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Efficacy of dietary D-alpha-tocopherol and DL-alpha-tocopheryl acetate for weanling pigs.

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... However, there were no known pathogenic challenges, and environmental stressors were minimal in the current study. Serum concentrations of α-tocopherol declined by 82% in pigs after the first month postweaning (effect of time, P < 0.05; Table 5), which is consistent with results reported by others showing reduced circulating vitamin E concentrations within the first few wk postweaning (Chung et al., 1992;Moreira and Mahan, 2002;Lauridsen, 2010). These changes are likely related to metabolic and environmental changes associated with weaning. ...
... For example, dl-α-tocopheryl acetate is commonly supplemented in nursery diets, but d-α-tocopherol is the predominant form of vitamin E in sow milk (Mahan, 1994;Lauridsen and Jensen, 2007). Chung et al. (1992) reported that supplementing d-α-tocopherol improved retention of serum vitamin E postweaning compared to dl-α-tocopheryl acetate, suggesting greater bioavailability of the alcohol form. Varying bioavailability among vitamin E sources is related to inefficient removal of the acetate group by carboxyl ester hydrolase before absorption in the intestinal lumen (Chung et al., 1992) because the activity of carboxyl ester hydrolase declines after weaning (Jensen et al., 1997). ...
... Chung et al. (1992) reported that supplementing d-α-tocopherol improved retention of serum vitamin E postweaning compared to dl-α-tocopheryl acetate, suggesting greater bioavailability of the alcohol form. Varying bioavailability among vitamin E sources is related to inefficient removal of the acetate group by carboxyl ester hydrolase before absorption in the intestinal lumen (Chung et al., 1992) because the activity of carboxyl ester hydrolase declines after weaning (Jensen et al., 1997). Furthermore, stressors at weaning may a-c Within each variable, means for a sample day without a common superscript differ (P < 0.05). ...
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This experiment evaluated the effects of including peroxidized corn dried distillers grains with solubles (DDGS) in diets for sows and nursery pigs on growth performance, vitamin E (VE) and Se status, and the incidence of Mulberry Heart Disease (MHD) of nursery pigs. Sows (n = 12) were fed corn-soybean meal diets (C-SBM) or C-SBM diets with DDGS (40 and 20% in gestation and lactation, respectively) for 3 parities. In the third parity, 108 weaned pigs (BW = 6.6 ± 0.36 kg) were blocked by BW within litter, assigned to pens (2 pigs/pen; 5 and 4 pens per litter for groups 1 and 2, respectively), and pens were assigned 1 of 3 nursery diets: 1) corn-soybean meal (CON), 2) 30% peroxidized DDGS (Ox-D), and 3) 30% Ox-D with 5× NRC (1998) level of VE (Ox-D+5VE) for 7 wk, in a 2 × 3 factorial arrangement of sow and nursery diets (n = 9 pens/treatment). The peroxidized DDGS source in nursery diets contained concentrations of thiobarbituric acid reactive substances (TBARS) and peroxide value that were 25 and 27 times greater than a reference corn sample. Sow colostrum, milk, and serum, as well as pig serum and liver samples were analyzed for α-tocopherol and Se concentrations. Pig serum was analyzed for glutathione peroxidase activity (GPx), TBARS, and sulfur-containing AA (SAA). Pig hearts were evaluated for gross and histopathological lesions indicative of MHD, but none were detected. Pigs from sows fed DDGS tended to have reduced (P = 0.07) VE in serum during lactation and reduced VE at weaning (P < 0.01; 5.6 vs. 6.7 ± 0.1 μg/mL) compared with pigs from sows fed C-SBM. Inclusion of DDGS in sow diets reduced the VE status of pigs during lactation, but not in the nursery when MHD can be a concern. Pigs fed Ox-D+5VE (P = 0.08) tended to have, and those fed Ox-D (P = 0.04) had greater ADFI than pigs fed CON, but ADG was not affected (P > 0.1) by nursery diet. Feeding Ox-D or Ox-D+5VE increased (P < 0.05) serum α-tocopherol compared with CON (2.5, 2.8, and 3.4 ± 0.09 μg /mL, respectively), but TBARS and GPx were not affected by nursery diet. Serum concentration of SAA was 40 to 50% greater (P < 0.01) for pigs fed Ox-D or Ox-D+5VE compared with those fed C-SBM, which was likely due to greater (P < 0.01) SAA intake for pigs fed Ox-D. The antioxidant properties of SAA may have spared VE and Se and masked any effect of Ox-D on metabolic oxidation status. Therefore, increasing the dietary VE concentration was unnecessary in nursery diets containing Ox-D.
... Maternal feeding constitutes the main transmission vehicle of this nutrient that provides the newborn piglet with the first defences against oxidative damage (Debier, 2007). However, serum vitamin E suffers an important decline after weaning (Chung et al., 1992) because of lower feed intake and increased stress that result in increased disease susceptibility. ...
... Transfer of α-tocopherol to piglets Piglets suffer a marked decline in α-tocopherol concentration after weaning (Chung et al., 1992;Mahan et al., 2000;Lauridsen et al., 2002). As micellized natural vitamin E (D-αtocopherol) was expected to be more efficiently accumulated than the synthetic form (Pumfrey et al., 1993;Pagan et al., 2005) and that water consumption would be more consistent than feed intake during the post-weaning period (Wilburn et al., 2008), we designed various strategies to study the effectiveness of supplementing piglets and/or sows with vitamin E. Supplementation ratios to piglets and/or sows were 1 : 1, 1 : 2 and 1 : 3 (natural vitamin E in water: synthetic in feed) trying to find a real equivalence between both forms of vitamin and administration vehicles that minimize piglet serum α-tocopherol decline after weaning. ...
... Moreover, as expected, sow serum α-tocopherol concentration increased with supplementation time (P < 0.001; Table 2) with it being interesting to note that the increase was higher when sows were supplemented with the natural vitamin E (contrast 3: interaction time × source, P < 0.001), mainly with 1/3-NAT (contrast 4: interaction time × dose: P = 0.011). Other authors have previously demonstrated that natural vitamin E was a superior source compared with synthetic (Chung et al., 1992;Mahan et al., 2000;Yang et al., 2009) and that the supplementation was more effective in increasing serum α-tocopherol when administered in the water supply than when it was added to the diet (Wilburn et al., 2008). Moreover, micellized natural vitamin E is better absorbed in plasma because micelles that transport vitamin E solubilized in their core (Pumfrey et al., 1993;Pagan et al., 2005). ...
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This study evaluated the strategy of supplementing oral micellized natural vitamin E (d-α-tocopherol) to either piglets and/or sows on α-tocopherol concentrations in piglets serum and tissues after weaning. One first experiment tested the influence of the vitamin E supplementation source (natural form in water v. the synthetic form in feed) and dose administered to piglets and/or sows on serum α-tocopherol concentration, α-tocopherol stereoisomer accumulation, antioxidant capacity and immune response of weaned piglets. A second experiment studied the effect of sow source and dose vitamin E supplementation on some of these parameters in piglets. Oral supplementation to sows with natural vitamin E as a micellized form (d-α-tocopherol) at the lowest dose produced a similar concentration of α-tocopherol in serum at days 2, 14 and 28 postpartum to those supplemented with threefold higher dose of the synthetic form in feed. At day 39 of age, neither piglet supplementation source nor dose significantly affected α-tocopherol accumulation in the serum, muscle, subcutaneous fat or liver. Those piglets from sows supplemented with the micellized alcohol form had higher RRR-α-tocopherol stereoisomers (P
... Adaptation as a result of a longer feeding period is arguably a poor argument as the enzyme responsible for this hydrolysis, carboxyl ester hydrolase, has a generic role in fat digestion while tocopheryl ester hydrolysis is likely only a fringe activity [7]. Chung et al. [8] obtained an efficiency ratio of 0.41 of T-Ac vs. T in piglets fed test diets over a 20-d period, well in line with our results. In contrast, Burton et al. [9] reported an efficiency ratio close to 1; however, these authors did not correct for the instability of T, but neither did Chung et al. [8]. ...
... Chung et al. [8] obtained an efficiency ratio of 0.41 of T-Ac vs. T in piglets fed test diets over a 20-d period, well in line with our results. In contrast, Burton et al. [9] reported an efficiency ratio close to 1; however, these authors did not correct for the instability of T, but neither did Chung et al. [8]. ...
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Vitamin E is typically supplied in the form of tocopheryl-acetate (T-Ac) since tocopherol (T) has stability issues. Tocopheryl-acetate, however, must be hydrolyzed in the intestines before it can be absorbed, a step that is purportedly rate-limiting for its bioavailability. The objective of this study was to compare the efficiency of absorption of T-Ac and T in broilers. In addition, two test procedures were evaluated in which animals received the test substances for either 2 or 4 days only. Animals were adapted to diets without supplemental vitamin E (feedstuffs contributed 14±1 ppm natural vitamin E (RRR-tocopherol)) till the age of 25 d (individual housing) or 28 d (group housing). Subsequently, they were fed T-Ac at 80, 53, 36, 24, or 16 ppm or T at 80, 40, 20, 10, or 5 ppm for a period of 4 d (4-di) or 2 d (2-dg), after which serum and liver were collected for analysis of vitamin E. Measured feed vitamin E levels were used for the data analysis; the recovery of T-Ac was 85%, and that of T was 39%. Both test procedures (2 or 4 days) yielded good quality data. Based on linear regression analysis, the relative efficiency with which T-Ac raised tissue levels as compared to T was 0.24 (2-dg) to 0.37 (4-di), with liver and serum yielding similar results. Analysis using more complex dose response models imply that the hydrolysis of T-Ac was strongly dose-dependent and that it could be saturated at doses above approximately 50 ppm in animals only briefly fed T-Ac; for T there was no evidence of saturation. These data imply that T, provided that stable forms can be developed, has the potential to be much more efficient at providing vitamin E to the animal, and on top, can yield much higher tissue levels, than T-Ac.
