Origen, Historia Y Situación Actual De La Oveja Pelibuey en México

Abstract

<p>Domestic sheep (<em>Ovis aries</em>) is descendant from Asian mouflon and was domesticated in the Near East. Later, sheep began its dissemination to West Africa, where it is believed that the ancestry of Pelibuey sheep came from. Pelibuey sheep were brought to America by the Spaniards to feed the crew of the boats. It is unclear whether these animals came directly from West Africa or from the Canary Islands. It is considered that Pelibuey sheep entered to Mexico between 1930 and 1940, although some authors think that this breed already existed in the country in the late nineteenth century. Since 1963, Pelibuey sheep has been the most studied breed in Mexico, due to its ability to produce in tropics, as well as its high adaptability to most agro-ecological zones of the country. A brief review about productive and reproductive traits in current Pelibuey herds, allowed to conclude that they are very similar to those of the first sheep studied almost 50 years ago. Currently, the breed has been subjected to non-planned crosses with other breeds to increase productivity, which puts in risk this important genetic resource. Therefore, there is a need to realize the conservation of the breed. </p>

Reproductive performance of hair ewes and rams implanted with melatonin previous to the anestrus season in northwest Mexico

“…Our study was conducted between latitudes 24 and 25ºN and represents the rst study related to reproductive seasonality of sheep in this particular area. Results of this investigation agreed with Arroyo et al (2007) and Arroyo (2011) regarding the existence of individuals apparently not affected by photoperiod. Such physiological particularity opens the opportunity to investigate molecular markers and potentially select against seasonality within the Pelibuey breed.…”

“…Using an intradermal applicator after a disinfection process with 2% povidone-iodine, randomly, ve rams received in their left ear pavilion two 18-mg melatonin (M36) subcutaneous implants (Dermatonin, Melatek LLC, Prairie du Sac, WI 53578 USA) Other ve rams received only one 18-mg melatonin subcutaneous implant (M18), while the ve remaining rams were not implanted (0-mg of melatonin) and were considered as the control group (mCTRL). To challenge the animals against the reproductive season, the period from March to June was considered the season of low fertility for the region (Arroyo, 2011). Implants were administered in February (0d) and at 30d, 60d, 90d and 120d postimplantation were performed andrological tests and blood collections to determine testosterone levels (Fig.…”

“…In this region, photoperiod effects have been reported to be variable in hair breeds. For instance, studies conducted with Pelibuey ewes on latitudes 27º N and 32º N suggested that within this breed, some females experience reductions in estral and ovarian activity (Macías-Cruz et al 2015, Silva-Ávila et al 2015, while others seem to have a lack of anestrus (Arroyo et al 2011). Interestingly, no studies related to reproductive seasonality on rams have been reported for this zone.…”

“…This geographical region offers the opportunity to commercialize ovine derived products nationally and internationally (Rodríguez-Pérez et al 2010). Nonetheless, the seasonal anestrus period occurring during spring and summer in these small ruminants poses a challenge to sustain a constant lamb production throughout the year (Malpaux et al 1997;Arroyo, 2011). Consequently, it has been noted that the adoption of technology and new management practices focused on manipulating sheep's reproductive e ciency are an imperative need in this productive zone (Leyva et al 2015).…”

“…Reproductive seasonality is a natural mechanism limiting reproductive activity of some species to ensure that females have their calvings during the most favorable time of the year (Arroyo, 2011). The main environmental factor controlling such seasonality in sheep is photoperiod (Williams and Helliwell, 1993;Rosa and Bryant, 2003;Correa and Riveros, 2017).…”