## 1 Introduction
However, concerning the non-contact determination of ash, ADF, and NDF cellulose concentrations, as well as fats, it is expedient to conduct research into the effectiveness of applying an optical method in the visible range from 380 to 780 nm [9]. According to the conducted literature review, the photoluminescence of the visible range demonstrates its effectiveness in terms of detecting okadaic acid (OA), a marine biotaoxin produced by microalgae that poses a significant threat to maritime, seafood safety, and human health. The results of processing experimental data showed that the reliability of detection using luminescence is confirmed by a coefficient of variation of 2.54% when employing alternative methods [10]. Luminescence is employed to identify the adulteration of butter by detecting non-dairy fats through the dependence of the intensity ratios of components in the extended spectrum of luminescence on palm oil content when excited at a wavelength of \(\lambda=266\) nm [11]. Additionally, it is used for the quantitative determination of fat content in milk [12]. The broader diagnostic functionality of plant products, including those that have undergone extensive processing, is provided by luminescent nanoprobes, enabling the diagnosis of heavy metal content, pesticides, and the presence of veterinary drugs, microbes, and mycotoxins [13]. Photoluminescence is a useful technique for the non-destructive and quick evaluation of cereals and other starchy products. Visible light peaking at around \(\lambda=460\) nm is observed from cereals, such as rice, wheat, barley, millet, flour, corn starch, and peanut, under the illumination of ultraviolet light at \(\lambda=365\) nm [14]. The photoluminescence method demonstrates its effectiveness in detecting riboflavin and its derivative flavin mononucleotide in cellulose materials [15], which also suggests the potential for identifying important vitamins in livestock feed. Moreover, photoluminescence has been actively utilized in the industrial processing of food products and the preparation of semi-finished goods. For instance, in the range of 550 nm, myoglobin in poultry meat actively fluoresces, allowing the degree of poultry cooking to be determined through its detection [16]. Similarly, for the detection of vitamin B2 (riboflavin) in cellulose materials, its concentration is determined in milk at peak intensity values of \(\lambda\) = 545 nm, by measuring the configuration of backscattering using ultraviolet LEDs, violet LEDs, or a blue LED as the excitation light [17]. In confirmation of the efficiency of detecting qualitative feed indicators and ensuring safety prior to direct animal consumption, photoluminescence enables the visualization of serum albumin within the range of 480 to 535 nm [18]. The most commonly used mathematical method for processing optical signals obtained from photodiodes is correlation-regression analysis, often accompanied by the pre-training of the hardware algorithm. In this process, preliminary results obtained through chemical analysis are utilized as the reference parameter for the corresponding sample. In the scope of this present study, we examined the prospect of utilizing the photoluminescence method as a tool for determining the dry matter content in livestock feed. To test the key hypotheses, a prototype device equipped with LEDs and photodiodes calibrated to a specific range of luminescence was developed for corn silage and compound feed. The goal of the presented research is to develop a laboratory apparatus and establish theoretical foundations for determining the nutritional value of agricultural feeds using photoluminescence.