ENZYMES TENDER ROLE
CURRENT research on meat quality includes the contribution of proteolytic enzymes to tenderness. Animals with a high and profitable lean tissue growth rate also have a high lean tissue turnover in the body. This also means they have a less efficient protein metabolism with higher turnover rates and more food nitrogen being excreted in the process. One of the challenges is to understand this enzyme-driven process.
"The enzymes involved also seem to keep working after slaughter and the implication is that continued selection for lean tissue growth rate could lead to tenderer meat by increasing the body concentration of proteolytic enzymes, even though selection reduces body fat," says Dr Webb.
One area of genetic research now showing potential promise is the identification of genes responsible for the numbers and types of body fibres which grow muscle at different rates. White or glycolytic fibres are associated with tougher meat, while red fibres are linked with quality. The interesting challenge is to locate the genes responsible for both fibre types as an aid to selection.
"This approach to influencing meat production and quality may be a long shot and we can barely afford the research input required. But it should not be dismissed," says Dr Webb.
His main hope for the future on the efficient production of quality pigmeat is through the accurate identification of a range of genes including those controlling growth rate, intramuscular fat and perhaps the different muscle fibre types. Pig gene maps based on the European PigMap project led from Edinburgh, Upsala in Sweden, and the USA, are now well advanced with over 1200 genes identified.
"Gene mapping progress is rapid and the next step will be to apply the knowledge to commercial pig production." *
• Exploiting enzymes which enhance tenderness of meat.
• Identifying genes for muscle fibre types.
• Gene mapping.
Maintaining intramuscular fat
• Genes discovered which increase intramuscular fat independently of backfat.
• Breeding using separate dam and sire lines.
• Increasing slaughter weights.
Using gene mapping to identify the genes that control inramuscular fat levels, muscle fibre types and growth rates is the main hope for meat quality in the future.