Effects of vitamin E and flaxseed on rumen-derived fatty acid intermediates in beef intramuscular fat

To elucidate the effects of dietary vitamin E with or without flaxseed on beef fatty acid composition, 80 feedlot steers were fed 4 diets: Control-E (451 IU dl-alpha-tocopheryl acetate/head/day), Control + E (1051 IU dl-alpha-tocopheryl acetate/head/day), Flax-E (10% ground) and Flax + E. Vitamin E had no effect on animal growth or carcass weight (p>0.05), while flaxseed-fed steers had greater average daily gain (p = 0.007), final live weight (p = 0.005) and heavier carcasses (p = 0.012). Feeding flaxseed increased the total n-3 fatty acid content of beef and this response was further accentuated by the inclusion of high levels of vitamin E in the diet. Feeding flax increased levels of some 18:3n-3 partial hydrogenation products including c15- and t13/14-18:1 and several 18:2 isomers (p<0.001) but decreased t10-18:1 (p<0.001). Vitamin E enhanced intramuscular levels of 18:3n-3 and its biohydrogenation products leading to greater accumulations of total n-3 fatty acids in lean ground beef. The consequences of increasing the concentrations of partially hydrogenated products on human health have yet to be investigated. Crown Copyright (c) 2011 Published by Elsevier Ltd. All rights reserved.