Page 19 - The Welfare of Cattle

xviii IntroduCtIon to the WhIte PaPers

The Use of Biotechnology to Improve Animal Welfare

Alison L. Van Eenennaam, MS, PhD
Department of Animal Science
University of California, Davis, CA

Professor Van Eenennaam comes from Melbourne, Australia and received her Masters and
PhD degrees from UC Davis. She’s been a Cooperative Extension Advisor working on dairy farms
in California and since 2002 has been a Cooperative Extension Specialist in Animal Genomics
and Biotechnology. Her research interests include the use of biotechnology to address some of the
animal welfare concerns and environmental impacts of animal production.
Genetic engineering is a process where scientists use recombinant DNA technology to introduce
desirable traits into an organism. All organisms share the same four-nucleotide building blocks in
their DNA, meaning that the same gene in different organisms will encode the exact same protein
whether it is being manufactured in an animal, plant, or microbe. Recombinant DNA is DNA with
fragments from two or more sources that have been joined together in the laboratory. A recombi-
nant animal carries a known sequence of recombinant DNA in its cells and will pass that on to its
offspring.
Genetic engineering accelerates the change that is associated with selective breeding. Gene
editing can precisely add, delete, or replace the genetic code to introduce a new gene or turn off an
existing gene. It can be used to correct diseases or disorders that have a genetic basis by altering the
error, change a less desirable trait, or insert a new desirable trait.
In cattle, it is possible to use gene editing to prevent the growth of horns, thereby eliminating the
pain and costs associated with dehorning, or increase resistance to mastitis, a major reason for cattle
death and removal from a herd. It can also prevent a protein from being made that is a major cause
of milk allergies, and increase resistance in cattle to tuberculosis and respiratory disease. Similar
benefits exist in other food animal species. Beyond health, but of great importance for animal
welfare, gene editing could produce only single gender of offspring (female for egg layers or dairy
production) or eliminating testes development so castration is no longer necessary.
Gene editing does not necessarily add any foreign DNA to the animal being edited and the
intended changes are similar to those already found naturally in the species. Editing allows a more
rapid change than natural breeding and it is expected to be used in combination with ongoing
genetic selection of the animals from natural breeding and artificial insemination programs. As an
example, the hornless Holstein carries the polled gene sequence that came from Angus cattle via a
breeding program, but could be more easily and quickly achieved via gene editing.
The following genetic traits are now recommended for consideration in a breeding program to
improve the welfare of dairy cattle: fertility, disease resistance, feet and leg conformation, calv-
ing ability, udder shape and support, body size and weight, productive live and longevity, mastitis
susceptibility, and daughter pregnancy rates. This is a positive step expanding the goals beyond the
previous emphasis on milk yield, milk fat, and milk protein. These newer additions are identified as
important traits associated with cattle welfare and may be more quickly accomplished by allowing
gene editing in combination with selective breeding.