The objective of this study was to quantify the differences in the activity of jejunal maltase and isomaltase between 2 groups of steers with average dry matter intake (DMI) and differing average daily gain (ADG). Dry matter intake and ADG were measured in crossbred steers (n = 69; initial body weight = 456 ± 5.0 kg) consuming a finishing diet containing 67.8% dry-rolled corn, 20.0% wet distillers grains with solubles, 8.0% alfalfa hay, and 4.2% vitamin/mineral supplement on a dry matter basis for 84 days. Jejunal mucosal samples were collected from 8 steers with the greatest (high) or least (low) ADG and average DMI (± 0.55 standard deviation). Homogenates of jejunal mucosa were incubated with increasing amounts of maltose and isomaltose to determine the disaccharidase kinetics. Total mucosal protein concentration (mg protein/g tissue; P = 0.45) of the mucosa and small intestinal weights (P = 0.69) did not differ between the groups. Neither the K_m of isomaltase (P = 0.15) or maltase (P = 0.21) differed between groups. The isomaltase V_max expressed per gram of protein tended to differ (P = 0.10) between groups of steers but did not differ (P = 0.13) when expressed on a tissue basis. Similarly, neither the maltase V_max expressed per gram of protein (P = 0.31) or tissue (P = 0.32) differed between groups. While previous studies have indicated that disaccharidase expression is associated with differences in ADG, data presented here indicate that differences in enzyme activity at the end of the finishing period are minimal.

中文翻译：

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简短交流：黏膜双糖酶动力学与平均日增重不同的公牛空肠中表达的关联。

本研究的目的是量化平均干物质摄入量 (DMI) 和平均日增重 (ADG) 不同的两组公牛之间空肠麦芽糖酶和异麦芽糖酶活性的差异。在食用含有 67.8% 干轧玉米、20.0% 可溶物湿酒糟、8.0% 苜蓿干草和84 天干物质基础上的 4.2% 维生素/矿物质补充剂。从具有最大（高）或最小（低）ADG 和平均 DMI（± 0.55 标准偏差）的 8 头公牛收集空肠粘膜样本。将空肠黏膜匀浆与越来越多的麦芽糖和异麦芽糖一起温育，以确定双糖酶动力学。总黏膜蛋白浓度（mg 蛋白/g 组织；P = 0.45) 的黏膜和小肠重量 ( P = 0.69) 在各组之间没有差异。异麦芽糖酶 ( P = 0.15) 或麦芽糖酶 ( P = 0.21)的 K _m在组间均无差异。每克蛋白质表达的异麦芽糖酶 V _max在各组公牛之间趋于不同（P = 0.10），但在组织基础上表达时没有差异（P = 0.13）。类似地，无论是麦芽糖酶V_最大每克蛋白质的表达（P = 0.31）或组织（P= 0.32) 组间不同。虽然之前的研究表明双糖酶表达与 ADG 的差异有关，但此处提供的数据表明，在整理期结束时酶活性的差异很小。