Determination of in Vitro True Digestibilities and Relative Feed Values of Wine Industry Grape Residues as Alternative Feed Source

Abstract

This study was carried out to determine the feed values of grape wastes of wine industry. In this study, wastes of wine industry; dried grape pomace, grape seeds and grape pomace pellets produced for fuel were used as feed sources. The nutrient contents, relative feed values (RFV), condensed tannin (CT) contents and in vitro true digestibilities (IVTD) of the wastes were determined. Daisy incubator was used to determine the in vitro digestibilities. The obtained data were analysed by one-way analysis of variance (ANOVA). While the lowest crude protein content (11.05% DM) was determined for grape seeds, the highest content (13.78% DM) was determined for pellets. Although grape seeds with a higher ether extract (EE) content than the others, it has a lower nitrogen free extracts (NFE) and higher cell-wall structural components (CWSC). Grape seeds had higher EE and CWSC and lower NFE compared to other forms. While the lowest IVTD value was determined for grape pomace pellets which had highest CT content, the highest digestibility value was determined for dried grape pomace (P<0.001). The dried grape pomace was found superior compared to other forms in terms of dry matter digestibility, dry matter consumption and RFV. However, in vivo animal feeding experiments are needed to attain more reliable results.