|Covey, Tanya -|
|Elam, Nathan -|
|Wester, David -|
|Ballou, Michael -|
|Hallford, Dennis -|
|Galyean, Michael -|
Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 7, 2010
Publication Date: January 5, 2010
Citation: Covey, T., Elam, N., Carroll, J.A., Wester, D., Ballou, M., Hallford, D., Galyean, M. 2010. Supplemental selenium source in Holstein steers challenged with intranasal bovine infectious rhinotracheitis virus: Blood metabolites, hormones, and cytokines. The Professional Animal Scientist. 26:93-102. Interpretive Summary: Selenium, an integral constituent of glutathione peroxidase, is a vital antioxidant during periods of stress. Given the multiple potential stressors that young calves may encounter in various stages of the production cycle, providing additional selenium as an antioxidant could prove to be beneficial. Therefore, scientists within the Livestock Issues Research Unit and Texas Tech University conducted a collaborative research project to evaluate the potential benefit of adding selenium to the diets of young calves as a means to provide immune protection and to enhance overall productivity. This portion of the study focused on the responses of serum metabolites, hormones, and cytokines in calves fed various sources of selenium for a period of thirty-five days prior to being exposed to with infectious bovine rhinotracheitis virus (IBRV). Our results indicated that in Holstein steers fed a basal diet with adequate selenium, supplying supplemental selenium from 2 different sources, did not seem to greatly influence the metabolic and immune responses associated with an IBRV challenge. The interrelationships between and among the variables we measured are intriguing, and although the present experiment did not yield profound treatment differences, the subtle treatment differences in proinflammatory cytokines and some metabolites (such as serum urea nitrogen concentration) warrant further research. Specifically, evaluation of the cellular, immunological, and metabolic responses to viral infections should lead to a greater understanding of the potential role of selenium in diets of immunologically stressed cattle, including identification of dose and duration of selenium supplementation required to favorably alter immune status and prevent or ameliorate bovine respiratory disease in stressed cattle.
Technical Abstract: As an integral constituent of glutathione peroxidase (GSH-Px), selenium (Se) is a vital antioxidant during stress. Calves are exposed to multiple factors that can lead to oxidative stress, including viral infection. Our objective was to evaluate the effects of supplementation of Se and Se source on immune function of Holstein steer calves challenged with infectious bovine rhinotracheitis virus (IBRV). Twenty-four Holstein steers (initial BW = 170 ± 0.6 kg) were assigned randomly to 3 treatments: 1) Control = no supplemental Se; 2) Sel-Plex = 1 mg/(steer/d) of Se from Se yeast (Sel-Plex; Alltech Inc., Nicholasville, KY); or 3) selenite = 5 mg/(steer/d) of Se from sodium selenite. Treatments were fed for 35 d before intranasal inoculation with IBRV (d 0) and continued through 21 d after the challenge. Whole blood Se was greater (P < 0.001) in Sel-Plex steers than the other 2 groups, but GSH-Px activity (P > 0.80) was not affected by treatment. Serum interleukin-1 beta concentrations tended to be greater (P = 0.09) in selenite steers vs. controls, and tumor necrosis factor-alpha concentrations 12 h after the challenge tended (P = 0.09) to be greater in steers fed Sel-Plex vs. controls. Steers in the selenite group had decreased (P < or = to 0.02) serum urea N at 4 and 72 h after the challenge compared with control steers, and steers receiving Sel-Plex had increased serum urea N at 72 h (P = 0.008) after the IBRV challenge compared with controls. Serum glucose concentrations tended (P = 0.06) to be less in steers that received the selenite treatment vs. no supplemental Se. Serum concentrations of NEFA (P > 0.40), insulin, cortisol, prolactin, and triiodothyronine were not affected (P > or = to 0.24) by treatment. Present data help to define the immune response to a viral challenge in cattle. Additional research is needed to clarify the role of Sel-Plex Se in immune response of cattle to viral infections.