... The dietary concentration (i.e. nutrient intake) of vitamin E (Chung et al., 1992;Lauridsen et al., 1999) Se (Kim and Mahan, 2001), and Trp (Le Floc'h et al., 2009) affects tissue and serum concentrations of these nutrients. The sum of triglyceride and cholesterol content of serum was a covariate for serum ␣-tocopherol analysis because concentrations of ␣-tocopherol are influenced by total serum lipids (Thurnham et al., 1986;Traber and Jialal, 2000). ...
... Other researchers have reported that circulating levels of vitamin E decline within the first few weeks post-weaning (Chung et al., 1992;Moreira and Mahan, 2002;Lauridsen, 2010). The metabolic oxidative system of pigs is clearly stressed during the post-weaning transition, which may increase sensitivity of young pigs to peroxidized lipids. ...
Article
This experiment was conducted to evaluate the effects of increasing dietary levels of peroxidized maize oil on growth performance and antioxidant status of nursery pigs. Weanling barrows (n = 128; initial body weight (BW) = 6.3 ± 1.4 kg) were blocked by initial BW and assigned randomly to 1 of 32 pens. Within block, pens were assigned randomly to 1 of 4 dietary treatments: 90 g/kg unheated maize oil, 60 g/kg unheated maize oil +30 g/kg rapidly peroxidized (RO) maize oil, 30 g/kg unheated maize oil +60 g/kg RO maize oil, or 90 g/kg RO maize oil. Diets were formulated to contain identical levels of total maize oil and standardized ileal digestible Lys to metabolizable energy (ME) ratios. Maize oil was heated for 12 h at 185 °C (air flow rate = 12 L/min) to yield RO (PV = 5.7 meq O2/kg; thiobarbituric acid reactive substances = 26.7 mg malondialdehyde eq/kg) maize oil. A 3-phase feeding program (phase 1 = d 0–4, phase 2 = d 4–14, and phase 3 = d 14–35) was used, and average daily gain (ADG), average daily feed intake (ADFI), gain to feed ratio (G:F), and energetic efficiency (g ADG/MJ of ME intake) were determined. Serum was collected on d 0, 14, and 35 from 1 pig per pen that was subsequently harvested to obtain liver and heart tissue. Final BW (19.5 vs 18.5 ± 0.6 kg for 0 vs 90 g/kg RO maize oil; P < 0.15) and ADG (377.5 vs 347.0 ± 13.6 g for 0 vs 90 g/kg RO maize oil; P ≤ 0.10) tended to decline linearly with increasing dietary RO, but ADFI was not affected. Consequently, G:F (P < 0.05) declined linearly by 1.4–4% with increasing dietary concentrations of RO maize oil. The α-tocopherol content of serum declined with increasing dietary concentrations of RO maize oil (linear and cubic; P < 0.01). These data suggest that RO maize oil negatively affects growth performance and the efficiency of energy utilization of nursery pigs linearly and reduces serum α-tocopherol content.
... Am stärksten war der Anstieg im Serum der Kontrollgruppe, bei welcher der α- (Chung et al. 1992). So fanden Meyer und sein Team heraus, dass die Serum-Tocopherol-Konzentration bei Schweinen in den ersten 2 ...
... In vielen Spezies wird die orale LD-50 erst bei ≥ 2 g/kg KM erreicht (FASEB 1975 Es wurde vermieden, eine zu hohe Dosis an Vitamin E zu füttern, da bei steigender Dosis der Anteil, der absorbiert wird, sinkt (Schmandke et al. 1969). Gleichzeitig durfte die Menge aber nicht zu gering sein, da nur bis zu 50 % der aufgenommenen Menge an Vitamin E auch tatsächlich absorbiert wird und der Serumverlauf bei zu geringem α-Tocopherol-Gehalt schwer darzustellen gewesen wäre (Chung et al. 1992 (Bieri 1972;Machlin et al. 1979;Roneus et al. 1986;Jensen et al. 1988 (Kovac 1977;Karpinski und Hidiroglou 1990;Hoppe 1991;. ...
... A further possibility could involve the use of the natural form of vitamin E (mainly composed of the RRR-stereoisomer) instead of the synthetic form (all-rac-α-tocopheryl acetate), which contains a mixture of eight stereoisomers. Indeed, it has recently been demonstrated that the natural form of vitamin E (D-α-tocopherol) is accumulated more efficiently than the synthetic form (Chung et al., 1992;Hoppe and Krennrich, 2000;Lauridsen et al., 2002;Mahan et al., 2000) due to the higher affinity of the α-tocopherol transfer protein for the natural RRR-stereoisomer (Hosomi et al., 1997). Likewise, drinking water could be an interesting vehicle for providing vitamin E to weaned piglets as water consumption is generally not compromised by weaning (Wilburn et al., 2008) and hence would not be affected by lack of appetite during this period. ...
... It is interesting to note that at weaning, serum α-tocopherol concentration was higher in those piglets from sows supplemented with natural vitamin E in drinking water when compared with those that received the synthetic form. This effect is related to that observed in sows' serum and is in part explained by a more efficient accumulation of the natural form (Chung et al., 1992;Lauridsen et al., 2002;Mahan et al., 2000). Moreover, the piglet serum α-tocopherol concentration decreased with time (P = 0.0001), especially from weaning to day 5 postweaning due to the increased stress and low feed intake. ...
Article
The influence of vitamin E supplementation (d-α-tocopherol) in drinking water administered concomitantly with the synthetic form in feed to sows during the lactation period and/or piglets post-weaned on tocopherol, and its transfer from sows to milk and piglet serum, as well as its antioxidant power and immune response, were investigated. Those piglets supplemented with natural α-tocopherol in drinking water and born from sows supplemented with the same form of vitamin E (SS-SP) had the highest serum α-tocopherol concentration at five days post-weaning, whereas the lowest serum α-tocopherol concentration was found for the group fed α-tocopheryl acetate and born from sows fed the same type of vitamin E (CS-CP). Intermediate values were found in those piglets provided with α-tocopheryl acetate born from sows supplemented with natural vitamin E in drinking water (SS-CP) and those provided with natural α-tocopherol in water born from sows supplemented with α-tocopheryl acetate (CS-SP) at five days post-weaning. From weaning to day 5, piglet serum α-tocopherol concentration decreased by 65% for CS-CP and SS-CP groups and 47% for groups CS-SP and SS-SP. The CS-SP and SS-CP groups had similar α-tocopherol concentrations in serum to the SS-SP group at 20 days post-weaning. The FRAP was significantly affected by the natural vitamin E supplementation of piglets (P = 0.037) which is in accordance with the differences observed in vitamin E concentration. The GSSH level in the SS-SP group was by approximately 20% and 25% lower (P = 0.0023) with respect to the CS-CP group at 5 and 20 days post-weaning, respectively. The immunoglobulin levels in piglet serum were not significantly affected by natural vitamin E supplementation in drinking water. The treatment effects observed were mainly due to vitamin E supplementation of piglets.
... The amplification conditions were 10 min at 45°C, 10 min at 95°C and 40 cycles of 15 s at 95°C and 45 s at 60°C. Ching et al., 2002;Chung et al., 1992;. Ching et al., 2002;Chung et al., 1992;. ...
... Ching et al., 2002;Chung et al., 1992;. Ching et al., 2002;Chung et al., 1992;. b Puls, 1994. ...
Article
Mulberry heart disease (MHD) in pigs is characterized by lesions of acute haemorrhagic myocarditis and myocardial necrosis. The objectives of this study were to determine the levels of vitamin E and selenium and 13 other trace minerals in heart and liver tissues and to determine the prevalence of certain viral infections in heart tissues from MHD-affected and MHD-unaffected pigs and the vitamin E and selenium concentration in feed samples from selected farms with MHD. Based on the pathological examination, 114 pigs were separated into MHD lesion-negative (L-NEG) (n = 57) and MHD lesion-positive (L-POS) (n = 57) groups. Seventy-three samples (40 L-NEG and 33 L-POS) were subjected to chemical analysis, and 66 (32 L-NEG and 34 L-POS) were subjected to PCR detection for viral pathogens. Lower (P < 0.05) levels of myocardial copper, lower (P < 0.05) levels of hepatic magnesium and higher (P < 0.05) levels of myocardial and hepatic sodium were detected in the L-POS cases. Although lower (P < 0.05) levels of hepatic selenium were detected in L-POS group, all were within the normal range. Analysis of feed samples (n = 22) revealed that selenium levels in all the samples were above the legal limit (0.3 ppm) for pigs. Vitamin E levels in all feed samples were above 20 IU/kg. Among the 66 pigs subjected to PCR detection, there were 19, 4, 13, 8, 2 and 1 animals positive for porcine circovirus type 2, porcine reproductive and respiratory syndrome virus, pan-herpes virus, porcine enterovirus, pan-pestivirus and porcine parvovirus, respectively. Clear evidence of viral association with L-POS was lacking.
