There is nothing new about selective breeding. Humans have
always encouraged crossing between the best animals and between
different breeds possessing individual characteristics they wanted
to combine for food and agriculture.
The use of reproductive biotechnology in animal breeding is also
not new. Artificial insemination has been around for 50 years. And
with animals, as with fish and crops, there are forms of genetic
manipulation already in use that do not involve direct modification
of the genes.
Embryo transfer from an excellent ewe is a case in point,
says Keith Hammond, FAOs senior officer on animal breeding.
This is a form of genetic manipulation, and its certainly
biotechnology. Embryo transfers are now common, with 440 000
recorded in cattle alone in 1998.
Improving animal productivity, reducing disease
But now genetic engineering is coming to animal breeding. Its obvious
uses will be to increase milk, meat and egg production and to improve
disease resistance, efficient use of feed and tolerance of harsh
environments in fact, those qualities that farmers have sought
from their animals for millennia.
However, the earliest applications may be animals that produce
non-food items. For example, plans are under way to introduce a
gene into sheep to make the udder secrete a silk protein from which
spider silk can be made. Immensely fine and strong, it can be used
for such benevolent purposes as surgical sutures. It may also soon
be possible to modify animal organs so they can be transplanted
into humans. And animals may be able to produce compounds needed
for vaccination and treatment.
A barrier to adoption of transgenic animals, compared to food crops,
is their much longer reproductive cycles, which makes research a
much slower process. Moreover, the patterns of genes that scientists
must identify and transfer are far more complex than those in plants.
Genetically modified animals will take longer to reach production
than crops and fish.
One obvious implication of genetic modification is the ethical
treatment of animals. Farming is an industry already much criticized
for its treatment of animals. And early attempts to produce transgenic
animals resulted in physiological anomalies, weakness and impaired
health and reproductive performance.
However, techniques have improved, and transgenic animals may be
no more likely to suffer from distressing birth defects than ordinary
ones. This is because the control inherent in genetic engineering
is more apt to reduce the likelihood of birth defects among offspring
of animals carrying damaging recessive genes. This will not reassure
those who believe that designer animals are simply wrong.
But genetic techniques should not necessarily be associated with
The health question
Genetic engineering has potential benefits for animal health
for producing vaccines and antibodies and for conferring resistance
to disease. Aside from the distress illnesses cause to the animal,
disease does appalling economic damage, especially in poor communities
that depend heavily on livestock. The implications for food security
Over the last 15-20 years, US$ 100 million has been spent
on attempts to control African swine fever, says FAO virologist
Peter Roeder. Theyve failed. Do we go on spending, or
do we try new methods?
The impact of modern biotechnology on animal health falls into
Diagnostics, such as the development of molecular kits to diagnose
animal diseases. It is now possible to analyse gene sequences
of microbes and parasites, allowing rapid and accurate diagnosis
of the exact type.
Vaccines. Recombinant vaccines those developed through
gene manipulation can be highly effective. A recombinant
rabies vaccine is already widely and successfully used in Europe
and the United States. Now several groups of researchers in
the United States and the United Kingdom are working on marked
recombinant vaccines for rinderpest to help in discriminating
between wild virus infection and vaccination.
Epidemiology, the study of the spread of diseases. Organisms
such as viruses evolve and mutate very quickly, and so do their
behaviour and resistance. From the sequence of an organisms
genes, it is possible to understand how and where it evolved
a process known as phylogenetics. This can show how the
organism is evolving now and what it will do next, helping to
identify the right vaccines for combating fast-evolving viruses
such as foot-and-mouth disease.
Genetic markers can now be inserted into vaccines, so that workers
in the field can distinguish between animals that have a disease
and those that have simply been vaccinated. This means that vaccinated
animals wont have to be destroyed on suspicion of being disease
carriers. And genetic markers are also about to become important
in food safety monitoring. For example, it will soon be possible
to detect foreign proteins in foodstuffs quickly and cheaply.
The use of genetic engineering to modify animals is bound to be
controversial. In particular, the arguments about ethics and animal
welfare will be fierce and will cut both ways.