Applications of molecular genetic technologies in livestock improvement

In recent years there has been spectacular progress in understanding the molecular genetic basis of growth and development of living organisms. Whilst the knowledge base is still very limited, molecular genetic technologies are just starting to find applications in the livestock industries. Although there are a large number of breeds and strains of livestock, the genetic similarity between them is largely unknown. Such knowledge is useful in designing conservation programs as well as in formulating breeding programs based on crossbreeding. Molecular genetic techniques can be used to construct a genetic profile for different populations/breeds/strains and thereby allow conclusions to be drawn about their similarity at the genetic level as distinct from the phenotypic (performance or appearance) level. Molecular genetic technologies can also be used to identify genes associated with important production traits such as tick resistance in cattle and bacterial resistance in pigs. Such traits are frequently found in so-called undeveloped breeds which have evolved in challenging environments. Once gene markers are identified, they can be used to better identify genetically superior animals for these traits. DNA-based fingerprinting systems are an efficient and cost effective basis for establishing pedigrees in many situations. In general, successful livestock development programs are based on multidisciplinary approaches. It will be important that the molecular genetic technologies, when developed, are integrated with other genetic and reproductive technologies such as performance and progeny testing and artificial insemination so as to maximise their impact.