... Some clinical studies, especially in humans, considered that the α-tocopherol-lipid (triglycerides + cholesterol) ratio is an accurate indicator to determine if the current circulating level is optimal [37]. Vitamin E is fat-soluble; therefore, it circulates linked to low-density lipoproteins and its absorption may be enhanced by other dietary lipid components [68]. In the current study, the pigs fed with a high dose of Vit E showed the highest α-tocopherol-lipid ratio but, at the same time, there were no differences between groups in the plasmatic lipid levels (such as cholesterol, triglycerides, and NEFA). ...
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This study aimed to assess the impact on growth, economic results, apparent nutrient digestibility (CTTAD), physiological variables, and animal behaviour when 214 fattening pigs (78 ± 8.5 kg of initial body weight and 130 ± 4.5 days of age) of both sexes (gilts and boars) were fed two levels of carob pulp (Cp, 0 vs. 20%) and two doses of vitamin E (Vit E, 30 vs. 300 IU/kg) for 40 days. No interaction effects between factors studied (Cp, Vit E, and sex) were observed on the variables. Most productive traits were unaffected by Cp or Vit E inclusion. However, the Cp increased the feed conversion ratio during the first 20 days. The Cp group showed a higher CTTAD of ether extract and hemicellulose but lower CTTAD of crude protein. Pigs fed Cp had a lower plasmatic urea content than the control group. The high Vit E doses increased the CTTAD of every nutrient and the plasmatic α-tocopherol content. The pigs fed Cp tended to spend more time eating in the early morning, likely to mitigate tannins' astringent effects. Dietary inclusion of 20% Cp in finishing high-conformation pigs is possible without affecting overall performance though it reduces nutrient CTTAD and increases feeding cost. Supra-nutritional doses of Vit E do not affect pig performance but increase the α-tocopherol deposition with potential antioxidant effects.
... As reported by Sivertsen [50], the National Veterinary Institute has considered plasma levels of vitamin E below 1.0 µg/mL as distinctly deficient, while normal is considered equal to 2.0 mg/L [51]. It should be underlined that the proportion of pigs with a plasma vitamin E level below 1.5 µg vitamin E/mL is very common [52,53]. ...
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Vitamin E is an essential nutrient usually recommended in post-weaning piglets, when a decline in the serum vitamin E concentration is observed. Selected polyphenols have the potential to partially replace vitamin E in animal feed. The aim of this study was to investigate the effect of the dietary inclusion of some commercial polyphenol products (PPs) on the growth performance, antioxidant status and immunity of post-weaning piglets. A total of 300 piglets (BW 7.18 kg ± 1.18) were randomly assigned to six dietary groups: CON− (40 mg/kg vitamin E); CON+(175.8 mg/kg vitamin E); and PP1, PP2, PP3 and PP4, in which 50% vitamin E of CON+ was replaced with PP with equivalent vitamin E activity. The PP1 group exhibited lower performance (p < 0.05) than the other dietary groups, but a similar performance to that commonly registered in pig farms. Dietary polyphenols did not influence the IgG concentration or the IL-6, IL-10, IFN-γ and TNF-α cytokine concentrations. A lower IL-8 level was found in the PP4 group than in the other groups. The diets that affected the vitamin A content showed the highest value (p < 0.05) in the PP1 group, and a trend was noted for vitamin E with a higher content in PP4 and CON+. The polyphenols-enriched diets, especially the PP3 diet, maintained an antioxidant capacity (whole blood KRL) similar to the CON+ diet. In conclusion, the replacement of vitamin E with all PPs enables partial vitamin E substitution in post-weaning piglets.
... The fact that the sows that received lower doses of natural vitamin E in water tended to have higher values in colostrum than those supplemented with the synthetic form, would in part indicate that the micellized natural alcohol form in water was more efficiently accumulated than the synthetic form. Other authors have demonstrated that natural vitamin E was superior compared to its synthetic counterpart [13,29,30] and that the supplementation was more effective in increasing serum α-tocopherol when administered in the water supply than when it was added to the diet [9]. Micellized natural vitamin E is better absorbed in plasma because micelles transport solubilized vitamin E in their core [10,11]. ...
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This study evaluated the effect of vitamin E supplementation source, and the dose given to sows or piglets, on the fatty acid profile of colostrum, milk, subcutaneous and intramuscular fat, and the oxidative status of piglets at 39 days of age. Sows (n = 10) were given 150 mg dl-α-tocopheryl acetate/d in feed, or 75 or 50 mg micellized-d-α-tocopherol/d in water from Day 103 of pregnancy. Weaning piglets from each group of sows (n = 7) received 3.33 mg dl-α-tocopheryl acetate/d in feed, or 1.7 mg micellized-d-α-tocopherol/d or 1.1 mg micellized-d-α-tocopherol/d in water for 14 days. Colostrum from sows supplemented with micellized-d-α-tocopherol had a lower proportion of C20:0 (P = 0.02), C18:4 n-3 (P = 0.03) and a higher C18:1 n-9 to C18:0 ratio than those given dl-α-tocopheryl acetate. Supplementation with micellized-d-α-tocopherol decreased the C18:0 proportion (P = 0.04) and the C18:1 n-9 to C18:0 ratio (P = 0.03) in milk, whereas the C18:1 n-7 proportion increased (P = 0.03) compared to dl-α-tocopheryl acetate. Composition was affected by the d-α-tocopherol dose. A similar trend to that observed in milk was observed in fatty acid composition in piglet fat. Piglets supplemented with micellized-d-α-tocopherol at low doses did not have different ferric reducing antioxidant power in muscle tissues (P = 0.31) than when they were supplemented with dl-α-tocopheryl acetate. Piglets given 1.7 mg micellized-d-α-tocopherol/d had lower oxidized glutathione than those given 1.1 mg/d (P = 0.0055). In conclusion, oral supplementation of sows (75 mg/d) and piglets (1.7 mg/d) with micellized natural vitamin E modified the fatty acid profile of piglet tissues and improved their oxidative status.
... Antioxidant activity of the tocopherol isomers varies, with α > β > γ > δ, and is related to the quantity, position, and conformation of methyl groups on the aromatic ring [180]. The most common form of vitamin E added to swine diets is synthetic dl-α-tocopheryl acetate, because of enhanced stability relative to the free alcohol form [181]. The most potent metabolic form of vitamin E is α-tocopherol [182], and it has greater abundance in vivo relative to other forms [178]. ...
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In livestock diets, energy is one of the most expensive nutritional components of feed formulation. Because lipids are a concentrated energy source, inclusion of lipids are known to affect growth rate and feed efficiency, but are also known to affect diet palatability, feed dustiness, and pellet quality. In reviewing the literature, the majority of research studies conducted on the subject of lipids have focused mainly on the effects of feeding presumably high quality lipids on growth performance, digestion, and metabolism in young animals. There is, however, the wide array of composition and quality differences among lipid sources available to the animal industry making it essential to understand differences in lipid composition and quality factors affecting their digestion and metabolism more fully. In addition there is often confusion in lipid nomenclature, measuring lipid content and composition, and evaluating quality factors necessary to understand the true feeding value to animals. Lastly, advances in understanding lipid digestion, post-absorption metabolism, and physiological processes (e.g., cell division and differentiation, immune function and inflammation); and in metabolic oxidative stress in the animal and lipid peroxidation, necessitates a more compressive assessment of factors affecting the value of lipid supplementation to livestock diets. The following review provides insight into lipid classification, digestion and absorption, lipid peroxidation indices, lipid quality and nutritional value, and antioxidants in growing pigs.
... Alpha-tocopherol is the most active isomer of the vitamin E family, and is the principle lipid-soluble antioxidant in tissues and blood (Rigotti, 2007). After absorption, α-T is transported in serum by lipoproteins where it initially functions to protect unsaturated fatty acids from free radical damage (Chung et al., 1992). In the current experiment, although all pigs had higher daily consumption of dietary α-T than NRC (1998) recommendations, pigs fed lipids that had been subjected to slow-or rapidoxidation exhibited lower serum α-T than pigs fed OL within the CN or CA treatment. ...
... After absorption, α-T is transported in serum by lipoproteins where it initially functions to protect Table 1 Within a lipid source, means with different superscript differ, P < 0.05. at Magrath Library, Serials Department on July 9, 2014 www.journalofanimalscience.org Downloaded from unsaturated fatty acids from free radical damage (Chung et al., 1992). In the current experiment, although all pigs had greater daily consumption of dietary α-T than NRC (1998) recommendations, pigs fed lipids that had been subjected to SO or RO exhibited lower serum α-T than pigs fed OL within the CN or CA treatment. ...
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To evaluate the effect of feeding thermally-oxidized lipids on metabolic oxidative status, gut barrier function, and immune response of young pigs, 108 barrows (6.67 ± 0.03 kg BW) were assigned to 12 dietary treatments in a 4 × 3 factorial arrangement in addition to a corn-soybean meal control diet. Main effects were 4 lipid sources [corn oil (CN), canola oil (CA), poultry fat (PF), and tallow (TL)] and 3 oxidation levels [original lipids (OL), slow oxidation (SO) of lipids heated for 72 h at 95°C, or rapid oxidation (RO) of lipids heated for 7 h at 185°C]. Pigs were provided ad libitum access to diets for 28 d, followed by controlled feed intake for 10 d. After a 24-h fast on d 38, serum was collected and analyzed for α-tocopherol (α-T), thiobarbituric acid reactive substances (TBARS), endotoxin, haptoglobin, IgA, and IgG. On the same day following serum collection, lactulose and mannitol were fed and subsequently measured in the urine to evaluate gut permeability. There was a source × peroxidation interaction for serum α-T concentration where pigs fed SO or RO had decreased (P < 0.05) serum α-T concentration compared with pigs fed OL in CA and CN diets, but not in pigs fed PF and TL diets. There was no source × peroxidation interaction for serum TBARS, but among all lipid sources, pigs fed SO or RO lipids had increased (P < 0.05) serum TBARS compared with pigs fed OL. In addition, pigs fed CN or CA had greater (P < 0.05) serum TBARS compared with pigs fed PF or TL diets. There was no lipid source × peroxidation level interaction, or lipid source or peroxidation level effects on serum endotoxin, haptoglobin, IgA, or IgG. Pigs fed lipid supplemented diets tended to have increased serum endotoxin (P = 0.06), IgA (P = 0.10), and IgG (P = 0.09) compared with pigs fed the control diet. There was no lipid source × peroxidation level interaction or lipid source or peroxidation level effects on urinary TBARS and lactulose to mannitol ratio. Compared with pigs fed the control diet, pigs fed diets containing lipids had a lower lactulose to mannitol ratio (P < 0.01). In conclusion, feeding weaning pigs diets containing 10% thermally-oxidized lipids for 38 d, especially vegetable oils containing greater concentrations of PUFA, appeared to impair oxidative status, but had little influence on gut barrier function or serum immunity parameters.
