Location: Livestock Issues ResearchTitle: The effect of feeding endophyte-infected fescue on the acute phase response to lipopolysaccharide in beef heifers Author
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/12/2014
Publication Date: 10/24/2013
Citation: Altman, A.W., Sanchez, N.C., Carroll, J.A., Schmidt, T.B., Vanzant, E.S., Mcleod, K.R. 2013. The effect of feeding endophyte-infected fescue on the acute phase response to lipopolysaccharide in beef heifers. Journal of Animal Science Supplement. 91 (E-Suppl. 2): 480-481 (Abstract TH14). Interpretive Summary:
Technical Abstract: 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 to determine the influence of feeding endophyte-infected fescue on the physiological and acute phase responses of beef heifers to a lipopolysaccharide (LPS) challenge. 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 -16, heifers were fitted with vaginal temperature probes and on day -1 heifers were fitted with indwelling jugular cannulas. On the day of challenge, sickness behavior scores were recorded and 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 µmicrogram/kg body weight at time 0 hour). Serum was analyzed for cortisol, interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6) concentrations. 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). Cortisol, IFN-gamma, TNF-alpha, and IL-6 concentrations increased for both groups from pre-LPS to post-LPS (P-value). Cortisol concentrations were unaffected (P = 0.31) by endophyte pre-LPS, and were greater (P = 0.01) in E+ heifers during the post-LPS period (50.1 vs 55.0 ng/mL). TNF-alpha was greater in E+ heifers during both the pre- (P < 0.01; 6.2 vs 6.0 pg/mL) and post-LPS periods (P < 0.01; 102.0 vs 62.7 pg/mL). Neither IFN-gamma nor IL-6 were affected by endophyte treatment during either period (P > 0.13). Sickness behavior scores were greater for E+ post-LPS (P < 0.01). Vaginal temperatures were greater for E- heifers pre-LPS (P < 0.01; 38.70 vs 38.61 C) and greater for E+ heifers post-LPS (P < 0.01; 38.98 vs 39.05 C). These data indicate that endophyte status affects the acute phase response when heifers are challenged with LPS.