Food Animal Internal Medicine Resident Auburn University Opelika, Alabama, United States
Abstract: Background- Intestinal immunity acquired after ingestion of colostrum is short-lived and may not protect calves throughout the susceptibility window for bovine rotaviral (BRoV) diarrhea. Hypothesis/Objectives - Prolonged feeding with transition milk from vaccinated cows will increase the persistence of intestinal BRoV passive immunity. Animals- 10 calves from a single dairy herd. Methods- Randomized clinical trial. Newborn dairy calves (male and female) received 3 L of maternal colostrum from cows vaccinated with 2 doses of a modified-live virus (MLV) BRoV vaccine before calving. 12 hours following colostrum intake, TM calves (n=5) were fed 3 L of transition milk (milkings 2nd – 6th) from BRoV-vaccinated cows twice daily until 14 days of age. MR calves (n=5) were fed 3 L of milk replacer twice daily for the same time. Serial serum and fecal samples, from 0-21 days of age, were collected to assess systemic and local BRoV antibodies using competitive ELISA. Results- The mean concentration of BRoV antibodies as determined by ELISA in serum was not statistically different between groups at any time point. On days 4, 7, 10, and 14 the mean concentration of BRoV antibodies in feces was significantly greater in TM calves compared with MR calves (TM: 94.76 ± 3.70, 92.44 ± 10.09, 58.76 ± 34.64, 85.08 ± 24.27 vs. MR: 16.86 ± 16.26, 4.90 ± 11.56, 5.86 ± 5.83, 3.62 ± 2.57, respectively). Conclusions and Clinical Importance- Greater persistence of intestinal BRoV antibodies while feeding dairy calves transition milk could reduce BRoV infection during that period.
