The effectiveness of cattle breeding is mostly determined Forage base. Currently, cattle productivity in the Russian Federation is increasing, and this requires a more careful approach to assessing the quality of feed. This primarily applies to such types of feed like hay, silage, haylage, which make up 60-85% in the average daily diet of livestock. The nutritional value of these types of feed depends mostly on the content and ratio of crude protein and crude fiber in perennial grasses when they are harvested. In the early phases of plant development, crude protein predominates in its composition, and the fiber content is insufficient. Therefore, mowing perennial grasses in these terms is irrational. With the growth and development of the plant, its transition to the heading stage, the crude protein content decreases with increasing fiber content. Harvesting perennial grasses at a time when they contain a large amount of fiber and low protein is also irrational since the low protein content in feed does not contribute to the growth of animal productivity. The optimum time for harvesting herbs is considered to be the time when the crude protein content is 14-16%, and crude fiber – 26-28%. Determination the content of these elements is a rather laborious and expensive process, the analysis lasts about three days. Only large agricultural enterprises can afford to carry out such analyses. At the same time, today, there are technologies for remote sensing of crops, which in this case can be carried out using unmanned aerial vehicles (UAVs). Currently, with their help, the nitrogen content in plants is determined. The authors of this paper propose a digital technique for remote determination of crude fiber and crude protein, which determines the optimal timing of the harvesting herbs.