Pahm Ameer A, Pedersen Carsten, Stein Hans H
Department of Animal Sciences, University of Illinois, 1207 West Gregory Drive, Urbana, Illinois 61801, USA.
J Agric Food Chem. 2008 Oct 22;56(20):9441-6. doi: 10.1021/jf801618g. Epub 2008 Sep 26.
Two experiments were conducted to measure the reactive Lys concentration in corn distillers dried grains with solubles (DDGS). In expt 1, reactive Lys was measured in 33 sources of DDGS using two procedures: the homoarginine procedure and the furosine procedure. The concentration of reactive Lys in DDGS was then correlated with the concentration of standardized ileal digestible (SID) Lys in DDGS fed to growing pigs. In expt 2, a factorial experiment was conducted using four ratios of condensed distillers solubles (CDS) and wet distillers grain (WDG). The ratios (wt/wt) of CDS to WDG were 0:100, 20:80, 40:60, and 100:0, and four subsamples from each combination were freeze-dried or oven-dried at 50, 75, or 100 degrees C. The dried samples were designated DDG, DDGS 20, DDGS 40, and CDS, respectively. All subsamples were analyzed for total Lys and for reactive Lys using the homoarginine procedure. Results of expt 1 showed that only 74.1% of total Lys was reactive if measured by the homoarginine procedure and 83.5% was reactive if measured by the furosine procedure. The concentration of SID Lys in DDGS was correlated with the concentration of reactive Lys measured by the homoarginine procedure ( r (2) = 0.70, P < 0.05) and by the furosine procedure ( r (2) = 0.66, P < 0.05). In expt 2, the concentrations of total Lys and reactive Lys were reduced ( P < 0.05) when addition of CDS or drying temperature of the samples was increased, but the reduction was greater ( P < 0.05) when both CDS addition and drying temperature were increased at the same time. After oven-drying at 100 degrees C, 75.7% of total Lys was reactive in DDG, but only 27.6 and 10.2% were reactive in DDGS 20 and DDGS 40, respectively. In conclusion, reactive Lys is correlated with the concentration of SID Lys in DDGS, and addition of CDS exacerbates the negative effects of heating on the concentration of total Lys and reactive Lys in DDGS.
进行了两项试验以测定玉米干酒糟及其可溶物（DDGS）中活性赖氨酸的含量。在试验1中，采用两种方法测定了33种DDGS来源中的活性赖氨酸：高精氨酸法和糠氨酸法。然后将DDGS中活性赖氨酸的含量与饲喂生长猪的DDGS中标准回肠可消化（SID）赖氨酸的含量进行相关性分析。在试验2中，采用析因试验，使用了四种浓缩酒糟可溶物（CDS）与湿酒糟（WDG）的比例。CDS与WDG的比例（重量/重量）分别为0:100、20:80、40:60和100:0，每种组合的四个子样本分别进行冷冻干燥或在50、75或100℃下烘干。干燥后的样本分别命名为DDG、DDGS 20、DDGS 40和CDS。所有子样本均使用高精氨酸法分析总赖氨酸和活性赖氨酸含量。试验1的结果表明，如果采用高精氨酸法测定，总赖氨酸中只有74.1%具有活性；如果采用糠氨酸法测定，则有83.5%具有活性。DDGS中SID赖氨酸的含量与采用高精氨酸法测定的活性赖氨酸含量呈正相关（r(2)=0.70，P<0.05），与采用糠氨酸法测定的活性赖氨酸含量也呈正相关（r(2)=0.66，P<0.05）。在试验2中，当CDS添加量增加或样本烘干温度升高时，总赖氨酸和活性赖氨酸的含量均降低（P<0.05），但当CDS添加量和烘干温度同时升高时，降低幅度更大（P<0.05）。在100℃烘干后，DDG中总赖氨酸的75.7%具有活性，但在DDGS 20和DDGS 40中分别只有27.6%和10.2%具有活性。总之，活性赖氨酸与DDGS中SID赖氨酸的含量相关，添加CDS会加剧加热对DDGS中总赖氨酸和活性赖氨酸含量的负面影响。
