Resumen

CERVANTES, Patricia et al. GENETIC POLYMORPHISM IN THE KAPPA-CASEIN LOCUS IN COWS OF DIFFERENT BREEDS AND CROSSBREEDS IN THE MEXICAN TROPIC. Rev Salud Anim. [online]. 2007, vol.29, n.2, pp.78-84. ISSN 0253-570X.

First results on genetic variability in the k-casein locus are reported for six bovine breeds in the Mexican Tropic. They were based on DNA analysis by PCR-RFLP of blood samples from 331 animals. The estimated gene frequencies for A allele of this protein, that resulted to be most abundant in 5 of the 6 populations analysed, were between 0.511 for Swiss and 0.702 for Holstein, with heterozygosis values observed in all the cases, superior to those expected. Based on this information, the Hardy-Weinberg equilibrium conditions were analysed, being Zebu breed the unique not showing lack of equilibrium in the locus studied. The information obtained in this work gives a perspective of this locus composition in the herds analysed and it evidences possibilities of application of this technology in selection strategies that improve the genetic response of breeds with milk intentions in the tropical region.

Palabras clave : genetic variability; milk proteins; genetic resources.

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