Total crude protein in a ration consists of soluble protein, degradable protein and rumen ungradable protein. Degradable protein is the same as fermentable protein; it’s the fraction that is potentially degradable in the rumen.
Rumen microbes make use of the fermentable protein to produce microbial protein. The rate at which the fermentable protein is broken down varies by feed material. In addition, the actual amount of fermented protein depends on the rate of degradation, ration composition and feed intake.
A lot of rapidly degradable protein has a positive impact on milk production. However, when there is too much degradable protein in the rumen relative to energy (positive RDP), excess ammonia can happen. Grass usually contains a lot of rapidly degradable protein. The rate of degradation is increased by ensiling and decreased by drying and adding acids. In many rations, this is a great advantage.