Current experiments with farm animals showed that it is possible to use grape by-products as a source of nutrients in animal nutrition. In the present experiment, we hypothesize that one reason for the variation among feeding trials, besides production steps affecting byproduct quality in winery, the variation among cultivars may have substantial contribution. The main aim of this study was to analyse grape pomace and stems from the area of Slovak Republic and Austria to evaluate their nutritional value for animals. In total, 54 samples of 3 grape varieties from 6 different locations were analysed. In each variety basic nutrients, antioxidant activity, total phenols, condensed tannins and proteins participation was determined according to standard analytical methods. The results show that the grape pomace had the highest ratio of crude proteins, crude fat and crude fibre with the solid concentrations of sugars, except of variety from red grape. Then, the grape stem is characterised with balanced content of crude protein, crude fibre and nitrogen free extracts with residual sugars and the highest antioxidant activity. By-products from the winery production have average nutritional value because of higher content of lignin that could be limiting factor for the digestibility. Neverthelles, there are interactions between the fibre fractions, condensed tannins, total polyphenols and antioxidant activity. Analysed data shows, that grape by-products have a potential in animal nutrition as a source of bioactive compounds, however there exists differences between the locations and varieties.
The objective of the present study was to determine the fatty acid profile of grape pomace, grape stem and grape bunch of three different cultivars of Vitis vinifera sp. (Green Veltliner, Pinot Blanc and Zweigelt) from two countries as a possible sources for animal nutrition. Fatty acid profile analysis was performed using the Agilent 6890 A GC machine. Significant differences (P <0.05) in fatty acid content of analyzed samples were detected between the countries, as well as between the cultivars within countries. Grape pomaces and grape bunches were rich in polyunsaturated fatty acids (70.91-71.86%), represented mainly by linoleic acid (69.79-70.32%), and low in saturated fatty acids (12.42-12.96%). Grape stems were characterized by a high saturated fatty acids content (24.46-30.85%), but on the other hand, these samples had the highest α-linolec acid concentration (9.98-14.52%). Oleic acid (12.24-15.17%) was the most abundant from monounsaturated fatty acids (12.69-15.33%) in all the analyzed samples. These results indicate a strong impact of the grape variety and location on the fatty acid profile of grape by-products and their potential to be evaluated as feed additives with high polyunsaturated fatty acids concentration in animal nutrition.
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