Location: Livestock Issues ResearchTitle: Endophyte-infected fescue alters components of the acute phase response to lipopolysaccharide in beef heifers Author
|Altman, Alex - University Of Kentucky|
|Carroll, Jeffery - Jeff Carroll|
|Schmidt, Ty - University Of Nebraska|
|Mcleod, Kyle - University Of Kentucky|
|Vanzant, Eric - University Of Kentucky|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 11/27/2013
Publication Date: 7/25/2014
Citation: Altman, A.W., Sanchez, N.C., Carroll, J.A., Schmidt, T.B., Mcleod, K.R., Aiken, G.E., Vanzant, E.S. 2014. Endophyte-infected fescue alters components of the acute phase response to lipopolysaccharide in beef heifers. Journal of Animal Science Supplement. 92(E-Supple. 1):26. Abstract #70.
Technical Abstract: Sixteen Angus and 8 Hereford X Angus (334.7 +/- 10.7 kilograms body weight) heifers were stratified by sire breed, temperament (using weaning exit velocity), and body weight and randomly assigned within strata to either an endophyte-infected (E+) or endophyte-free (E-) diet for 10 days to determine the influence of feeding endophyte-infected fescue on physiological and acute phase responses of beef heifers to a lipopolysaccharide (LPS) challenge. Heifers were individually penned in 3.0 x 3.7 meter stalls and fed at 1.8 X NEm. Diets contained 20% fescue seed, 30% cottonseed hulls, 36% cracked corn, 10% supplement, 4% molasses, and MGA at 0.5 miligrams/head/day and were balanced to meet protein and mineral requirements. Heifers were fitted with vaginal temperature probes on day -16 (prior to treatment implementation), and indwelling jugular cannulas on day -1. Caudal vein areas were measured on days -16 and -2. On the day of LPS challenge (day 0), sickness behavior scores (SBS) were recorded and blood samples were collected from heifers at 0.5 hour intervals from -2 to 8 hours, and again at 24 hours relative to LPS administration (0.5 microgram/kilogram body weight at time 0 hour). Data were analyzed separately within pre- and post-challenge periods with the Mixed Procedure of SAS, using repeated measures in a completely randomized design. Decrease in caudal vein area from day -16 to dat -2 was greater with E+ (P < 0.01) and was the only variable to show significant sire breed effects (P = 0.06). Cortisol, IFN-gamma, TNF-alpha, and IL-6 concentrations increased for both groups from pre-LPS to post-LPS. Pre-LPS cortisol (P = 0.10) and IFN- ' (P = 0.08) concentrations were higher in E+ than E- heifers but no treatment differences were observed post-LPS (P = 0.30). No difference was observed in TNF-alpha concentration or SBS between E+ and E- heifers in pre- or post-LPS periods (P = 0.33). IL-6 was not affected by endophyte pre-LPS (P = 0.34), but was greater in E+ heifers post-LPS (P = 0.01). Vaginal temperature response post-LPS was bimodal and described using cosinor analysis for mean temperature and wave amplitude and duration. The first wave was unaffected by treatment (P > 0.30). The second wave showed a greater duration for E+ (P = 0.09), but no effect for mean or amplitude (P > 0.57). These data indicate that endophyte status affects particular components of the acute phase response when heifers are challenged with LPS.