Use of polyphenol-rich grape by-products in monogastric nutrition. A review

Plants and their biologically active chemical constituents present numerous opportunities for improving animal production by inclusion in the diet. In recent years, interest has grown in the antioxidant and antimicrobial properties of a number of polyphenols found in different plants. The by-products of the wine industry (grape pomace, skin and seeds) and wine polyphenol extracts contain a wide range of bioactive compounds. However, studies on grape by-products are very limited, despite their richness polyphenolic substances. In this context, the purpose of this review is summarize recent advances of research in grape by-products including the phenolic composition, mechanism of intestinal and hepatic conjugation, plasma transport and elimination in bile and urine, and biological activities such as antioxidant and antimicrobial effect. Given their antioxidant activity, the inclusion of these by-products in feed rations would not only enhance the oxidative stability of the meat and reduce the amount of additives like vitamin E but also improve meat quality through direct addition of these natural antioxidants, thereby helping to meet consumer demand for healthier meat products. With respect to antimicrobial activity, they enhance the growth of specific beneficial bacteria strains in the intestinal tract while competitively excluding certain pathogenic bacteria.