... This might lead to lowering incidence of related diseases, such as enteritis, pneumonia and sepsis (Lykkesfeldt and Svendsen, 2007). The results on growth performance are in agreement with previous studies on post-weaned piglets (Chung et al., 1992;Wilburn et al., 2008) which reported no improvement in the ADG or FCR due to dietary level of a-tocopheryl acetate. ...
Article
The application of Kit Radicaux Libres (KRL) test to assess total blood antioxidant activity in pigs was evaluated. The KRL has been validated and is widely used in humans for assessing the effectiveness of natural or pharmaceutical treatments, and in vitro to evaluate the antioxidant activities of natural or synthetic antioxidants. In this study the sensitivity of the KRL test in assessing the effectiveness of dietary antioxidant supplementation (vitamin E and plant extract) was evaluated in two different phases of pig breeding. The first trial, in post-weaned piglets (40 piglets/group) fed dietary vitamin E supplementation for 60days, indicated that there was a higher total antioxidant activity (P=0.032) of whole blood and of red blood cells (P=0.001) than for control pigs. The second trial indicated that long-term supplementation of water soluble plant extract (20 pigs/group) from the leaves of Verbenaceae (Lippia spp.) tended (P=0.091) to increase antioxidant activity in the whole blood of treated, rather than control pigs. These results indicate that the KRL might be recommended as one of efficient means for evaluating antioxidant activity of dietary ingredients fed to pigs.
... In general, the retinol and retinyl palmitate contents reflected the retinyl acetate concentration of the diets. The a-tocopherol content was higher in the adipose tissue, followed by the liver and the muscle samples, in accordance with earlier findings (Chung et al., 1992;Buckley et al., 1995). The retinol and retinyl palmitate concentration significantly increased with a high dVitA in all tissues. ...
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This study aimed to assess the interaction between different dietary vitamin A (dVitA) levels and the same concentration of vitamin E (100 IU all-rac-α-tocopheryl acetate/kg feed) in growing-finishing pigs. In the first experiment, two fat sources × two dVitA levels (0 v. 100 000 IU) were used. The supplementation of 100 000 IU dVitA induced a range of 5.13 to 30.03 μg retinol/g liver, 62.78 to 426.88 μg retinol palmitate/g liver, and 0.60 to 1.96 μg retinol/g fat. Dietary fat did not affect retinol or retinyl palmitate deposition in pigs. The high concentration of dVitA produced lower fat and liver α-tocopherol concentrations, and increased susceptibility of muscle tissue to oxidation. A second experiment was carried out to study the retinol and α-tocopherol retention at different withdrawal times prior to slaughter (two dVitA levels; 0 v. 100 000 IU). A high dose of 100 000 IU vitamin A during a short 2-week period was enough to induce α-tocopherol depletion in liver and fat to a similar extent as when 100 000 IU were administered during the whole fattening. Muscle, fat and liver α-tocopherol concentrations were not affected by dVitA in the 1300-13 000 IU/kg range, but liver α-tocopherol concentration was higher when vitamin A was removed from the vitamin mix 5 weeks prior to slaughter (experiment 3).
... There is also a question regarding whether synthetic dl-a-tocopherol acetate is as effective as the natural atocopherol form (Huang et al., 1982;Chung et al., 1992). These researchers suggested that the alcohol form may have greater biological activity than the acetate ester commonly used in supplementation of poultry diets. ...
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The objectives of this experiment were to determine the effects of high dietary levels of vitamin E on growth performance and pulmonary hypertension syndrome (PHS) mortality. Male broiler chicks (Cobb 500) were randomly assigned to one of four dietary treatments consisting of standard starter and grower diets supplemented with 0, 17, 46, and 87 mg dl-alpha-tocopherol acetate/kg. To encourage the development of PHS, air temperature in the house was 32 and 28 C for Weeks 1 and 2, dropped to 18 C during Week 3, and kept between 10 and 15 C during Weeks 4 through 7. Also, chicks were placed in floor pens on litter used for five previous flocks and ventilation reduced to increase dust and ammonia in the house. Ammonia levels increased from an initial 18 to 36 ppm on Day 42 with the increase in ammonia corresponding to an obvious increase in dust in the air. Lung and liver tissue obtained at 2, 5, and 7 wk of age were analyzed for tissue alpha- and gamma-tocopherol by liquid chromatography. Dietary vitamin E had no effect on body weight, feed intake, or feed efficiency. Cumulative PHS mortality through 7 wk of age was 21% and was also unaffected by dietary treatment. Liver and lung alpha-tocopherol concentrations exhibited a dose-response increase to dietary tocopherol and there was a high correlation between lung and liver tissue alpha-tocopherol (r = 0.72, P < 0.05). Whereas gamma-tocopherol concentrations in lung and liver were unaffected by dietary treatment, liver and lung exhibited age-dependent increases in both alpha- and gamma-tocopherol. Despite dose-dependent increases in tissue alpha-tocopherol, supplementation of diets with up to 87 mg dl-alpha-tocopherol acetate had no effect on growth performance or PHS mortality in broilers under the conditions used in this study.
... The mechanisms and interactions among various stereoisomers of a-tocopherol and their influence on tissue RRRa-tocopherol until recently was limited. However, a growing body of evidence from studies with various species including rats (Weiser & Vecchi, 1981;Leth & Sondergaard, 1983;Ogihara et al. 1985;Ingold et al. 1987;Behrens & Madere, 1991;Weiser et al. 1996), seals (Engelhardt, 1977), fish (Hung et al. 1982), sheep (Hidiroglou et al. 1988b(Hidiroglou et al. , 1992, cattle (Hidiroglou et al. 1988a) and pigs (Chung et al. 1992;Mahan et al. 2000) indicated that the uptake of isomers of the natural configuration 2R was significantly higher than that of the configuration 2S, though the extent of discrimination between the 2R and 2S isomers varied somewhat among species. ...
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This chapter aims to integrate recent scientific advances in vitamin nutrition of pigs. Vitamin A may influence both ovarian steroidogenesis and the uterine environment by affecting ovarian progesterone production. The pig uterus secretes a large amount of several proteins in response to progesterone. Like vitamin E, ascorbic acid plays a role in protection against oxidative processes, which is important for both protection of sperm, and the breakdown of highly reactive oxygen molecules and radicals in granulosa and luteal cells and also immune function. Besides toxicity resulting from excess vitamin A, vitamin D is the vitamin most likely to be toxic for both humans and livestock. Excessive intake of vitamin D produces a variety of effects, all associated with abnormal elevation in blood calcium. Vitamin provision may have impact on health of pigs when taking into account that all vitamins have direct or indirect influence on the immune response.
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The vitamin E family includes tocopherols and tocotrienols, which are essential lipid-soluble antioxidants necessary for human and livestock health. The seeds of many plant species, including maize, have high gamma (γ)-tocopherol but low alpha (α)-tocopherol contents; however, α-tocopherol is the most effective antioxidant. Therefore, it is necessary to optimize the tocopherol composition in plants. α-Tocopherol is synthesized from γ-tocopherol by γ-tocopherol methyltransferase (γ-TMT, VTE4) in the final step of the tocopherol biosynthetic pathway. In the present study, the full-length coding sequence (CDS) of γ-TMT was isolated from Zea mays, named ZmTMT. The ZmTMT CDS was 1059 bp in size, encoding 352 amino acids. Recombinant ZmTMT was expressed in Escherichia coli and the purified protein effectively converted γ-tocopherol into α-tocopherol in vitro. A comparison of enzyme activities showed that the activity of ZmTMT was higher than that of GmTMT2a (Glycine max) and AtTMT (Arabidopsis thaliana). Overexpression of ZmTMT increased the α-tocopherol content 4–5-fold in transgenic Arabidopsis and around 6.5-fold in transgenic maize kernels, and increased the α-/γ-tocopherol ratio to approximately 15 and 17, respectively. These results show that it is feasible to overexpress ZmTMT to optimize the tocopherol composition in maize; such a corn product might be useful in the feed industry in the near future.
