Ruminant and Swine Clinic, Free University of Berlin, 14163 Berlin, Germany.
Ruminant and Swine Clinic, Free University of Berlin, 14163 Berlin, Germany; Institute for Veterinary Epidemiology and Biostatistics, Free University of Berlin, 14163 Berlin, Germany.
J Dairy Sci. 2019 Apr;102(4):3609-3614. doi: 10.3168/jds.2018-15617. Epub 2019 Feb 1.
Few studies have compared individual variability of an intravenous glucose tolerance test (ivGTT) obtained daily in young cattle. The objective of this study was to evaluate the repeatability of glucose traits and insulin responses derived from ivGTT during 3 consecutive days in Holstein-Friesian cattle (bulls: n = 4, steers: n = 3, heifers: n = 3). Blood collections were performed from min 0 (basal concentrations) to min 63 (last measurement). Additional estimates included maximal concentration for glucose and insulin, glucose half-life time (GHLT), and glucose and insulin area under the curve. Glucose traits showed higher repeatability when compared with insulin responses. On average, the glucose trait and insulin response with the lowest coefficient of variation was GHLT (0.7%) and insulin area under the curve (21.3%), respectively. In addition, a general linear model with repeated measures was used to test for significant differences in glucose and insulin concentrations over time at different trial days. Both glucose and insulin concentrations were influenced by time point but not by trial day or time point × trial day. The results from this study showed that individual insulin responses were more variable than glucose traits. The high repeatability of GHLT evidenced the strict regulatory glucose disposal mechanisms occurring in young Holstein-Friesian cattle, whereas insulin responses showed high variability despite controlled management and nutritional practices.
很少有研究比较过在年轻牛群中每天进行的静脉葡萄糖耐量试验（ivGTT）的个体变异性。本研究的目的是评估荷斯坦弗里森牛（公牛：n=4，阉牛：n=3，小母牛：n=3）在连续 3 天内进行 ivGTT 时获得的葡萄糖特征和胰岛素反应的可重复性。从 min 0（基础浓度）到 min 63（最后一次测量）进行血液采集。其他估计值包括葡萄糖和胰岛素的最大浓度、葡萄糖半衰期（GHLT）以及葡萄糖和胰岛素的曲线下面积。与胰岛素反应相比，葡萄糖特征的重复性更高。平均而言，变异系数最低的葡萄糖特征和胰岛素反应分别为 GHLT（0.7%）和胰岛素曲线下面积（21.3%）。此外，还使用具有重复测量的一般线性模型来测试不同试验日在不同时间点的葡萄糖和胰岛素浓度的显著差异。葡萄糖和胰岛素浓度均受时间点影响，但不受试验日或时间点×试验日影响。本研究结果表明，个体胰岛素反应比葡萄糖特征更具变异性。尽管采用了严格的管理和营养措施，但 GHLT 的高重复性证明了年轻荷斯坦弗里森牛中严格的葡萄糖处置调节机制。
