Kenny. This is from my Zoeits rep:
Ah yes. So actually is some truth to that. Our immunological man Dr.Cortese stated this. So yes u did read that guessing maybe Drovers!?
So it is complicated but in summary if the (young) calf did not get exposed to a Modified live vaccine by the dam or ever and is given both 7way clostridial 5way MLV, the antibodies from dams milk blocks many fractions of these vaccines. Now keep in mind on a (good) day only 70% of calves vaccinated have a response. And if the cow is vaccinated correctly that calf is already carrying many of the antigens the vaccine is carrying.So that is one way around it.
Next is using a different route like the vaccines in the nose. That's why Inforce 3 is something everyone is pretty high on right now.