Objective
To determine whether vaccination of lactating cattle with an Escherichia coli J5 bacterin-toxoid would produce a significant short-term change in milk production.
Design
Randomized, controlled clinical trial.
Animals
84 healthy, lactating cows (42 Holsteins and 42 Jerseys).
Procedure
Control and vaccinated cows were paired on the basis of breed, days in milk, daily milk production 1 week prior to vaccination, and parity. One cow in each pair was inoculated IM with a commercially available bacterin-toxoid according to label directions; the other cow was given saline solution. Cows were milked twice daily for 5 days before and 5 days after inoculation. Milk production was compared by ANCOVA.
Results
Vaccinated cows produced significantly less milk than did control cows at the second and third milkings after inoculation. At these milkings, milk production in vaccinated cows was approximately 7% less than that of controls.
Clinical Implications
Vaccination of lactating cattle with an E coli J5 bacterin-toxoid may cause a significant short-term decrease in milk production. (J Am Vet Med Assoc 1996;209:1291–1293)
