Specifications establish that the use of fermented feed is absolutely forbidden to feed cattle for Parmigiano Reggiano producion. Therefore, the use of silage feed is forbidden, whilst this is largely used in other parts of Italy. Indeed, this fermented feed leads to the presence of bacteria in milk (clostridia spores that are resistant to heat) that cause harmful fermentations that give rise to defects in the cheese during its lengthy maturation (swelling of the cheese mass caused by undesired development of gas).
The only way to prevent these harmful microbial activities is using additives or physical milk centrifugation techniques. But producers have always opposed to the adoption of non-natural practices and thus the use of any additives in the production of Parmigiano Reggiano is absolutely forbidden.
These strict regulations for the feeding of cattle are particularly important because it is what cattle eats that leads to a good quality milk that is suitable to make Parmigiano Reggiano. Furthermore, it is forage that determines the positive “bacterial flora” that establishes the link with the land and characterises the milk first and the cheese later.
Parmigiano Reggiano is a PDO, i.e. Protected Designation of Origin, product where the word “origin” refers to the area where it is made, which “influences” the product because of this very bacterial activity that is left totally free in Parmigiano Reggiano since there are no additives that can change fermentations and enzymatic activities during its maturation process.