Ontogeny of the immune response: effect of protein energy malnutrition in neonatal calves.

Immunocompetence of neonatal, Holstein bull calves fed for maximal growth (Control; n = 4) or protein energy malnutrition feeding (PEM; n = 4) for four weeks was assayed in vitro and in vivo. All calves exhibited elevated cortisol levels for ten days postnatally. At this time calves also were neutrophilic and lymphopenic. In addition lymphocyte function, as measured by lymphocyte proliferation and interleukin-2 activity, was reduced at this time as compared to older calves. After two weeks of protein energy malnutrition feeding, calves had significantly lower body weight, lymphocyte interleukin-2 activity and lymphocyte proliferation when compared with age-matched controls. Two weeks after protein energy malnutrition ration reversal, interleukin-2 activity and lymphocyte proliferation was comparable for both groups. There was no significant difference in serum cortisol concentration between control and protein energy malnutrition calves. The kinetics of the protein energy malnutrition group's primary humoral immune response was retarded, thus significantly lower antibody levels to K99 antigen were observed 8 to 12 days postimmunization. There was no significant difference between groups when comparing secondary response to K99 antigen.