Response of peripheral blood mononuclear cells to mitogenic stimulation in young calves

Sixteen Holstein bull calves were used to evaluate effects of increasing blood BHBA, as a consequence of ruminal development, on response of peripheral blood mononuclear cells to mitogenic stimulation. Calves were blocked by date of birth and assigned to weaning at 35 or 49 d of the study. Calves began the study at 4 d of age. Milk replacer was fed at 10% of BW to d 7 prior to weaning; thereafter, milk replacer offered was reduced by 50%. Calf starter was offered from d 1. Blood was sampled at wk 0, 2, 4, 6, 8, and 10 at 4 h after the a.m. feeding. Blood glucose declined, and blood BHBA increased, as calf starter intake increased. Blood BHBA increased at weaning in each treatment group and exceeded 1 mM during the week of weaning. Responses of peripheral blood mononuclear cells to stimulation with concanavalin A, pokeweed mitogen, or phytohemagglutinin were unaffected by increasing blood BHBA and increased with age. Increased concentration of blood BHBA in young calves from increased starter intake did not impair immune response.