Luminescence properties of ground feed grain with varying fat content

The objective of the study is to determine informative photoluminescence parameters of wheat, oat, and barley feed grains to monitor their fat content. The studies were conducted in 2024 at the Federal Scientific Agroengineering Center VIM in the Laboratory of Innovative Technologies and Technical Means of Feeding in Animal Husbandry. To prepare the samples, the grains were pre-ground using a laboratory mill. Fat content in the ground samples was varied by irrigating them with vegetable oils. Fat content was monitored using a FOSS NIRS DS2500 infrared feed analyzer. Spectral luminescence characteristics were measured using a CM 2203 spectrofluorimeter. Initially, excitation (absorption) characteristics were measured, and the maxima of these were used to determine the photoluminescence spectra. Integral excitation and photoluminescence parameters, as well as statistical parameters of the excitation spectra of the feed, were calculated. As the fat concentration in milled grain increases, its luminescent capacity decreases, which is explained by concentration quenching. The qualitative statistical parameters of excitation (absorption) change relatively weakly and non-systematically; therefore, the most informative photoluminescence fluxes are those excited by radiation at 282/290 nm, 362 nm, and 414/424 nm. The dependences of the integral photoluminescence fluxes on the fat concentration for all studied grain millings can be statistically reliably approximated by linear functions. Moreover, the determination coefficients for wheat are 0.971–0.987, for oats – 0.943–0.995, and for barley – 0.852–0.984. For the development of a method and the creation of a universal device for monitoring the fat content in grain feed, the use of photoluminescence fluxes excited by radiation at 362 nm is most appropriate.