Agriculture Reference
In-Depth Information
Thornton (2010) identified and discussed three
major areas, briefly addressed below.
The recent and future use of new emerging
methods for genetic selection of animals with
desirable traits is especially exciting. New molec-
ular genetic tools likely will accelerate the focus
on important traits and the rate of improvement
of multiple traits beyond productivity, such as
targeted product quality, longevity, improved
animal health and welfare, and resistance to
environmental stressors. Chapter 5 of this topic
as well as Leakey
et al
. (2009) address various
techniques, such as DNA-based testing for
marker genes indicating desirable traits, trans-
genic animal selection and cloning, and all are
thought to hold significant potential for the
future. The rate of genetic progress should accel-
erate appreciably as well. For example, genomic
selection is projected at least to double the
genetic gain for milk yield of dairy cows by effec-
tively reducing the generation interval com-
pared with traditional selection techniques
(Hayes
et al
., 2009). Genomic selection is likely
to revolutionize selection of desirable traits in
animals amongst countries and lead to special-
ized genotypes that specifically fit local or
regional environmental and market conditions.
This should help make animal agriculture more
sustainable in these regions.
Preservation of genetic diversity also is cru-
cial to the broader future sustainability of animal
agriculture. This has been raised as a concern of
the narrowly focused breeding programmes in
some developed countries (Chapter 5; Nielsen
et al
., 2006; Van Raden, 2007). If animal agri-
culture is to contribute to demands for food
and farmers' livelihoods in the future in both
developed and developing countries, preserving
genetic diversity of animals will be crucial so
that animals of different genotypes can be
selected and used in various and changing envi-
ronments (e.g. due to climate change or different
feed resources). Policy and institutional frame-
works to preserve genetic diversity and sustain-
able use of the wide range of current breeds are
needed so that animals can be selected that can
be sustainable under various environmental and
economic situations (FAO, 2007).
Genetic improvement
The genetic potential of animals obviously is the
first critical factor controlling the prospect of
improved productivity and production efficiency.
Tremendous improvements in this area were
made in the last half-century using conventional
animal breeding and genetic selection tech-
niques and programmes (Leakey
et al
., 2009;
Chapter 5), almost exclusively in developed
countries. Simultaneously, the nutrient compo-
sition of animal products also evolved via genetic
selection to meet demand. Selection techniques
included specific breed selection or substitution,
within-breed selection for specific phenotypic
traits (e.g. rate of gain, carcass quality traits, or
milk yield and composition) and crossbreeding.
Overall on-farm genetic progress typically
ranged from 1% to 3% per year for single or mul-
tiple trait selection in both poultry and swine
breeding programmes (Smith, 1984). Similar
progress was achieved in dairy cattle in Europe,
North America, New Zealand and Australia
using sophisticated progeny testing programmes
and artificial insemination (Simm, 1998; Simm
et al
., 2004). Rate of genetic improvement in
beef cattle and sheep, while substantial, was less
with less aggressive use of progeny testing and
artificial insemination. Whereas most of the
genetic progress was made in developed coun-
tries, there is considerable potential to employ
these same traditional genetic selection tech-
niques in developing countries if the most
important traits are identified and sufficiently
heritable, and appropriate data recording and
evaluation programmes can be developed. Some
desirable and more important traits likely are
quite different among developing countries with
quite different climatic and environmental chal-
lenges than have been the focus in developed
countries in more temperate regions. For exam-
ple, moderate to high yielding dairy cattle breeds
selected for temperate conditions are not sus-
tainable in harsher environments where envi-
ronmental (e.g. heat stress) and feed resource
challenges exist (King
et al
., 2006). Crossbreeding
with local cattle adapted to the conditions offers
potential in those regions.
Nutritional improvement
In the last century, the nutrient and energy
requirements of farm animals in various
