Could these words also be used to refer to mutton and lamb meat respectively?
You would have to use the word "et" afterwards. "Koyun eti ve kuzu eti"
How is it THE sheep and THE lamb? Should "the sheep" not be " koyunu", and "The lamb" should be "Kuzuyu"? Please explain to me, thanks in advance! :)
They aren't the subject of the sentence, because there is no sentence.
In other European languages, where the use of 'to be' is required, it may be so. However, in others, I'll use Malay as an example since it's my native tongue, it is not so.
'Koyun ve kuzu', translated literally to English would mean (a)sheep and (a)lamb. You said this is not considered a sentence. But Turkish has zero copula, like Malay(generally speaking). Translated, it would be '(seekor)biri-biri dan (seekor)anak biri-biri'. And we consider this a sentence. Why? Opinion is why. I do not know if Turkish follow the same way Malay considers what is a sentence, but it is to be noted that languages are not always the same.
A lamb is a baby sheep. Lamb meat is also called "lamb", whereas adult sheep meat is called "mutton". Lamb tastes far superior to mutton.
Is it by chance that I had to guess both words in this case? (In fact, I knew kuzu from a menu.)