Selenium transfer to fast-growing pigs from inorganic and organic selenium sources.

Selenium (Se) is an essential microelement for pigs. In pigs, Se deficiency can lead to fatal, degenerative changes in various muscle groups, including heart muscle, compromised boar fertility and increased morbidity due to weakened immune status. Problems related to Se- deficiency seem to reemerge in feed efficient, fast-growing pigs in Norway. One aim of a large study was to assess the influence of different Se-sources on Se-levels in muscle in Norwegian pigs.

Female pigs originating from Landrace*Yorkshire (LY) crossbred sows and Duroc*Duroc (DD) purebred boars (n=24, ~30 kg body weight (BW)) were randomly allocated into eight groups. The pigs were fed eight different diets of pelleted feed supplemented with 100 mg VitE/kg feed. Three different Se-sources were added at varying levels – Sodium selenite (Na2SeO3), Se-yeast (Sel-Plex®, Alltech), and selenomethionine (SeMet, Excential Selenium4000®, Orffa). One group received a diet without Se-supplementation (control). Two biopsies from M. longissimus dorsi (MLD) were taken during the study using a biopsy-pistol, before initiating the feeding trial and at ~70 kg BW. Samples from MLD were also collected after slaughtering. Total Se-concentrations in MLD and feed samples were measured using inductively coupled plasma mass spectrometry (ICP-MS) and are presented as mean±SD.

The mean Se-concentration in the control diet was 0.05±0.004 mg/kg. The diets supplemented with Na₂SeO₃ contained 0.21±0.01, 0.33±0.006 or 0.36±0.02 mg Se/kg feed. Organic Se supplemented feed contained 0.32±0.00 mg Se/kg (Sel-Plex), and 0.32±0.02, 0.48±0.03, and 0.59±0.03 mg Se/kg (SeMet), respectively.

ICP-MS-results from MLD samples showed an initial Se-concentration of 0.32±0.02 mg Se/kg at 30 kg BW. The Na₂SeO₃ supplementation led to final mean MLD concentrations of 0.29±0.03 mg Se/kg in the low supplemented group, and 0.34±0.02 mg Se/kg in the high supplemented one, respectively. In the Seyeast-supplemented group, the final mean Se levels in MLD were 0.56±0.02 mg Se/kg. The SeMet-supplemented pigs showed final Se-MLD levels of 0.85±0.04 mg Se/kg (low Se-supplementation), and 2.07±0.15 mg Se/kg (high Se-supplementation). Samples from the control group showed decreased Se-levels at the time of slaughter (0.18±0.01 mg Se/kg).

When comparing with controls and Na₂SeO₃-supplemeted animals, high Se-retention was observed in MLD from pigs receiving organic Se. Thereof, pigs receiving SeMet-supplemented feed showed the highest Se concentrations in MLD collected at the abattoir. Further analyses should demonstrate if Se supplementation at different levels with various Se-sources modulates the health condition in Norwegian pigs.

Disclosure of Interest: None Declared.