Analysis of the nutritional composition of fennel straw by near-infrared spectroscopy

This study aimed to construct a predictive model for the nutritional composition of fennel (Foeniculum vulgare) straw using near-infrared reflectance spectroscopy technology. Fennel straw samples (n = 109) were collected in Minqin County, Gansu Province, and the absorbance values were obtained by scanning the samples with a near-infrared spectrometer. The dry matter (DM), crude protein (CP), organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF), crude ether extract (EE), and crude ash (Ash) contents were determined. The modified partial least squares method was used to construct a prediction model of each nutrient component and for external verification. The coefficient of determination (RSQ) and performance to deviation (RPD) for validation of DM, CP, OM, NDF, ADF, and Ash content were 0.853～0.951 and 2.574～4.239, respectively. The model’s predictive power was good and can be used for detection. However, the RSQ and RPD of EE content were 0.806 and 2.259, respectively, suggesting that the calibration model could only be used for rough screening of samples for EE content.