|Covey, Tanya -|
|Elam, Nathan -|
|Wester, David -|
|Galyean, Michael -|
Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 30, 2009
Publication Date: January 5, 2010
Citation: Covey, T., Elam, N., Carroll, J.A., Wester, D., Galyean, M. 2010. Supplemental selenium source in Holstein steers challenged with intranasal bovine infectious rhinotracheitis virus and in newly received beef heifers: Performance, morbidity, antibody titers, and blood cell counts. The Professional Animal Scientist. 26:82-92. 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 study 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 performance, intake, and overall health of Holstein and beef calves supplemented with 2 different sources of selenium for a period of thirty-five days prior to being exposed to infectious bovine rhinotracheitis virus (IBRV). Our results indicated that supplementing basal diets that contained adequate selenium with additional selenium had minimal effects on body weight changes, dry matter intake, rectal temperature, and blood cell types in Holstein steers in an IBRV challenge model and on performance and morbidity in newly received heifers in a feedlot setting. Although present data help to define responses to a virus challenge in cattle, further evaluation is required to determine whether dose or duration of selenium supplementation influences immune status in stressed cattle to an extent sufficient to affect animal performance, overall health, and economic outcomes.
Technical Abstract: Viral infection in newly received feedlot cattle can lead to oxidative stress. As a constituent of glutathione peroxidase (GSH-Px), Se plays a vital antioxidant role. Our objective was to evaluate effects of Se source on performance and health of calves challenged with infectious bovine rhinotracheitis virus (IBRV; Exp. 1) or in field conditions (Exp. 2). In Exp. 1, 24 Holstein steers (initial BW = 170 + or - 0.6 kg) were given either: 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 28 d before steers were inoculated with IBRV (d 0) and continued 21 d after the challenge. Treatments did not affect BW or DMI (P > 0.20) from 7 d before through 21 d after the challenge. Supplemental Se (P = 0.02) increased IBRV titer values on d 21. The IBRV challenge induced a febrile response; however, there were no treatment differences (P > 0.10) in RT. Total red and white blood cell counts, percentage of white blood cell types, and hemoglobin concentrations did not differ (P > or = to 0.11) among the 3 treatments. In Exp. 2, newly received, crossbred heifers (4 pens/treatment) were fed the same treatments as in Exp. 1, except selenite was supplied at 1 mg/(heifer/d) for 28 d. No treatment differences (P > 0.10) were observed for performance or health during Exp. 2. Results help to define the effects of Se supplementation and source on the immune response to viral infections in cattle.