Effect of dietary inclusion of clinoptilolite on antibody production by dairy cows vaccinated against Escherichia coli

This study investigated the effect of the dietary inclusion of clinoptilolite, either alone or in combination, with intramuscular administration of Se, on antibody production by dairy cows vaccinated in late pregnancy against enterotoxigenic strains of Escherichia coli. Thirty-four clinically healthy pregnant Holstein heifers were randomly assigned to 1 of 4 treatments and vaccinated (days 210 and 240 of gestation) against E. coli with a multivalent vaccine. Treatment A (n = 8) was offered the basal ration supplemented with 200 g clinoptilolite/day and was injected with 0.1 mg/kg selenium (sodium selenite 0.5%) on the days of vaccination; treatment B (n = 9) was fed the basal ration supplemented with 200 g clinoptilolite/day; treatment C (n = 8) was injected with 0.1 mg/kg selenium on the days of vaccination and treatment D (n = 9) served as controls. The calves born were consuming the colostrum of their dams. Specific antibody titres against E. coli were determined with ELISA in blood serum samples of the heifers (210 and 240 of gestation and immediately after calving) and their calves (at birth, 12, 24 and 48 h after calving) and in composite colostrum samples (0, 12, 24 and 36 h post calving). During the first week of age all calves were monitored for the incidence of diarrhea. The administration of clinoptilolite alone and particularly in combination with selenium significantly increased the antibody titres against E. coli in blood serum of heifers and calves and in the colostrum of heifers. The incidence of diarrhea in calves was not significantly different among treatments. In the context of this experiment clinoptilolite administration, either alone or in combination with selenium appeared to improve the immune response of heifers vaccinated against E. coli and to provide enhanced protection to their calves.