Faldet M A, Satter L D, Broderick G A
U.S. Dairy Forage Research Center, Madison, WI 53706.
J Nutr. 1992 Jan;122(1):151-60. doi: 10.1093/jn/122.1.151.
Soybeans were heated in a forced air oven at 120 and 130 degrees C for 60 and 180 min, and at 140, 150 and 160 degrees C for 10, 30, 60, 90 and 120 min. Two types of measurements were used to determine optimal heat treatment of soybeans to maximize protein utilization by ruminants. One was to estimate the rate and extent of protein degradation in the rumen using an in vitro ruminal system. The second was to determine the nutritional availability of lysine. Methods used to determine available lysine were an indirect fluorodinitro-benzene chemical method and a rat growth assay. The product of undegraded intake protein and available lysine content was used to estimate the amount of lysine that would escape ruminal degradation and be available for intestinal absorption. As heat input increased, ruminal undegraded intake protein increased, and protein degradation rates and total and available lysine decreased. As temperature increased, the time required to maximize post-ruminal available lysine decreased. The optimal heat treatment for soybeans heated in a forced air oven was: 140 degrees C for 120 min or greater, 150 degrees C for 60 min or 160 degrees C for 30 min. A loss of 15-22% of chemically determined available lysine was necessary to achieve the heat treatment that resulted in maximal post-ruminal available lysine.
大豆在强制通风烘箱中于120℃和130℃加热60分钟和180分钟，以及在140℃、150℃和160℃加热10分钟、30分钟、60分钟、90分钟和120分钟。使用两种测量方法来确定大豆的最佳热处理方式，以最大化反刍动物对蛋白质的利用率。一种是使用体外瘤胃系统估计瘤胃中蛋白质降解的速率和程度。第二种是确定赖氨酸的营养可利用性。用于确定可利用赖氨酸的方法有间接氟二硝基苯化学法和大鼠生长试验。未降解摄入蛋白质与可利用赖氨酸含量的乘积用于估计可逃过瘤胃降解并可用于肠道吸收的赖氨酸量。随着热量输入增加，瘤胃未降解摄入蛋白质增加，蛋白质降解率以及总赖氨酸和可利用赖氨酸减少。随着温度升高，使瘤胃后可利用赖氨酸最大化所需的时间减少。在强制通风烘箱中加热大豆的最佳热处理条件是：140℃加热120分钟或更长时间，150℃加热60分钟或160℃加热30分钟。要实现能使瘤胃后可利用赖氨酸最大化的热处理，化学测定的可利用赖氨酸需损失15 - 22%。
