Download LINK project: Genetic control of meat quality (LK0626)

EXECUTIVE SUMMARY
SLP LINK Project LK0626
Genetic control of meat quality
Start date: 01/10/1999
End date: 31/03/2003
Partners:
Meat & Livestock Commission
Roslin Institute
Rowett Research Institute
Sponsor:
Ministry of Agriculture, Fisheries & Food (now Defra)
Aims and objectives
The aim of this project was to develop genetic predictors of meat quality in pigs.
Approach
Candidates for genes controlling a variation in a trait of interest (e.g. meat quality)
can be identified in two ways. From knowledge of the trait and the physiological
mechanisms and processes thought to be involved – “physiological candidate genes”
can be identified and tested.
For example, meat quality can be assumed to be
associated with the characteristics of muscle tissue. Therefore, genes known to be
involved in the development of muscle might be considered as candidates. The
alternative approach involves identifying candidate genes on the basis of their
location, i.e. which chromosome they are found on and where on the chromosome.
This second approach relies upon knowledge of the location of genes on pig
chromosomes and methods for determining which chromosomal locations are
associated with variation in the trait of interest.
Results
Developing embryos were isolated from Duroc and Large White pigs, muscle tissues
were sampled and stored. Proteins and RNA (the messenger molecule that act as
an intermediate between genes and proteins) were isolated. From comparisons of
the proteins present in Duroc and Large White embryos of equivalent ages and from
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comparisons of the gross morphology of the developing muscles we found some
evidence of differences in the timing of some aspects of muscle development
between the breeds.
Regions on pig chromosomes 5 and 9 associated with variation in some meat quality
parameters, including the ease with which the meat could be sheared, were identified
in an earlier study.
These regions, however, were only approximately defined,
equivalent to defining the location of a house as being in London. Only a few genes
had already been mapped to these locations in pigs at the start of the project. By
exploiting knowledge of the equivalent region of the better characterised human
genome (the organisation of genes, chromosomes and genomes is conserved
amongst animals including pigs and humans) we were able to assign several more
genes to the regions shown earlier to be associated with variation in meat quality. By
characterising the DNA around these genes we were able to develop several new
genetic markers (variable DNA sequences that can be tracked from parent to
offspring) in the regions of interest. These new genetic markers allowed us to repeat
the tests for association between the regions of interest and variation in meat quality.
Unfortunately, rather than allowing us to map the genes responsible for the meat
quality effects with greater precision, the analyses with the additional information
provided by the new markers provide no compelling support for the original
observations. On the basis of these genetic analyses we have no strong evidence
for the hypothesis that the so-called ‘Duroc effect’ is controlled by a single major
gene that confers improvements in meat quality, specifically tenderness, through
differences in the fibre composition of Duroc muscles compared to muscles for other
breeds.
Potential benefits to the food chain and/or the environment:
The identification of genetic determinants of meat quality would allow a simple
genetic test for the desirable genetic variant to be developed. Such a test could be
exploited to allow a rapid and targeted improvement of UK breeding stock and
provide a test that gives quality assurance and allows appropriate processing of
carcasses in the slaughter-house.
Knowledge and technology transfer:
The original research proposal was designed to build upon the results of previous
studies that had suggested that the so-called ‘Duroc effect’ is controlled by a single
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major gene that causes the fibre make-up of muscles in Duroc pigs to differ from
those of other pig breeds with the meat derived from the muscle being more tender.
Unfortunately, the results from this research project do not provide convincing
support for this hypothesis. Nevertheless a small desk-based feasibility study is
being undertaken with Genesis Faraday SPARK funding to examine how genetic
markers for meat quality could be exploited by pig breeding companies.
CONTACT
Dr Alan Archibald
Roslin Institute
Roslin
Midlothian
EH25 9PS
Tel: 0131 527 4200
Fax: 0131 440 0434
[email protected]
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