Potential Gain From Insertion Of Major Genes Into Dairy Cattle
This research discusses the use of transgenesis to “enhance” the genetic nature of dairy cows for economic purposes, finding that the high cost of producing transgenes may be recovered when additive or dominant genes are introduced into commercial herds. However, a significant amount of progeny testing would be required to confirm the theorized results.
A few major genes have been isolated and cloned (growth hormone, casein, and mastitis-resistance genes), but transgenesis cannot be used within commercial populations prior to resolving technology deficiencies, for example ways to control the time and location of gene expression and identification of the site of insertion. Progeny tests require large numbers of daughters and tests for potential effects, though this research theorizes that “with highly controllable gene expression, transgenes may permit temporary increases in rate of genetic progress for traits currently of primary importance.”
While focused on the economic benefits of genetically altering dairy cows, the research also has implications for animal welfare. Welfare-related genes pose a challenge because they “cannot be selected for because they are not carried by individuals of high genetic merit.”