HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ching, S. Articles by Fastinger, N. D. Search for Related Content PubMed PubMed Citation Articles by Ching, S. Articles by Fastinger, N. D.

Evaluating the antioxidant status of weanling pigs fed dietary vitamins A and E^1,2,3

The Ohio State University and the Ohio Agricultural Research and Development Center, Columbus 43210-1095

⁴ Correspondence:
2027 Coffey Road (phone: 614/292-6987; fax: 614/292-7116; E-mail:
mahan.3{at}osu.edu).

	Abstract

Top Abstract Introduction Materials and Methods Results Discussion Implications Literature Cited

 
Two experiments evaluated the relationship of vitamin E (source and level) and vitamin A (level) on the apparent absorption and retention of both vitamins in weaned pigs. Both experiments used a combined total of 460 crossbred pigs ([Yorkshire x Landrace] x Duroc), housed in elevated 1.2- x 1.2-m crates containing five pigs per pen. Experiment 1 was a 2 x 2 x 2 factorial arrangement of treatments in a randomized complete block design conducted in seven replicates. Levels of vitamin A (2,200 or 13,200 IU/kg), vitamin E (15 or 90 IU/kg), and two vitamin E sources (D--tocopheryl acetate [D-TAc] or DL--tocopheryl acetate [DL-TAc]) were evaluated over a 35-d period. Vitamin A or E levels and the two vitamin E sources did not affect pig performances to 20 kg BW. Serum retinol and -tocopherol concentrations increased (P < 0.01) as the dietary level of each vitamin increased. Serum -tocopherol declined as dietary vitamin E level increased when vitamin A level increased resulting in an interaction (P < 0.05). Serum -tocopherol concentrations were higher (P < 0.05) at 35-d postweaning when D-TAc was the vitamin E source. Experiment 2 was a 3 x 2 factorial arrangement of treatments conducted in six replicates. Three levels of vitamin A (2,200, 13,200, or 26,400 IU/kg) and two sources of vitamin E (D-TAc or DL-TAc) each provided at 40 IU/kg diet were evaluated over a 35-d period. Pig performances to 35-d postweaning were not affected by the dietary variables. Serum -tocopherol (P < 0.01) and retinol (P < 0.05) concentrations increased as their respective vitamin level increased. Serum (P < 0.05) and liver (P < 0.01) -tocopherol concentrations both declined as dietary vitamin A levels increased resulting in interaction responses. Serum -tocopherol concentration was higher (P < 0.05) at 35-d postweaning when d-TAc was the vitamin E source. Dietary vitamin E sources had no effect on serum or liver retinol concentrations. These results demonstrated that both supplemental vitamin A and vitamin E increased in the blood as their dietary levels increased. However, as dietary vitamin A level increased, serum and liver -tocopherol concentrations declined, suggesting a reduced absorption and retention of -tocopherol when weaned pigs were fed high dietary vitamin A levels.

Key Words: Pigs • Vitamin A • Vitamin E • Weaning

	Introduction

Top Abstract Introduction Materials and Methods Results Discussion Implications Literature Cited

 
The postweaning decline in pig serum -tocopherol and Se concentrations has been associated with the onset of the deficiency of these nutrients (Mahan and Moxon, 1980, Meyer et al., 1981). Although the FDA (1974, 1987) has stipulated that supplemental Se cannot exceed 0.30 mg Se/kg diet, the fortification levels of vitamins A and E are not regulated. The NRC (1998) recommends 16 IU vitamin E/kg diet for pigs weighing < 10 kg and 11 IU/kg for those > 10 kg BW, with dietary vitamin A levels of 2,200 and 1,750 IU/kg diet suggested for the same weight periods, respectively.

A recent survey of commercial companies producing swine feeds reported that vitamin E added to pig starter diets averaged 57 IU/kg (Coehlo, 2000). The survey indicated that the lower and upper 25% fortification levels of vitamin E averaged 40 and 74 IU/kg, respectively. Vitamin A averaged 10,878 IU/kg with the lower and upper 25% levels averaging 7,378 and 14,228 IU/kg, respectively. Both vitamins were being supplemented at approximately 3.5- to 5-fold higher than NRC (1998) requirements.

High dietary vitamin A levels have been shown to reduce vitamin E absorption in several species (Blakely et al., 1991; Drott et al., 1993). Consequently, high fortification levels of vitamin A could exacerbate the vitamin E and Se deficiency postweaning if the same responses are shown to occur in pigs. Chung et al. (1992) reported higher serum and tissue -tocopherol concentrations when D-tocopherol rather than when DL--tocopheryl acetate was fed. Although these researchers did not use the acetylated form of D--tocopherol in their study, their results imply that the form of vitamin E may be a factor in the absorption and retention of vitamin E.

