|Van Amburgh, M - CORNELL UNIV., ITHACA, NY|
|Foote, M - CORNELL UNIV., ITHACA, NY|
|Smith, J - CORNELL UNIV., ITHACA, NY|
Submitted to: American Dairy Science Association Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: July 25, 2000
Publication Date: N/A
Technical Abstract: Nutrient requirements of preruminant dairy calves are not well described. Current practices, often favoring a least cost approach, may compromise growth performance and health. The present study evaluated and compared immune function in neonatal calves on a higher nutritional plane with that of calves fed a diet meeting current industry standards. Colostrum-fed Holstein bull calves (n=19) were assigned randomly at approx. 4 d of age to 1 of 2 treatment groups. Treatment (TRT) 1 calves were fed a 20% crude protein (CP):20% fat milk replacer (MP) at a rate of 1.4% BW of dry matter (DM)/d for 8 wk. Calves assigned to TRT 2 were fed a 30% CP:20% fat MR at a rate of 2.4% BW of DM/d. The functional capacity of mononuclear (MNL) populations from peripheral blood collected at 0, 4, 6 and 8 wk during the study period was estimated using a battery of in vitro tests. Nitric oxide (NO) and interferon-gamma production by mitogen-stimulated MNL were influenced by nutritional plane, whereas mitogen-induced DNA synthesis and secretion of tumor necrosis factor-alpha and polyclonal immunoglobulin were unaffected. The total number of peripheral blood leukocytes was also unaffected by nutritional plane. These results suggest that increased dietary energy and protein can modulate specific aspects of the neonatal immune system. Additional research is necessary to determine if these changes reflect increased immunocompetency (i.e. infectious disease resistance). Leukocytes from all calves demonstrated age-related changes in their capacity to produce IgM, both cytokines and NO and to synthesize DNA, possibly reflecting the maturation of the calf's immune system.