Submitted to: Joint Meeting of the ADSA, AMSA, ASAS and PSA
Publication Type: Abstract only
Publication Acceptance Date: 2/18/2006
Publication Date: 7/9/2006
Citation: Foote, M.R., Nonnecke, B.J., Waters, W.R., Beitz, D.C., Fowler, M.A., Johnson, T.E., Miller, B.L. 2006. High growth rate fails to enhance adaptive immune responses of neonatal calves and is associated with decreased T cell viability [abstract]. American Dairy Science Association-American Society of Animal Science 2006 Joint Annual Meeting. p. 163. Interpretive Summary:
Technical Abstract: The objective of the study was to evaluate effects of three targeted growth rates [No Growth (or maintenance, NG), Low Growth (LG), and High Growth (HG)] on adaptive (antigen-specific) immune responses of preruminant calves vaccinated with Mycobacterium bovis bacillus Calmette-Guerin (BCG) and ovalbumin (OVA) 3 wks after initiation of dietary treatments. Growth rates for NG (.11 kg/d), LG (.58 kg/d), and HG (1.16 kg/d) calves differed (P < .001) throughout the experimental period. Blood leukocyte populations from HG calves had lower (P </= .05) mononuclear leukocytes (MNL) percentages and higher (P </= .05) granulocyte percentages than maintenance-fed (NG) calves. CD4+ T cell percentages increased (P </= .05) with age in NG and LG calves, a characteristic of maturing calves, but failed to increase in HG calves. Growth rate did not affect (P > .05) percentages of CD45RO+ (memory) CD4+ and CD8+ T cells, OVA-specific serum IgG1 and 2 concentrations, or PPD-induced interferon-gamma and nitric oxide (NO) secretion by MNL. Antigen (i.e., PPD)-elicited delayed-type hypersensitivity responses of NG and HG calves were similar (P > .05) and exceeded (P </= .05) responses of LG calves. In resting and antigen-stimulated MNL cultures, viabilities of CD4+, CD8+, and gamma delta TCR+ T cells from HG calves were lower (P < .05) than those of the same T cell subsets from NG and LG calves. In conclusion, adaptive immune responses were affected minimally by growth rate. Results suggest that protein-energy malnutrition in the absence of weight loss is not detrimental to antigen-specific immune responses of preruminant calves and that an increased growth rate does not benefit these responses. The negative effect of a high growth rate on T cell viability may influence infectious disease resistance of the calf.