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Is dietary selenite transformed into elemental selenium by rumen micro-organisms? Comparison of mineral and organic selenium forms in cows.

M. A. Hachemi

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06-22-2020

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Abstract:

M114
Is dietary selenite transformed into elemental selenium by rumen micro-organisms? Comparison of mineral and organic selenium forms in cows.
M. A. Hachemi*1, E. Pinloche1, M. De Marco1, S. Fredin2, M. Briens1. 1Adisseo France SAS Commentry, France, 2Adisseo USA Inc Alpharetta, GA.

The lower efficacy of mineral selenium (Se) forms for status improvement compared with organic ones is largely described. However, limited results indicate it could be related to the formation of elemental Se (Se (0)) by rumen microorganisms (RMO). To test this hypothesis, we fed several forms of Se and measured the whole total Se (Tot-Se) as well as the speciation of Se (0) in rumen fluid and plasma of cows. Eleven ruminally cannulated nonlactating Prim Holstein cows were divided into 4 groups and fed for 23 d either a control diet (hay and protein-energy concentrate) (CON; n = 2), or the same control diet supplemented with 10 mg of Se top-dressed as sodium selenite (SS; n = 3), zinc-L-selenomethionine (Zn-SeMet; n = 3 or hydroxy-selenomethionine (Selisseo 2% Se; OH-SeMet; n = 3)). Rumen fluid (RF) was collected on d 22 and 23 and blood for plasma was collected from the tail vein on d 22, both 4 h after morning feeding. Plasma and freeze-dried RF were used for Tot-Se and Se (0) measurement by ICP-MS and HPLC-ICP-MS, respectively. Data were analyzed with a Kruskal-Wallis test. Results of plasma Tot-Se were CON: 32; SS: 94; Zn-SeMet: 127; OH-SeMet: 147 �g Se/kg of fresh material with significant differences within groups (P < 0.05) except between CON and SS groups (P > 0.05). The concentration of Tot-Se in RF was not different between the 2 sampling days. The concentration of Se in RF was positively correlated with the concentration of Se in plasma (R2 = 0.96) and followed the same hierarchy. Se (0) was measured in RF but was not detected in any group except the SS group. The proportion of Tot-Se present as Se (0) in the SS treatment was 42%. We conclude that plasma Tot-Se is representative of rumen Se level and confirmed the higher bioavailability of organic Se forms, particularly OH-SeMet. Those results also confirm a transformation of SS into elemental Se, which could explain the lower bioavailability for SS.

Keywords: elemental selenium, selenomethionine, cows.

Biography: AcknowledgementsI am a vet and I have a master's degree in animal nutrition. I work at Adisseo as health by a Nutrition project manager.�My job is to provide new insights towards the improvement of our products on animal growth and wellbeing and to innovate other nutritional solutions and services to resolve farm animals' health issues.