Which unit of measure should be employed for the NOAEL?

In order to calculate the MOS, the NOAEL must have an unit of measure (um) expressed as mg/kg * bw/d.
This is due to the fact that MOS does not have a um and therefore, since SED is expressed as mg/kg * bw/d, NOAEL must show the same um.
The problem arises when sources show NOAELs expressed as part per milions (ppm), percentage of diet (% feed) etc and the user need a way to convert them into mg/kg * bw/d.
To do that, standardized and universally accepted (at least from European Commission) values of weight and diet intake for different animals are needed.
We have managed to find these data in order to perform all the conversion we needed.
To further facilitate and speed up the compilation of the PIF we inserted the already converted vlaue into our datasheets.