Boucher S E, Pedersen C, Stein H H, Schwab C G
Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA.
J Dairy Sci. 2009 Aug;92(8):3951-8. doi: 10.3168/jds.2008-1993.
Three samples of soybean meal (SBM), 3 samples of expeller SBM (SoyPlus, West Central Cooperative, Ralston, IA), 5 samples of distillers dried grains with solubles (DDGS), and 5 samples of fish meal were used to evaluate the furosine and homoarginine procedures to estimate reactive Lys in the rumen-undegraded protein fraction (RUP-Lys). One sample each of SBM, expeller SBM, and DDGS were subjected to additional heat treatment in the lab to ensure there was a wide range in reactive RUP-Lys content among the samples. Furosine is a secondary product of the initial stages of the Maillard reaction and can be used to calculate blocked Lys. Homoarginine is formed via the reaction of reactive Lys with O-methylisourea and can be used to calculate the concentration of reactive Lys. In previous experiments, each sample was ruminally incubated in situ for 16 h, and standardized RUP-Lys digestibility of the samples was determined in cecectomized roosters. All rumen-undegraded residue (RUR) samples were analyzed for furosine and Lys; however, only 9 of the 16 samples contained furosine, and only the 4 unheated DDGS samples contained appreciable amounts of furosine. Blocked RUP-Lys was calculated from the furosine and Lys concentrations of the RUR. Both the intact feed and RUR samples were evaluated using the homoarginine method. All samples were incubated with an O-methylisourea/BaOH solution for 72 h and analyzed for Lys and homoarginine concentrations. Reactive Lys concentrations of the intact feeds and RUR were calculated. Results of the experiment indicate that blocked RUP-Lys determined via the furosine method was negatively correlated with standardized RUP-Lys digestibility, and reactive RUP-Lys determined via the guanidination method was positively correlated with standardized RUP-Lys digestibility. Reactive Lys concentrations of the intact samples were also highly correlated with RUP-Lys digestibility. In conclusion, the furosine assay is useful in predicting RUP-Lys digestibility of DDGS samples, and the guanidination procedure can be used to predict RUP-Lys digestibility of SBM, expeller SBM, DDGS, and fish meal samples.
使用三份豆粕（SBM）样品、三份压榨豆粕样品（SoyPlus，西中合作社，爱荷华州拉尔斯顿）、五份干酒糟及其可溶物（DDGS）样品和五份鱼粉样品，来评估呋喃素和高精氨酸方法，以估算瘤胃未降解蛋白质部分（RUP-Lys）中的反应性赖氨酸。对一份SBM、一份压榨豆粕和一份DDGS样品在实验室进行额外热处理，以确保样品间反应性RUP-Lys含量有较宽范围。呋喃素是美拉德反应初始阶段的副产物，可用于计算被阻断的赖氨酸。高精氨酸是由反应性赖氨酸与O-甲基异脲反应形成的，可用于计算反应性赖氨酸的浓度。在之前的实验中，每个样品在瘤胃中进行原位培养16小时，并在切除盲肠的公鸡中测定样品的标准化RUP-Lys消化率。对所有瘤胃未降解残渣（RUR）样品分析其呋喃素和赖氨酸含量；然而，16个样品中只有9个含有呋喃素，且只有4个未加热的DDGS样品含有可观量的呋喃素。根据RUR的呋喃素和赖氨酸浓度计算被阻断的RUP-Lys。完整饲料和RUR样品均采用高精氨酸方法进行评估。所有样品与O-甲基异脲/BaOH溶液孵育72小时，并分析赖氨酸和高精氨酸浓度。计算完整饲料和RUR的反应性赖氨酸浓度。实验结果表明，通过呋喃素方法测定的被阻断的RUP-Lys与标准化RUP-Lys消化率呈负相关，通过胍基化方法测定的反应性RUP-Lys与标准化RUP-Lys消化率呈正相关。完整样品的反应性赖氨酸浓度也与RUP-Lys消化率高度相关。总之，呋喃素测定法可用于预测DDGS样品的RUP-Lys消化率，胍基化方法可用于预测SBM、压榨豆粕、DDGS和鱼粉样品的RUP-Lys消化率。
