It would appear from their website that this is a #1 crushed granite grit, for young and bantam chooches, treated with probiotics. Probiotics is a generalized term for some combination of digestive enzymes, beneficial digestive bacteria, and yeasts. When you research probiotics, manufacturers don't list the actual ingredients in their supplements as it would be proprietary information. Even if ingredients were listed they would be for human "probiotics," I have no idea what might constitute poultry probiotics.
What might be in probiotics? Amylase enzymes that break down long chain starches/carbohydrates (sugars) into short chain sugars that are more easily processed. Lactobacilis, a beneficial gut bacteria, most often used in cheese and yogurt processing. Acetobacter, the bacteria the turns alcohol into vinegar, also considered a beneficial gut bacteria for some odd reason. Brewer's yeast, which is a generic form of Sacchromyces cereviserae, which is used for everything from bread making yeast to beer and wine making. Yeasts convert short chain sugars to alcohol and CO2. At least these are the activities of these ingredients outside the digestive tract. Debate still goes on to the effectiveness in the digestive system. Hard telling how these would react to being in soil as most would not find it suitable environment.
It is very pricey too, compared to plain, crushed granite poultry grit.
BTW, when my stomach is sour, I find a couple spoonfuls of live culture yogurt, and a shot of raw apple cider vinegar, sets me right again. I've not bought into the whole probiotics as anything more than a scam to make a few bucks.
A brewer, wine and mead maker, I know a thing or two about yeasts and enzymes. Saccharomyces cerevisiae could be considered the wild phenotype. Most breweries, wineries have developed their own cultivars specific for the beers/wines they make and technically this would be specifically for ales. Saccharomyces carlsbergensis is lager yeast. The taxonomy for yeast is almost as complex as for semps. 
