Supplementing beef cattle finishing diets containing wheat distillers grain with feed enzymes to decrease the ratio of n-6/n-3 fatty acids in meat
The objective of this study was to determine the effects of dietary feed enzyme (FE) supplementation on fatty acids (FA, % of total FA) profiles of the pars costalis diaphragmatis (PCD) muscle of beef cattle fed finishing diets with or without inclusion of wheat dried distillers grain with solubles (DDGS). One hundred and sixty crossbred yearling steers (initial BW 495 ± 37.9 kg) were blocked by BW and randomized into 16 pens (10 steers/ pen). The pens were randomly assigned to 1 of 4 treatments: 1) control (CON; 10% barley silage and 90% barley grain-based concentrate); 2) WDG (CON diet substituting 30% wheat DDGS for barley grain); 3) WDGL (WDG diet supplementing with low FE; 1 mL FE/kg diet DM); and 4) WDGH (WDG diet supplementing with high FE; 2 mL FE/kg diet DM). The PCD samples were collected from cattle at slaughter at the end of the finishing period (120 d) with a targeted live weight of 650 kg. Data were analyzed using the MIXED procedure of the SAS (SAS Institute Inc.), considering treatment (diet) as fixed effect. Contrasts were generated to compare the CON and WDG diet. Linear and quadratic orthogonal contrasts were generated to exam the effect of increasing FE in the diet containing wheat DDGS. Concentration of total polyunsaturated fatty acids (PUFA) in muscle was greater (P < 0.01; 4.52 vs. 3.41), whereas total monounsaturated FA tended (P = 0.08; 45.0 vs. 47.1) to be less for steers fed WDG than steers fed CON. In addition, inclusion of wheat DDGS into the diet vs. diet containing no DDGS increased (P < 0.01) concentration of conjugated linoleic acids and vaccenic acid (CLA+VA; 1.22 vs. 0.78) and decreased (P = 0.03) total trans FA (excluding CLA and VA; 0.98 vs. 1.27), consequently resulted in higher (P < 0.01) ratio of n-6/n-3 PUFA (10.95 vs. 7.72). Increasing FE application in wheat DDGS diets linearly decreased (P = 0.02) the ratio n-6/n-3 FA (10.95 to 9.23) in muscle without affecting amount of individual or total FA. These results suggest that application of FE in finishing diets containing wheat DDGS may improve FA profiles of beef which could benefit human health.
Keywords: beef, fatty acid, feed enzyme