|Smith, J - CORNELL UNIV, ITHACA, NY|
|Van Amburgh, M - CORNELL UNIV, ITHACA, NY|
Submitted to: American Dairy Science Association Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: July 26, 2001
Publication Date: N/A
Technical Abstract: At approximately 2.5 mo of age, heifer calves, raised and housed at Cornell University, began receiving a diet formulated to support 1 kg/d gain (controls, n=6) or a diet containing protected CLA (treated, n=6). Total CLA was included in the diet at 1% of DM intake. The CLA- supplemented diet was formulated to support the same levels of ME and MP allowable gain as the control diet. Peripheral blood was collected at the initiation of the study (100 kg BW) and at 6.5 (200 kg BW) and 9.5 (300 kg BW) mo of age. Anticoagulated blood was maintained at room temperature and shipped overnight to the NADC where the composition and function of circulating mononuclear leukocyte (PBML) populations were evaluated. The composition of PMNL was unaffected by dietary treatment or age. Percentages of CD3+ T cells (and CD4+, CD8+ and gamma/delta T cell subsets) and B cells in the PBML population was unaffected by dietary CLA; however, the proportion of T cells did increase with age. Percentages of PBML expressing activation antigens were also unaffected by dietary CLA or age. Leukocyte function was evaluated in vitro by measuring interferon- gamma (IFN-gamma), nitric oxide, and tumor necrosis factor-alpha secretion in PBML cultures, both unstimulated and mitogen-stimulated. Dietary CLA did not affect these functions. The only exception was greater IFN-gamma secretion by PWM-stimulated cells from heifers supplemented with CLA. Although these data suggest dietary CLA had minimal effect on the composition and function of PBML from healthy calves, additional research is needed to determine if dietary CLA would benefit calves experimentally or naturally infected with pathogens causing significant morbidity or mortality in the field.