Resumen

TOLEDO ALVARADO, Hugo O.; BERRUECOS VILLALOBOS, José М.  y  VAZQUEZ PELAEZ, Carlos G.. Bos indicus x Bos taurus gene proportion over weaning weight and age at first parturition in a multi-breed population. Rev. mex. de cienc. pecuarias [online]. 2015, vol.6, n.1, pp.1-13. ISSN 2448-6698.

Records of 1,289 cows at first calving with different proportions of Bos Indicus and Bos Taurus genes (Charolais, Brown Swiss, Simmental, Holstein Friesian, Salers) were analyzed. The cows were both purebreds and crossbreds from a commercial herd born between 1966 and 2006. They were used to estimate the Zebu genes optimum combination on weaning weight adjusted to 270 d (WW) and age at first calving (AFC) in the tropics of México. Likewise, heterosis retention (RVH) and their contribution to WW and AFC, was estimated. Multiple regressions analysis was used to select the best two, three or more crossbreed's model for each trait, according to the square of the multiple correlation coefficients (R²) and the Mallow statistic (CP). The results showed higher heterosis for WW between 42 to 70 % of Bos indicus genes. On the other hand, the best response to heterosis for a lower AFC was found in a proportion of Zebu genes ranging from 27 to 40 %. The retention of heterosis showed that the greatest potential for WW was 76 to 78 % and 79 to 92 % for AFC. These results demonstrate the importance of non-additive effects in both traits, and the need for controlled crosses.

Palabras llave : Heterosis; Retention of heterosis; Zebu; Weaning weight; Age at first calving; Bovine.