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Vitamin E (VE), an indispensable vitamin in piglet feed formula. Among other things, it affects tissues including small intestine tissues and in particular its major unit intestinal epithelial cells. Previously limited in vivo experiments have focused on the effect of VE on the intestine, particularly digestion and absorption. VE has been shown to inhibit proliferation of some types of cells. This experiment was conducted to test the hypothesis that VE affects intestinal functions by influencing the intestinal epithelial cell proliferation. Thirty 21-day old weaned [(Yorkshire × Landrace) × Duroc] piglets with body weights of 6.36 ± 0.55 kg were randomly divided into 5 VE-containing feeding formula group. The treatments were: 1. 0 IU (control); 2. 16 IU; 3. 32 IU; 4. 80 IU; and 5. 160 IU. The treatments lasted 14 days. At the end of the experiment, all subjects were sacrificed to obtain blood and tissue samples. The results suggest that VE did not affect the growth performance. VE did tend to decrease jejunal crypt depth (CD) (linear, P = 0.056) and villus width (VW) (linear, P< 0.05). Sucrase activity significantly decreased in the adding 80 IU VE compared to the control (P < 0.05). Jejunal crypt, cell proliferation in 80 IU group significantly decreased compared to the control group (P < 0.05). This study suggests that dietary VE may affect intestinal morphology and functions by inhibiting weaned piglet jejunal epithelial cell proliferation.
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A vitamin E study was carried out with 12 pregnant guinea pigs utilizing a stable isotopic technique in order to assess the transfer of various forms of vitamin E (natural and synthetic alpha tocopherol) across the placenta and the mammary gland following a continuous oral dosing (60 mg d3-RRR-alpha-tocopheryl acetate/kg + 60 mg d6-all-racemic-alpha-tocopheryl acetate/kg) throughout gestation and lactation with deuterium labeled vitamin E. At late term pregnancy (day 60) and through early lactation (days 1-5), dams and their corresponding fetuses/neonates were sacrificed and various tissues collected for subsequent analysis for levels of the two forms of alpha tocopherol to establish the extent of transfer of vitamin E as well as their relative bioavailability. Vitamin E analysis from fetal and neonatal tissues that included the adrenals, brain, heart, kidneys, liver, lungs, muscle, plasma and spleen indicated a substantial transfer of deuterium labeled alpha tocopherol compounds across the placenta and through the mammary gland. In addition the data showed that in all tissues examined including fetal/neonatal and maternal, that a strong preferential discrimination in favor of the natural form (RRR) of alpha tocopherol as compared to the synthetic form (all-racemic alpha tocopherol) was observed. The relative bioavailability (natural:synthetic alpha tocopherol) across fetal and neonatal tissues was on average 1.85/1, with a range from 1.78/1 to 1.90/1. Maternal tissues on average showed a ratio of 1.82/1, with a range from 1.72/1 to 1.99/1. A higher bioavailability (P less than or equal to 0.05) was observed with natural than synthetic alpha tocopherol as evidenced by a higher ratio of d3/d6 in all tissues examined. Colostrum contained the highest amount of total vitamin E which followed a gradual decline (P greater than or equal to 0.05) over the remaining 4 day lactation period. The data obtained from this study raise further questions on the current accepted biological potencies of natural: synthetic alpha tocopherol (1.36/1), respectively.
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Almonds are an important dietary source of lipids, protein, and α-tocopherol. It has been demonstrated that the physical form of almond kernels influences their digestion and absorption, but the role of thermal processes on the digestion of almonds has received little attention. The objectives of this study were to examine the gastric emptying and nutrient composition of gastric chyme from pigs (used as a model for the adult human) fed a single meal of either raw or roasted almonds over a 12-h postprandial period (72 pigs total, 6 pigs at each diet-time combination). Concentrations of glucose, triacylglycerols, and α-tocopherol in peripheral plasma during the 12-h postprandial period were determined. For dry matter and lipid, the gastric emptying profile was not different between raw and roasted almonds. Roasting almonds also did not influence gastric pH, or plasma glucose or triacylglycerols levels. In contrast, the gastric emptying of protein was more rapid for raw almonds compared to roasted almonds (P < 0.01) and intragastric protein content exhibited segregation (P < 0.001) throughout the stomach, with raw almonds having a higher level of segregation compared to roasted almonds. Postprandial plasma α-tocopherol levels were, on average 33% greater (P < 0.001) after consumption of raw almonds, most likely as a result of the higher concentration of α-tocopherol in raw almonds compared to roasted almonds. Roasting of almonds did not influence the overall gastric emptying process, but did lead to differences in the distribution of protein in the stomach and to the gastric emptying of protein.
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The aim of this study was to evaluate the effect of increased vitamins E and C doses in the feeding of sows at the last stage of gestation (90 day) and during lactation on the performance of sows and their piglets. The study was carried out in two seasons (winter and summer) on 139 multiparous sows, divided into three groups: control diet – vitamin E 60 mg/kg, experimental diet – vitamin E 200 mg/kg, experimental diet – vitamin E 200 mg/kg + vitamin C 500 mg/kg. In spite of an increased concentration of these vitamins in the serum of piglets, no clear effect on the rearing results was found. However, an advantageous post-effect of the vitamins fed to sows was shown. The addition of vitamin E together with vitamin C significantly reduced the body temperature of sows after farrowing and considerably reduced the number of sows culled after rearing.
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A total of two hundred 35-week-old (Hy-line brown) layers were randomly assigned to 4 treatments with 10 replications and 5 layers per replicate (1 layer per cage). Dietary treatments were: (1) CON (basal diet); (2) S150, CON + synthetic vitamin E (VE) 150 IU/kg; (3) N50, CON + natural VE 50 IU/kg; and (4) N75, CON + natural VE 75 IU/kg. Dietary VE led to a greater Haugh unit (HU) and VE concentration in yolk (p0.05) throughout the experiment. Blood characteristics were not affected by the administration of VE. Moreover, no difference (p>0.05) was observed on the laying hens’ performance and egg quality between the synthetic and natural VE supplementation. In conclusion, dietary VE improved the VE concentration in yolk and the HU compared with the CON group. VE concentration of yolk and most characteristics were consistent in those birds fed Nat E Ac (50 or 75 IU/kg) compared with those fed Syn E Ac treatment (150 IU/kg), indicating the relative bioavailability of natural VE was two or three times greater than synthetic VE in laying hens.
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The difference in bioactivity between d- and dl- forms of α-tocopherol is reflected in the currently established United States Pharmacopoeia Standards for vitamin E activity. Current evidence strongly supports the concept that the presently accepted values assigned to the d- and dl- forms of α-tocopherol and corresponding acetate esters are valid for application to farm animals. Consequently, there is no known advantage to supplementing animal feeds with d- forms of vitamin E (α-tocopherol) so long as what is supplemented is provided in International Units and not in milligrams.
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A simple method is described which permits, avoiding saponification, α-tocopherol and α-tocopheryl acetate measurement in semi-synthetic diets for experimental animals by HPLC, with both UV and fluorescence detection. Phenyldodecane was chosen as internal standard with remarkable performances, and EDTA and BHT were added to prevent oxidation in aqueous and non-aqueous phases respectively. The mobile phase was methanol–water (94:6, v/v) at a flow-rate of 2 ml/min. Samples were homogenized and extracted twice with n-hexane by probe sonication. Extracts were evaporated to dryness and redissolved with chloroform–methanol (1:1, v/v). Validation parameters were studied between 25 ng and 6 μg for α-tocopherol and between 3 and 24.2 μg for α-tocopheryl acetate, which corresponds to the range of values in the existing diets. Results had correlation coefficients >0.99; recoveries >85%; R.S.D.
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Vitamin E is an essential micronutrient for humans and animals due to its antioxidant and non-antioxidant biological activities. The α-tocopherol acetate form is often used in foods and other products due to its high biological activity and chemical stability. In this study, we examined the influence of carrier oil type on the bioaccessibility and molecular form of emulsified vitamin E using a simulated gastrointestinal model. Oil-in-water emulsions containing α-tocopherol acetate were prepared using quillaja saponin as a natural surfactant, and either long chain triacylglycerols (LCT) or medium chain triacylglycerols (MCT) as carrier oils. The rate and extent of lipid digestion was higher for MCT- than LCT-emulsions, which was attributed to differences in the water dispersibility of the free fatty acids formed during lipolysis. Conversely, the total bioaccessibility of vitamin E after digestion was higher for LCT- than MCT-emulsions, which was attributed to the greater solubilisation capacity of mixed micelles formed from long chain fatty acids. The conversion of α-tocopherol acetate to α-tocopherol after in vitro digestion was also considerably higher for LCT- than MCT-emulsions, which may impact the subsequent absorption of vitamin E. Overall, this research has important implications for the design and fabrication of effective emulsion-based delivery systems for increasing the bioavailability of vitamin E.
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Vitamin E is an essential micronutrient for humans and animals due to its antioxidant and non-antioxidant biological activities. In this study, an emulsion titration assay was used to quantify the kinetics and extent of vitamin E and vitamin E acetate solubilization in model mixed micelles. The composition of the mixed micelles was designed to mimic those produced during digestion of lipids in the human small intestine: bile salts, phospholipids, and free fatty acids. Initially, the optimum conditions required to form model mixed micelles were established. The solubilization capacities of vitamin E and vitamin E acetate in the mixed micelles were then compared. The solubilization capacity of the mixed micelles for vitamin E was higher than that for vitamin E acetate, which was attributed to differences in the ability of the vitamin molecules to be incorporated into the micelle structure. The solubilization capacities also depended on the composition of the mixed micelles: micelle solubilization of vitamin E was increased by the presence of phospholipid (DOPC), but did not depend strongly on the presence of free fatty acid (octanoic acid or linoleic acid). Overall, this research has important implications for understanding the digestion, absorption, and transportation of vitamin E in the human gastrointestinal tract and for designing suitable delivery systems to increase its bioaccessibility.
