Composição química bromatológica de Andropogon gayanus cultivar planaltina predita pelo NIRS e analisada por via úmida

Abstract

The objective of this study was to compare the nutrient content of Andropogon gayanus cultivar Planaltina grass obtained from UFU / FAMEV NIRS equipment with the values obtained by wet path analysis, to identify if the global calibration models of NIRS equipment are adequate to predict the composition. chemical-bromatological. Thus, the dry analyzes at NIRS were performed at the Laboratory of Bromatology and Animal Nutrition (LABAN), belonging to the Faculty of Veterinary Medicine (FAMEV) of the Federal University of Uberlândia (UFU), located in Uberlândia-MG, in the months of august to september 2019 while the wet analyzes were carried out at Embrapa Cerrados Plant Analytical Chemistry Laboratory, located in Brasília-DF, from september to october 2018. The samples used were from Andropogon gayanus cultivar Planaltina grass, which after cutting 20 cm above the ground were dried and ground to the size of 1 mm. After grinding, they were wet-analyzed for determinations of dry matter (DM), mineral matter (MM), crude protein (CP), neutral detergent insoluble fiber (NDF), acid detergent insoluble fiber (ADF) according to methodologies proposed by Detmann et al. (2012). The ground samples were placed in the equipment's own cuvette and scanned in NIR Near-Infrared Reflectance Spectrometer (NIRS), Spectra Star model 2600 XT series of Near Infrared Analyzers (Unity Scientific®) in duplicates. In order to obtain the contents of DM, MM, CP, NDF and ADF, the NIRS models were used, using the calibration curve called Pasto, and the results were read directly on the equipment screen. The mean DM, MM, CP, NDF and ADF levels obtained by wet analysis and the use of NIR equipment were compared by paired T test at 5% probability using a randomized block design. There were significant differences in nutrients predicted by NIRS and wet analysis (P≤0,05). For dry matter and mineral matter analysis, NIRS overestimated the contents, while for NDF, ADF and CP, the NIRS underestimated, which shows that this equipment when using global calibration models are not able to correctly predict the composition bromatological chemistry of forages of tropical climate.