28 November 1997

Change of diets can give quality a boost

Healthier meat. Thats the

aim of government research

which could help improve

the nutrition of the nation.

Sue Rider finds out why and

how scientists are changing

meat quality

LEAN meat is already healthy when eaten as part of a well balanced diet.

Other than fish, it is the only significant source of the type of long chain polyunsaturated fatty acids (PUFAs) known as Omega 3. These are beneficial because they reduce blood cholesterol, and improve the immune system, fertility and cell function.

More good news is that meat quality can be improved further still by changing the composition of animal diets. This was the central message to emerge from New Meats – a MAFF research conference held last week at the University of Bristols school of veterinary science, Langford.

Opening the conference, MAFFs David Hunter said the industry could now produce meat that contributes even more to a healthy diet by bringing it more in line with the recommendations of the health of the nation white paper produced by the Committee on Medical Aspects of Health (COMA). This wants us to eat less saturated fat and more beneficial polyunsaturated fatty acids, particularly the Omega 3 types. "We recognise that it is up to every individual to decide what level of meat intake is right for them, but we can make that meat as healthy as possible." Mr Hunter said there were many ideas which could be raided. It was up to the industry to recognise the opportunities and respond to them.

So what tools would let the industry manipulate meat quality? Grazed grass was one, according to Richard Dewhurst of the Institute of Grassland and Environmental Research, Aberystwyth.

As the cheapest food for ruminants, grazed grass represents a safe and natural route to increase the delivery of Omega 3 fatty acids into the human food chain, he said. It combines the need to improve product quality with the need to focus production on home-produced feeds in the post-BSE era – and with the need to reduce concentrate feeding and production costs.

Fresh grass contains high levels of the beneficial Omega 3 fatty acid known as linolenic acid (LNA). Higher levels of LNA in grass-fed beef compared with silage-fed beef, contribute to consumer preference for grass finished beef, said Dr Dewhurst.

LNA levels fall when grass is wilted before ensiling, which explains why silage fed beef is lower in valuable PUFAs.

Linseed also increases LNA, and improves the flavour of beef.

But Dr Dewhurst cited some research to show that two to three times as much LNA is transferred from grass or silage to meat or milk than from linseed diets.

For the future, IGER plans to breed grasses high in Omega 3, reduce Omega 3 loss during ensiling and in the rumen, and increase its recovery from feed into meat and milk.

Grass-fed beef is healthier and tastes better than silage-fed beef, say scientists, because it contains more of the beneficial Omega 3 fatty acids. Work is underway to raise beneficial fatty acids in grass to make meat even healthier.

Grazed grass is a safe and nutritious way to raise the delivery of Omega 3 fatty acids into the human food chain… Richard Dewhurst.

PUFAS POSITIVE EFFECTS

Saturated fatty acids raise blood cholesterol and increase risk of heart disease; polyunsaturates (PUFAs) have positive effects – they lower blood cholesterol.

Most beneficial are the long chain PUFAs – it is recommended diets should include a higher concentration of longer chain Omega 3 (also known as n-3) PUFAs and less of the n-6 PUFAs, which are found in plant oils and widely consumed. Synthesis of the Omega 3 PUFAs starts with linolenic acid, from which are produced other beneficial long chain Omega 3 acids, in particular DHA and EPA acids, which are present in oily fish.

Meat is the only significant source of long chain n-3 PUFAs in the diet other than fish, and, because we eat more meat than fish, meat has an important role in providing these nutrients. Researchers are keen to find out how to feed animals to increase levels of beneficial PUFAs in meat.