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The present study investigated the effect of dietary fats rich in polyunsaturated fatty acids (soybean oil), mono‐unsaturated fatty acids (olive oil) and saturated fatty acids (beef tallow) on the susceptibility of low‐density lipoproteins (LDL) to lipid peroxidation in pigs. In a cross‐over design with three periods, nine pigs were fed each of the fats in daily amounts of 250 g for two weeks. The susceptibility of LDL to lipid peroxidation was determined by Cu ²⁺ ‐catalysed oxidation. The lag phase before onset of oxidation, the rate of diene formation during propagation phase and the maximal amount of dienes produced during oxidation were considered for assessing the oxidative susceptibility. The LDL of pigs fed soybean oil had a higher oxidative susceptibility than the LDL of pigs fed beef tallow or olive oil. Probably, the increased susceptibility of LDL from pigs fed soybean oil to lipid peroxidation is due to an enrichment of LDL with linoleic acid whereas an enrichment of LDL with oleic acid in pigs fed olive oil or beef tallow reduced its oxidative susceptibility. The concentration of total tocopherols in plasma, expressed per mol lipid, was not influenced and that in LDL was only slightly influenced by the dietary fat, indicating that the dietary fat had only a small effect on vitamin E status. Pigs fed soybean oil had increased concentrations (expressed per mol lipid) of thiobarbituric acid reactive substances in plasma, suggesting an enhanced lipid peroxidation relative to pigs fed olive oil or beef tallow. The effect of dietary fats on the susceptibility of LDL to lipid peroxidation might be of physiological relevance because oxidatively modified LDL play an important role in the progress of atherosclerosis. Zusammenfassung Der Einfluß des Fettes auf die Oxidationsanfälligkeit der Lipoproteine geringer Dichte beim Schwein In der vorliegenden Arbeit wurde der Einfluß verschiedener Fette, nämlich von Sojaöl mit einem hohem Anteil mehrfach ungesättigter Fettsäuren, von Olivenöl mit einem hohen Anteil einfach ungesättigter Fettsäuren sowie von Rindertalg mit einem hohen Anteil gesättigter Fettsäuren auf die Oxidationsanfälligkeit der Lipoproteine geringer Dichte (LDL) beim Schwein untersucht. Dazu erhielten neun Schweine entsprechend eines Cross‐over Versuchsplans mit drei Versuchsperioden von jeweils zwei Wochen Dauer jedes der drei Fette in einer Zulage von 250 g pro Tag einmal. Die Oxidationsanfälligkeit der LDL wurde durch das Ausmaß der durch Kupferionen induzierten Oxidation bestimmt. Als Meßparameter wurden hierbei die Zeit bis zum Einsetzen der Oxidation, die Rate der Bildung konjugierter Diene sowie die maximal erreichte Konzentration konjugierter Diene herangezogen. Die Zulage von Sojaöl führte zu einer deutlich erhöhten Oxidationsanfälligkeit der LDL im Vergleich zur Zulage von Rindertalg oder Olivenöl. Diese erhöhte Oxidationsanfälligkeit bei der Sojaölzulage ist vermutlich auf eine Anreicherung von Linolsäure in den LDL zurückzuführen. Bei der Zulage von Olivenöl und Rindertalg zeigte sich hingegen eine Anreicherung von Ölsäure in den LDL, was vermutlich die geringe Oxidationsanfälligkeit der LDL der mit diesen Fetten gefütterten Tiere erklärt. Die Konzentrationen der Gesamt‐Tocopherole (bezogen auf die Lipidkonzentrationen) wurden durch die Art des Fettes nicht (Plasma) bzw. nur geringfügig (LDL) beeinflußt. Folglich hatte die Art des Fettes keinen starken Einfluß auf den Vitamin E‐Status der Tiere. Bei Zulage von Sojaöl ergaben sich im Vergleich zu den Zulagen an Olivenöl oder Rindertalg erhöhte Konzentrationen Thiobarbitursäure‐reaktiver Substanzen im Plasma, was auf eine erhöhte Lipidperoxidation in vivo hinweist. Der Einfluß des Diätfettes auf die Oxidationsanfälligkeit der LDL dürfte von großer physiologischer Bedeutung sein, da oxidativ modifizierte LDL in vivo eine wichtige Rolle bei der Entstehung der Arteriosklerose Rolle spielen.
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We determined the effect of pasture feeding (P0) or sorghum feeding with 2500 IU/head/d; (G2500) or without (G0) vitamin E supplementation on the color stability of gluteus medius (GM), longissimus lumborum (LL) and semimembranosus (SM). Diets did not affect the total pigment concentration of the muscle. Color stabilities were G2500 > P0 > G0 for fresh GM and SM and G2500 > G0 > P0 for fresh LL. Color stabilities of aged beef from the P0 and G2500 treatments were similar and higher than those from unsupplemented animals. Color stability of minced beef ranked as: P0 aged > G0 and G2500 fresh > P0 fresh > G0 and G2500 aged.
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This study aimed to compare the efficacy of dietary α-tocopherol with that of dl-α-tocopheryl acetate, both either alone or in combination with vitamin C (ascorbic acid), on the growth performance, survival, and stress resistance of angelfish, Pterophylum scalare, juveniles. Juveniles were fed ad libitum for four weeks with Artemia enriched with no vitamins (control), vitamin C (Tc), α-tocopherol (Tα), dl-α-tocopheryl acetate (T dl ), α-tocopherol and vitamin C (Tα+C), and dl-α-tocopheryl acetate and vitamin C (T dl+C). After four weeks, an osmotic stress test was performed using seawater (25g/L) to evaluate juvenile’s resistance to stress. Whole-body glucose and cortisol were used as stress indicators. At the end of the feeding trial, growth performance and survival of the juveniles fed vitamin-enriched Artemia were significantly (P<0.05) higher than for the control fish. Best performance was recorded for the Tα+C group. Survival, however, was not significantly (P>0.05) different between the vitamin-fed groups. Osmotic stress significantly elevated the stress indicators, whole-body cortisol and glucose levels (P<0.05), highest and lowest values being observed in control and Tα+C groups, respectively. Survival after osmotic stress of juveniles fed the Tα+c diet was significantly higher (by 46.2%, P<0.001) than for controls. Results suggested that α-tocopherol has greater efficacy than dl-α-tocopheryl acetate and enriching Artemia with α-tocopherol and vitamin C together improves growth performance, survival, and stress resistance of angelfish juveniles.
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Atlantic salmon (Salmo salar) juveniles were fed a basal diet coated with 16% sardine or capelin oil (68 or 42 g n-3 PUFA per kg dry diet, respectively), each supplemented or not with 300 mg dl-α-tocopheryl acetate per kg. The unsupplemented diets contained 28 ± 4 and 31 ± 9 mg/kg α-tocopherol, respectively. There was a 5–7-fold increase in whole body α-tocopherol concentration in response to vitamin E supplementation, but the relative distribution of α-tocopherol between organs was similar in all groups. There was only a weak effect of dietary n-3 PUFA on the tissue levels of α-tocopherol. The ratio of α-tocopherol to PUFA in the fish tissues is probably critical in protection against lipid oxidation, and may modulate the vitamin E requirement. During smoltification, the whole body α-tocopherol concentration was unchanged or slightly increasing. All groups showed a 40–50% reduction of α-tocopherol concentration in the kidney and adipose tissue, possibly linked to changes in osmoregulation and mobilization of vitamin E. The body level of α-tocopherol seems to be higher in fish than in mammals. A species-specific tissue “distribution key” for α-tocopherol appears to be present in several fish and mammal species.
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A trout diet was supplemented with 0, 8.5, or 15 g/100 g of flaxseed oil (FO). To prevent lipid oxidation of fillets, FO-supplemented diets were also enhanced with 0, 400, and 900 mg/kg of alpha-tocopheryl acetate (α-TA). Total fat, moisture content, lipid oxidation, fatty acid profile, and α-tocopherol content of fillets were determined following fish harvest on days 0, 30, 60, 90, and 120. FO supplementation resulted in increased (P<0.05) concentration of omega-3 fatty acid (ω3 FA) in fillets, mainly due almost two-fold increase (P<0.05) of α-linolenic acid, while docosahexaenoic and eicopentaenoic acids slightly decreased (P<0.05). Regardless of supplementing trout diets with FO or α-TA, no (P>0.05) difference of the total fat in fillets was measured. The highest (P<0.05) α-tocopherol content in fillets was determined when supplementing trout with 900 mg/kg of α-TA at day 120. The effect of retarding lipid oxidation in fillets was recorded after supplementing trout with α-TA for 60 days. Our results indicate that regardless of FO level in trout diet, 900 mg/kg of α-TA can prevent lipid deterioration of fillets. However, to achieve more pronounced antioxidant effect in the ω-3-enhanced trout fillets, a synergetic effect of antioxidants and anaerobic packaging with α-TA supplementation should be investigated.
