I don't know the origin of the surname Nachtrieb, but the modern German word 'Nachtrieb' is actually Nach + Trieb. Unfortunately I don't know how to translate it. Simply put, it is the opposite of 'Vortrieb', a word with four different translations on
http://dict.leo.org .Nachtrieb is also in daily use, but strangely it's not in the dictionary...
Zilberschlag seems to be the Yiddish form of German Silberschlag. This means the 'Z' should not be pronounced as 'ts' as would be the case in a German name (unless someone called Zilberschlag tells you to, of course. The owner of a name is always right). Silber=Silver, Schlag=Strike, so it seems to be an occupational name. Kupfer- (copper) and Gold- (gold) schlag also exist as surnames.