Two studies were therefore conducted to determine if the two vitamin E sources at various vitamin A or E levels would affect serum and tissue concentrations of -tocopherol and retinol in the weaned pig.

	Materials and Methods

Top Abstract Introduction Materials and Methods Results Discussion Implications Literature Cited

 
The first experiment evaluated the effect of providing two sources of vitamin E at two dietary levels and at two dietary levels of vitamin A on postweaning pig performance and serum retinol and -tocopherol concentrations. The experiment was conducted as a 2 x 2 x 2 factorial arrangement of treatments in a randomized complete block design in seven replicates. The two dietary vitamin E sources (D--tocopheryl acetate [^D-TAc]; Stuart Products, Bedford, TX and DL--tocopheryl acetate [^DLTAc]; BASF, Mt. Olive, NJ) were each added at 15 or 90 IU/kg with vitamin A supplemented as retinyl acetate at 2,200 or 13,200 IU/kg diet.

A total of 280 crossbred ([Yorkshire x Landrace] x Duroc) pigs weaned at 23 ± 2 d of age at an average 6.3 kg BW were allotted in groups of five pigs per treatment pen by weight, sex, and litter. Diets were formulated to a 1.35% lysine (total) level for the 0- to 14-d period, with a second diet containing 1.25% lysine (total) fed during the 14 to 35-d period. Diets met or exceeded NRC (1998) recommendations for all nutrients (Table 1). Both sources of vitamin E (D-TAc, DL-TAc) and vitamin A were independently premixed with ground corn and added to treatment diets at the expense of dietary corn.

Blood samples were collected via cardiac puncture in vacuum tubes from the pigs in five of the replicates at 2- and 5-wk postweaning. Blood samples were placed on ice, transported to the laboratory, centrifuged at 2,200 x g at 4°C for 10 min, with serum collected and stored at -20°C for later analysis.

The second experiment was a 2 x 3 factorial arrangement of treatments in a randomized complete block design and conducted in six replicates. The study evaluated the effects of the two vitamin E sources (D-TAc and DL-TAc) added at 40 IU/kg and three dietary levels of added vitamin A (2,200 13,200, 26,400 IU/kg).

A total of 180 crossbred pigs of the same genetic combination as in Exp. 1 were used in this study. Five pigs/pen allotted on the basis of weight, sex, and litter were housed and managed as in Exp. 1. Diets were formulated to 1.50% lysine (total) during the 0- to 14-d postweaning period and to a 1.25% lysine (total) level for the 14- to 35-d period. All nutrients met or exceeded NRC (1998) recommendations (Table 1).

At the start of the trial a total of 10 pigs were randomly selected from allotted animals and bled via cardiac puncture using vacuum tubes. At 14- and 35-d postweaning, all pigs were bled via cardiac puncture, processed, and serum stored for the later analysis of -tocopherol and retinol as in Exp. 1. From normal nonallotted animals, six pigs at weaning and one randomly selected pig from each treatment pen at the end of the experiment were stunned by electric shock and killed by exsanguination. Livers were collected, frozen in liquid N, and stored frozen (-20°C) until analyzed later for -tocopherol and retinol.

Analytical Procedures.
Serum samples were prepared for -tocopherol and retinol analysis based on the procedures of Bieri et al. (1979). Because of the light and heat sensitivity of vitamin A, the samples for retinol analyses were completed under red or yellow light with samples placed in amber vials and lids during the analytical process.

Both -tocopherol and retinol were determined by HPLC following the procedures of Zaspel and Csallany (1983). All-trans retinol and all-trans acetate were used as standards and obtained from Sigma Chemical Co. (St. Louis, MO). Tocopherol standards were obtained from United States Biochemical Corporation (Cleveland, OH).

Pig performance, serum, and tissue data were analyzed using the mixed model analysis of variance procedure (Proc Mixed) of SAS (SAS Inst. Inc., Cary, NC). In both experiments time was included in the statistical model with the data also analyzed using the mixed model analysis procedure and repeated measures analysis. The pen was the experimental unit for all measurements.

	Results

Top Abstract Introduction Materials and Methods Results Discussion Implications Literature Cited

 
Performance Responses.
Dietary vitamin E and vitamin A levels or vitamin E sources (D-TAc or DL-TAc) evaluated in these experiments did not affect pig gains, feed intakes, or gain:feed ratios (P > 0.15) for the 35-d postweaning period (Tables 2 and 3). The results suggest that dietary levels of vitamin E up to 5.6-fold (Exp. 1) and dietary vitamin A levels (Exp. 2) up to 12-fold above current NRC (1998) standards had no effect on postweaning pig performances to 20 kg BW.

