Artificial selection in animals

Artificial selection livestock

Easycare sheep Traits selected for:  bare backside  bare belly  bare legs  short tail  bare head. > Less flystrike, easier to shear, animal welfare (don’t need to dock tails) = $$$

How would you integrate the Easycare traits into the general population?

Natural selection Selective breeding/artificial selection Inbreeding Artificial insemination Embryo transfer/splitting Marker assisted selection Cloning Genetic manipulation of animals

Artificial insemination Females (e.g. dairy cows) are inseminated with sperm from selected stud (e.g. bull). Studs are ranked/selected based on breeding values for different traits (e.g. growth rate, resistance to disease). Breeding values are calculated from measuring specific traits in their offspring.

Embryo transfer

Used with high value donors - embryos are transferred to a lower value surrogate. Embryos can be selected prior to implantation (MAS). Donor can then be rebreed. Donor cow can be inseminated up to 20 times a year compared with usual 1 pregnancy a year.

Marker assisted selection Molecular technique (DNA based) that links gene markers with desirable traits. Marker and gene responsible for trait are closely linked on chromosome and hence co- segregate. Genetic test can be done on a few cells. So can test on embryos prior to implantation and well before trait is displayed (e.g. milk production)