Pig International - March 2012 - 11

10 Cover story

|

It is likely that we will be able to
get the whole genome of the pig
for relatively little money in the
foreseeable future.
Individual gilt testing unit at ACMC's
Beeford headquarters, left.

Pig breeding genetic research advances
The cornerstone of any pig breeding program is quality phenotypic measurements.
By Roger Abbott
Twenty-fi ve years ago livestock
breeding companies were using
the theory of multi-trait indexing as
their latest tools for driving genetic
improvement in their pig breeding lines.
This means animals were individually
measured for different traits. "Recorded
physical measurements for these traits
were fed into an index and the merit
of the animals being tested would
be expressed as a single number,"
says Ed Sutcliffe, technical director
of UK pig breeding company ACMC.
"This number would allow all
pigs in a specific batch to be ranked
according to merit, from which the
best all-round pigs could be selected
for further breeding," says Sutcliffe.

Best Linear Unbiased Prediction
However, the advent of the
Best Linear Unbiased Prediction,
BLUP, statistical theory helped
animal breeders up their game.

"With the same physical
measurements, the application of
BLUP analysis meant that not only was
selection more accurate, but we can
compare pigs over time and between
environments," says Sutcliffe. "We
are no longer bound by the constraint
of comparing animals in a common
environment (at a given point in time).
"We are making better use of the
expensive physical measurements. Use
of BLUP technology also opened up
the ability to predict the genetic merit
of offspring. While the accuracy of the
prediction may not have been high, it
was another tool to help pig breeders
make selection decisions," he said.

Pig DNA testing
In the early 1990s, molecular
biology, through DNA testing,
started to find a very important
place in pig breeding.
"I should make it clear that I
am not talking about direct genetic
modification. The most famous example

of DNA testing in pig breeding is the
identification of the halothane gene
as being directly related to Porcine
Stress Syndrome, which is still
widely used today. Much research
was done but limited use was made
when searching for these so-called
DNA 'markers'," he explains.
"Once an association between a
physical characteristic and a particular
sequence of DNA at a known location
was made, the DNA marker could
be used to select for the physical
characteristic without having to
measure the pig for the trait itself,"
says Sutcliffe. "These DNA markers
are useful for selecting traits that are
difficult to measure in the live pig, such
as meat quality. The problem is that
the association between the physical
characteristic and DNA marker does
not always hold true and can change
over time. Also, including more than
a couple of markers in selection
decisions is not straight-forward."
While Moore's law (that computing

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Table of Contents for the Digital Edition of Pig International - March 2012

Contents
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
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