Acta Veterinaria Scandinavica 2007, 49:1 http://www.actavetscand.com/content/49/1/1 from sows to piglets is limited [9], and that plasma Se con- centrations in weanlings are highly dependant on Se lev- els in the post-weaning diet [10]. In Norway, as in most of Scandinavia, harvested grain is low both in Se and vit E [11]. However, most pigs are fed commercial diets, fortified with standardized amounts of vit E and Se. In the last decade, the use of specialized lac- tation and weaner diets has become widespread, and the amounts of vit E added to these feeds have gradually been increased [12]. Vit E supplements above 100 mg/kg are now common in feed for weanling pigs in Norway, in accordance with the recent recommendations of Moreira & Mahan [8] and others. On the other hand, the use of additional supplements with vitamins or minerals is uncommon [12]. In the present investigation we have examined the con- centrations of both vit E and Se in the plasma of sows and piglets at weaning and in pigs in the first weeks after wean- ing, under field conditions in a number of representative Norwegian pig herds. The aim was to assess the adequacy of present feeding regimes in the Norwegian pig industry with respect to vit E and Se status for pigs in the weaning period. Materials and methods Herds and feeding Six normal pig breeding herds were selected for the study. Only herds registered in In-Gris, the Norwegian litter recording system [13], were included. Batch organised far- rowing was used in all the herds, all were fed standard commercial concentrates with no additional supple- ments, and all were located within 200 kilometres from Oslo. Within these criteria, the herds were selected mainly on the basis of practical considerations to make the collec- tion of samples feasible. The pigs were Norwegian Lan- drace and hybrids with Large White, and the litters were of varying parity. Information on feeding and management in the selected herds was recorded, but no changes were done to the choice of feed or the normal feeding and management routines in the herds in relation to the study. Commercial diets for breeding sows and/or weanling pigs were used in all the herds. According to the feed labels, the feeds used both for the sows and the weanling pigs were supple- mented with 0.30–0.40 mg Se per kg, in the form of sodium selenite; and 110–161 mg vitamin E per kg, as α- tocopheryl acetate. Design and sampling In each herd, one farrowing group of sows with litters scheduled for weaning in January or February 2003 was chosen. Within each of these groups, three sows with lit- ters were selected at random, and the farrowing and wean- ing days for each litter recorded. For the selected litters, the average age at weaning was 37.2 days, with standard deviation 5.6 days and range 32–49 days. At the day before weaning (day -1) blood samples were drawn from the sows and five piglets in each litter. In selecting the pig- lets for sampling, an even sex distribution within each lit- ter group was sought. The sampled piglets were marked individually, and their body weights recorded. At days 4, 8 and 18 after weaning, blood samples were again drawn from the marked pigs, and new body weights recorded. The original aim was to secure a full sample set from 3 pigs in each litter, taking into account that some piglets would die in the period. However, the loss of weanling pigs in the selected litters was small, so none of the litters ended up with less than 4 full sets. In those litters having 5 full sets, one sample set from the most numerous sex was chosen at random and discarded. All samples were drawn in 10 ml heparinized Vacutainer® tubes. Chemical analysis In the laboratory, a few ml of blood was taken out from each sample before centrifugation, and stored separately. All blood and plasma samples were stored at -20°, and analysed within 3 months. Vit E (α-tocopherol) and Se concentrations were determined in all 306 plasma sam- ples. In addition, Se concentrations in whole blood were determined in samples from one sow from each farm, and in all samples from two of her piglets; 54 samples alto- gether. Vitamin E concentrations were determined with HPLC. After precipitation of proteins with ethanol (+1% ascorbic acid), tocopherols in the plasma samples were extracted with hexane. The hexane was evaporated and the residue redissolved in ethanol. Vit E concentrations were meas- ured with a Perkin-Elmer HPLC unit, using a Supelguard C18 aptron precolumn, a reversed-phase C18 separation column with a methanol-water (95/5) mobile phase, and a Shimadzu fluorescence detector. Calculations were based on the use of tocol as an internal standard in all samples. The recovery of tocol was within 90–110%. Detection limit for α-tocopherol was 0.1 µg/ml. Selenium concentrations were determined by atomic absorption spectrometry with a hydride generator system [14], using a Varian SpectrAA-30 with a VGA-76 vapour generation accessory. Before analysis, each sample was prepared by oxidative digestion in a mixed solution with concentrated nitric and perchloric acids, using an auto- mated system with a Tecator 1012 Controller and 1016 Digester heating unit. The method is accredited (NS-EN ISO/IEC 17025). A quality control system using regular analyses of a blood standard (proficiency tested pig blood 1992) with value 0.20 ± 0.02 µg/g was adopted as refer- Page 2 of 9 (page number not for citation purposes)