Application of genetic information to high quality beef production
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We can often observe a difference in the growth performance or other economical traits between different breeds of animals (a simple example is the difference in marbling betweenJapanese Blacku and other breeds of beef cattle). In addition, some individuals within a breed clearly show higher growth performance than other individuals even within one breed or herd. If this variation is genetically inherited then the potential exists to identify the responsible gene or locus, and include this information in breeding program to develop more productive and sustainable animal production. The goal of molecular genetics research is to identify DNA variation and to show that this variation is associated with variation in the traits of interest. Or more simply to show that the identified locus confers a significant effect on the phenotype of the animal. Elucidation of the differences in an inherited character at the gene level will contribute not only to more effective livestock breeding but also to the comprehension of the physiological mechanism(s) which underlie the character.
There are various types of DNA polymorphism or difference that exist between individuals. These include deletion (or insertion or addition) of a (large) part of a gene, a deletion or insertion of several nucleotides or single nucleotide changes (SNPs). However, there is no correlation between the size of the DNA change and the phenotypic effect, for example, even a large phenotypic change may result from a SNP. However, in terms of identification of the responsible change it is easier to “catch” the causative sequence change when it is large. For example, a large deletion (of several hundred bp) is more easily identified than a causative SNP or single base insertion or deletion (at least with today’s methods). Although, it is still very difficult to identify the responsible gene and responsible sequence change (causative mutation), we already knew the series of work and tools required to perform and prepare for trait mapping and identification of these genes. Here I introduce recent work in this field from beef cattle genetics which has been developed to commercial usage.