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.

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losses of crude protein during ensiling of herbages, in contrast to carbohydrates, do not affect the reduction of its content; their form is changed into greater solubility non-protein compounds and also highly degraded forms, which lower the efficiency of the microbial protein synthesis in the rumen. these processes are accompanied by a change of amino acid composition of herbage protein and decrease in intestinal digestibility of protein from feeds as a result of the formation of indigestible complexes with carbohydrates (adin). reduction of protein degradation in silages is achieved by accelerated acidity through addition of acids or dominance of homofermentative bacteria. the positive effects of fermentation inhibitors or sorbents use, as well as the wilting of raw material on the level and rate of protein degradation were demonstrated by many researchers. a greater contribution of protein nitrogen and reduction of deamination in silages can also be obtained by using bacteria inoculants. increasing the proportion of protein nitrogen is accompanied by the improved efficiency of microbial protein synthesis. Key words: silage, legumes, proteolysis, crude protein, nitrogen fractionsCurrent interest in the excessive nitrogen emission to the environment, in the form of ammonia to the atmosphere and nitrates into groundwater, in animal production primarily concerns ruminants, and results from low utilization of nitrogen (Huhtanen, 2010). The quantity of the nitrogen pool leaving the animal body depends on the efficiency of nitrogen conversion which in milk production is 18-30%, and in meat production 10-20%, which is far below the potential of cattle, which exceeds 40% (Dewhurst et al., 1996; Frank et al., 2002). These losses result from the low efficiency of microbial protein synthesis in the rumen, caused on the one hand by rapid and excessive degradation of plant protein,

The aim of this study was to determine the effect of vitamin E and polyphenols on the antioxidant potential and meat quality of broiler chickens fed diets supplemented with low-quality oil. The experimental materials comprised 120 male Ross 308 broilers (six treatments, 10 replications, two birds per replication). Dietary supplementation with vitamin E and/or polyphenols was applied in the following experimental design: group I (negative control) – without supplementation without low-quality oil; group II (positive control) – without supplementation + low-quality oil; group III – supplementation with 100 mg kg-normal1 of vitamin E+ low-quality oil; group IV – 200 mg kg-normal1 of vitamin E + low-quality oil; group V – 100 mg kg-normal1 of vitamin E and 100 mg kg-normal1 of polyphenols + low-quality oil; group VI – 200 mg kg-normal1 of polyphenols + low-quality oil. Rapeseed oil oxidised under laboratory conditions was added to the diets of broiler chickens from groups II to VI. The applied antioxidants had no effect on the growth performance of chickens fed oxidised oil. Increased dietary inclusion levels of vitamin E and/or polyphenols improved the antioxidant status in the blood and increased the content of non-enzymatic antioxidants in the liver and breast muscles of broilers fed low-quality oil. The tested antioxidants had no influence on carcass quality parameters in chickens fed oxidised oil. However, birds fed diets with the addition of vitamin E were characterised by a higher gizzard weight and higher pH of gizzard digesta. Dietary supplementation with vitamin E and polyphenols or polyphenols alone contributed to a lighter colour and lower pH of breast muscles and an increase in the content of fat and ash in the breast muscles of broilers fed oxidised oil. The breast muscles of birds given 100 or 200 mg kg-normal1 of supplemental vitamin E were characterised by higher concentrations of n-6 polyunsaturated fatty acids (PUFAs) and hypocholesterolemic fatty acids (DFAs), a more desirable chemDFA/OFA ratio, and a lower atherogenicity index (AI). Polyphenols combined with vitamin E can be a valuable component of diets for broiler chickens when the problem of low-quality oil occurs.

one of the well known biological functions of betaine is that of a methyl donor. therefore, betaine may partly replace choline and methionine in the diet. another widely documented role of betaine is to restore and maintain the osmotic balance. as an organic osmotic compound, betaine regulates the water balance, thus exerting a stabilizing influence on tissue metabolism, particularly within the digestive tract. as a donor of methyl groups necessary for various reactions in the body, betaine is indirectly involved in lipid metabolism. Due to its metabolic functions, betaine is also believed to play a significant role in energy metabolism in pigs. of particular note are the results of experiments in which a positive effect of betaine supplementation was observed as the energy content of the diet was decreased.Energy supplied by feed is used by the body for maintenance and production purposes. Cereals are the main energy source in diets for pigs. The energy concentrations in the ration may be also increased by adding fat to feed; however, a rise in energy levels achieved in this way is limited by physiological and technological factors. The energy content of the ration may be also increased by the administration of feed additives, including feed enzymes.Using an alternative approach, additional energy can be obtained through precise control over metabolic processes in the body. The knowledge of physiological processes at the level of cell metabolism makes it possible to influence body protein (muscular tissue) or fat deposition using substances that impact protein and fat metabolism. Previous investigations suggest that betaine supplementation may contribute to attaining the above goal in pigs (Szramko et al., 2006 a). Some authors have pointed out the fact that the effect of betaine is greater when it is added to diets Brought to you by | University of Ottawa OCUL Authenticated Download Date | 8/6/15 11:26 AM