View this table: [in this window] [in a new window]   Table 2. Effect of dietary vitamin E source and level and vitamin A level on postweaning pig performance and serum retinol and serum -tocopherol concentrations (Exp. 1)a

Serum -tocopherol concentrations (Exp. 2) declined from weaning to 14 d postweaning (Table 3), responses consistent with previous reports (Mahan and Moxon, 1980; Meyer et al., 1981). The decline in serum -tocopherol during the postweaning period was, however, opposite to that of serum retinol where its concentration increased.

When the dietary vitamin E level increased (Exp. 1) serum -tocopherol concentration increased (P < 0.01) at both the 14- and 35-d postweaning periods, but was highest (P < 0.05) at the 35-d period and higher when the D-TAc (P < 0.05) rather than when the DL-TAc form was fed (Table 2). In Exp. 2, when a constant amount of vitamin E was supplemented (i.e., 40 IU/kg) there was a trend (P < 0.10) for serum -tocopherol concentrations to be higher by 14-d postweaning when the D-TAc form was provided. However, at the 35-d postweaning period serum -tocopherol concentration was clearly higher (P < 0.05) when the D-TAc rather than when the DL-TAc form was fed, responses consistent to those of Exp. 1.

As the dietary vitamin A levels increased at the 35-d period (Exp. 2) serum -tocopherol concentrations were higher when the D-TAc form of vitamin E rather than when the DL-TAc form was fed (Table 3). This resulted in a dietary vitamin A x vitamin E level interaction response (P < 0.05). Although the same general interaction response occurred at the 14-d period, the interaction response was not significant (P > 0.15). In Exp. 1 when two dietary vitamin E levels were compared (i.e., 15 vs 90 IU/kg), increasing levels of vitamin A resulted in lower (P < 0.05) serum -tocopherol concentrations in both vitamin E groups at 35 d postweaning, but not at 14 d postweaning (Table 4).

View this table: [in this window] [in a new window]   Table 4. Treatment effects of dietary vitamin E source and level and vitamin A level on serum -tocopherol and serum retinol concentrations (Exp. 1)a

Liver -tocopherol concentrations were lower at 35 d postweaning than at weaning (P < 0.01) in Exp. 2, with the decline exacerbated as the dietary vitamin A level increased (P < 0.05; Table 3). Although the dietary D-TAc form resulted in higher numerical liver -tocopherol concentrations at each vitamin A level, the vitamin E source or the interaction effect was not significant (P > 0.15).

	Discussion

Top Abstract Introduction Materials and Methods Results Discussion Implications Literature Cited

 
Vitamin A and E fortification levels in commercial swine starter diets are generally added in excess of NRC (1998) standards. This is generally done because of various indigenous and environmental factors present on many commercial swine farms that might cause the animal to have a higher requirement or factors that could cause deterioration of dietary vitamins (Coehlo, 2000). Our results indicate that when vitamin A or E levels were increased by a substantial level above NRC (1998) standards, there was neither a beneficial nor a detrimental effect on postweaning pig performances. These responses are consistent with those of Hoppe et al. (1992) who showed no difference in weaning pig performance responses when diets contained 40,000 IU vitamin A/kg. Peplowski et al. (1980) also showed no performance differences when 200 IU vitamin E/kg diet was fed to weaned pigs.

As the dietary level of vitamin E increased, serum and liver -tocopherol concentrations of the weaned pig responded in a positive manner. Vitamin E level or source, however, did not affect the concentration of retinol in the serum or liver tissue.

When the two sources of vitamin E were compared, higher serum concentrations of -tocopherol resulted when the D-TAc form was fed. This suggests a higher relative absorption and perhaps bioavailability of the D-TAc form of the vitamin. This response is consistent with the results of Mahan et al. (2000) who reported that reproducing swine had higher serum -tocopherol and tissue retention of -tocopherol when the D- rather than the DL-form of vitamin E was fed.

Increasing dietary vitamin A levels up to 12-fold higher than NRC (1998) standards in weanling pig diets did increase serum and liver retinol concentrations with liver concentrations increasing more than serum. Retinol concentrations were substantially higher in the liver than serum at similar dietary levels of vitamin A confirming that liver tissue was a more sensitive indicator of the pig’s vitamin A status. Liver retinol was higher at the 35-d postweaning period than at weaning when 2,200 IU/kg diet was fed, implying that the level was adequate for increasing retention of the vitamin in the weaned pig.

