Milk fat enriched in n-3 fatty acids

Feeding dairy cows with rumen protected n-3 fatty acids (FAs) derived from oilseeds or marine oils significantly increased the proportion of these acids in milk fat. Feeding protected canola/soybean oilseed (70/30, w/w) and soybean oilseed/linseed oil (70/30, w/w) supplements increased the proportions of C18:3 from 0:8 to 2.49 and 0.64 to 8.45%, respectively. Feeding protected soybean oilseed/tuna oil (70/30, w/w) increased the proportions of eicosapentaenoic (C-20:5) and docosahexaenoic (C-22:6) from 0 to 0.86 and 0 to 1.41%, respectively, in milk fat. There were also increases in the proportions of linoleic (C18:2) and a simultaneous reduction in the saturated FAs myristic (C-14:0) and palmitic, (C 16:0) concentration, with no significant change in the proportion of stearic acid (C 18:0). These changes in the fatty acid composition had pronounced effects on the thermal characteristics of milk fat with a much higher proportion of liquid fats at lower temperatures, which will improve spreadability, of butter. The proportions of n-3 FAs increased in milk fat at higher supplementation rates, however, the efficiency of transfer declined. This relationship between supplementation and transfer rate will determine the optimal feeding regimes necessary to produce the desired proportions of n-3 FAs in milk and dairy products. (C) 2002 Elsevier Science B.V. All rights reserved.