Substitution of wheat dried distillers grains with solubles for barley silage and barley grain in a finishing diet increases polyunsaturated fatty acids including linoleic and alpha-linolenic acids in beef

Abstract

Wheat dried distillers grain with solubles (WDDGS) contain low levels of starch, but are high in protein and fiber and have been used as a substitute for barley grain in commercial Western Canadian finishing diets for beef cattle. This study investigated effects of WDDGS on fatty acid profiles of meat when it was substituted for barley silage in a barley grain finishing diet. Steers (n=240; 489±30.0kg) were fed one of four finishing diets consisting of a barley based concentrate (barley grain plus additives), barley silage and WDDGS (dry matter (DM) basis) in ratios of 850:150:0 (CON), 650:100:250 (WDDG25), 650:50:300 (WDDG30), and 650:0:350 (WDDG35) over a 12wk period. Substitution of WDDGS for barley silage increased (P<0.01) concentrations of total polyunsaturated fatty acids (PUFA), including linoleic acid and alpha-linolenic acid (ALA) in pars costalis diaphragmatis muscle without affecting major trans fatty acids. Replacement of 100 and 150g silage with 200g of barley grain/kg feed DM with WDDGS increased (P<0.05) ALA, from 0.32g in CON to 0.40 and 0.41g/kg of total fatty acids in WDDG30 and WDDG35, respectively. Results suggest that replacement of barley silage with up to 350g WDDGS/kg DM increases total PUFA and omega-3 fatty acids in beef.