The popularity of plant-based feed additives in livestock production has increased significantly in the last decade. Polyphenols are secondary plant metabolites which contain bioactive components and deliver positive effects for humans and animals. They are renowned for their anti-inflammatory, immunomodulatory and anti-mutagenic effects. Polyphenols have antioxidant properties, and they minimize the negative consequences of oxidative stress. their antioxidant capacity is comparable to that of the major biological antioxidants: vitamins e and c. Despite those advantages, polyphenols are characterized by low bioavailability, and further research is needed to harness their full potential in livestock farming. This article presents a review of findings from recent studies investigating the efficacy of polyphenols in monogastric nutrition, with special emphasis on their antioxidant properties.

The study was aimed at verification of the following hypothesis: differences in antioxidant capacity of diets consisting of different cereals and byproducts affect the antioxidant status of the consumers of these diets. To validate that hypothesis this study investigated the contents of polyphenols and alpha-tocopherol as well as the total antioxidant capacity (TAC) in vitro of cereals and their fractions (barley, husked and naked oat, oat bran, and triticale); the nutritional and antioxidant properties of diets containing these cereals, applied in a 4-week feeding experiment on rats, were also assessed. Among the cereals examined, the highest TAC was reported for barley (13.16 micromol of Trolox/g) and the lowest for naked oat (3.84 micromol of Trolox/g). Compared with cereals, the TAC of buckwheat waste was 2-3 times higher (25.2 micromol of Trolox/g). The antioxidant capacity of diets, calculated in vitro, ranged from 6.35 micromol of Trolox/g for naked oat type diet to 10.51 micromol of Trolox/g for barley type diet. Results of an in vitro study were confirmed in changes of glutathione peroxidase (GPx) activities and the level of thiobarbituric acid-reactive substances (TBARS) in the serum of rats fed diets with the highest and lowest antioxidant capacities in vitro; the barley diet increased the activity of GPx (37.63 units/mL) and decreased the level of TBARS (4.82 microg/g), whereas the naked oat diet had an opposite effect (31.16 units/mL and 5.91 microg/g, respectively).

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the present review summarizes the results of 37 experiments in which different types and levels (from 0.5 to 29.7%) of fibrous supplements were used in the formulation of diets for weaned piglets. Diets were supplemented with different sources of insoluble dietary fiber (iDF), soluble dietary fiber (sDF), or mixed DF sources. Most of the applied DF sources decreased the ileal and fecal organic matter digestibility, and they often lowered crude protein digestibility. A moderate addition (1.5-8%) of iDF sources increased average daily feed intake (ADFI) and, frequently, average daily gains (ADG). Sources of sDF as well as high inclusion levels of fiber-rich feeds tended to decrease ADFI and ADG. Improved fecal consistency, decreased diarrhea incidence and antibiotic interventions were confirmed in piglets fed diets with added lignocellulose, cooked or raw oat hulls and wheat bran. the dietary inclusion of idF rather than sdF sources improved gastrointestinal tract (GIT) development, enzyme activity and gut morphology. An increase in the counts of beneficial gut microbiota and the concentrations of short-chain fatty acids was stimulated by diets with addition idF or sdF sources. such diets also slowed down proteolytic fermentation which negatively affects the colonic mucosa. Some research findings indicate that iDF sources improve intestinal barrier function. the analyzed experimental data suggest that the addition of 1.5-2% of a lignocellulose preparation, 2% of oat hulls, 4-8% of coarse wheat bran to diets for weaned piglets may be recommended to promote GIT development and health, and to improve growth performance.