Dietary vitamin A did seem to affect the apparent absorption and retention of vitamin E in the weaned pig confirming that an interrelationship exists between these two vitamins. As the dietary vitamin A level increased there was a negative impact on both the serum concentration and liver retention of -tocopherol. This response was independent of the source of vitamin E. The results suggest that high dietary levels of vitamin A could have a detrimental effect on the young pig’s vitamin E status during the postweaning period and could be detrimental to the antioxidant status of the pig during the postweaning period. Sklan and Donoghue (1982) and Blakely et al. (1991) demonstrated that high levels of dietary vitamin A (>100,000 IU/kg) resulted in lower serum -tocopherol concentrations in chicks and rats.

An interrelationship in the relative absorption rates of both vitamins A and E has been previously shown. A lowered intestinal absorption of -tocopherol occurred when low levels of retinoic acid were fed (Bieri et al., 1981). Inadequate bile acids have also been shown to inhibit -tocopherol absorption (Bieri and Tolliver, 1982). Muller et al. (1976) demonstrated that supplemental bile salts increased the hydrolysis of tocopheryl acetate. Although pancreatic esterase’s for hydrolyzing the retinol (retinyl ester hydrolase) and tocopherol (carboxyl ester hydrolase) from their acetylated form is low during the initial postweaning period (Hedemann and Jensen, 1999), Lauridsen et al. (2001) showed that the in vitro hydrolysis of tocopheryl acetate was also inhibited by retinyl acetate. These results suggest that the hydrolysis of the ester on the acetylated vitamin E compounds might be low during the immediate period postweaning and that a high dietary level of vitamin A could hinder the absorption of -tocopherol.

These phenomena are more pronounced with younger rather than the older animals. For example, Anderson et al. (1995) did not demonstrate any detrimental effect of high dietary vitamin A levels on serum or tissue concentrations of -tocopherol in grower-finisher pigs. During the postweaning phase there is a greater relative growth response of weanling pigs, particularly for muscle tissue thus requiring a higher need for both vitamins. Because of the weanling pigs low feed intake, low adipose and tissue reserves of -tocopherol, lowered pancreatic esterases, and a declining postweaning serum -tocopherol concentration, the dependence on dietary vitamin E is higher than in later growth phases. The lower vitamin E status of the young weanling pig may be compromised by several factors. Consequently, high dietary levels of vitamin A in pig starter diets could exacerbate the antioxidant status and hasten the onset of the vitamin E deficiency in younger swine. The interactive effects of the two vitamins would be expected to be less severe in older swine.

	Implications

Top Abstract Introduction Materials and Methods Results Discussion Implications Literature Cited

 
Swine diets are often fortified with high levels of vitamins A and E. High vitamin A levels may exacerbate the antioxidant status of the weaned pig by reducing the absorption and retention of -tocopherol. In contrast, high levels of dietary vitamin E do not seem to affect the absorption or retention of retinol in the weaned pig. It appears that high dietary levels of either vitamin do not improve pig performance responses, and high levels of vitamin A may be detrimental to the vitamin E status of the young pig.

	Footnotes

 
¹ Salaries and research support were provided by state and federal funds appropriated to the Ohio Agric. Res. and Dev. Center and The Ohio State University.

² Appreciation is expressed to K. Mays for animal care and data collection, F. Cihla and M. Watts for laboratory analysis, and B. Bishop for statistical analyses.

³ The experimental use of animals and procedures followed were approved by the University Animal Care Committee.

Received for publication October 9, 2001. Accepted for publication April 23, 2002.

	Literature Cited

Top Abstract Introduction Materials and Methods Results Discussion Implications Literature Cited

 


Anderson, L. E., Sr., R. O. Myer, J. H. Brendemuhl, and L. R. McDowell. 1995. The effect of excessive dietary vitamin A on performance and vitamin E status in swine fed diets varying in dietary vitamin E. J. Anim. Sci. 73:1093–1098.[Abstract]

Bieri, J. G., and T. J. Tolliver. 1982. Reversal by bile acid on the inhibition of alpha-tocopherol absorption by retinoic acid. J. Nutr. 112:401–403.[Abstract/Free Full Text]

Bieri, J. G., T. J. Tolliver, and G. L. Catignani. 1979. Simultaneous determination of alpha-tocopherol and retinol in plasma or red cells by high pressure liquid chromatography. Am J. Clin. Nutr. 32:2143–2149.[Abstract/Free Full Text]

