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Detailed information and articles on grass seed and related matters |
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The effect of forage on human health
Forages, Fat and Flavour
Amongst the conflicting ‘evidence’ about diet and health with which consumers are bombarded, ruminant products (milk, cheese, beef and lamb) have been criticised for the possible adverse effects of their saturated fatty acids on human health. As a result, methods of altering the fatty acid composition of these products are of great interest. Cotswold Seeds takes a look at work carried out by Nigel Scollen and Richard Dewhurst at IGER, Aberystwyth.
The Department of Health has recommended an increase in the intake of unsaturated fatty acids and, in particular, Omega 3, a type of polyunsaturated fatty acid found in fish oils, because they are thought to be beneficial to human health, especially in reducing the risks of coronary heart disease. Green plants are the primary source of these fatty acids. Fish, which derive their fatty acids from marine plankton, are used extensively in concentrated animal foods, but forage plants would represent a more natural and environmentally sustainable source of these fatty acids. At IGER, they have investigated the potential to exploit this source of fatty acids. Fresh grass contains a high proportion of fatty acids and the amount varies within the plant, depending on the factors such as stage of maturity and light treatments. The reason that these fatty acids are important is because they are absorbed by the animal and then appear in our food.
Fatty acids in grasses
IGER looked at the changes in fatty acid levels in a range of grass species and varieties at different times of the year. They found the amount varied considerably at different cutting times. In grass in November, for example, levels were highest with Italian ryegrass and hybrid ryegrass (about 15g/kg DM), intermediate with Perennial ryegrass and lowest with Fescues, Timothy and Cocksfoot. However, the opposite trend was found in the following summer’s results.
The benefit to farmers is that, potentially, plant breeders selecting new strains of grasses could select for certain types of desirable fatty acids, enabling the production of milk and meat to have greater appeal to customers.
Fatty acids in grass silage
IGER looked at the effects of silage-making techniques on the quantity and quality of fatty acids in the silage produced. A series of silages was made from Perennial ryegrass. The grass was treated in different ways in the field and was found that wilting, for 68 hours, had the most dramatic effect with a dramatic loss of fatty acids. The major differences in fatty acid composition were largely due to wilting and not the silage making process itself.
Fatty acids and beef
IGER has investigated the opportunity to manipulate the fatty acid composition of beef, and the resulting effects on meat quality, by feeding animals on feed sources which are rich in beneficial fatty acids. The results clearly demonstrated that feeds containing beneficial fatty acids can be translated into meat, which is beneficial to human health and interestingly enhances the flavour of the meat.
Conclusion
There is no doubt that the consumer is interested in health issues and is knowledgeable about the food they eat. Information is increasingly available and this means that quality of food will continue to rise up their list of priorities. Let us hope that work at IGER leads to enhanced foods quality through something as simple as grass.
Forage Matters Summer 1999
- This work is being carried out in collaboration with Dr Jeff Wood and his team at the University of Bristol and is funded by MAFF.
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