|Schwertner, Luke - Texas Tech University|
|Carroll, Jeffery - Jeff Carroll|
|Ballou, Michael - Texas Tech University|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 7/11/2010
Publication Date: 10/11/2010
Citation: Hulbert, L.E., Schwertner, L., Carroll, J.A., Ballou, M. 2010. Intra- and inter-dairy heifer variation of cellular neutrophil functions [abstract]. 2010 American Society of Animal Science Meeting, July 11-15, 2010, Denver, CO. Journal of Animal Science. 88(E-Supplement 2):T154.
Technical Abstract: Immune competence of dairy cattle is difficult to determine as a healthy immune system requires the resolution of pathogen invasion without excessive host-tissue damage. Neutrophil phagocytosis (PG) is important for eliminating pathogens, but PG induces an oxidative burst (OB), which helps destroy the pathogen but also can damage the neutrophil and surrounding tissue. Neutrophil adhesion molecule L-selectin (L) mediates neutrophil rolling in the periphery allowing for "surveillance" of pathogens while its counterpart, Beta-integrin (Beta), allows for neutrophil anchoring to epithelial cells and migration into tissue from the periphery. The objectives of these studies were to examine inter-heifer variation (Exp.1, n = 36, 13-16 mo. of age) as well as intra-heifer variation (Exp. 2, n = 12, days = 3) of neutrophil functions. Phagocytosis and OB were determined by 2-color flow cytometry using propidium iodide labeled enterotoxigenic E. coli and the oxidation of dihydrorhodamine, respectively. Adhesion molecule expressions were also determined using flow cytometry and expressed as the mean fluorescence intensities. In Exp. 1, neutrophil PG and OB were highly correlated (R2 = 0.50), while adhesion molecules L and Beta were moderately correlated (R2 = 0.39). Inter-heifer coefficients of variation (CV) were low for PG (19.9%) and Beta (18.5%), but high for OB (51.1%) and L (38.0%). In Exp. 2, there were day effects (P less than or equal to 0.01) for PG, OB and Beta, but not L (P greater than or equal to 0.10). Neutrophil PG intra-heifer CV was the least among all immune parameters (11.0%) while OB was the most variable at 22.43%. Adhesion intra-heifer CVs were 17.6 for Beta and 16.1 for L. These data indicate that neutrophil migration into tissue and subsequent phagocytosis of an E. coli were more similar between and within Holstein heifers than either the oxidative killing or surveillance potential. Therefore, the OB and L expression are more likely to contribute to individual heifer variation in immune competence.