Hi Cyprian,
I am not sure what is your background.
But assuming you have a very limited knowledge about feed processing, pelleting and extrusion technology, your question is a very very broad one.
Assuming you have some knowledge about feed processing, then you should know that feed manufacturing is affected by diet composition (ingredients), ingredients physical quality ( e.g. particle size); specs and type of the equipment (e.g. die size), production rate, steam quantity and quality etc..
Also, what does optimizing mean? what are you producing in an extruder? to feed which animal?
My advice is to read more about feed processing, books or published studies first, and then you will be able to narrow down your question.
Regards,
Khaled