Effects of season and superovulatory treatment on embryo yields in fine-wool Merinos maintained under field conditions

Contents The aim of the study was to assess the effects of superovulatory treatment (multiple FSH-dose vs single-shot FSH treatment) and seasonality on embryo yields in fine-wool Merino ewes. Treatment based on multiple FSH-dose consisted of 200mg of FSH (Folltropin ®) administered in seven decreasing doses. Single-shot treatment consisted of a single dose of 70mg of FSH+eCG. In ewes treated with multiple FSH doses, number of recovered embryos was higher (6.0±0.5 vs 3.5±1.0), while non-fertilization rate was lower (12.8±3.9 vs 40.3±9.5) during the breeding season when compared to the non-breeding season (p<0.05); although similar values of recovered Grades 1-2 embryos were observed between seasons. During the breeding season, proportion of responding ewes (98.1 vs 57.1%), ovulation rate (13.9±0.8 vs 3.2±1.2), recovered structures (7.9±0.6 vs 1.7±0.7), total recovered embryos (6.0±0.5 vs 1.2±0.6) and good-quality embryos (5.1±0.5 vs 0.9±0.6) were higher for the multiple FSH-dose treatment than for the single-shot protocol. In a similar way, in the non-breeding season, ovulation rate (11.3±1.8 vs 6.0±1.1) and recovered structures (6.6±1.2 vs 2.7±0.6) were higher for the multiple FSH injections protocol than those for the single-shot treatment, resulting in higher recovered Grades 1-2 embryos (3.2±0.9 vs 1.4±0.5). Current results indicate that seasonal anestrus affected embryo yields when applying multiple FSH-dose superovulatory treatment in Merino ewes, by decreasing the number of recovered embryos although the number of recovered good-quality embryos was not affected. During both seasons, multiple FSH injections produced higher ovarian response and number of viable embryos than the single-shot treatment. © 2010 Blackwell Verlag GmbH.

Bibliographic Details

Main Authors:	Cueto, M. I., Gibbons, A. E., Pereyra-Bonnet, F., Silvestre, P., González De Bulnes, Antonio
Format:	artículo biblioteca
Language:	English
Published:	Wiley 2011
Online Access:	http://hdl.handle.net/20.500.12792/6018 http://hdl.handle.net/10261/291920
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