Department of Dairy Science, University of Wisconsin, Madison 53706.
College of Animal Science and Technology, China Agricultural University, Beijing, China, 100083.
J Dairy Sci. 2018 Nov;101(11):9971-9977. doi: 10.3168/jds.2017-14027. Epub 2018 Sep 13.
This study compared dry matter (DM) predictions of 3 handheld near-infrared spectrophotometer (NIRS) units (Moisture Tracker, Digi-Star Inc., Fort Atkinson, WI) to conventional oven drying at 60°C using 2 alfalfa and 2 corn silages. In addition, on-farm DM methods [microwave, Koster tester (Koster Moisture Tester Inc., Brunswick, OH), and food dehydrator methods] were also compared. Corn and alfalfa silages (1,600 g) obtained from the University of Wisconsin Dairy Cattle Center (DCC) and the Arlington Research Station (ARS) were analyzed for DM daily for 20 d. Two NIRS calibration methods were also tested within each unit. The DM predicted from the factory-preset calibrations was NIR. The adjusted DM prediction was NIR, where the average difference between oven-dried and NIR determined on duplicate forage samples for 3 d before the experiment was used as a bias adjustment for all subsequent DM determinations. The average predicted DM from the 20 scans was recorded as the forage DM. The process was repeated 3 times with each NIRS unit. Two 100-g subsamples of each forage were also oven-dried for 48 h at 60°C daily in a forced-air oven. Oven DM of ARS and DCC alfalfa silages were 37.3 ± 1.1% and 48.5 ± 1.9%, respectively (mean ± standard deviation). Oven DM of ARS and DCC corn silages were 34.7 ± 1.2% and 37.4 ± 0.5%, respectively (mean ± standard deviation). Dry matter determinations from NIR were on average 3.5 units higher than the oven DM values. The NIR DM predictions were on average 1.7 DM units lower than the oven DM values. Additionally, differences among the 3 NIR probe results were detected (43.1, 40.7, and 41.3% DM, respectively), but all other results were similar between probes. Determinations of DM by the microwave and food dehydrator were also similar with the 60°C, 48-h oven method, whereas the Koster tester was lower than the oven. The handheld NIRS units more accurately predicted DM content of the alfalfa silage but were not as accurate with corn silages when the factory preset calibrations were corrected for bias.
本研究比较了 3 种手持式近红外光谱仪（NIRS）（Moisture Tracker，Digi-Star Inc.，Fort Atkinson，WI）与 60°C 常规烘箱干燥法对 2 种苜蓿青贮和 2 种玉米青贮的干物质（DM）预测值。此外，还比较了田间 DM 方法[微波、Koster 测试器（Koster Moisture Tester Inc.，Brunswick，OH）和食品脱水器方法]。威斯康星大学奶牛中心（DCC）和阿灵顿研究站（ARS）获得的玉米和苜蓿青贮（1600 g）每天进行 DM 分析 20 天。在每个单元中还测试了两种 NIRS 校准方法。工厂预设校准的 DM 预测值为 NIR。调整后的 DM 预测值为 NIR，实验前 3 天对重复的饲料样本进行的烘箱干燥和 NIR 测定之间的平均差异被用作所有后续 DM 测定的偏置调整。20 次扫描的平均预测 DM 被记录为饲料 DM。每个 NIRS 单元重复该过程 3 次。每个饲料的另外 2 个 100-g 样本也在强制空气烘箱中每天在 60°C 下干燥 48 小时。ARS 和 DCC 苜蓿青贮的烘箱 DM 分别为 37.3±1.1%和 48.5±1.9%（平均值±标准差）。ARS 和 DCC 玉米青贮的烘箱 DM 分别为 34.7±1.2%和 37.4±0.5%（平均值±标准差）。NIR 的 DM 测定值平均比烘箱 DM 值高 3.5 个单位。NIR DM 预测值平均比烘箱 DM 值低 1.7 个 DM 单位。此外，还检测到 3 个 NIR 探头结果之间的差异（分别为 43.1%、40.7%和 41.3% DM），但所有其他结果在探头之间均相似。微波和食品脱水器的 DM 测定值与 60°C、48 小时烘箱法相似，而 Koster 测试器则低于烘箱。手持式 NIRS 单元更准确地预测了苜蓿青贮的 DM 含量，但在对偏置进行校正后，对玉米青贮的预测精度不如工厂预设校准。
