Alenka Levart

Evaluation of different vitamin E recommendations and bioactivity of α-tocopherol isomers in broiler nutrition by measuring oxidative stress in vivo and the oxidative stability of meat

The aim of this study was to compare recommendations for vitamin E supplementation regarding high polyunsaturated fatty acid intake and to compare the bioactivity of RRR- and all-rac-α-tocopherol with respect to oxidative stress in vivo and the oxidative stability of broiler meat. Fifty male broilers were divided into 5 groups. All groups received diets with a high inclusion of fat (7.5%), one with palm fat and the others with linseed oil, which were either unsupplemented or supplemented with vitamin E to contain in total 85 or 200 IU of vitamin E as all-rac-α-tocopherol and 85 IU as RRR-α-tocopherol. Oxidative stress in vivo was studied by measuring the DNA damage; measuring malondialdehyde (MDA) in plasma, liver, and breast muscle; and analyzing the antioxidant capacity of the lipid-soluble compounds, total antioxidant status of plasma, and antioxidant enzyme assays. The tocopherols in plasma, liver, and breast muscle were also analyzed. In vitro oxidative stability was studied by measuring MDA in fresh, stored, and heat-treated breast meat. Linseed oil, as opposed to palm fat, induced DNA fragmentation and MDA formation. Both forms and concentrations of vitamin E reduced DNA damage and breast muscle MDA. The groups receiving 200 IU of all-rac-α-tocopherol and 85 IU of RRR-α-tocopherol had much higher values for antioxidant capacity of lipid-soluble compounds than did the controls. No differences were observed in the values of antioxidant enzymes. The α-tocopherol levels in tissues and plasma were significantly influenced by the level of α-tocopherol supplementation. Malondialdehyde formation in meat from the vitamin E-supplemented groups was decreased in comparison with that from the control linseed oil group. We conclude that both vitamin E concentrations were insufficient to prevent all harmful effects of lipid oxidation in vivo and that both were equally effective. On the contrary, to ensure good stability of meat lipids, higher vitamin E supplementation is needed, especially after heat treatment. The results of in vivo oxidative stress and meat lipid oxidation confirmed the currently accepted bioactivity of the RRR-α- to all-rac-α-tocopherol ratio of 1.39 in in vivo and in vitro systems.

Oxidative stress markers in canine atopic dermatitis

There are no data in the veterinary literature relating to oxidative stress in canine atopic dermatitis (CAD). The study aimed to determine levels of oxidative stress markers, plasma malondialdehyde (MDA), total antioxidant capacity (TAC), whole blood glutathione peroxidase (GPX) and erythrocyte superoxide dismutase (SOD), in 15 CAD patients and 17 healthy dogs. A correlation between CADESI (Canine Atopic Dermatitis Extent and Severity Index) score and MDA was also determined. Significantly higher plasma MDA levels were found in patients than in healthy dogs. The significant, highly positive correlation determined between CADESI score and MDA in the patient group indicates an association between the severity of CAD and the extent of oxidative damage to membrane lipids. There were no significant differences in TAC, GPX and SOD between patients and healthy dogs. Our findings suggest that oxidative stress with increased lipid peroxidation could be involved in the pathogenesis of atopic dermatitis in dogs.

Fatty acid composition of lamb meat from the autochthonous Jezersko-Solčava breed reared in different production systems.

Thirty two autochthonous Jezersko-Solčava lambs were used to investigate the effect of production (pasture vs. stable) and weaning system (suckling vs. weaned) on fatty acid composition of Longissimus dorsi intramuscular fat in a 2 × 2 factorial design. Pasture lambs had lower intramuscular fat concentration (P<0.0001) more PUFA and trans C18:1, more ALA (P=0.0322), ARA (<0.0001) and EPA (0.0149) but less SFA (P<0.0001) than stable lambs. Weaning system affected PUFA (P=0.0040) and MUFA (P=0.0070) but not SFA and trans C18:1 fatty acids. The interaction of production system and weaning system was significant mainly for trans C18:1 and trans C18:2 fatty acids. Finally, lamb meat from all four treatments which are traditionally used in rearing of Jezersko-Solčava lambs are favourable from the nutritive point of view, due to their low n-6/n-3 ratio.

The comparison of black currant juice and vitamin E for the prevention of oxidative stress.

