Effects of Feeding Distillers Grains in a Yearling Beef System on Meat Quality

Abstract Text: Distillers grains fed in a yearling beef production system were evaluated to determine the effects of lifetime exposure to distillers grains on meat quality characteristics. Crossbred heifers (n = 229; initial BW = kg 225 ± 2) were used in a randomized block design in a 2 x 2 x 2 factorial arrangement of treatments. Factors included winter supplementation while grazing corn stalks with modified distillers grains (MDGS) at either 0.91 kg (LW) or 2.3 kg (HW) on a DM basis; summer grazing supplementation with dry distillers grains at 0.6% BW (SS) on a DM basis daily or no supplementation (NS); and finishing diet containing either 40% Sweet Bran (SBF) or 40% MDGS (DGF) on a DM basis. Heifers were stratified by BW and randomly assigned to treatment prior to start of each phase within previous treatments. Choice grade strip loins (n = 12) were collected from each of the 8 treatments. After 7 d postmortem aging, strip loins were fabricated into 2.5 cm thick steaks. Discoloration scores were determined during 7 d retail display by a 5-member panel.  The remaining strip loin was aged an additional 14 d before fabrication was repeated. The HW supplementation increased discoloration 15% compared to LW supplementation (P < 0.01). Summer supplementation interacted with finishing diet (P = 0.01), with SS increasing discoloration by 30% within SBF (P = 0.01); but no differences between SS or NS in steaks from DGF cattle (P = 0.95). Finishing diet had no effect (P > 0.10) on discoloration scores for retail d 1 - 5 and d 1 - 3 for steaks aged 7 and 21 d, respectively; however, scores increased for the DGF (P < 0.01) compared to SBF on d 6 - 7 and d 4 - 6 for steaks aged 7 and 21 d, respectively. Winter supplementation interacted with finishing diet  within SBF, with HW causing fatty acid 18:2 and  total polyunsaturated fatty acids concentrations on a weight percentage basis to increase 21% and to increase 19% (P = 0.02 and 0.01, respectively), but no observed differences in DGF steaks (P = 0.43 and 0.33, respectively).  Supplementing with DGS prior to finishing was not additive in impacting the color stability and overall shelf-life of retail beef when finished using MDGS, however, polyunsaturated fatty acids from MDGS fed during the backgrounding phase can affect beef quality.

Keywords: Beef, Distillers grains, Shelf life