"He collects a sample of our cows."
Translation:Hij neemt een monster van onze koeien.
The English version "he collects a sample of our cows" literally means he takes some cows - the cows are the sample. I guess he takes them away in a big truck. Whereas the sentence "he collects a sample from our cows" could mean he collects eg blood or something else from the cows. Which does the dutch sentence (which uses "van") mean.