Distribution and Bioaccessibility of Selenium and Selenium Speciation in Selenium-Enriched Piglets

Selenium, as an essential trace element, exerts health effects that are contingent not only on the quantity consumed but also on the specific selenium species present in the dietary. The aim of this study was to investigate the effects of different selenium supplements on the distribution of selenium content, the forms of selenium, and its in vitro bioaccessibility in piglets. Inductively coupled plasma mass spectrometry and high-performance liquid chromatography (HPLC-ICP/MS) were applied to analyze the selenium content and its speciation in tissues and organs of piglets fed with three selenium supplements, sodium selenite (SS), selenium-enriched Cardamine hirsute (CH), and selenium-enriched yeast (SY). The bioaccessibility experiments on the livers of selenium-enriched piglets were conducted by simulating human gastrointestinal digestion. It was found that the kidney has the highest selenium content among the 12 examined organs. The efficacy of different selenium sources in improving the selenium content in piglets ranked in descending order, is as follows: SY, SS, and CH. The predominant form of selenium in the longissimus dorsi muscle is selenomethionine (SeMet), accompanied by smaller quantities of selenocysteine (SeCys) and methyl selenocysteine (MeSeCys). In contrast, the predominant selenium form in the liver is SeCys, along with SeMet and MeSeCys. Piglets fed with Se-enriched yeast exhibited a significant increase in the content and proportion of SeMet in both the longissimus dorsi muscle and liver. Additionally, different selenium species demonstrated varied G and GI bioaccessilities, with SeMet being the highest and SeCys the lowest.