Hoffman P C, Brehm N M, Bauman L M, Peters J B, Undersander D J
Department of Dairy Science, University of Wisconsin, Madison 53706, USA.
J Dairy Sci. 1999 Apr;82(4):764-70. doi: 10.3168/jds.S0022-0302(99)75294-X.
Legume and grass silage samples (n = 121) were collected from commercial forage testing laboratories (trial 1). Samples were dried at 55 degrees C for 48 h, ground, scanned on a near-infrared reflectance spectrophotometer, and analyzed for crude protein (CP), soluble CP, acid detergent fiber (ADF) CP, and neutral detergent fiber (NDF) CP by wet chemistry methods. Sixty samples were selected for calibration development, and the remaining samples were used for equation validation. Near-infrared reflectance spectroscopy accurately predicted the CP content of the silages (R2 = 0.96), but prediction of soluble CP, ADF CP, and NDF CP was markedly less accurate. The coefficients of determination and standard errors of calibration for CP, ADF CP, NDF CP (percentage of DM), and soluble CP (percentage of CP) were as follows (0.96 and 0.80, 0.77 and 0.24, 0.72 and 0.71, and 0.82 and 4.40). In a second study, legume and grass silage samples (n = 32) were dried at 55 degrees C and ground (2 mm). Duplicate dacron bags containing 5 g of silage were incubated in the ventral rumen of three ruminally cannulated cows for 0, 3, 6, 12, 24, 48, and 72 h. In situ protein fractions, including rapidly degraded protein, slowly degraded protein, undegradable protein, degradation rate, and rumen-undegradable protein, were determined. Original samples were reground (1 mm) and scanned. Previously defined near-infrared spectroscopy calibration procedures were conducted. Coefficients of determination for in situ CP fractions were R2 > 0.92 with the exception of degradation rate (R2 = 0.87). Data suggest that in situ protein fractions are better predicted by near-infrared reflectance spectroscopy than by laboratory protein fractions.
从商业饲料检测实验室采集了豆类和禾本科青贮饲料样本（n = 121）（试验1）。样本在55摄氏度下干燥48小时，研磨后在近红外反射分光光度计上扫描，并通过湿化学方法分析粗蛋白（CP）、可溶性CP、酸性洗涤纤维（ADF）CP和中性洗涤纤维（NDF）CP。选择60个样本用于校准开发，其余样本用于方程验证。近红外反射光谱法准确预测了青贮饲料的CP含量（R2 = 0.96），但对可溶性CP、ADF CP和NDF CP的预测准确性明显较低。CP、ADF CP、NDF CP（占干物质百分比）和可溶性CP（占CP百分比）的校准决定系数和标准误差如下（0.96和0.80、0.77和0.24、0.72和0.71以及0.82和4.40）。在第二项研究中，将豆类和禾本科青贮饲料样本（n = 32）在55摄氏度下干燥并研磨（2毫米）。将装有5克青贮饲料的两个涤纶袋在三头装有瘤胃瘘管的奶牛的瘤胃腹侧中培养0、3、6、12、24、48和72小时。测定原位蛋白质组分，包括快速降解蛋白、缓慢降解蛋白、不可降解蛋白、降解率和瘤胃不可降解蛋白。将原始样本重新研磨（1毫米）并扫描。采用先前定义的近红外光谱校准程序。原位CP组分的决定系数除降解率外（R2 = 0.87）均R2 > 0.92。数据表明，近红外反射光谱法比实验室蛋白质组分能更好地预测原位蛋白质组分。
