Redesigning Animal Agriculture

4 The Impact of Genomics on Livestock
Production
Ross Tellam
CSIRO Livestock Industries, Queensland Bioscience Precinct, Australia
Abstract
The unique genome of a livestock animal represents the potential of that individual in a particular production
environment. In contrast, the different genomes of individuals of a livestock species reflect the
genetic plasticity of the species as a whole and the diversity of genetically determined phenotypes that
can be produced by the species. Exploitation of this individual variation within a species is at the heart
of livestock breeding programmes. The bovine genome sequence in ‘draft’ form will be completed in
2007. The availability of the sequence and very large numbers of single nucleotide polymorphisms
will have profound effects on beef cattle, dairy cattle and sheep production by enabling acceleration
of the selection of animals with desirable production traits. Many livestock industries are poised to
capture the benefits from this enormous wealth of genome sequence information because they have
comprehensive databases containing phenotypic and pedigree data for large numbers of animals,
intensively use genetics in breeding programmes and efficiently manage reproductive perform ance.
The immediate challenge facing the livestock industry is the integration of new technological capabilities
into existing breeding programmes and production systems.
The Fidelity and Plasticity of the Genome
The genome of a living organism consists
of DNA sequence information that codes
for the protein building blocks of life as
well as instructions on their assembly and
control. Within the context of a few generations
the genome is largely unchanging,
transmitting this information from parent
to offspring with remarkable fidelity. The
combination of this genetic information
with environmental influences defines the
production potential of a livestock animal.
At the molecular level this potential reflects
the interaction between environmental factors
and gene activities. Contrasting in some
ways with this process is the enormous
phenotypic variation of individuals within a
species and the remarkable form and physiological
differences, even between highly
related species that share great similarity in
their DNA sequences. These observations
are rationalized in the context of differing
timescales, in which the generational fidelity
applies over relatively brief periods of
time, whereas genomic variation between
individuals is a function of evolution of the
species and occurs over many generations
and long timescales. In the latter instance,
advantageous mutations are propagated
within the species and these both define
the species and lead to individual variation
within the species. The diversity of phenotypes
generated by this process reflects the
©CAB International 2007. Redesigning Animal Agriculture
46 (eds D. Swain, E. Charmley, J. Steel and S. Coffey)