In layman’s terms, what does metabolizable protein (MP) mean? Metabolizable protein (MP) is the total amount of amino acid absorbed in the small intestine. The main sources of amino acid to the intestine are rumen-undegradable protein (RUP), microbial crude protein (MCP), and to a lesser extent, endogenous crude protein (ECP).

These absorbed amino acids will be used by the animal in numerous metabolic processes, such as milk production, immune system, reproduction, etc.


How is it measured?

Measurement of RDP and RUP can be done in situ or in vitro, and measurement of microbial crude protein requires a more elaborate technique, sampling content from the rumen, abomasum and small intestine, and using external markers.


What impact does it have on a ration?


Balancing rations for RDP, RUP and MP leads to an improvement in nitrogen efficiency, which has a direct effect on nitrogen excretion, feed costs and performance.


Please explain what this does in the ration.

In order to optimize production with the least-cost diet, it is fundamental to know the RDP and RUP for each feedstuff as well as the animal’s requirement for each amino acid at different stages of production.


What percentage of your clients do you think really understand this value?

I would say that 100 percent of the field nutritionists are aware of the importance of balancing a diet based on amino acid requirements – and probably 80 percent would be able to explain in detail how MP is measured and calculated. PD

Gustavo Cruz is a ruminants R&D manager with Cargill. He can be contacted by email.