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Der Einfluss von Vitamin E und Selen auf Eutergesundheit und Qualität der Milch wurden mit Hilfe einer Meta-Analyse geprüft. Die Literaturrecherche erfolgte nach den Richtlinien von PETERS et al. (2006) und KUNZ et al. (2009), wonach zunächst eine breit angelegte Schlagwortrecherche dem Auffinden potenziell relevanter Literaturstellen (n = 1843) diente. Nach Durchsicht der Abstracts und Titel wurden 1664 Literaturstellen verworfen, von den restlichen 179 Literaturstellen die Volltexte beschafft und beurteilt. 22 Studien konnten in den systematischen Review aufgenommen werden, wo sie von vier Gutachtern (zwei Agrarwissenschaftler, zwei Veterinärmediziner) nach einer eigens entwickelten Checkliste bewertet wurden. Es fanden 19 Studien Eingang in die Meta-Analyse, die mit dem Statistikprogramm „R“ (Version 2.9.1), Package „meta“ (Version 0.9-19) nach vorangegangener Datenaufbereitung, durchgeführt wurde. Es wurde mit einem Konfidenzintervall von 95 %, dem relativen Risiko (Mastitis), den Mittelwerten (Milchzellzahl, Milchleistung, Oxidationsstabilität) und der inversen Varianz Methode gerechnet. Die durchgeführte Meta-Analyse zeigt, dass mit einer Supplementationsmenge von ≥ 1000 IU Vitamin E und ≥ 3,6 mg Selen pro Tier und Tag das durchschnittliche relative Mastitisrisiko im 1. Laktationsdrittel um 34 % gesenkt werden kann. Der Einfluss von Selen ist stärker als jener von Vitamin E (-40 % vs -30 %). Der Effekt von all-rac-Tocopherol ist mit einer durchschnittlichen Mastitisrisikoreduktion um 53 % hoch, aber im Gegensatz zu dl-Tocopherolacetat (-26 %) nicht signifikant unterschiedlich. Die intramuskuläre Applikation von Vitamin E und Selen ist der subkutanen oder oralen Supplementation überlegen (-35 % vs -29%). Durch die Supplementation von ≥ 1000 IU Vitamin E und ≥ 3,0 mg Selen wird eine signifikante durchschnittliche Milchzellzahlreduktion im 1. Laktationsdrittel um -23 000 Zellen je ml Milch erreicht. Auch hier dominiert der Einfluss von Selen über den von Vitamin E (-23 700 vs -7 500 Zellen je ml Milch). Das weite Konfidenzintervall des Effekts von organischem Selen auf die Milchzellzahl (von -37 000 bis +23 000 Zellen je ml Milch) lässt jedoch nur eine vorsichtige Interpretation des Effekts von Selen auf den Milchzellzahlgehalt zu. Durch die orale Supplementation von Vitamin E und Selen kann eine deutlich höhere durchschnittliche Milchzellzahlreduktion erreicht werden als durch intramuskulärer Supplementation. Mit einer Supplementationsmenge von ≥ 1000 IU Vitamin E und ≥ 3,6 mg Selen pro Tier und Tag erhöht sich die durchschnittliche Milchleistung im 1. Laktationsdrittel signifikant (+0,96 kg Milch). Der Einfluss von Selen ist marginal (+ 0,4 kg Milch pro Tier und Tag), während der von Vitamin E (+ 6,5 kg Milch pro Tier und Tag) außerordentlich hoch ist. Ebenfalls gering sind die Unterschiede zwischen oraler (+0,8 kg Milch pro Tier und Tag) und intramuskulärer Supplementation (+0,6 kg Milch pro Tier und Tag). Deutlich höher hingegen war der 81 Unterschied zwischen den Effekten von organischem (+0,04 kg Milch pro Tier und Tag) und anorganischem Selen (+0,8 kg Milch pro Tier und Tag) auf die Milchleistung. Die Oxidationsstabilität der Milch kann durch die Supplementation von ≥ 400 IU Vitamin E signifikant verbessert werden (- 1,96 TBA Einheiten). Vor allem die Zulage von dl-Tocopherol wirkt sich positiv auf die Membranstabilität der Milchfette aus (- 3,36 TBA Einheiten), während der signifikante Einfluss von all-rac-Tocopherol verhältnismäßig klein ist (- 1,90 TBA Einheiten). Der Geschmack der Milch wird durch die Supplementation von Vitamin E und Selen nicht signifikant beeinflusst. Durch die kombinierte Supplementation von Vitamin E und Selen in der Trockenstehphase und in den ersten vier Wochen p. p. kann in Selenmangelregionen eine Verbesserung der Eutergesundheit von Milchkühen erreicht werden.
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Bio-availability of different alpha-tocopherol forms in livestock animals is measured by the increase in plasma or tissue concentrations of alpha-tocopherol after oral administration. It is generally accepted that RRR-alpha-tocopheryl acetate (natural source vitamin E derived from vegetable oil) has a higher bio-availability compared to all-rac-alpha-tocopheryl acetate (synthetic vitamin E, i.e. alpha-tocopherol produced by chemical synthesis). However, different bio-availability ratios have been reported in the literature. The major reason for conflicting results in literature studies was the inability to separate the proportion of alpha-tocopherol originating from test materials, from the proportion of alpha-tocopherol originating from basal dietary ingredients and pre-feeding. This causes significant variability. For bio-availability determination, a baseline or control treatment is essential. The estimation of bio-availability without correction for basal vitamin E status will lead to incorrect interpretation of the results. When using proper methodologies, it is possible to correct for the impact of alpha-tocopherol intake from basal ingredients and alpha-tocopherol originating from pre-feeding, therefore yielding results reflecting the true relative bio-availability of different alpha-tocopherol substances. When reviewing literature data a critical evaluation of the method used in determination of relative bio-availability is recommended.
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ANIMAL and human studies have shown that the biological activity of vitamin E sources is dependent on their particular stereochemistry and chemical form (Ingold and others 1987, Ferslew and others 1993, Acuff and others 1994, Kiyose and others 1995). The two most common commercial sources of vitamin E are natural analogues (d- or RRR-a-tocopherol) and synthetic derivatives (dl- or all-rac-atocopherol) with their corresponding stabilised acetate esters. Usually, synthetic vitamin sources are, for the most part, equal in efficacy and structure to the natural source of that vitamin; however, this is not the case for vitamin E (Burton and others 1998). The source of vitamin E with the highest biological activity is natural a-tocopherol that has been isolated from seed oils. Synthetic vitamin E is made from petrochemicals. The difference between natural and synthetic vitamin E is their chemical structures. Natural vitamin E contains one isomer, RRR-a-tocopherol, which has eight different forms; these are alpha-, beta-, gamma- and 8-tocopherols and alpha-, gamma- and delta-tocotrienols. Many different tocopherol and tocotrienol derivatives have been synthesised, but these are most commonly based on racemic a-tocopherol, which contains equimolar amounts of eight stereoisomers, with only one being identical to the natural RRR-isomer. Synthetic vitamin E contains equimolar amounts of eight stereoisomers, of which one is identical to the natural RRR-isomer. The body preferentially transports and incorporates the natural isomer, thereby making the bioavailability of synthetic vitamin E less than that of natural vitamin E (Acuff and others 1994, Burton and others 1998).
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Relative vitamin E status of pigs fed natural or synthetic vitamin E was evaluated based on serum and tissue alpha-tocopherol concentrations. Individually fed finishing gilts at a BW of 70.5 kg (n = 24) were allotted to dietary treatments based on initial BW. The 5 dietary treatments consisted of a positive control diet using synthetic vitamin E acetate (Syn E Ac) supplemented at 22 mg/kg, and 4 dietary levels of natural vitamin E acetate (Nat E Ac) supplemented at 6.71, 8.33, 11.00, and 16.18 mg/kg of diet. Before initiation of the 32-d experiment, pigs were fed a non-vitamin E-fortified diet for 30 d. Diets were formulated to contain true ileal digestible lysine of 0.9 and 0.8% for the pretest and test diets. Serum samples were collected on d 15 and 32, whereas tissue samples were collected on d 32 for alpha-tocopherol analysis. Serum alpha-tocopherol concentrations on d 15 and 32 were greater (P < 0.05) in pigs fed 8.33, 11.00, or 16.18 mg/kg of Nat E Ac than in pigs fed 22 mg/kg of Syn E Ac. When compared with pigs fed 22 mg/kg of Syn E Ac, alpha-tocopherol concentrations were greater (P < 0.05) in 6 tissues (heart, kidney, spleen, liver, lung, and adipose) in pigs fed 16.18 mg/kg of Nat E Ac; greater (P < 0.05) in heart, kidney, spleen, liver, and adipose tissue in pigs fed 11.00 mg/kg of Nat E Ac; and greater (P < 0.05) in spleen, loin, and adipose tissue in pigs fed 8.33 mg/kg of Nat E Ac. As dietary Nat E Ac increased from 6.71 to 16.18 mg/kg, serum alpha-tocopherol increased linearly (P < 0.01) on d 15 and 32 of the experiment. Increasing dietary Nat E Ac linearly increased (P < 0.05) alpha-tocopherol concentrations for lung, heart, kidney, spleen, and liver. These results indicate that Nat E Ac was an effective vitamin E source and its relative bioavailability was substantially greater than 1.36 for finishing swine when compared with Syn E Ac.
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Vitamin E in nutritional supplements in its most common form is alpha-tocopheryl acetate. Available stereoisomeric forms are RRR- (1 stereoisomer) and all-rac- (8 stereoisomers). We evaluated the relative bioavailability of RRR- and all-rac-alpha-tocopheryl acetate using the deuterium-labeled isotopes [5-CD3] 2R, 4'R and 8'R-alpha-tocopheryl acetate (d3), and [5,7-(CD3)2]-all-rac-alpha-tocopheryl acetate (d6). Six adults (three males, three females), aged 25-59 y, received 150 mg each of d3 and d6 for 11 consecutive days. Blood samples were collected on days -1, 0, 1-11, 13, 14, 20, 25, 30, 60, 74, 88, 102, 122, and 137. Plasma and red blood cell tocopherol were evaluated by using HPLC and gas chromatography/mass spectrometry to distinguish between d3 and d6 tocopherols. Cholesterol, triglycerides, and LDL and HDL cholesterol were measured. Relative bioavailability of d3 when compared with d6 was 2.0 +/- 0.06 when area under the plasma time concentration curve (AUC d3/d6) by trapezoidal rule (P < 0.05) was used. Correcting for lipid yielded the same finding. Unlabeled tocopherol (d0) decreased (P < 0.05) with vitamin E administration. It was concluded that the ratio of bioavailability of RRR-/all-rac-alpha-tocopheryl acetate is significantly greater than the currently accepted ratio of 1.36.
