Forms of selenium in vitamin-mineral mixes differentially affect serum alkaline phosphatase activity, and serum albumin and blood urea nitrogen concentrations, of steers grazing endophyte-infected tall fescue

Abstract

The goal of this study was to test the hypothesis that sodium selenite (ISe), SEL-PLEX (OSe), vs. a 1:1 blend (MIX) of ISe and OSe in a basal vitamin-mineral mix would differentially affect serological and hepatic parameters of growing steers grazing toxic endophyte-infected tall fescue-mixed forage pasture. Predominately Angus steers (BW = 183 ± 34 kg) were randomly selected from herds of fall-calving cows grazing endophyte-infected tall fescue-mixed pasture and consuming vitamin-mineral mixes that contained 35 ppm Se as ISe, OSe, and MIX forms. Steers were weaned, depleted of Se for 98 d, and subjected to summer-long common grazing of an endophyte-infected tall fescue-mixed pasture (0.51 ppm total ergovaline + ergovalinine; 10.1 ha). Steers were assigned (n = 8 per treatment) to the same Se form treatments upon which they were raised. Se treatments were administered by daily top-dressing 85 g of vitamin-mineral mix onto 0.23 kg soyhulls, using in-pasture Calan gates. The PROC MIXED procedure of SAS was used to assess the effect of Se form treatments on serum parameters at day 0, 22, 43, 64, and 86. After slaughter, the effect of Se treatment on hepatic alkaline phosphatase (tissue nonspecific isoform, TNALP) mRNA, protein, and albumin protein content was assessed using the PROC GLM procedure of SAS. Fisher’s protected LSD procedure was used to separate treatment means. Partial correlation analysis was used to evaluate the relationship among whole blood Se concentration and serum parameters, accounting for the effect of time. Across periods, MIX steers had more (P ≤ 0.04) serum albumin than OSe and ISe steers, respectively. However, the relative hepatic bovine serum albumin protein content was not affected (P = 0.28) by Se treatments. Serum alkaline phosphatase activity was greater (P ≤ 0.01) in MIX and OSe steers. Similarly, hepatic TNALP protein content in MIX steers was greater (P = 0.01) than ISe steers. Partial correlation analysis revealed that serum albumin, blood urea nitrogen, and alkaline phosphatase activity were correlated (r ≥ 0.23, P ≤ 0.02) with whole blood Se concentration. In summary, consumption of 3 mg Se/d as OSe or MIX forms of Se in vitamin-mineral mixes increased serum albumin concentration and alkaline phosphatase activity, the reduction of which is associated with fescue toxicosis. We conclude that the organic forms of Se ameliorated the depression of 2 of known serological biomarkers of fescue toxicosis.

Gene expression profiling indicates a shift in ammonia assimilation capacity along the hepatic acinus induced by different forms of selenium in vitamin–mineral mixes fed to beef steers grazing on toxic endophyte-infected tall fescue

“…In a previous study, growing steers that grazed on HE of a similar concentration of ergovaline and ergovalinine (0.52 ppm) and consumed a vitamin-mineral mix that contained ISe as the form of supplemental Se developed symptoms of fescue toxicosis, including reductions in their serum prolactin concentrations and levels of alkaline phosphatase activity (Brown et al, 2009;Jackson et al, 2015). Similarly, we also observed reductions in the serum prolactin concentrations and serum alkaline phosphatase activity levels of the ISe-treatment steers in the present study (Jia et al, 2019). In addition, we reported previously that the hepatic alkaline phosphatase content observed in the ISe steers in the present study was lower than that observed in the MIX and OSe steers (Jia et al, 2019).…”

Pituitary and liver selenoprotein transcriptome profiles of grazing steers and their sensitivity to the form of selenium in vitamin-mineral mixes

“…The change in selenoprotein gene expression by the liver indicates that MIX steers have a greater redox signaling capacity and capacity to manage oxidative damage than ISe steers. We conclude that inclusion of 3 mg Se/d OSe or MIX forms of Se in free-choice vitamin-mineral mixes alters the selenoprotein transcriptome of both the pituitary and liver of growing steers consuming a Sedeficient (0.07 ppm) endophyte-infected tall fescue forage, in an ostensibly positive manner, consistent with the Se treatmentspecific amelioration of important markers of fescue toxicosis in these same steers (Jia et al, 2018;Li et al, 2019;Jia et al, 2019).…”

“…To date, our research has shown that the form (inorganic, organic, 1:1 mix of inorganic:organic) of supplemental (3 mg/d) dietary Se affects the concentration of Se in whole blood and expression of certain genes in the testes of neonatal calves (Cerny et al, 2016), livers of replacement beef heifers (Matthews et al, 2014), and livers (Jia et al, 2018) and pituitaries (Li et al, 2019) of growing beef steers. Most recently, we have reported (Jia et al, 2018;Jia et al, 2019) that the whole blood concentration of Se in Study 2 steers was greater for OSe (11%) and MIX (7.5%) vs. ISe steers, indicating a greater whole-body Se assimilation for OSe and MIX steers. In addition, the OSe and MIX steers of Study 2 had greater concentrations of serum prolactin and albumin (Jia et al, 2018), and serum alkaline phosphatase activity (Jia et al, 2019) than ISe steers, and were positively correlated with whole blood Se concentrations.…”

“…Most recently, we have reported (Jia et al, 2018;Jia et al, 2019) that the whole blood concentration of Se in Study 2 steers was greater for OSe (11%) and MIX (7.5%) vs. ISe steers, indicating a greater whole-body Se assimilation for OSe and MIX steers. In addition, the OSe and MIX steers of Study 2 had greater concentrations of serum prolactin and albumin (Jia et al, 2018), and serum alkaline phosphatase activity (Jia et al, 2019) than ISe steers, and were positively correlated with whole blood Se concentrations.…”

Selenium Biofortified Alfalfa Hay Supplemented to Dairy Heifers During the Peripartum Affects the Antioxidant Function of Albumin but Has Little Impact on Metabolic and Immune Function

“…To further complicate the interpretation of the urea data, an increase in blood urea concentration in Se supplemented animals was also observed in rats supplemented with inorganic Se [48] and in one year old Angus steers fed organic Se [49] but not in multiparous dairy cows [41,50]. Thus, it is possible that the observed increased circulating urea by feeding Se-bioforti ed hay might only be associated with the young age of the cows used.…”