Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE.
J Anim Sci. 2019 Apr 29;97(5):2087-2098. doi: 10.1093/jas/skz086.
The objective of this study was to evaluate the effects of feeding high-protein corn distillers grains on fresh beef quality. Steers (n = 60) were fed one of five diets for 190 d (six pens with 10 cattle/pen/diet): a corn control (Control), 40% high-protein dry distillers grains plus solubles (HP-DDGS), 40% dry distillers grains plus solubles (DDGS), 40% wet distillers grains plus solubles (WDGS), or 40% bran plus solubles (Bran). Eighteen Choice carcasses (three cattle per pen) were randomly selected within each treatment; however, two carcasses were lost during carcass selection. Strip loins (Longissimus lumborum, IMPS # 180) were collected, divided into three equal portions, and aged for 2, 9, or 23 d. Steaks were fabricated following each aging period and placed under retail display (RD) conditions for 0, 4, or 7 d. Pen was the experimental unit. Hot carcass weight at harvest was 391 kg (SD 31.6 kg). Dietary treatment had no effect on tenderness (Warner-Bratzler shear force) within each aging period (P > 0.05). After 7 d of RD, following all aging periods, steaks from cattle fed HP-DDGS had the greatest visual discoloration except for DDGS and Bran after 23 d (P < 0.05). The steaks from cattle fed HP-DDGS had lower (P < 0.05) redness (a*) values than all other treatments following 7 d of RD. Lipid oxidation increased (P < 0.001) during RD at all aging periods, as measured via thiobarbituric acid reactive substance (TBARS). A day of RD-by-dietary treatment effect (P < 0.001) was observed for lipid oxidation. After 7 d of RD, steaks from cattle fed HP-DDGS had higher TBARS than all other treatments except WDGS (P < 0.01). A trend was found for sarcomere length (P = 0.07), with steaks from cattle fed Bran having the longest sarcomere length compared with all other treatments. An aging effect was found for free calcium content (P < 0.001) where steaks aged 9 and 23 d had significantly higher levels of free calcium than those aged 2 d. There was a tendency (P = 0.07) that steaks from cattle fed WDGS contained more free calcium than steaks from cattle fed DDGS or Bran. Although there were no statistical differences, there was a trend (P = 0.07) that steaks from cattle fed HP-DDGS had higher levels of PUFAs and C18:2. These results suggest that feeding high protein distillers grains has no detriment on tenderness, but may alter the lipid profile of the muscle, resulting in decreased color stability, increased lipid oxidation, and decreased shelf life.
本研究旨在评估饲喂高蛋白玉米酒糟对鲜牛肉质量的影响。选择 60 头阉牛，饲喂五种日粮，每组 10 头牛，每头阉牛 1 个重复，共 6 个重复，每个重复 10 头牛，试验期 190d：玉米对照组（Control）、40%高蛋白干酒糟及其可溶物（HP-DDGS）、40%干酒糟及其可溶物（DDGS）、40%湿酒糟及其可溶物（WDGS）或 40% bran 及其可溶物（Bran）。每个处理组中随机选择 18 个 Choice 胴体（每个重复 3 个），但在胴体选择过程中丢失了 2 个。采集腰大肌（Longissimus lumborum，IMPS # 180），分成 3 等份，分别在 2、9 和 23 d 进行成熟。在每个成熟阶段后制作牛排，并在零售展示（RD）条件下放置 0、4 或 7 d。试验以重复为单位。收获时热胴体重为 391kg（SD 31.6kg）。在每个成熟阶段，日粮处理对嫩度（W-B 剪切力）没有影响（P＞0.05）。RD 后 7d，在所有成熟阶段后，饲喂 HP-DDGS 的牛的牛排的视觉变色最大，除了 23d 的 DDGS 和 Bran（P＜0.05）。在 RD 后 7d，饲喂 HP-DDGS 的牛的牛排的红色值（a*）显著低于其他所有处理组（P＜0.05）。在所有成熟阶段的 RD 期间，脂质氧化均增加（P＜0.001），通过硫代巴比妥酸反应物（TBARS）测量。RD 期间存在日粮处理效应（P＜0.001）。RD 后 7d，饲喂 HP-DDGS 的牛的牛排的 TBARS 高于除 WDGS 以外的所有处理组（P＜0.01）。发现肌节长度存在趋势（P=0.07），与其他所有处理组相比，Bran 组的肌节长度最长。游离钙含量存在成熟效应（P＜0.001），9 和 23d 成熟的牛排中的游离钙含量显著高于 2d 成熟的牛排。WDGS 组牛排中的游离钙含量有高于 DDGS 或 Bran 组的趋势（P=0.07）。尽管没有统计学差异，但存在趋势（P=0.07），即饲喂 HP-DDGS 的牛的牛排中多不饱和脂肪酸（PUFAs）和 C18:2 的含量更高。这些结果表明，饲喂高蛋白酒糟对嫩度没有不利影响，但可能会改变肌肉的脂质谱，导致颜色稳定性降低、脂质氧化增加和货架期缩短。