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An experiment was conducted to compare the efficacy of two dietary sources and an injectable form of vitamin E (VE) to improve the VE status of poults. Six of the treatments consisted of a factorial arrangement of three concentrations and two sources of dietary VE. Turkeys in these treatments received 12, 80, or 150 IU of either dl-alpha-tocopheryl acetate or d-alpha-tocopherol (d-alpha-TOC)/kg of diet. The seventh treatment consisted of a single subcutaneous injection of d-alpha-TOC at 1 d of age. Poults in this treatment were subcutaneously injected in the dorsal area of the neck with 25 IU of d-alpha-TOC, this amount being approximately equivalent to the amount poults would consume if their diet was supplemented with 150 IU of VE/kg during their 1st wk of life. Concentration, source, or route of VE administration did not affect growth parameters, plasma creatine kinase, plasma triglycerides, or liver lipid peroxidation as measured by the thiobarbituric acid reactive substances assay (TBARS). Plasma, red blood cells (RBC), and liver alpha-TOC decreased from hatching to 14 d of age in poults fed either source of VE. The use of 80 or 150 IU of dietary VE (either source) reduced (P < 0.05) the extent of depletion of alpha-TOC at all ages and also reduced the susceptibility of RBC to hemolysis. There was no effect of source of dietary VE on concentration of alpha-TOC in plasma, RBC, or liver, or on RBC hemolysis. Subcutaneous injection of 25 IU of d-alpha-TOC at Day 1 increased (P < 0.05) alpha-TOC concentration until 7 d of age. Also, d-alpha-TOC injection reduced (P < 0.05) RBC susceptibility to hemolysis through 21 d of age. Data showed that one single subcutaneous injection of 25 IU of d-alpha-TOC at 1 d of age was as effective as 80 IU or more of dietary VE through 21 d to improve the alpha-TOC status of poults.
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Two experiments were conducted to examine the effects of the form of alpha-tocopherol or interactions of alpha-tocopherol with vitamin A on its bioavailability. In Experiment 1, Holstein steers were fed a diet that was low in vitamins A and E for 1 mo; then, steers were blocked by body weight (X = 97.5 kg) and assigned randomly to one of four oral treatments: 1) no added vitamins, 2) 442 mg of retinyl acetate, 3) 1342 mg of D-alpha-tocopherol, or 4) 442 mg of retinyl acetate and 1342 mg of D-alpha-tocopherol. Each treatment was given as a pulse dose. Blood was sampled over a 36-h period. Concentrations of plasma retinyl palmitate peaked at 2 to 6 h postsupplementation for all calves and then peaked again at 22 to 28 h for calves receiving vitamin supplements. Concentrations of plasma alpha-tocopherol peaked earliest with D-alpha-tocopherol supplementation alone at 12 to 20 h after supplementation, but simultaneous supplementation with retinyl acetate resulted in lower plasma alpha-tocopherol concentrations. Plasma retinyl palmitate decreased during peak alpha-tocopherol concentrations. In Experiment 2, blood and tissue were analyzed after a single gastric tube administration of a powder (DL-alpha-tocopheryl acetate) or a liquid (D-alpha-tocopherol) form of vitamin E to Holstein calves. Plasma and kidney concentrations of alpha-tocopherol were higher when calves were fed D-alpha-tocopherol than when calves were fed the DL-alpha-tocopherol acetate form. Concentrations in the liver, spleen, adipose tissue, heart, muscle, cellular blood fraction, and gut did not differ between the two forms.
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This paper describes a simple method for the analysis of tocopherols in tissues by which frozen tissues-70 degrees C were pulverized at dry ice temperatures (-70 degrees C) and immediately extracted with hexane. There was no need to remove the coeluting lipids from tissues by saponification, since at that level of neutral lipids in the sample, there was no reduction in fluorescence response. For the analysis of oil, in which large amounts of neutral lipids were coextracted, a 20% reduction of fluorescence response was observed, but the response was equal for all tocopherol forms, and was appropriately corrected. Saponification was used only when tocopherol esters were present, and only after an initial hexane extraction to remove the free tocopherols in order to avoid their loss by saponification, particularly non alpha-tocopherol and tocotrienols. All the tocopherols and tocotrienols were separated on a normal-phase diol (epoxide) column that gave consistent and reproducible results, without the disadvantages of nonreproducibility with silica columns, or the lack of separation with reversed-phase columns. The tocopherols were quantitated by using a tocopherol form not present in the sample as an internal tocopherol standard, or using an external tocopherol standard if all forms were present, or when the sample was saponified. Piglet heart and liver samples showed the presence of mainly alpha-tocopherol, with minor amounts of beta- and gamma-tocopherol and alpha-tocotrienol, but no delta-tocopherol. Only small amounts of tocopherol esters were present in the liver but not in the heart.
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We have previously reported that both the source of dietary fish oil and the chemical form of vitamin E supplied in the diet affect the vitamin E status of immune cells in rats. The purpose of this study was to investigate further the effect of fish oil source on immune cell vitamin E status using free alpha-tocopherol (alpha-T) at the AIN recommended level as the sole source of vitamin E. Sixty weanling female rats were fed semipurified, high fat (20 g/100 g) diets containing either tocopherol-stripped lard (LRD), menhaden fish oil (MFO), sardine fish oil (SRD) or cod liver oil (CLO) as the primary lipid source. Endogenous alpha-T concentration was measured and equalized to 150 mg/kg oil by addition of free RRR-alpha-T to each lipid source, allowing for a final concentration of alpha-T in the mixed diet of 30 mg/kg. An additional group of rats was fed LRD without supplemental vitamin E (LRD-) as a negative control. After feeding experimental diets for 5 or 10 wk, tissues were collected for alpha-T analysis by HPLC. After 5 wk, plasma and liver alpha-T (micromol alpha-T/g lipid) were significantly lower in SRD- and CLO-fed rats compared with LRD-fed rats. At 10 wk, only plasma alpha-T in CLO-fed rats remained significantly depressed. Plasma and liver alpha-T concentrations (micromol alpha-T/g lipid) were not significantly lower in MFO-fed rats than LRD-fed rats at either time point. Compared with LRD, feeding MFO to rats for 5 or 10 wk resulted in significantly greater alpha-T content of immune cells. In similar fashion, SRD-fed rats, compared with LRD-fed rats, also had significantly greater alpha-T content in splenocytes at both time points and greater thymocyte alpha-T at 10 wk. In all instances, the alpha-T status of rats fed CLO was indistinguishable from that of rats fed the vitamin E-free diet (LRD-). These data further demonstrate the complexity of the relationship between vitamin E status and dietary (n-3) polyunsaturated fatty acids (PUFA).
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This chapter discusses the determination of various forms of vitamin E in tissues and diets by high-performance liquid chromatography (HPLC) using normal-phase diol column. Vitamin E is a generic term that includes a mixture of tocopherols (T) and tocotrienols (T3) that differs in the number and position of methyl groups on the fused chromanol ring and the absence or presence of three double bonds in the isoprenoid side chain. The present method for the determination of all the vitamin E forms in tissues eliminates the thawing step by pulverizing the tissue at dry ice temperature. Total vitamin E is extracted with hexane and analyzed directly by HPLC using diol column and fluorescence detection, without prior saponification of the sample. The method is modified for the analysis of diets to determine both free and esterified vitamin E. The chapter discusses the response factors of the different forms of vitamin E, the use of internal standards to quantitate vitamin E, and the structure and properties of the diol column. The diol column appears to combine the superior separation of normal-phase silica columns with the added stability and reproducibility that the epoxide structure of the packing material provides. The chapter concludes with a discussion of the influence of triacylglycerols on the quantitation of vitamin E using fluorescence detection.
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The objective of this study was to examine the in vitro hydrolysis of vitamin E esters (alpha-tocopheryl acetate, alpha-tocopheryl succinate and alpha-tocopheryl nicotinate) by pancreatic carboxyl ester hydrolase (CEH) at the concurrent presence of different bile acids at different concentrations. The assay was performed by measuring the amount of alpha-tocopherol released by porcine pancreatic juice upon addition to different solutions of alpha-tocopheryl esters, which were dispersed in bile acid mixed micelles at 37 degrees C, pH 7.4. The CEH activity was 10 U in the final assay, and the optimal concentration of cholate in this in vitro-system was determined to 30 mM for the hydrolysis of alpha-tocopheryl acetate. The hydrolysis of alpha-tocopheryl esters required presence of pancreatic juice and bile acids, and the results showed furthermore that the ability of pancreatic CEH towards hydrolysis of different alpha-tocopheryl esters increased with increasing lipophility, irrespective of the type or concentration of bile acid present in the assay. Likewise, retinyl palmitate was hydrolyzed at a faster rate than retinyl acetate. The structure of the bile acid influenced the rate of hydrolysis. Thus, cholate followed by glycodeoxy- and glycochenodeoxycholate were the most effective activators of CEH among the bile acids tested in this assay. The presence of gamma-tocopherol or all-trans-retinyl acetate in the assay showed a non-competitive inhibition of the hydrolysis rate of alpha-tocopheryl acetate.
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