Black currant is known as a fruit with a very strong in vitro antioxidative capacity, but its in vivo antioxidant efficacy has not yet been characterized. The aim of the experiment was to determine the potency of black currant juice in comparison to vitamin E, for decreasing oxidative stress. Oxidative stress was induced by high intake of polyunsaturated fatty acids (PUFAs) in pigs as a model for humans. Twenty-four growing pigs were divided into four groups. All groups received isocaloric daily rations composed of an equal amount of basal diet that was supplemented with starch (CONT), linseed oil (OIL), linseed oil and black currant juice (OIL+BCJ), or linseed oil and vitamin E (OIL+VIT E). The experiment confirmed that the high proportion of PUFAs in the OIL group increased oxidative stress. In comparison with the OIL group, vitamin E supplementation significantly lowered plasma malondiadehyde (MDA) and the 24-hour urine MDA excretion rate, and reduced the degree of DNA damage in leukocytes to the level of the CONT group. The black currant juice intake failed to significantly decrease plasma MDA and 24-hour urine MDA excretion rate, but did reduce the degree of DNA damage in leukocytes to the level of the CONT group, as well as increase plasma beta+gamma-tocopherol concentrations. Although black currant juice did not reduce the formation of MDA, it efficiently prevented DNA damage induced by the high intake of PUFAs. It could be concluded that under these experimental conditions vitamin E was more efficient as an antioxidant that black currant juice.

Effect of Ganoderma lucidum (Reishi mushroom) or Olea europaea (olive) leaves on oxidative stability of rabbit meat fortified with n-3 fatty acids

The objective of the present study was to evaluate the effect of Ganoderma lucidum (Reishi mushroom) or Olea europaea (olive tree) leaves on oxidative stability of rabbit meat fortified with n-3 fatty acids. Forty-eight slovenska kunka (SIKA) rabbits were divided into four homogeneous groups. The control group (CONT-) received diet with 6% palm fat; other groups received diet with 6% linseed oil and were either unsupplemented (CONT+) or supplemented with 1% of G. lucidum (REISHI) or O. europaea leaves (OLIVE). Rabbits were slaughtered and fatty acid composition, concentration of vitamin E and malondialdehyde (MDA) in back muscle were analyzed. The results showed that linseed oil addition improved fatty acid composition by increasing polyunsaturated fatty acid (PUFA) proportion, decreasing proportion of saturated fatty acid (SFA) and reducing n-6/n-3 ratio in rabbit meat. Groups that were supplemented with linseed oil had lower content of α-tocopherol and higher content of γ-tocopherol, compared to the CONT- group. The addition of potential antioxidants did not effectively prevent oxidation of rabbit meat.

Fatty acid composition of milk produced in organic and conventional dairy herds in Italy and Slovenia

Abstract Thirty eight bulk milk samples were collected from 19 organic and conventional farms in Italian Region of Friuli Venezia Giulia and Slovene Regions of Obalno-Kraška and Goriška with the aim to determine variation in fatty acid (FA) composition between two States and between two production systems. Results show that milk from Slovene organic farms contain the highest proportion of saturated FA (SFA; 70.32 %) and the lowest proportion of monounsaturated FA (MUFA; 25.49 %). Milk from both production systems in Slovenia contained greater proportions of n-3 polyunsaturated FA (PUFA; 0.99 and 1.20 % in conventional and organic farms, respectively) and lower proportions of n-6 PUFA (2.60 and 2.33 % in conventional and organic farms, respectively) than Italian milk samples (0.54 and 0.68 % n-3 PUFA and 3.03 and 3.39 % n-6 PUFA in conventional and organic farms, respectively). The ratio between n-6 and n-3 PUFA was thus lower in Slovene than in Italian milk samples, yet they did not differ statistically between production systems within the States. Slovene milk samples contained higher proportions of conjugated linoleic acid (CLA; 0.72 and 0.64 % in conventional and organic farms, respectively) than Italian milk samples (0.45 and 0.49 % in conventional and organic farms, respectively).

The effect of α-tocopherol, sweet chestnut wood extract and their combination on oxidative stress in vivo and the oxidative stability of meat in broilers

