Phosphorus! Horses are unique because they absorb phosphorus from their hindgut… which is a stroke of genius on a horses part… here is why.
Phosphorus in grains, legumes/oilseeds is bound up in a compound called phytate. ‘Phytate bound phosphorus’ is as good as indigestible for most monogastrics who absorb phosphorus from their small intestine (like pigs and poultry).
But horses enlist the help of their oh so useful hindgut bacteria to break down the phytate for them and release the phosphorus for absorption! Clever!!
So if you ever read statements about specific ingredients like soybean meal containing indigestible phosphorus because they contain phytate, think two things:
1. ALL grains and legumes/oilseeds contain phytate; and
2. Horses have got a useful arrangement with bacteria and a different site of absorption (their hindgut) that allows them to access the phosphorus.
Its a very well designed aspect of the horse’s gastrointestinal tract!!