Grain samples of 51 spring barley (Hordeum vulgare L.) genotypes, including two-row, six rows, covered and hull-less were used for investigation of endosperm beta-glucan content. A significant difference (p-value is less than 0.001) between genotypes in beta-glucan content was observed. On average, the six-row barleys had slightly higher beta-glucan content. Far six-row genotypes it ranged from 35.9 to 47.1 mg kgE-1 with the mean value of 41.4 mg kgE-1, but for tw0-row barleys - 38.0 mg kgE-1 within the range of 33.2-44.9 g kgE-1. Six-row genotypes had a higher coefficient of variation in comparison with two-row genotypes. Hull-less genotypes had significantly higher beta-glucan content than the covered ones (49.3 mg kgE-1 and 38.9 mg kgE-1 respectively). The standard deviation of the mean values of beta-glucan content for covered genotypes was lower than for the hull-less ones. The mean values in 2005 were well plotted against data from the previous season for genotypes included in the two years trial. There were two distinct clusters of covered and hull-less genotypes. Beta-glucan content for varieties bred in Latvia ranged from 33.2 mg kgE-1 for two-row variety 'Malva' to 46.0 mg kgE-1 for six-row variety 'Druvis'.

Feeding livestock a balanced diet with a differentiated crude protein (CP) content, depending on the lactation phase, can reduce nitrogen emissions from livestock excrement and urine. A higher content of non-starch polysaccharides in livestock diets improves feed absorption in the livestock body and, consequently, nitrogen is emitted more from protein present in livestock manure than from urea acid present in livestock urine. The aim of the study is to calculate the ammonia emission reduction potential in Latvia by optimizing the feeding of dairy cows and ensuring life longevity, as well as provide justification for ammonia emission reduction in dairy farms. Calculations made by using the NorFor Model for optimization of dairy cow (Bos primigenius f. taurus) diets revealed that compared with lowyielding cows, a higher CP content diet fed to high-yielding cows at the beginning of lactation increased the amount of nitrogen (N) in their excrement and urine by 90–180 g dE−1. Reducing the CP content in the cow diet by an average of 10 g kgE−1 dry matter (DM) during mid-lactation resulted in the same trend. Reducing the CP content in the cow diet during late lactation and the dry period by another 20–30 g kgE−1 of DM, N emissions from excrement and urine significantly decreased. Increasing the lifespan of dairy cows also means reducing ammonia emissions from the farm. By increasing the number of lactations per cow on dairy farm, it is possible to reduce the number of heifers per cow. The total reduction of ammonia emissions in Latvia was calculated based on a long-term projection of a decrease of 0.1 heifer per dairy cow. Ammonia emissions could be reduced by 0.051 kt by decreasing the number of heifers by 12.54 thou. at the planned increase in the lifespan of dairy cows by 2030.