Abstract. The aim of the research is to create source material for breeding forage rye that combines stable productivity over the years, high protein content in the grain, and low content of water-soluble pentosans. The object of research was winter rye. Research methods Research on these tasks was carried out in 2016–2018 in the conditions of the South-Western Urals using generally accepted methods. The predecessor is dead fallow. Soil is chernozem with a predominance of leached, typical and carbonate varieties with the following agrochemical indicators: humus content in the topsoil – 7–9 %, pH value – 7.2–7.6, total nitrogen in the arable layer of the soil – 0.4 %, mobile potassium and phosphorus (according to Machigin) – respectively 20.5 mg/100 g and 10.2 mg / 100 g of dry soil, calcium – 5.6 %. The recommended rate of mineral fertilizers is N60P60K60. Scientific novelty. For the first time, 3 promising winter rye varieties selected in the Bashkir scientific research Institute and 2 samples of the All-Union Research Institute of Plant Breeding were studied in climatic conditions of south-western Cis-Ural. The content of water-soluble polysaccharides (WSP) and the water extract viscosity (WEV) were evaluated. The breeding value of plants was studied. Results The main indicators of the nutritional quality of winter rye grain are found to depend on both the variety (genotype) and the influence of external conditions (phenotype). It was detected that the content of water-soluble polysaccharides and the dynamic viscosity of the grain meal water extract are in a linear relationship (r = 0.98). They are unstable indicators and have a variable character. There are two varieties (Kombaynnyay 3 i Krupnozernaya 2) with the lowest WSP and WEV values and a high protein content in the grain. They can serve as source material to develop fodder crops in conditions of the Republic of Bashkortostan. The rye WEV was found to increase significantly in dry years, and decrease in wet years. The comparative evaluation of grain crops showed that the WEV of winter rye exceeded that of winter wheat by 3.5 times, spring wheat by 3.7 times, and winter triticale by 3.1 times. It was found that the samples with lower WSP and WEV indicators had small grains, low grain unit and higher protein content.