210 Maternal dietary organic selenium improves selenium status in neonatal lambs compared with single maternal or neonatal injection of inorganic selenium

Abstract The objective of this study was to compare the efficiency of three industry standard practices for improving the selenium (Se) status in neonatal lambs. Pregnant Polypay ewes (n = 27) at around 40 d pre-partum were enrolled in the study. The ewes were fed with grass silage and grain and, at 40 d from expected lambing, randomly allocated to one of three groups: 1) a single injection of 25 g sodium selenate as BO-SE/kg body weight (BW) at 4 wk before expected parturition (Inj-E) and not injection in the lambs; 2) no injection of BO-SE in the ewe but injection of 4.38 mg sodium selenite as BO-SE at 3 d of life of the lambs (Inj-L); and 3) no injection of BO-SE to the ewes or lambs but the ewes were fed 3.6 mg Se/day as Se-yeast (Yst-E) through the duration of the study (40 d prepartum + 30 d postpartum). Lambs were nursed by their own dams for 30 d without access to other feed (i.e., only milk). Blood was collected from the lambs at d 3 and 10 of life to measure 14 minerals, including Se, using ICP-MS. Glutathione peroxidase activity (GPx) was measured using a commercial kit. Data were analyzed using a GLIMMIX of SAS with an ARH covariance with treatment and time as the main effect, with lambs nested in ewe as a random effect. The number of lambs/ewes was used as a covariate. The injection of BO-SE in the ewes did not affect concentrations of Se in the lambs at birth, as there were no differences in whole blood Se between lambs in Inj-E and lambs in Inj-L at 3 d of life (i.e., before Inj-L received the BO-SE). The injection of BO-SE did not affect the level of Se in the whole blood of lambs 7 d after the injection compared with baseline (i.e., 3 d of life). Consequently, there was no difference in whole blood Se between lambs in Inj-E and Inj-L groups (177 vs. 167 ng/mL, respectively). However, injection of Se in pre-parturient dams did improve GPx activity in offspring (P = 0.04). Lambs in Yst-E had significantly greater concentrations of Se in whole blood compared with the other two groups at both 3 and 10 d of life (281 ng/mL; P < 0.001). Our data demonstrate that the typical industry standard approach of injecting inorganic Se in prepartum ewes or neonatal lambs is ineffective while feeding Se-yeast to dams was effective in improving Se status in lambs.