Insufficient dietary vitamin e increases the concentration of 7beta-hydroxycholesterol in tissues of rats fed salmon oil

Potential of plant polyphenols to combat oxidative stress and inflammatory processes in farm animals

Polyphenols are secondary plant metabolites which have been shown to exert antioxidative and antiinflamma tory effects in cell culture, rodent and human studies. Based on the fact that conditions of oxidative stress and inflammation are highly relevant in farm animals, polyphenols are considered as promising feed additives in the nutrition of farm animals. However, in contrast to many studies existing with model animals and humans, potential antioxidative and antiinflammatory effects of polyphenols have been less investigated in farm animals so far. This review aims to give an overview about potential antioxidative and antiinflammatory effects in farm animals. The first part of the review highlights the occurrence and the consequences of oxidative stress and inflammation on animal health and performance. The second part of the review deals with bioavailability and metabolism of polyphenols in farm animals. The third and main part of the review presents an overview of the findings from studies which investigated the effects of polyphenols of various plant sources in pigs, poultry and cattle, with particular consideration of effects on the antioxidant system and inflammation.

Effects of fish oil and conjugated linoleic acids on expression of target genes of PPAR alpha and sterol regulatory element-binding proteins in the liver of laying hens

In mammals, (n-3) PUFA and conjugated linoleic acids (CLA) act as activators of PPAR alpha and alter nuclear concentrations of sterol regulatory element-binding proteins (SREBP) in the liver, and thereby influence hepatic lipid catabolism and synthesis. In this study, we investigated the hypothesis that (n-3) PUFA and CLA exert similar effects in the liver of laying hens. Thirty hens (64 weeks old) were fed diets containing 30 g/kg of sunflower oil (control), fish oil (salmon oil) or CLA in TAG form (containing predominantly cis-9, trans-11 CLA and trans-10, cis-12 CLA) for 5 weeks. Hens fed fish oil had a higher expression of some PPAR alpha target genes and a lower nuclear concentration of SREBP-2 in the liver and lower concentrations of cholesterol and TAG in plasma than control hens. Nuclear concentration of SREBP-1 and its target genes involved in lipogenesis were not altered in hens fed fish oil. Hens fed CLA had increased concentrations of TAG and cholesterol in the liver. However, their mRNA levels of PPAR alpha target genes and nuclear concentrations of SREBP-1 and SREBP-2 as well as mRNA levels of their target genes in the liver were largely unchanged compared to control hens. The results of this study suggest that (n-3) PUFA cause a moderate activation of PPAR alpha and lower cholesterol synthesis but do not impair fatty acid synthesis in the liver of laying hens. CLA lead to an accumulation of TAG and cholesterol in the liver of hens by mechanisms to be elucidated in further studies.

Effects of peroxidation products in thermoxidised dietary oil in female rats during rearing, pregnancy and lactation on their reproductive performance and the antioxidative status of their offspring

The present study was performed to investigate whether lipid peroxidation products in thermoxidised dietary oil fed during rearing, pregnancy and lactation influences the reproductive performance of female rats and the antioxidant status of their offspring. Twenty-four female rats were divided into two groups at 4 weeks of age. They were fed diets containing fresh or oxidised oil (the latter prepared by heating at a temperature of 50°C for 16 d) for 14 weeks. At the age of 12 weeks female rats were mated. The number of total pups and pups born alive was not different between both groups. However, individual pups and litters of dams fed oxidised oil were lighter at birth and gained less weight during the suckling period than those of dams fed fresh oil (P>0·05). Pups of dams fed oxidised oil contained less protein and more fat in their carcasses than those of dams fed fresh oil (P>0·05). The milk of dams fed oxidised oil had a lower concentration of triacylglycerols and a lower energy content than that of dams fed the fresh oil (P>0·05). The pups of dams fed oxidised oil had higher concentrations of lipid peroxidation products in the liver at birth and day 19 of lactation than those of dams fed fresh oil (P>0·05). In conclusion, the present study shows that feeding oxidised oil with a high concentration of lipid peroxidation products to female rats during rearing, pregnancy and lactation influences the development and antioxidant status of fetus and suckling pups.

Supplementation of vitamins C and E increases the vitamin E status but does not prevent the formation of oxysterols in the liver of guinea pigs fed an oxidised fat

BACKGROUND

Dietary oxidised fats are a source of oxidative stress. They cause deleterious effects in animal organism by lowering the antioxidant status of tissues and enhancement of the formation of lipid oxidation products. The vitamins E and C might be useful to prevent the formation of oxidation products by dietary oxidised fats.

AIM OF THE STUDY

The purpose of this study was to investigate whether or not supplementation of diets with vitamins E and C is able to prevent oxidative stress and the formation of lipid oxidation products caused by dietary oxidised fats. Among lipid oxidation products, oxysterols should be particularly considered because of their high pathophysiological effects.

METHODS

Male guinea pigs were divided into five groups. Four groups were fed diets with an oxidised fat supplemented with 35 or 175 mg alpha-tocopherol equivalents/kg and 300 or 1000 mg of vitamin C/kg for 29 days. One group, used as a control, was fed the same basal diet with fresh fat with 35 mg alpha-tocopherol equivalents/kg and 300 mg of vitamin C/kg.

RESULTS

The guinea pigs fed the oxidised fat diet with 35 mg alpha-tocopherol equivalents/kg and 300 mg vitamin C/kg had significantly lower concentrations of tocopherols in various tissues, higher concentrations of various oxysterols and thiobarbituric acid-reactive substances in the liver, higher concentrations of glutathione in the liver and lower concentrations of glutathione in erythrocytes than the control animals fed the fresh fat. Increasing the dietary vitamin E concentration from 35 to 175 mg alpha-tocopherol equivalents/kg and/or the dietary vitamin C concentration from 300 to 1000 mg/kg increased tissue tocopherol concentrations in guinea pigs fed the oxidised fat but did not influence concentrations of oxidation products in the liver and glutathione concentrations in liver and erythrocytes.

CONCLUSION

The results demonstrated that supplementation of vitamins E and C improves the vitamin E status but does not prevent the formation of lipid oxidation products in the liver of guinea pigs fed oxidised fats.