Is this a maintenance type supplement?
I understand that it is an immune booster, so that would make me think that it should only be fed 1-2 times per year. If you continually feed it would lose efficacy.

At the local feedstore all available is Bovine version, is this appropriate for horses?
Asking due to having a young gelding that is not "blooming" and tends to be higher stress.

I used to feed it to a horse that had ulcers.  Long before there were so many choices for ulcer treatment. Fed a small amount morning and night. The actual purpose of colostrum is to build immunity in baby mammals in the first hours of life.   It does not build immunity in a grown animal at all. That is not what I fed it for. 

I dont think it would do anything after the first 12 hours of life.   Waste of money for anthing older than that. 

Once a foal is past 12-24hours old max, feeding colostrum does not enter the blood stream. I don't see how it would do anything other than get digested. 

Great topic here. Colostrum can be effective past early life stages. It is an amazing nutrient when you look at what it is and how it actually works. Do most animals need it other than at birth? Usually not. Does it work later in life? yes. I was involved in a clinical study using colostrum as an important part of a total program to treat  AIDS in Africa in the mid 1990's. It was a pretty interesting study that did prolong life by jump starting the patients immune system for a period of time. While promissing, the procedure was eclipsed by pharmaceutical treatments. We have also used it for horses with viral infections with positive results.

Colostrum contains IgG, an Immunoglobulin, that provides the equivilent of a softward download for an animals immune system. Kind of a blue print to a blank sheet of paper for a newborn. As an animal ages, that blue print may become a little blurry. While the imune system may still function fine to cope with most invasions that arise, a weakened immune system can become overwhelmed, and unable to cope with extreme stress. Infections like strangles may respond to colostrum support, though there is not a lot of clinical work done in this area. In effect, colostrum that is high in IgG can basically freshen up normal immune response in animals under stress at any stage of life. 

Not all colostrum is the same, and higher IgG levels do provide a better result. IgG in colostrum is the same component whether it is in colostrum from mice or the Blue Whale. So, colostrum from one species of mamal is basically effective in any other species. 

Very interesting information, Mr Winn