Bieri, J. G., A. Wu, and T. J. Tolliver. 1981. Reduced intestinal absorption of vitamin E by low dietary levels of retinoic acid in rats. J. Nutr. 111:458–467.[Abstract/Free Full Text]

Blakely, S. R., G. V. Mitchell, M. Y. Jenkins, E. Grundel, and P. Whittaker. 1991. Can thaxanthin and excess vitamin A alter -tocopherol, carotenoid and iron status in adult rats. J. Nutr. 121:1649–1655.[Abstract/Free Full Text]

Chung, Y. K., D. C. Mahan, and A. J. Lepine. 1992. Efficacy of dietary D -tocopherol and DL -tocopheryl acetate for weanling pigs. J. Anim. Sci. 70:2485–2492.[Abstract]

Coehlo, M.2000. Poultry, swine, dairy vitamin supplementation updated. Feedstuffs July 3 p 12.

Drott, P., S. Muerling, and M. Gebre-Medhin. 1993. Interactions of vitamin A and E and retinol-binding protein in healthy Swedish children-evidence of thresholds of essentiality and toxicity. Scand. J. Clin. Lab. Investig. 53:275–280.[Medline]

FDA. 1974. Food additives permitted in feed and drinking water of animals: selenium. Final rule, Federal Register 39:1355.

FDA. 1987. Food additives permitted in feed and drinking water of animals: selenium. Final rule, Federal Register 52:21001.

Hedemann, M. S., and S. K. Jensen.1999. Vitamin E status in newly weaned pigs is correlated to the activity of carboxylester hydrolase. Australian Pig Sci. Assoc. Adelaide, Australia p 181.

Hoppe, P. P., F. J. Schöner, and M. Frigg. 1992. Effects of dietary retinol on hepatic retinol storage and on plasma and tissue alpha-tocopherol in pigs. Internat. J. Vit. Nutr. Res. 62:121–129.

Lauridsen, C., M. S. Hedemann, and S. K. Jensen. 2001. Hydrolysis of tocopheryl and retinyl esters by porcine carboxyl ester hydrolase is affected by their carboxylate moiety and bile acids. J. Nutr. Biochem. 12:219–224.[Medline]

Mahan, D. C., Y. Y. Kim, and R. L. Stuart. 2000. Effects of vitamin E sources (RRR- or all-rac--tocopheryl acetate) and levels on sow reproductive performance, serum, tissue, and milk -tocopherol contents over a five parity period, and the effects on the progeny. J. Anim. Sci. 78:110–119.[Abstract/Free Full Text]

Mahan, D. C., and A. L. Moxon. 1980. Effects of dietary selenium and injectable vitamin E-selenium for weanling swine. Nutr. Rep. Int. 21:829–836.

Meyer, W. R., D. C. Mahan, and A. L. Moxon. 1981. Value of dietary selenium and vitamin E for weanling swine as measured by performance and tissue selenium and glutathione peroxidase activities. J. Anim. Sci. 52:302–311.[Abstract/Free Full Text]

Muller, D. P. R., J. A. Manning, P. M. Mathias, and J. T. Harries. 1976. Studies of the intestinal hydrolysis of tocopheryl esters. Int. J. Vit. Nutr. Res. 46:207–210.

NRC.1998. Nutrient Requirements of Swine. 10th ed. National Academy Press. Washington, DC.

Peplowski, M. A., D. C. Mahan, F. A. Murray, A. L. Moxon, A. H. Cantor, and K. E. Ekstrom, 1980. Effect of dietary and injectable vitamin E and selenium in weanling swine antigenically challenged with sheep-red blood cells. J. Anim. Sci. 51:344–351.[Abstract/Free Full Text]

Sklan, D., and S. Donoghue. 1982. Vitamin E response to high dietary vitamin A in the chick. J. Nutr. 112:759–765.[Abstract/Free Full Text]

Zaspel, B. J., and A. S. Csallany. 1983. Determination of alpha-tocopherol in tissues and plasma by high performance liquid chromatography. Anal. Biochem. 130:146–150.[Medline]

This article has been cited by other articles:

				M. A. Gorocica-Buenfil, F. L. Fluharty, C. K. Reynolds, and S. C. Loerch Effect of dietary vitamin A restriction on marbling and conjugated linoleic acid content in Holstein steers J Anim Sci, September 1, 2007; 85(9): 2243 - 2255. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Ching, S. Articles by Fastinger, N. D. Search for Related Content PubMed PubMed Citation Articles by Ching, S. Articles by Fastinger, N. D.