Abstract

GASTELUM-DELGADO, Miguel A. et al. Circannual estrous behavior in Pelibuey ewes under arid conditions of Northwestern of Mexico. Rev. mex. de cienc. pecuarias [online]. 2015, vol.6, n.1, pp.109-118. ISSN 2448-6698.

In order to determine the circannual estrus behavior of Pelibuey ewes under arid conditions of Northwestern Mexico (32^o NL), 22 adult ewes were maintained in confinement conditions with constant feeding during one year. Daily, morning and afternoon, the ewe group was exposed to one of three ram fitted with an apron to detect estrus behavior. Annual averages of temperature, relative humidity and temperature-humidity index were 25.3±8.1 °C, 33.1±10.7 % and 72.0±8.4 units, respectively. Monthly percentage of ewes in estrus was lower (P<0.05) from January to June than from July to December. The 100 % of ewes showed estrus signs in each month from July to December (P>0.05). Compared with others months, a higher (P<0.05) percentage of ewes showed shorter estrus (<24 h) in February and March, contrarily, the proportion of ewes with longer estrus (>36 and <48 h) was higher (P<0.05) in June and August. In conclusion, under arid-dry conditions of Northwestern Mexico, Pelibuey ewes decrease their estrus activity from January to June, and high environmental temperatures of summer are not a factor affecting the estrus presence in this sheep breed.

Keywords : Hair sheep; Reproductive activity; Estrus Heat stress.