why do you need to vaccanate cattle twice. what is the reason the medicine needs to be given 14-21 days after first shot. is it necessary to give it a second time. if so why can't you double up on the initial shot. thanks
The first shot gets the immune system starting to kick in, the second just finishes the job. Don't know why that is, but you can't just "double up" on the first shot.
You can bet that if some company came up with a oneshot vaccine for the diseases that require a booster that they would have by now. Ad it would probably sell for several times what the two does vaccines do.