Finding a working additive for modern dairy cows is not an easy exercise, as we must first consider the rumen microbiota’s role that precedes the cow’s own digestive efforts.
Additives were first developed for monogastric species. Actually, the word developed is not correct — additives have always existed for all species, but it was the ban on antibiotics, or the need to reduce their usage, for monogastrics that gave additives such a boost scientifically and commercially. From there, it was only a small step in reasoning to look for applications of the same additives for ruminant species. They are all animals, after all, and they consume — more or less — the same or similar ingredients. This is partly true, and partly misleading; something that has led to many disappointments.