Energetic evaluation of a lipopolysaccharide challenge in growing beef steers

Authors: CANTERBURY, LANDON - Texas Tech University; Broadway, Paul; DORNBACH, COLTEN - Texas Tech University; CHILDRESS, KALLIE - Texas Tech University; THOMPSON-SMITH, AUBREY - Texas Tech University; GRANT, MADDIE - Texas Tech University; BAKER, MADDY - Texas Tech University; Sanchez, Nicole; SMITHYMAN, MCKENZIE - New Mexico State University; GALYEAN, MICHAEL - Texas Tech University; HALES, KRISTIN - Texas Tech University

Submitted to: EAAP International Symposium on Energy and Protein Metabolism and Nutrition
Publication Type: Abstract Only
Publication Acceptance Date: 4/5/2025
Publication Date: 9/15/2025
Citation: Canterbury, L.G., Broadway, P.R., Dornbach, C.W., Childress, K.D., Thompson-Smith, A.C., Grant, M.S., Baker, M.G., Sanchez, N.C., Smithyman, M.M., Galyean, M.L., Hales, K.E. 2025. Energetic evaluation of a lipopolysaccharide challenge in growing beef steers. EAAP International Symposium on Energy and Protein Metabolism and Nutrition.

Interpretive Summary:

Technical Abstract: Available energy in cattle is important for immune activation, the acute phase response, and for combatting and recovery from an infection. Kvidera et al. (2016) noted that cattle may use more than 1 kg of glucose within 12 h after being challenged with lipopolysaccharide (LPS), which induces an inflammatory response, and the acute phase response can be replicated to simulate a diseased state (Smock et al., 2023). Failure to consume adequate energy during this time could limit the ability of the immune system to fight off a pathogen or virus, thereby extending the duration of an immune challenge or worsening the negative effects. Therefore, we evaluated the whole-body energetic cost of an activated immune system after a lipopolysaccharide challenge. Growing beef steers (n = 6; BW = 273 kg ± 25.2) were used in a randomized complete block design with steers as the experimental unit. Period (PRE- or POST-lipopolysaccharide [LPS]) was included in the model as a fixed effect and steer as a random effect. Steers were fasted 48 h before indirect respiration calorimetry measurements. Steers were placed in stalls, and their heads were secured into portable headboxes for gas (O2, CH4, CO2) exchange collections before the LPS challenge (PRE-LPS). After 24 h in the headboxes, gas collection bags were changed, and LPS was administered (0.20µg of LPS/kg of BW) through a jugular catheter. After LPS administration, another 24-h gas exchange was obtained (POST-LPS). Blood samples were collected for analyses of complete blood count, serum chemistry, and blood glucose determination. Fasted heat production did not differ between PRE and POST-LPS periods (P > 0.36). Oxygen consumption did not differ between periods (P = 0.43), whereas methane production decreased (P = 0.01) from PRE to POST-LPS, as the fast was extended. After the LPS challenge, circulating white blood cells decreased by 83% (P = 0.01), neutrophils decreased by 94% (P = 0.01), and lymphocytes decreased by 75% (P = 0.01). Blood glucose decreased 65% (P = 0.01) between 1 and 4 h POST-LPS administration. Differences among blood variables indicate that an acute immune response occurred because of LPS administration. It is likely that the small number (n = 6) of steers in this pilot study precluded our ability to detect a difference in heat production before and after an intravenous LPS challenge. Nonetheless, the approach used should provide a basis for additional research to more clearly define the effects of an activated immune system on whole-body energetics.