Submitted to: International Journal for Vitamin and Nutrition Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2005
Publication Date: 12/20/2005
Citation: Foote, M.R., Nonnecke, B.J., Waters, W.R., Palmer, M.V., Beitz, D.C., Fowler, M.A., Miller, B.L., Johnson, T.E., Perry, H.B. 2005. Effects of increased dietary protein and energy on composition and functional capacities of blood mononuclear cells from vaccinated, neonatal calves. International Journal for Vitamin and Nutrition Research. 75(5):357-368. Interpretive Summary: There is considerable interest utilizing intensified milk replacers to optimize growth performance in young, rapidly growing dairy calves. The present study investigated the immunological benefits of intensified nutrition (i.e., optimized growth performance) in vaccinated calves. This study confirmed the growth-promoting effects of feeding an intensified milk replacer to newborn calves. This study also demonstrated that feeding an intensified milk replacer affects minimally immune responses of vaccinated calves. These data suggest that feeding a commercially available, standard milk replacer in a non-stressed environment provides sufficient nutrients to sustain antigen-specific immune responses to induced by vaccination. This work will benefit dairy farmers, calf producers and large animal veterinarians worldwide by providing new information regarding the nutritional requirements necessary to assure optimal immune function in milk replacer-fed calf.
Technical Abstract: Effects of increased protein and energy provided by an intensified milk replacer on antigen specific, cell-mediated immune response of the neonatal calf were examined. Calves were fed a standard (0.45 kg/d of a 20% crude protein, 20% fat milk replacer; n = 11) or intensified (1.14 kg/d of a 28% crude protein, 20% fat milk replacer; n = 11) diet from 1 to 6 wk of age. All calves were vaccinated with Mycobacterium bovis, bacillus Calmette-Guerin (BCG) at 1 wk of age. The daily weight gain of intensified-diet calves (0.62 kg/d) was greater than the weight gain of standard-diet calves (0.29 kg/d). Liver, kidney, heart, thymus, and subcervical lymph node from intensified-diet calves were heavier than the same organs from standard-diet calves. Flow cytometric analysis of peripheral blood mononuclear cell (PBMC) populations indicated that CD4**+ cell, gammadelta TCR**+ cell, and monocyte percentages, although unaffected by diet during the first 5 wk of the study, were higher in intensified-diet calves at wk 6. The decline in gammadelta TCR**+ cell percentages and increase in B cell percentages with increasing age seen in all calves are characteristic of the maturing immune system of the calf. CD8**+ T cell or B cell percentages were not affected by diet. In intensified-diet calves, percentages of CD4**+ expressing interleukin-2 receptor increased and percentages of gammadelta TCR**+ cells expressing interleukin-2 receptor decreased with time. The same populations in standard-diet calves did not change with time. Percentages of CD4**+ and CD8**+ T cells, and B cells expressing MHC class II antigen were unaffected by diet or age. Although mitogen-induced interferon (IFN)-gamma and nitric oxide (NO) secretion increased with age for all calves, PBMC from intensified-diet calves produced less IFN-gamma and more NO than did cells from standard-diet calves at wk 6 of the study. Antigen-induced secretion of IFN-gamma and NO also increased with age but was unaffected by diet. Antigen-elicited delayed-type hypersensitivity was unaffected by diet suggesting increased dietary protein and energy did not alter adaptive immunity in vivo. Overall, these results suggest that feeding calves a commercially available, intensified milk replacer affects minimally the composition and functional capacities of PBMC populations. Additional research is necessary to determine whether these subtle effects influence the calf’s susceptibility to infectious disease.