Acta Veterinaria Scandinavica 2007, 49:1 http://www.actavetscand.com/content/49/1/1 ical time for the young pigs, and post-weaning diarrhoea and other weaning-related diseases are important health problems. The fall in plasma vit E after weaning observed in feeding trials has led to considerable interest for the forms of vit E used in feed supplements. Some of the fall may be related to a lower intestinal carboxyl ester hydrolase activity in pigs in the post-weaning period [26]. When given in equal amounts, the natural d-α-tocopherol leads to higher plasma vit E levels than the more stable dl-α-tocopheryl acetate normally used in pig feeds [1]. However, most of this difference may be explained by the difference in bio- logical activity between d-α-tocopherol and the racemic dl-α-tocopherol [27]. While some authors strongly advo- cate the use of additional supplements with d-α-tocophe- rol in its alcohol form [7], others have found that the post- weaning fall in plasma vit E may be counteracted by increasing the levels of dl-α-tocopheryl acetate in the feed ration [8,16]. Because of the functional interrelationship between vit E and Se, another possible approach to pro- tect the health of weanling pigs is to try to increase the Se levels in piglets before weaning. A further increase in the Se level fed to the sows is probably neither efficient [9] nor practicable, as feed regulations in the EU and the EEC set an upper total limit in the feed at 0.5 mg Se/kg [28]. Thus, other ways of supplementing piglets with Se in the nurs- ing period may be worth consideration. Conclusion In conclusion, our results suggest that the vit E and Se sta- tus in the weaning period may still be suboptimal for a large proportion of pigs with present feeding regimes in Norway, but that the plasma levels of the two nutrients may partially compensate for each other, as they tend to change in opposite directions in the first weeks post- weaning. In our opinion, the results warrant a renewed evaluation of the amounts and methods used for supply of both vit E and Se to piglets and weanling pigs in Nor- way. Competing interests The two companies that have supported this study eco- nomically are both involved in the marketing of vitamins and feed additives to pigs in Norway. Neither of them has been involved in the planning or performance of the study or in the interpretation of the results. None of the authors are affiliated to these companies in any other ways. Authors' contributions TS and BB conceived of the study, and TS is the main author of the paper. EV did the main part of the practical work; both with blood sampling, chemical analysis, pri- mary analysis of the results and first preparation of tables and figures. AB was responsible for the chemical work and was the main tutor for EV, especially in the chemical and analytical part. BB selected the pig herds and did most of the arrangements with the farmers. All authors have to some extent participated both in the planning, the practi- cal work and the interpretation of the results, and all authors have read and approved the final manuscript. Acknowledgements We are grateful to Mrs. Cathrine Hexeberg Marka for practical help with the blood sampling, to Mrs. Elisabet Mo and Mrs. Monika Strand for instruc- tion and support in the analytical work, to Prof. Stig Larsen for help in the planning of the study, and to Prof. Eystein Skjerve and Prof. Aage Tverdal for help with the statistical analysis. The study was supported economically by the companies Felleskjøpet Fôrutvikling and Nettovet a/s, and by H. B. Guldahl's endowment. References 1. Chung YK, Mahan DC, Lepine AJ: Efficacy of dietary D-α-toco- pherol and DL-α-tocopheryl acetate for weanling pigs. J Anim Sci 1992, 70:2485-2492. 2. Håkansson J, Hakkarainen J, Lundeheim N: Variation in vitamin E, glutathione perroxidase and retinol concentrations in blood plasma of primiparous sows and their piglets, and in vitamin E, selenium and retinol contents in sows' milk. Acta Agric Scand , Sect A, Anim Sci 2001, 51:224-234. 3. Meyer WR, Mahan DC, Moxon AL: Value of dietary selenium and vitamin E for weanling swine as measured by performance and tissue selenium and glutathione peroxidase activities. J Anim Sci 1981, 52:302-311. 4. Teige J, Tollersrud S, Lund A, Larsen HJ: Swine dysentery: the influence of dietary vitamin E and selenium on the clinical and pathological effects of Treponema hyodysenteriae infec- tion in pigs. Res Vet Sci 1982, 32:95-100. 5. Wuryastuti H, Stowe HD, Bull RW, Miller ER: Effects of vitamin E and selenium on immune responses of peripheral blood, colostrum, and milk leukocytes of sows. J Anim Sci 1993, 71:2464-2472. 6. Hedemann MS, Jensen SK: Vitamin E status in newly weaned pigs is correlated to the activity of carboxylester hydrolase. In Proceeding of the 7th biennial conference of Australian Pig Science Asso- ciation. 28. Nov. - 1. Dec.1999, Adelaide Edited by: Cranwell PD. Wer- ribee, Victoria, Australian Pig Science Association; 1999:181. 7. Stuart RL, Kane E: Vitamin E form, source may be important for swine. Feedstuffs 2004, 76(34):11-14. 8. Moreira I, Mahan DC: Effect of dietary levels of vitamin E (all- rac-tocopheryl acetate) with or without added fat on wean- ling pig performance and tissue α-tocopherol concentration. J Anim Sci 2002, 80:663-669. 9. Mahan DC, Moxon AL, Hubbard M: Efficacy of inorganic sele- nium supplementation to sow diets on resulting carry-over to their progeny. J Anim Sci 1977, 46:738-746. 10. Mahan DC, Moxon AL: Effect of increasing the level of inorganic selenium supplementation in the post-weaning diets of swine. J Anim Sci 1978, 46:384-390. 11. Frøslie A, Karlsen JT, Rygge J: Selenium in animal nutrition in Norway. Acta Agric Scand 1980, 30:17-25. 12. Sterten H: Personal Communication. Felleskjøpet Fôrutvikling as, Norway; 2005. 13. In-Gris: Årsstatistikk 2002 (Yearly statistics 2002). Hamar, Fag- senteret for kjøtt/ Norsvin; 2003:1-12. 14. Norheim G, Haugen A: Precise determination of selenium in tissues using automated wet digestion and an automated hydride generator - atomic absorption spectroscopy system. Acta Pharmacol Toxicol 1986, 59, suppl. VII:610-612. 15. Altman PL, Dittmer DS: Blood and other body fluids 3rd printing edition. Bethesda, Maryland, Federation of American Societies for Experimen- tal Biology; 1971:14. 16. Bonnette ED, Kornegay ET, Lindemann MD, Hammerberg C: Humoral and cell-mediated immune response and perform- ance of weaned pigs fed four supplemental vitamin E levels Page 8 of 9 (page number not for citation purposes)