Climatic conditions for soybean cultivation in Latvia are challenging because of their variability. In addition, the sum of sunlight hours and the ratio of temperature and precipitation required to produce a quality crop are unpredictable. There is a risk that even early soybean varieties will not ripen due to weather conditions in a region. Studies show that soybean plants, including the green part of the crop, are well suited for animal nutrition prepared as hay or silage. The aim of this study was to evaluate the chemical composition of different soybean varieties harvested before ripening and assess them as hay or silage raw material. Weight, protein, fat, ash, fibre, acid detergent fibre (ADF) and neutral detergent fibre (NDF) of soybean varieties ‘Erica’, ‘Bolgar’ and ‘Viola’ green mass were determined at different stages of maturity. The results of the study showed a significant increase in protein (from 9.18% to 12.06%) and fat (from 1.18% to 4.40%) content of the dry matter variety ‘Bolgar’ from September to October. The protein content of the dry soya green mass was not affected by variety at the same developing stage but significantly changed among different stages of maturity. As the plant develops, the sucrose content in the green mass increases, the same as the total sugar content.

The article presents the results of studies of two samples of fenugreek: blue (Trigonella coerulea (Desr.) Ser.) and hay (Trigonella foenum graecum L.) on the set of economic, biological and biochemical parameters. The researched samples of fenugreek have a wide range of variability of indicators depending on the terms of sowing and weather conditions. More rapid development was shown by fenugreek species on the summer sowing dates (III decade of June) with a vegetation period of 36–37 days. To obtain a high yield of green mass of fenugreek plants, the early spring (II–III decade of April) and late spring (I decade of May) sowing terms were more suitable. The obtained green mass yield was: 5.7–6.9 t∙haE–1 – blue fenugreek, and 7.3–9.3 t∙haE–1 – hay fenugreek, with the content of the dry matter being 12.4–28.4%, the sum of sugars 2.5–5.0% and vitamin C – 38.0–51.8 mg∙(100 g)E−1. To obtain spices called “mushroom grass”, it is promising to use hay fenugreek with early spring (II–III decade of April) and late spring (I decade of May) terms of sowing, as a more developed vegetative mass is formed with the dry weight yield of plants 1.3–1.4 t∙haE–1. An increase in the amount of precipitation by 1 mm resulted in fluctuations of green mass yield from 15.0 to 77.3 kg∙haE–1 and dry mass yield from 0.693 to 25.9 kg∙haE–1.

Since plant protein is generally accepted as sustainable and environmentally friendly, production of new plant protein-based products is expanding and a raw material is diversified to ensure a high-value and complete meal. The objective of the study was to compare chemical composition and amino acid provision of pea-buckwheat, pea-barley and pea-oat extruded mixtures with the aim to look for new products to diversify diet using the best plant protein resources. Within the research, amino acid scores of hull-less barley, buckwheat, hull-less oat and grey pea as an indicator of raw material protein quality were evaluated. The highest scores of essential amino acids were found in oat and pea protein. Amino acid scoring patterns of raw material – oat ‘Stendes Emilija’ and grey pea ‘Bruno’ fully meet the requirements for essential amino acid supply. The protein of buckwheat is the richest in lysine (4.3 g 100gE−1 protein) among studied cereals, although the difference in the essential amino acids was not significant. The results of the research showed that pea-barley and pea-buckwheat composite mixtures meet human needs better if pea protein is used in the proportion 65:35 with barley or buckwheat flour than in the proportion 35:65. The high protein content – 43.33% and 43.96%, the sum and composition of essential amino acids, and high level of total dietary fibre – 11.9% and 13.7% are the main reasons to consider the mixtures (including as a base for smoothies) as a complete meal.