Dairy Words

What is the Indo-European root of Sk. *dujh- 'to milk'?
I find no *dheugh- in my references with that meaning.

What is the P.I.E. root of Sk. ruh- 'to ascend'? I can
find no *reugh- in 'The American Heritage Dictionary of
I.E. Roots', but I do find *reugh-men 'cream' there. Is
*reugh-men based on the missing *reugh- 'ascend'? Does
the Farsi roughan 'fat' come from *reughmen? Thanks you.

David