Data/hora: 17/05/2024 11:15:33

Biblioteca(s): 	Embrapa Pecuária Sudeste.	
Data corrente: 	04/01/2011	
Data da última atualização: 	30/06/2023	
Autoria: 	MACHADO, R.; BERGAMASCHI, M. A. C. M.; OLIVEIRA, C. A.; BINELLI, M.	
Afiliação: 	RUI MACHADO, CPPSE; MARCO AURELIO C MEIRA BERGAMASCHI, CPPSE; C. A. OLIVEIRA, DOCENTE USP; M. BINELLI, DOCENTE USP/SÃO PAULO.	
Título: 	Ovarian function in Nelore beef cows (Bos indicus) after different hormonal treatments to induce ovulation.	
Ano de publicação: 	2010	
Fonte/Imprenta: 	In: INTERNATIONAL RUMINANT REPRODUCTION, 8., 2010, Anchorage. Proceedings... Missouri: University of Missouri, 2010,	
Idioma: 	Português	
Conteúdo: 	Synchronization of ovulation is a tool to carry out timed artificial insemination. However, available protocols to induce ovulation provide variable results. This study evaluated different treatments to induce ovulation in Nelore (Bos indicus) cows. Group GnRH/PGF2 (n=40) received the Ovsynch protocol1 based on the administration of two injections of GnRH agonist (Buserelin acetate; 8 g i.m.) given 9 d apart and a PGF2 analogue (d-Cloprostenol; 0.15 mg i.m.) given 48 h before the 2nd GnRH injection; Group Norg (n=30): animals received 3 mg Norgestomet and 5 mg Estradiol valerate i.m. with an auricular implant containing 3 mg Norgestomet at an unknown stage of the oestrous cycle (d 0). On d 9, the implant was withdrawn; and group NorgeCG (n=30): same treatment as Norg plus Equine Chorionic Gonadotrophin (eCG; 400 IU, i.m.) at implant removal2. Ovulation rate was determined by ultrasound and cows that ovulated were submitted daily to transrectal ultrasound assessment of follicular and luteal dynamics, as well as determination of plasma progesterone concentration (P4) up to the subsequent natural ovulation. All treatments induced synchronized ovulation in most cows (62.5%, 70.0% and 70.0% respectively to GnRH/PGF2, Norg and NorgeCG; P>0.05). Inter-ovulatory interval (22.50.7 d) as well as diameter of the dominant follicle at luteolysis (9.61.1 mm) and preovulatory follicle diameter at the induced (12.730.69 mm) and subsequent natural (13.170.52 mm) cycle were not affected (P>0.05) by treatments. Overall function of the corpus luteum (CL) generated after induced ovulation was affected by treatments (P<0.05), except the luteal phase length, which was similar among cows (17.60.5 d). Respectively for GnRH/PGF2, Norg, and NorgeCG, the maximum volume of CL (mm3) was: 7117.3125.7a, 5437.8405.9b and 6927.5405.9a; the day of CL maximum volume was: 14.40.6a, 7.70.5c and 9.20.5b; the plasma P4 concentration (ng/mL) at that day was: 6.21.7a, 4.50.5b and 6.10.5a; the highest plasma P4 (ng/mL) in the estrous cycle subsequent to induction of ovulation was 6.81.7 b, 6.40.6b and 8.20.6a and the day in the estrous cycle of highest plasma P4 was 13.40.6a, 11.40.6b and 11.30.6b. In conclusion, GnRH/PGF2 based protocol delays the increase in progesterone concentration after synchronized ovulation, which can be potentially hazardous to embryo transport, maternal recognition of pregnancy and maintenance of early gestation3. eCG may be added to the Norg protocol when luteal function is to be optimized because it increased the dimensions of the CL and concentration of progesterone over the subsequent estrous cycle compared to Norg alone.	
Palavras-Chave: 	Hormanal treatment; Ovarian.	
Thesaurus Nal: 	reproduction.	
Categoria do assunto: 	G Melhoramento Genético	
Registro original: 	Embrapa Pecuária Sudeste (CPPSE)	
Exemplares: 	CPPSE - (19972-1) - UPC - RA - DD - PROCI-2010.00312 - MAC - 2010.00312 - DIS