In the master's thesis, we compared the nutritional value and quality of grass silage from different farms, analyzed in the course of Feed Science. The purpose of the research was to evaluate the nutritional value and quality of the analyzed grass silages and, based on the content of nutrients and quality indicators, to determine differences between samples and between years and successive cuttings. The research included 98 samples of grass silages analyzed between 2022 and 2026 at the Biotechnical Faculty, Department of Animal Science. The samples were contributed by students from their own or nearby farms, with samples of poorer quality intentionally included in the analysis. The students evaluated the samples organoleptically and performed a chemical analysis, which included a complete proximate analysis, determination of detergent fiber (NDF, ADF), mineral substances and silage quality indicators (pH, volatile fatty acids and ammoniacal nitrogen). From the chemical composition, we calculated the nitrogen-free extract, non-fiber carbohydrates, metabolizable energy (ME) and net energy for lactation (NEL) content. The statistical program SAS/STAT was used to process the data. The results showed a large variability between samples. Compared to the literature, the analyzed Slovenian grass silages were on average drier and lower in energy. The average contents of quality indicators were mostly within the recommended contents, which indicates that the silages are on average of good quality. Statistically significant differences were found for some nutrient contents between individual years and successive cuttings, for quality indicators there was a statistical difference between years, but there were no statistical differences between successive cuttings. The results show that the nutritional value of grass silages in Slovenia is significantly affected by the time of cutting or the maturity of the grass.
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