Replacing cottonseed meal and sorghum grain with corn dried distillers' grains with solubles in lamb feedlot diets: carcass, trained sensory panel, and volatile aroma compounds traits.
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In a randomized design study, lambs were individually fed with ad libitum access to 70.9% concentrate diets for 56 d in individual pens. The positive control diet (CNTL) contained cottonseed meal (CSM), sorghum grain, and cottonseed hulls, but no dried distillers' grains with solubles (DDGS). Four treatment diets were similar to CNTL but did not contain CSM. Corn DDGS replaced 0% (0DDGS), 33% (33DDGS), 66% (66DDGS), or 100% (100DDGS) of the sorghum grain in the treatment diets. At 48-h postmortem, the longissimus muscle (LM) was removed from the carcass, cut into chops, frozen, thawed, cooked, and evaluated by a trained sensory panel. Lambs fed CNTL were compared with 0DDGS using contrasts and linear and quadratic effects were evaluated among the four DDGS diets. Lambs fed CNTL had greater (P 0.03) hot carcass weight (HCW) and LM area than lambs fed 0DDGS. As DDGS incrementally replaced sorghum grain, marbling linearly decreased (P = 0.03), LM area tended to linearly increase (P = 0.06), and skeletal maturity tended to linearly decrease (P = 0.06). As DDGS incrementally replaced sorghum grain, flavor attributes quadratically increased to 33DDGS then decreased (brown, roasted, umami; P 0.03), quadratically decreased to 33DDGS then increased (metallic; P = 0.004), or linearly decreased (lamb flavor identity; P = 0.03). Volatile aroma compounds 2-(hexyloxy)-ethanol decreased and 2,3-octanedione and methyl pyrazine increased quadratically with an increase in DDGS (P < 0.05). Additionally, 2-heptenal, heptanal, and 2-pentyl furan increased linearly, while 2-butanone decreased linearly as DDGS increased in the diet (P < 0.05). Results indicate that carcass and sensory characteristics and volatile aroma compounds are not negatively affected, in fact brown, roasted, and umami flavors are enhanced, when 33% DDGS replaces CSM and sorghum grain in Dorper lamb feedlot diets.