INFLUENCE OF CUTTING AND SEASON ON THE FATTY ACID COMPOSITION OF FORAGE CROPS FOR GRAZING FORAGE BEEF PRODUCTION

摘要

IntroductionLittle information is available on the effect of the nature of pasture lipids on beef lipids. Unsaturated fatty acids, particularly n-3 polyunsaturated fatty acids (PUFA) and conjugated linoleic acid (CLA), may be beneficial to human health. Milk and meat are the only significant sources of CLA in the human diet and appears to be related to the consumption of fresh pasture by ruminants (Elgersma et al, 2003). Sources of variation in forage lipid concentration are plant species, growth stage, temperature and light intensity. Fresh forage contains a high proportion (50-75%) of its total fatty acid content in the form of n-3 linolenic acid. Levels of linolenic acid vary with plant factors such as stage of maturity and with light treatment. Fatty acid profiles are distinctive to particular species, which confirms that fatty acid composition of forages is under considerable genetic control (Dewhurst et al., 2001). This offers the potential to select for forages with higher concentrations or altered types of fatty acids.