Acta Veterinaria Scandinavica 2007, 49:1 http://www.actavetscand.com/content/49/1/1 Table 2: Relative contribution of farm and litter to variation in plasma vit E and Se Variable: Source of variation: Farm Litter Remnant variance Variable: Source of variation: Farm Litter Remnant variance Vit E At D -1 D -1 to D 4 12.5% 13.7% 73.7% 25.7% 0.4% 73.8% At D -1 D -1 to D 4 2.8% 20.2% 77.0% 15.9% 3.4% 80.6% All herds: Herds 2 to 6: Vit E Se At D -1 D -1 to D 4 32.0% 18.0% 50.0% 45.6% 33.4% 21.0% Se At D -1 D -1 to D 4 16.6% 32.6% 50.7% 11.4% 22.7% 65.8% Bodyweight At D -1 Daily gain 66.7% 9.4% 23.9% 58.2% 2.3% 39.4% Bodyweight At D -1 Daily gain 8.3% 26.1% 65.7% 31.9% 7.1% 61.0% Variance component analysis of variation in the following variables of plasma vit E, plasma Se and bodyweight in weanling pigs: Start values at day -1 (At D -1), changes from day -1 to day 4 (D -1 to D 4), and daily bodyweight gain from day -1 to day 18 (Daily gain). Relative contribution from different sources of variation to the total variance of each variable, with and without herd 1 included. National Veterinary Institute has considered plasma levels of vit E below 1.0 µg/ml as distinctly deficient, while the Danish Institute of Agricultural Sciences usually considers plasma vit E concentrations below 1.5 µg vit E/ml to indi- cate a state of deficiency [18]. At day -1, only 7% of the piglets had plasma concentrations of vit E below 1.5 µg/ ml. In the period from day 4 to day 18, however, the pro- portion of pigs with plasma vit E below 1.5 µg vit E/ml varied between 39 and 56%. At day 8, 17% of the pigs had plasma vit E concentrations that were even below 1.0 µg vit E/ml. For selenium, Ullrey [19] and Mahan [20] consider serum concentrations from 0.08 to 0.15 ppm Se as normal in pigs, while Blood & Radostits [21] declare above 0.120 µg/ ml serum as normal levels, and 0.005 to 0.060 µg/ml as deficient. In the present study, 54% of the piglets had plasma Se concentrations below 0.08 µg/g at day -1, and 19% had concentrations at 0.06 µg/g or less. From day 4 to day 8, however, only 1–3% of the pigs had plasma Se concentrations below 0.08 µg/g, and at day 18 no pigs were found to have Se concentrations below this limit. The present study includes a limited number of pig herds, but with the exception of herd 1 with its unusually high weaning age, we consider the herds included to be fairly representative for pig herds registered in the Norwegian In-Gris system. The In-Gris litter recording system includes the majority of pig breeding units in Norway, with 70.1% of all breeding sows in 2002 [13]. For herds 2 to 6, the results of this study were quite consistent, with limited variation both between and within herds. In our opinion, our results do therefore suggest that a large pro- portion of Norwegian piglets under present feeding con- ditions has acceptable vit E levels, but marginal Se levels in plasma at weaning. They also suggest that plasma vit E levels drop to marginal or deficient levels in a large part of Norwegian weanling pigs in the first weeks post-weaning, while plasma Se in the same period seems to rise to acceptable levels. It must be emphasised that our results are only representative for healthy weanling pigs. In pigs that develop diarrhea around weaning vitE absorption may be significantly reduced [22]. The clinical significance of these findings is more difficult to assess. In feeding trials with different vit E and Se levels, effects on daily weight gain and other performance parameters are generally not observed [8]. No special dis- ease problems were seen or reported by the participating farmers in the present study. Cardiac and skeletal muscle degeneration and liver necrosis are the most typical and dramatic disease conditions seen in vit E and Se deficient pigs [23]. In Norway these conditions usually affect older pigs, and they have become less frequent after Se supple- mentation was introduced in 1980 [24]. The most impor- tant consideration may be whether marginal vit E and Se levels around weaning affect the disease resistance in the pigs. Vit E and Se deficient pigs may have impaired immune responses [5,25], and have been shown to be more susceptible to swine dysentery [4]. Weaning is a crit- Page 7 of 9 (page number not for citation purposes)