Reproductive activity of Pelibuey ewe during the anoestrus season: Influence of the male presence [Actividad reproductiva de la oveja Pelibuey durante la época del anestro: Influencia de la presencia del macho]
Por:
Valencia J., Porras A., Mejía O., Berruecos J.M., Trujillo J., Zarco L.
Publicada:
1 ene 2006
Resumen:
Reproductive activity of Pelibuey ewes during the anoestrus was determined at 19° lat.N. Twenty six adult Pelibuey ewes and their twenty one nuliparous daughters were used. During the first year, adult and nuliparous ewes were subjected to daily estrous detection from December to July with Pelibuey rams fitted with an apron. During the second year, females were isolated from males and ovarian activity was followed by progesterone concentrations for the same months. Monthly estrous proportion from January to April was higher (P < 0.05) in adult (100, 96.1, 84.6 y 96.1%) than in nuliparous ewes (42.8, 57.1, 52.3, 61.9%). In the first year, ten adult and four nuliparous ewes cycled in a regular and continuous manner during the whole observation period. During the second year, ovulatory activity showed different patems in the experimental groups; following March, there was a percentage reduction up to June (adults) and July (nuliparous). Eigth adult ewes showed a continues ovulatory activity. It is concluded that some Pelibuey ewes have the capacity to show a continuous reproductive activity during the anoestrus months. This capacity is lower in nuliparous than in adult ewes. The presence of the male during estrous detection exerts an stimulatory effect on estrous activity. Identification of ewes that cycle in an continuous manner open the possibility to establish a selection program toward this trait.
Filiaciones:
Departamentos de Reproducción y de Genética, Facultad de Medicina Veterinaria y Zootecnia, Universidad National Autónoma de México, 04510, México, D.F., Mexico
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