Data/hora: 12/06/2024 21:08:20

Biblioteca(s): 	Embrapa Caprinos e Ovinos.	
Data corrente: 	13/10/2004	
Data da última atualização: 	13/10/2004	
Autoria: 	HUCHKOWSKY, S. L.; BARTLEWSKI, P. M.; RAWLINGS, N. C.	
Título: 	Ovarian follicular development and endocrine function in non-prolific Western With Face ewes with early or late onset of seasonal anestrous.	
Ano de publicação: 	2002	
Fonte/Imprenta: 	Small Ruminant Research, v.46, n. 2-3, p. 191-199, 2002	
Idioma: 	Inglês	
Conteúdo: 	The aim of this study was to see if there were differences in antraI follicle development and endocrine profiles among non-prolific Western White-Faced ewes entering anestrous early (January-February; n = 6) or late (March; n = 6), using daily transrectal ultrasonography of ovaries and hormone measurements, over a 17-day period during mid-anestrous (May). The ovarian follicles were measured and categorized by size (1-2, 2, 3, 4 and ³5 mm in diameter). For determination of the patterns of FSH and LH secretion, a 12 h intensive bleed, with blood samples taken every 12 min, was carried out 2 days after the end of scanning period. A bolus injection of GnRH (250 mg per ewe) was given 6 h into the period of intensive blood collection. The ewes entering anestrous early had significantly lower numbers of 2 and ³5 mm follicles when compared with ewes entering anestrous laie. Similar results were observed for the numbers of aIl follicies > 1 mm in size, total and maximum follicie diameters of aIl follicies ³2 mm in size, and the number of ³5 mm follicies growing by ³1 mm each day. ln contrast, significantly more 4 mm follicies were recorded in ewes entering anestrous early. Daily serum concentrations of FSH and estradiol as weIl as the peak concentration increases in daily serum FSH concentrations and duration of successive estradiol fluctuations, were greater (P < 0.05) in the early compared to late anestrous ewes. Various parameters of the GnRH-induced surges ofFSH and LH did Dot differ (P > 0.05) between ewes entering anestrous early or laie. We concluded that the timing of the onset of seasonaI anestrous in Western White-Faced ewes affected the number and size of ovarian antraI follicies as weIl as circulating levels of FSH and estradiol, but not pituitary responsiveness to GnRH at mid-anestrous. 
	
Palavras-Chave: 	Anestro; Comportamento reprodutivo; Sazonal; Ultra-som.	
Thesagro: 	Ciclo Estral; Endocrinologia; Ovelha; Ovino; Reprodução Animal.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Caprinos e Ovinos (CNPC)	
Exemplares: 	CNPC - (17173-1) - ADC - AP - -- -  -  - v.46,p.191 - DIS