I've been asked this question myself many times, not only on this forum, but others .
For years and years I have always had the same response.
ALPHA-7 -- this Clostridial product was formulated to be more imuno responsive for NEW born calves. I absolutely will not be without this product at calving time, and is very important to get the response you need, to get it in them ASAP -- mine get it before they even get up and for sure, before they nurse. Of course, I only have a dozen cows, so I would have no excuse not to.
Reason -- I will also maintain this thought -- that a very high percentage, if not MOST, of the scours related problems calves have are due to Clostridial infection soon after birth, It is in the ground in every pasture in this country as far as I am concerned. Depending on the year, whether or not it is frozen or wet, this bug ( s ) - there are several - will either cause rapid problems - ie scours with no real cure and a lingering poor doing calf, OR, it will quietly sit and wait for the day that you go notice you have a dead calf -- no apparent reason.
Entero-toxemia - over eating disease (ARG), C-D -- all the same . Clostridium Perfringens types C-D are the main or most publisized, but there are several more -- even type A.
Bottom line is, if I had just enough cash to buy one thing for these babies, -- trust me -- it will always be Akpha - 7 for newborns. I also , at 30 days, booster them with the more common name -- Vision 7 or 8.
I give this behind the front leg so as not to see a lump if one forms. This is a fairly invasive vaccine -- in the oil form, and will leave some pretty hefty lumps if given in the neck -- especially if it accidently goes IM instead of Sub Q.
Thats my take on Alpha 7 -- worth it's weight in gold on my place!
Terry