Well, I'm curious about what other people think, but to me, using the word "some" would be equal to "roughly" here and I wouldn't use the word roughly in combination with the number "ten". I would agree in a sentence like "My horses eat some two hundred apples a day" or if you use a range between two numbers in a sentence like "The horse eats some ten to twenty apples", but not in the given sentence here. What do you think?
Using "some"/"roughly" in this sentence would be translated at "Das Pferd isst grob/ungefähr zehn Äpfel" and that's too vague to use these very words here. But I'm open to contrary opinions.