Genetic Engineering of Milk Proteins

Changes in the productivity, composition or appearance of plants and animals have, traditionally, been achieved by means of selective breeding, drawing upon naturally occurring variations within the gene pool of a species. Many commercial plant species such as cereals and members of the brassica family bear very little resemblance to their ancestral forms and their productivity is very substantially higher. Changes achieved with domesticated animals are less dramatic but, in conjunction with improved animal husbandry, selective breeding has been so successful in increasing the milk yield of dairy cattle that within the European Union, quotas have had to be imposed in order to limit surpluses. By the use of artificial insemination and embryo transplants, an individual bull with the desired characteristics can produce thousands of offspring.