Effects of sodium selenite and L-selenomethionine on feed intake, clinically relevant blood parameters and selenium species in plasma, colostrum and milk from high-yielding sows.

A field study in periparturient sows fed different dietary concentrations of either sodium selenite or L-selenomethionine (SeMet) was conducted to evaluate feed intake, haematological and biochemical parameters as well as to describe some key selenium (Se) species, namely selenoprotein P (SelP), selenoalbumin (SeAlb) and selenomethionine (SeMet) as well as total Se in plasma, colostrum and milk. Thirty-two sows were allotted to four treatments from 30 days (d) prepartum throughout on average a 32 d lactation period. Sodium selenite supplemented diets contained 0.40 and 0.60 mg Se/kg feed, while SeMet supplemented feed contained 0.26 and 0.43 mg Se/kg feed. Concentrations of sodium selenite and SeMet in complete feed exceeded the upper limits for total dietary Se and added organic Se, respectively, according to the European Union legislation. Blood samples were collected at initiation of the study, at farrowing and at weaning. Colostrum samples were collected at farrowing and milk samples at weaning. Se species were subjected to liquid chromatography, and total Se and Se species were determined using inductively coupled plasma mass spectrometry. The SeMet supplemented diets resulted in higher feed intake and in higher levels of total Se, SelP, SeAlb and SeMet in colostrum compared with sows fed sodium selenite. Similar results were obtained for levels of total Se and SeMet in milk at weaning. The higher dietary sodium selenite concentration in sows' feed did not increase the Se transfer into colostrum or milk when compared with those receiving the lower level of sodium selenite. However, the increase in serum-Zn from initiation until farrowing, observed in sows fed SeMet as well as the higher glutamate dehydrogenase activity in sodium selenite supplemented sows in this period might indicate a higher requirement of antioxidant defence in sodium selenite-supplemented sows. To our knowledge, the present data on Se species in plasma, colostrum and milk of sows represent the most complete investigation of Se in sows conducted to date. A higher amount of the above-mentioned Se species in the colostrum of sows supplemented with SeMet might strengthen the piglets' antioxidative system and passive immunity as well as improve their average daily weight gain. The higher feed intake in sows fed diets supplemented with SeMet is an interesting finding that warrants further investigation.

Effects of dietary sodium selenite and organic selenium sources on immune and inflammatory responses and selenium deposition in growing pigs.

The study was conducted to compare effects of different dietary Se sources (sodium selenite [NaSe], Se-enriched yeast [Se yeast] or L-selenomethionine [SeMet]) and one Se-deficient control diet on the expression of selected genes, hematological and clinical biochemical parameters, and muscle morphology in two parallel trials with finisher pigs. Se concentrations in blood plasma and tissues were also monitored. From the pigs in one of the parallel groups, muscle samples obtained from Musculus longissimus dorsi (LD) before and during the trial were examined. The pigs in the other parallel group were challenged once with lipopolysaccharide (LPS) intravenously. Transcriptional analyses of LD showed that selenogenes SelenoW and H were higher expressed in pigs fed Se-supplemented diets compared with control. Furthermore, the expression of interferon gamma and cyclooxygenase 2 was lower in the Se-supplemented pigs versus control. In whole blood samples prior to LPS, SelenoN, SelenoS and thioredoxin reductase 1 were higher expressed in pigs fed NaSe supplemented feed compared with the other groups, possibly indicating a higher level of oxidative stress. After LPS exposure glutathione peroxidase 1 and SelenoN were more reduced in pigs fed NaSe compared with pigs fed organic Se. Products of most above-mentioned genes are intertwined with the oxidant-antioxidant system. No significant effects of Se-source were found on hematologic parameters or microscopic anatomy. The Se-concentrations in various skeletal muscles and heart muscle were significantly different between the groups, with highest concentrations in pigs fed SeMet, followed by those fed Se yeast, NaSe, and control diet. Consistent with previous reports our results indicate that dietary Se at adequate levels can support the body's antioxidant system. Our results indicate that muscle fibers of pigs fed organic Se are less vulnerable to oxidative stress compared with the other groups.