Pig International - March 2012 - 12
Integrating genomic selection into pig breeding programs promises to deliver
greater rates of improvement in the future for important traits such as litter size.
power doubles every two years)
may be commonly known, a similar
phenomenon (exponential improvement)
has been seen in the costs and speed
associated with reading genotypes
of animals from DNA samples.
"This has opened up yet more
possibilities for animal and pig
breeders," says Sutcliffe.
"Knowing the genotype of pigs at
many locations along the chromosomes,
and knowing the genotype of pigs in
the pedigree of pigs, it is possible to
track sections of chromosomes being
inherited down the generations.
"It is also possible, knowing the
performance of these animals, to assign
values to these segments of the animal's
genome as to how they influence a
given quantitative trait such as growth,
backfat and feed intake," he said.
There was a lot of press coverage
in the 1990s, for example, about
breeding companies that were chasing
the "holy grail" of being able to pluck
a hair out of a new-born piglet and
then confidently decide whether or
not to select the animal for breeding.
Sutcliffe points out that three or
four years ago, it was also suggested
that coupling genotype data to
statistical analyses would allow a
reduction in the collection of the
expensive physical measurements.
March/April 2012 | www.WATTAgNet.com
Pig breeders physically measure
a couple of generations and also
genotype them to assess the "value" of
the chromosome segments. Then they
would simply genotype the next few
generations and work out their merit
by summing the "values" of each of the
chromosome segments they carried.
"This would obviously appeal
to breeding companies chasing the
holy grail. They would not have to
spend as much on performance
trait measurements - but would
have to spend money on genotyping
more animals instead," he says.
New hybrid approach
However, in keeping with the fast
pace of technological development
in the molecular biology field, this
idea has largely been discarded
and replaced by a hybrid of BLUP
and the molecular approach.
Each pig is given a standard BLUP
value and a new genomic value.
Using the genomic value would
roughly increase accuracy by 25%
above BLUP evaluation alone.
"So, rather than reduce the
importance (less animals being
measured) of the phenotypic
measurements, the current
improvements in pig breeding are
yet again extracting as much value
Ed Sutcliffe, technical director
of ACMC Ltd.-"Pig farmers can
look forward to a great deal of
improvement on the genetic front."
as possible from the expensive
phenotypes," said Sutcliffe. "While
the technology surrounding animal
breeding develops a pace, there
is one truism which persists.
"The cornerstone of any pig
breed improvement program was,
is, and always will be, good quality
phenotypic measurements. While
knowing the DNA sequence of a
particular animal can tell breeders
a lot, knowing how the "collection
of genes" - the animal's genome -
actually equates to performance will
always be more important," he said.
As for the future of molecular
biology in animal breeding - it is
generally understood that the latest
thinking will quickly be outdated.
"It is thought likely that rather than
reading the genotype at a few thousand
places, we will be able to get the whole
genome of animals for relatively little
money in the foreseeable future," said
Sutcliffe. "This will be like going from
reading the first letter on every 14th
page of a book with 840,000 pages to
reading every letter of every word.
Let's hope Moore's Law continues
for many years to come if we are to
make any sense out of all this data."
In other words, pig farmers can look
forward to a great deal of improvement
on the genetic front.
Table of Contents for the Digital Edition of Pig International - March 2012
Pig International - March 2012 - Cover1
Pig International - March 2012 - Cover2
Pig International - March 2012 - Contents
Pig International - March 2012 - 2
Pig International - March 2012 - 3
Pig International - March 2012 - 5
Pig International - March 2012 - 6
Pig International - March 2012 - 7
Pig International - March 2012 - 8
Pig International - March 2012 - 9
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Pig International - March 2012 - 11
Pig International - March 2012 - 12
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Pig International - March 2012 - Cover3
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