Research on Crude Protein Contents in Medicago Sativa Hay Harvest During 2008-2009 Using FT-NIR Spectrometry

Medicago sativa or Alfalfa is a flowering plant that belongs to Pea Family that is widely grown throughout the world as forage for cattle, and is most often harvested as hay. Medicago Sativa usually has the highest nutritive value of all common hay crops. This work aims to highlight a way for direct, non-destructive analysis of crude protein content in Medicago sativa hays. The primary objective was to build a model for crude protein calibration for Medicago sativa based on FT-NIR spectroscopy. The samples for analysis were collected over two experimental years (2008-2009) from field trials from the research station– Agricultural Development, Jucu. In order to construct the model, references values are needed; for this reason, crude protein content was determined using the classical Kjeldahl method (Kjeltec Auto Analyser, Tecator). The values for crude protein ranged from 12.63% to 19.12% on the dry matter basis. The regression models build was based on Partial Least Squares (PLS) calculated with the SIMPLS algorithm, using different pre-processing techniques and leave-one-out cross validation. Calibration of the two years together drove to a coefficient of determination for cross validation,R2, of 0.965. The robustness of the model was confirmed by applying it to independent samples (external validation) where the coefficient of determination was R2 = 0.977, RMSEP = 0.8. The results obtained indicated that NIRS can be used to determine crude protein, which could be used as a criteria for quality control of Medicago sativa hays.