Submitted to: Nuestra Cabana
Publication Type: Trade Journal
Publication Acceptance Date: April 30, 1999
Publication Date: May 2, 1999
Citation: Casas, E. 1999. Genetic markers: their use in the identification of regions responsible for the expression of economically important traits. Nuestra Cabana Magazine. p. 6-10. Technical Abstract: The objective of animal breeding programs is to identify individuals within a population that will produce the next generation. These programs have altered the allelic frequencies of genes to improve dairy and beef cattle. Bovine genetic material is organized in 30 chromosomes, and the groups of chromosomes is known as genome. A gene is the responsible unit for the expression of a productive trait, and can have one or several forms. Each form of a gene is known as an allele, and it is assumed that selected animals have better alleles for production when compared with contemporaneous animals. Despite this assumption, little is known about which genes are involved in productive traits given that milk and beef production, as other economically important traits, are controlled by the genetic material in combination with the environment. Until recently there was no methodology that allowed to identify the location of the genes in the genome, however, development of new technology has made this possible. Genetic maps have been developed for each bovine chromosome, making use of genetic markers. The latter are short sequences of DNA located throughout each chromosome. These sequences have polymorphism, which is the term to express they have many forms, or multiple alleles. This characteristic has made them a key element in the development of linkage maps. Therefore, a linkage map could be compared with a highway, where the mile marker is the equivalent of a genetic marker, having a unique position within the chromosome. Using these and other tools it has been possible to establish the cause of different conditions affecting dairy and beef cattle.