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.

This study was conducted to evaluate animal performance, carcase characteristics and meat quality of young bulls and steers (Charolais × Holstein-Friesian), fattened until 15 and 18 months of age. One half of 40 young bulls were castrated at 2 or 3 weeks of age. Starting at 7 months of age, they received grass silage supplemented with concentrates. At the end of the fattening period, the animals were slaughtered, and carcase quality and the quality of meat from Musculus longissimus thoracis (MLT) were evaluated. Bulls had a higher carcase dressing percentage, and their carcases had higher lean meat content than steers. MLT from steers had higher intramuscular fat (IMF) content (by 0.89%); it was less tough, more tender and palatable. IMF from bulls had higher concentrations of polyunsaturated fatty acids (PUFAs) and a higher n-6/n-3 PUFA ratio than IMF extracted from steer meat. Older animals had higher carcase quality than those slaughtered at 15 months of age, and slaughtering at a later age had no negative influence on meat quality.

Apart from others factors, carcass quality is determined by the animal's age and body weight (BW) at the end of the fattening period. The aim of this study was to determine the optimum finishing weight of young crossbred 'Polish Holstein Friesian' (PHF) x 'Limousin' (LIM) steers and bulls, based on their slaughter value. The experimental materials comprised 60 animals, including 30 bulls and 30 steers, fed farm-made feeds. At 2 or 3 wk of age, one half of calves were castrated. Bloodless castration was carried out using a rubber elastrator. Calves were reared under a conventional system, and were fattened semi-intensively. Daily gains ranged from 800 to 950 g. Calves were fattened to 450, 500, 550, or 600 kg BW. Carcass value was estimated after slaughter. Fatty acid profile was determined by gas chromatography in fat extracted from samples of muscle longissimus dorsi (MLD). Bulls, compared with steers, were characterized by a higher slaughter value, including a higher carcass dressing percentage by 1.07-2.60%, higher carcass conformation, and lower carcass fatness. In steers, an increase in live BW was accompanied by a considerable increase in fat content (higher than bulls), as confirmed by a significant (p ≤ 0.01) interaction. The intramuscular fat of bulls was characterized by higher concentrations of fatty acids delivering health benefits, and a more desirable polyunsaturated fatty acids/saturated fatty acids (PUFA/SFA) ratio. Fat from bulls contained higher levels of PUFAs by 2.34 g 100 g-1 on average. Semi-intensive fattening of PHF x LIM bulls to slaughter weight of 600 kg BW is recommended due to an increase in carcass value. Steers should be fattened to slaughter weight of 500-550 kg BW to prevent excessive fat deposition

The effect of slaughter weight and fattening intensity on changes in carcass fatness in young Holstein-Friesian bulls

The aim of this study was to determine the effect of a polyphenol product (PP) (Proviox) and vitamin E on the antioxidant status and meat quality of broiler chickens fed diets contaminated with ochratoxin A (OTA). One hundred and twenty ROSS 308 broiler chickens were randomly divided into six groups (10 replications, 2 birds per replication). Group I received an uncontaminated and unsupplemented diet, diets of groups II to VI were contaminated with OTA at 172 µg and 200 µg/kg for the starter and grower period, respectively. Furthermore, diets of groups III, IV and V were supplemented with vitamin E at 100, 200 and 100 mg, respectively, and to diets of groups V and VI additionally 100 and 2200 mg PP was added, respectively. Supplementation with PP and vitamin E had no significant effects on the growth performance, dressing percentage or carcass trait parameters of broiler chickens. In chickens exposed to stress, dietary supplementation with vitamin E and/or PP improved the total antioxidant status (p ≤ 0.05), enhanced the blood activity of antioxidant enzymes (p ≤ 0.01) and increased the concentrations of non-enzymatic antioxidants (p ≤ 0.01) in the liver and breast muscles. Regardless of the administered antioxidants, chickens fed diets contaminated with OTA were characterised by lower dressing percentage (p ≤ 0.01), a higher proportion of the liver in the carcass (p ≤ 0.01), lower carcass fat content (p ≤ 0.01), and longer small intestines (p ≤ 0.01) and caeca (p ≤ 0.01). Dietary supplementation with PP improved the water-holding capacity of meat (p ≤ 0.01). The breast muscles of chickens fed diets supplemented with PP and vitamin E were characterised by higher (p ≤ 0.05) concentrations of eicosapentaenoic acid (C_20:5). It was concluded that PP can be an insufficient component of diets for broiler chickens to improve growth performance and mitigate the negative effects of high dose of OTA in diets.