Biodiversity and genetics of beef quality, a review

Preservation of biodiversity and genetic improvement of livestock populations are often considered to be antagonistic. Biodiversity affects meat quality (MQ) on different levels: among species (only three species yield 88% of the world's meat); among breeds within species (there are more than 3000 cattle breeds worldwide, but about half are at an unknown risk of extinction, and only one-fourth of the others are not endangered); among animals within breed (in cattle populations with millions of individuals the median effective size is equivalent to only about 100 unrelated animals); and between alleles within animal genes (the inbreeding coefficients of individual animals are increasing with selection, and particularly genomic selection [GS]). Beef quality traits are very particular because they cannot be directly measured on living animals. The genetic improvement of beef quality can be pursued by different techniques. In chronological order, they are: phenotypic selection, which has created breed differentiation (not useful for MQ traits); selective breeding (heritability of beef quality traits varies considerably according to breed, trait and conditions; indirect selection through NIRS predictions, etc., (could be useful); the fixation of major gene mutations (the myostatin gene for double muscling, calpain (CAPN)-calpastatin (CAST) genes for beef tenderness; diacylglycerol O-Acyltransferase 1 for beef marbling, etc.); genomic and other omic approaches (strong increase in scientific studies, genome-wide association studies (GWAS), GS, gene network identification, etc.); the cloning of animals (not useful); and the cloning of tissues (cultivated meat).