| Photoluminescence spectroscopy was used to determine the botanical composition of diet samples containing six pre-digested arid desert rangeland plants. This fluorescence technique was a rapid, accurate, non-invasive method for the determination of the botanical composition of pre- and post-digested plant samples.; One advantage fluorescence has over absorption-based spectroscopic techniques (i.e., NIRS) is the ability for increased dimensionality in the data set (i.e., emission spectra at multiple excitation wavelengths). A previous fluorescence study involved only one wavelength of excitation. That study determined plant species discriminate could be achieved from the emission spectra of buffered saline extracts from plant material samples. Although, yet unknown species contribute to luminescence in the blue-green region of the spectrum (400-600 nm), the present study used fluorescence excitation-emission matrices (EEM) to study the extracts of several pre- and post-digested plant material samples. The extract solution used was a phosphate buffer saline solution (PBS, pH 12.5). Successful discrimination between extracts of pre-digested samples of plants containing the toxin swansonin (Astragalus lentiginosus and Oxytropis sericea) and plants without this compound by applying chemometic tools (i.e., PCA and MPCA) to the collected spectra. Also, applying PCA and MPCA to fluorescence spectra enabled identification and discrimination among pre-digested plant species (Astragalus lentiginosus (Asle), Astragalus drumondii (Asdi), Astragalus Laxamanii (Asla), Astragalus wingatanus (Aswi), Oxytropis lambertii (Oxla) and Oxytropis sericea (Oxse)). Using the same technique, another group of samples contained both pre- and post-digested samples of goat diets was studied. Good discriminate of the pre-digested samples (Medicago sativa L. (alfalfa), and Trifolium spp (clover), Pistacia lentiscus (P. lentiscus ), Phyllirea latifolia (P. latifolia), Pinus brutia (P. brutia), and feed concentrate ) was achieved as separate clusters in MPCA calibration models. Blue-green fluorophores were characterized using PARAFAC in terms of their excitation-emission profiles. These fluorophores among the studied plants were found to be unique in their number and excitation-emission profiles. Post-digested samples of clover and alfala hay were successfully distinguished using both PARAFAC and MPCA calibration models constructed from the same plant in the pre-digested forms, independent of the animal.; A portable multi LED (light emission diode) source spectrofluorometer was constructed to replace bulky commercial fluorometer for potential field measurements. The new spectrofluorometer used eight different color LEDs as different excitation sources and emission spectra were collected with each light source. Performance tests using reference fluorophores of the portable spectrofluorometer showed good reproducibility and accuracy. Although, the portable instrument exhibited higher limits of detection (LOD) compared with a commercial spectrometer, they were comparable to bulky portable instruments described in the literature. |