1. This study examined the effect of α-tocopherol (α-T), sweet chestnut wood extract (SCW) and their combination on oxidative stress in vivo and oxidative stability of meat in broilers given diets rich in PUFA. 2. A total of 60 male broilers were individually caged and divided into 6 groups of 10. The C-PALM group received a diet with 7·5% palm fat and the other 5 groups with 7·5% linseed oil. The linseed oil groups were either un-supplemented (C-LIN) or supplemented with α-T or/and SCW as follows: αT-85 (C-LIN diet + 68 IU vit E as all-rac-α-T/kg), αT-200 (C-LIN diet + 183 IU vit E as all-rac-α-T/kg), SCW (C-LIN diet + 3 g SCW/kg) and αT-SCW (C-LIN diet + 68 IU vit E as all-rac-α-T/kg + 3 g SCW/kg). Different parameters of oxidative stress were measured. 3. Linseed oil induced DNA fragmentation and malondialdehyde (MDA) formation, while α-T reduced both parameters, and SCW reduced the DNA damage. A combination (αT-SCW) also reduced plasma MDA. Larger antioxidant capacity of lipid soluble compounds were recorded in groups αT-85, αT-200 and αT-SCW than in the controls but there were no differences between these groups in antioxidant enzymes and total antioxidant status. A combination (αT-SCW) increased tocopherol concentrations in breast muscle and in comparison to the C-LIN group MDA concentrations were reduced in groups αT-85, αT-200 and αT-SCW. 4. It can be concluded that neither of the α-T concentrations were able to prevent all the negative effects of lipid oxidation in vivo and only high concentrations of α-T improved the stability of meat. With the exception of DNA damage, SCW had no impact on in vivo and in vitro measured markers of oxidative stress but may have a sparing or regenerating effect on α-T.

Vitamin E supplementation in canine atopic dermatitis: improvement of clinical signs and effects on oxidative stress markers

Low levels of plasma vitamin E concentrations were found in canine atopic dermatitis (CAD). The present study was aimed at determining the effect of an eight-week vitamin E supplementation on clinical response (Canine Atopic Dermatitis Extent and Severity Index (CADESI-03) scores and pruritus intensity) in dogs with atopic dermatitis. Levels of oxidative stress markers (plasma malondialdehyde and total antioxidant capacity (TAC), blood glutathione peroxidase and erythrocyte superoxide dismutase, plasma and skin vitamin E concentrations) were also determined. Twenty-nine dogs with CAD were included in the study. Fourteen received vitamin E (8.1 IU/kg once daily, orally) and 15 received mineral oil as placebo (orally). All dogs were treated with antihistamine fexofenadine. Levels of oxidative stress markers (with the exception of skin vitamin E), CADESI-03 and pruritus intensity were determined at the beginning, then every two weeks. Skin vitamin E was determined at the beginning and at the end of the treatment. Significantly higher plasma levels of vitamin E and TAC were observed in the vitamin E group than in the placebo group. CADESI-03 scores determined throughout the treatment in the vitamin E group were significantly lower than in the placebo group. The findings of this study support the supplementation of vitamin E in dogs with atopic dermatitis.

Effect of production system on fatty acid composition of meat from Simmental bulls

Abstract The objective of the study was to asses the effect of the production system on fatty acids (FA) composition of intra-muscular fat of three muscles (longissimus dorsi, semitendinosus, diaphragmae) from Simmental bulls. Bulls (n=8) were fattened either with maize silage and concentrates or on pasture. Grazing bulls showed a significant lower percentage of saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA), but had higher percentage of polyunsaturated fatty acids (PUFA) and conjugated linoleic acid. The n-6/n-3 PUFA ratio was significantly lower (P<0.001) and the PUFA/SFA ratio was significantly higher (P<0.001) in muscles of grazing bulls. The lowest SFA percentage was found in semitendinosus (36.5±0.8) followed by longissimus dorsi (44.4±0.8) and diaphragmae (48.2±0.8) muscle. The percentage of PUFA and n-3 PUFA was the highest in semitendinosus muscle, while the n-6/n-3 PUFA ratio was similar in all three analysed muscles.

Effect of sex and slaughter weight on meat and fat quality of the Krškopolje pig reared in an enriched environment

Improvements in meat quality are sought through sources of variation along the meat chain, including breed and production system. Hence, the aim of this study was to determine slaughter weight and sex effects on the meat quality of the indigenous Krskopolje pig breed reared in a feed-enriched indoor environment for the growing-finishing periods. Raised in this enriched environment, the intramuscular fat (IMF) content of the loin was 1.5–2.5% higher than previously reported for other production systems. Slaughter weight (119–132 kg or >135–170 kg) influences on meat colour and IMF composition were observed. Animals from the light group had lighter coloured meat with lower Japanese colour scores as well as higher saturated fatty acid (SFA) and lower monounsaturated fatty acid (MUFA) proportions in the IMF. A lower proportion of MUFA was also observed in the IMF from gilts than barrows. Furthermore, a higher proportion of SFA was found in the IMF from the gilts. However, the lower IMF content in the gilts negates any apparent compositional advantages between the sexes. The IMF content and composition of the Krskopolje pig reared in an enriched environment suggests good commercial potential of this breed.