The study evaluated the effects of repeated oral exposure to LPS and lipoteichoic acid (LTA) on immune responses of dairy cows. Thirty pregnant Holstein cows were randomly assigned to two treatment groups. Cows received orally either 2 ml of 0.85% sterile saline solution (control group), or 2 ml of sterile saline solution containing three doses of LPS from Escherichia coli 0111 : B4 along with a flat dose of LTA from Bacillus subtilis. Blood and saliva samples were collected and analyzed for serum amyloid A (SAA); LPS-binding protein (LBP); anti-LPS plasma IgA, IgG and IgM; TNF-α; and IL-1. Results showed greater concentrations of IgA in the saliva of treated cows compared with the controls (P < 0.01). Treated cows had lower plasma concentrations of anti-LPS IgA, IgG and IgM Abs, and TNF-α than the controls (P < 0.05). There was a tendency for the concentrations of plasma LBP (P = 0.06) and haptoglobin (P = 0.10) to be lesser in the treatment group, although no differences were found in the concentration of plasma SAA and IL-1 (P > 0.10). Overall, the results of this study indicate that repeated oral administration with LPS and LTA stimulates innate and humoral immune responses in periparturient dairy cows.
Keywords: Oral; innate and humoral immunity; lipopolysaccharide; lipoteichoic acid.