Feeding dehydrated alfalfa increases polyunsaturated fatty acids concentration in Marchigiana beef muscle.

Beef meat is a low fat food (<5 % fat). However, the fatty acid composition of beef is relatively saturated (approximately 45-50 %). The polyunsaturated/saturated fatty acids (P/S) ratio in beef is approximately 0.1, the ideal being about 0.4 (Department of Health, 1994). This can cause critical comments to beef meat related to human health. Set against this, the ratio of n-6:n-3 fatty acids is beneficially low, approximately 2.0, reflecting the considerable amounts of n-3 polyunsaturated fatty acids (PUFA) in beef, particularly alpha-linolenic acid (C18:3n-3) and the long chain PUFA, eicosapentaenoic acid (C20:5n-3) and docosahexaenoic acid (C22:6n-3). Also American consumers have been advised to reduce consumption of saturated fat and total energy from fat in order to lower plasma cholesterol (NRC, 1989). Meat (and milk) from ruminants also represents the major dietary sources of conjugated linoleic (CLAs). The 9-cis, 11-trans-octadecadienoic acid, accounts for 75-90 % of total CLAs in meat. To improve the healthiness of beef, strategies for raising the P/S ratio whilst keeping n-6:n-3 low and boosting CLA are required. The P/S ratio in the total human diet should be >0.4 with an n-6:n-3 ratio <4. Several opportunities exist to change the fatty acid composition of beef by feeding diets rich in long chain PUFA such as C18:3n-3 (alpha-linolenic acid) which are present at high concentrations in grass and in mixed feed containing for example linseed (La Borde et al., 1999; Mills et al., 1992; Pezzi et al., 2004; Scollan et al., 2001; Scollan et al., 2002). Green plants are the primary source of n-3 fatty acids. Forages such as grass or legume hay contain a high proportion (50-75 %) of total fatty acids as the alpha-linolenic acid. Since fish consumption, a major source of dietary long-chain n-3 PUFA, is relatively low in Italy, research has focused on improving the fatty acid composition of meats. The aim of this work is to evaluate the opportunity of enhancing the concentration of n-3 fatty acids in beef muscle by feeding dehydrated alfalfa.[...]