Location: Livestock Issues Research
Title: The effect of feeding endophyte-infected fescue on the metabolic response to a provocative immune challenge in beef heifers Authors
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2013
Publication Date: October 24, 2013
Citation: Altman, A.W., Sanchez, N.C., Carroll, J.A., Schmidt, T.B., Mcleod, K.R., Vanzant, E.S. 2013. The effect of feeding endophyte-infected fescue on the metabolic response to a provocative immune challenge in beef heifers. Journal of Animal Science Supplement. 91(E-Suppl. 2): 651 (Abstract 632). Technical Abstract: To determine the effect of endophyte-infected fescue on the metabolic response of beef heifers to a lipopolysaccharide (LPS) challenge, Angus heifers (n=22; 292 +/- 9.0 kg body weight) were paired by body weight and randomly placed on either an endophyte-infected (E+) or endophyte-free (E-) diet for 10 days. Heifers were individually penned in 3.0 x 3.7 m stalls and fed at 1.8 X energy for maintenance. Diets contained 20% fescue seed, 30% cottonseed hulls, 36% cracked corn, 10% supplement, and 4% molasses, and were balanced to meet protein and mineral requirements. On day -1, heifers were fitted with indwelling jugular cannulas. On the day of challenge, blood samples were collected and serum isolated from heifers at 0.5-hour intervals from -2 to 8 hours, and again at 24 hours relative to LPS administration (0.5 microgram/kg BW at time 0 hour). Serum was analyzed for glucose, insulin, non-esterified fatty acids (NEFA), blood urea nitrogen (BUN), creatinine, and beta-hydroxybutyrate (beta-HB). Data were analyzed separately within pre- and post-challenge periods with the Mixed Procedure of SAS, using repeated measures in a completely randomized design. Within period, no treatment by time interactions were detected (P > 0.10). Insulin was decreased both pre-and post LPS in E+ heifers (P < 0.10; 0.50 vs 0.46 ng/mL for pre- and 1.17 vs. 1.02 ng/mL post-LPS). Glucose was unaffected (P = 0.87) by endophyte status pre-LPS, and was decreased (P < 0.01) for E+heifers post-LPS (78.1 vs 71.2 mg/dL). Concentrations of NEFA were decreased (P = 0.06) in E+ heifers pre-LPS (0.11 vs 0.08 mM) but were unaffected (P = 0.85) by endophyte status post-challenge. Although both BUN and creatinine differed (P < 0.01) between E+ and E- during both periods, BUN was decreased in E+ heifers (1.10 vs 1.04 mg/dL pre-LPS and 1.17 vs 1.04 mg/dL post-LPS), whereas creatinine was increased in E+ heifers (1.31 vs 1.41 mg/dL pre-LPS and 1.16 vs 1.29 mg/dL post-LPS). Concentrations of beta-HB were not different (P = 0.47) pre-LPS, and were decreased (P < 0.01) in E+ heifers post-LPS (1.06 vs 0.97 nM). These results indicate that exposure to fescue endophyte alters the metabolic response of heifers to LPS challenge.