 77.2 ± 4.3 h). Experiment 2 was designed to determine the effect of GnRH34 on the fertility of suckled beef cows. Nelore cows (n = 506) were treated as Experiment 1. On Day 8, cows were painted in the sacrocaudal region to identify cows that displayed estrus. On Day 9 (05:00 p.m.), cows were randomized to receive same treatment as Experiment 1, control (n = 252), or GnRH (n = 254). All cows were TAI 48 h after P4 insert removal. At TAI, estrus was evaluated, and deemed to have occurred in cows without a tail-head chalk mark (>75% paint loss). Cows treated with GnRH 34 h after P4 insert removal had greater (P = 0.01) pregnancy per AI (P/AI) than cows that only received ECP (63.0% and 50.4%). No difference (P = 0.5) was observed in the proportion of cows that displayed estrus between treatments. Furthermore, cows that displayed estrus had greater (P < 0.01) P/AI than cows that did not. Treatment with GnRH, given at 34 h after P4 insert removal, increased (P < 0.05) P/AI in cows that did not show estrus at TAI. In summary, treatment with GnRH 34 h after P4 insert removal was associated with earlier ovulation and resulted in greater P/AI in suckled Nelore cows treated with an estradiol/P4-based protocol for TAI.	
Palavras-Chave: 	Gonadotropina.	
Thesagro: 	Fertilidade Animal; Gado de Corte; Gado Nelore; Hormônio; Inseminação Artificial; Ovulação; Reprodução Animal; Vaca de Corte.	
Thesaurus Nal: 	Animal fertility; Animal reproduction; Artificial insemination; Beef cattle; Beef cows; Gonadotropin-releasing hormone; Nellore; Ovulation.	
Categoria do assunto: 	L Ciência Animal e Produtos de Origem Animal	
Registro original: 	Embrapa Rondônia (CPAF-RO)	
Exemplares: 	CPAF-RO - (18679-1) - UPC - AP - DD -  -  -  - DIS