Inorganic and Organic Selenium Speciation of Seleno-Yeasts Used as Feed Additives: New Insights from Elemental Selenium Determination

Abstract

Seleno-Yeasts (SY) used as feed additives are known to contain different Selenium (Se) species. Seleno-Yeasts has been shown, on previous analytical methods, to contain selenomethionine (SeMet), selenocysteine (SeCys), selenate (SeIV) and selenite (SeVI), and various other organic and inorganic Se forms identified but rarely quantified. A new advanced method has allowed elemental Se (Se0), an inorganic Se species, to be quantified, thereby obtaining better insight into the proportion of inorganic Se in SY products. The study aimed to quantify the Se0 in SY products and assess the proportion of inorganic Se in SY. The Se speciation of 13 fresh commercials SY from different suppliers and batches, was assayed for the total Se, inorganic Se species (SeIV, SeVI and Se0), and organic Se species (SeMet and SeCys). Results on total Se were in line with the expected Se concentrations for all evaluated samples. The proportion of Se present as Se0 ranged from 3.6% to 51.8%. The quantity of Se0 in the SY products, added to SeIV and SeVI, indicated an average proportion of inorganic Se of 14.2% for the 13 analyzed SY products. The proportion of Se as SeMet ranged from 19.0% to 71.8%, (average of 55.8%), and a large variability in the SeMet content was observed. The SeCys content was also variable, with an average of 3.8%, relative to the total Se. In conclusion, advances in the analytical characterization have revealed that SY products can have a significantly high proportion of inorganic Se, which could affect the bioavailability of Se from SY supplements and explain their variable and lower bio-efficacy than pure SeMet supplements, such as hydroxy-selenomethionine.

Effects of different selenium sources and levels on the physiological state, selenoprotein expression, and production and preservation of selenium-enriched eggs in laying hens

“… Davis and Fear (1996) suggested that different selenium forms can influence the distribution and deposition of selenium between the yolk and albumen. SY, being a fermentation product, predominantly contains selenium in the form of selenomethionine (60–84%), but it also contains selenium in various organic and inorganic forms such as selenocysteine, selenate and selenite, whereas the absorption and metabolism mechanisms of many selenium compounds are not yet fully understood ( LeBlanc and Mester, 2021 ; Hachemi et al, 2023 ). Hence, this discrepancy in selenium deposition between SM and SY in the yolk and albumen may be attributed, at least in part, to these factors.…”

The effect of hydroxy‐selenomethionine on the productive and reproductive performance of old broiler breeders

“…Another potential reason is the high bioavailability of OH‐SeMet, as the chemical structure of OH‐SeMet is very similar to methionine, and Met‐tRNA cannot distinguish between methionine and OH‐SeMet. This allows OH‐SeMet to combine directly with proteins in the body, and be used as a source of Se (Hachemi et al, 2023 ). It has been suggested that higher expression of selenoprotein may better demonstrate the nutritional status and metabolic function of Se (Wang et al, 2022 ).…”