Zhang G J, Wang Y, Yan Y H, Hall M H, Undersander D J, Combs D K
Department of Animal Science, Ningxia University, Yinchuan, China.
Department of Agronomy, University of Wisconsin, Madison, WI, USA.
Heliyon. 2021 Jun 14;7(6):e07313. doi: 10.1016/j.heliyon.2021.e07313. eCollection 2021 Jun.
Undigested forage neutral detergent fiber (uNDF) from long-term ruminal in situ incubations are used to estimate indigestible neutral detergent fiber (iNDF). Measurement of iNDF is important in forage evaluation because it defines the potentially digestible pool of neutral detergent fiber (NDF). Near-infrared reflectance spectroscopy (NIRS) can be calibrated to in situ reference sets to rapidly predict uNDF. Our objective was to compare uNDF estimates after 240 h of incubation when two types of bags were used in the in situ reference method. The bags compared were 4 cm × 5 cm Ankom F57 bags (25 micron pore size), and 5 cm × 10 cm Ankom in situ bags (50 micron pore size). Alfalfa samples from Pennsylvania and Wisconsin ( = 144) of different varieties and harvest intervals were used. One-half or two gram samples, respectively, were weighed into the small and large bags in triplicate. Mass to surface area was 0.05 and 0.02 g/cm for the small and large bags, respectively. The iNDF content after 240 h incubation was evaluated by two types bags in three rumen-cannulated Holstein cows. Each dried and ground forage was also scanned to determine the visible-near-infrared-reflectance spectra with a FOSS 6500 spectrophotometer. Prediction equations were developed for each bag type using modified partial least square regressions. The estimated iNDF fraction from small and large bags were 13.75% and 9.97%, respectively (SED = 0.39, < 0.001). The coefficient of determination for calibration (R), cross-validation (1 - VR), calibration standard deviation (SEC), and interactive authentication standard deviation (SECV) was 0.94, 0.92, 0.85 and 0.98 for values determined with the small bag and 0.88, 0.85, 1.12 and 1.27 for iNDF for values determined with the large bag, respectively. Results indicate that iNDF varies among alfalfa cultivars and NIRS can be used to quickly and quantitatively estimate iNDF content in alfalfa. Bag type influences 240h NDF residues. NIRS predictions of iNDF from the small bag calibration set had higher R and lower SEC and SECV than the large bag calibrations.
长期瘤胃原位培养得到的未消化饲草中性洗涤纤维（uNDF）用于估算不可消化中性洗涤纤维（iNDF）。iNDF的测定在饲草评估中很重要，因为它定义了中性洗涤纤维（NDF）的潜在可消化部分。近红外反射光谱法（NIRS）可针对原位参考集进行校准，以快速预测uNDF。我们的目标是比较在原位参考方法中使用两种类型的袋子培养240小时后的uNDF估算值。所比较的袋子为4厘米×5厘米的安科F57袋（孔径25微米）和5厘米×10厘米的安科原位袋（孔径50微米）。使用了来自宾夕法尼亚州和威斯康星州的不同品种和收获间隔的苜蓿样品（n = 144）。分别将0.5克或2克样品一式三份称重放入小袋和大袋中。小袋和大袋的质量与表面积之比分别为0.05克/平方厘米和0.02克/平方厘米。在三头装有瘤胃瘘管的荷斯坦奶牛中，用两种类型的袋子评估培养240小时后的iNDF含量。还对每种干燥和研磨后的饲草进行扫描，用FOSS 6500分光光度计测定可见 - 近红外反射光谱。使用改进的偏最小二乘回归为每种袋子类型建立预测方程。小袋和大袋估算的iNDF比例分别为13.75%和9.97%（标准误 = 0.39，P < 0.001）。小袋测定的iNDF值的校准决定系数（R）、交叉验证（1 - VR）、校准标准差（SEC）和交互验证标准差（SECV）分别为0.94、0.92、0.85和0.98，大袋测定的iNDF值的分别为0.88、0.85、1.12和1.27。结果表明，iNDF在苜蓿品种间存在差异，NIRS可用于快速定量估算苜蓿中的iNDF含量。袋子类型会影响240小时的NDF残留量。小袋校准集对iNDF的NIRS预测比大袋校准具有更高的R以及更低的SEC和SECV。
