The point is, in english, we do not differ the genders of most words. While in most latin languages, like Italian, that's always done (with few exceptions). In eng. "the cat" can either mean a male or female cat, but in italian we have different words for those. "Il gatto" for the male cat, "la gatta" for the female cat. Same for plurals: i gatti and le gatte. We just gotta get used to always define the genders of what we are talking about, it's an exercise to be done.
I really have a problem with the insistence that we translate "le gatte" with the definite article in English because they simply don't have the same meaning/usage in English and Italian. "Le gatte" means "cats in general" and "the cats" indicates that we refer to a specific group of cats. Correct me if I'm wrong.
mjnrstc: You may be indignant for no reason. I think you are "comparing apples and oranges" in this case - in English, like you mentioned, we sometimes use "the cats" to talk about specific cats. In this example "The cats drink milk" , could be discussing the cats in a group that are drinking their milk, as apposed to a group of cats that are not drinking their milk, like in an experiment. (So I know that scientist might use this sentence "as is".) Because it can be a logical and correct English sentence under the right context. I know we don't have context to prove our points one way or another. I just find it easier [and faster] to make up content to do the lessons. Like the lesson about "two women alone", making up that these women were trapped as a group of two on an island alone for example - this imaginary scenario made this a proper English sentence. I can usually find a scenario that can :"justify" the proper use of the translated sentence. I know sometimes we really have to stretch our imagination coming up with "the proper content". Sometimes lessons let you "not have to add an awkward article", such as in the English translation of "Fruit" for the French Lesson: Elle mange des fruits -I wrote as an answer: "She eats fruit." This answer was accepted. I didn't have to write: "She eats the fruit" to get it right. But even when Duolingo is not perfect, I don't mind because I am getting a "free" language tree - that has been very well thought out and is "gifted" to us that can appreciate it! :-)
I've used both of those answers and gotten it wrong several times. If there were actual tips and notes for the sections like the app reminds us to check then I think a lot of the questions would answer themselves. I've had to use theitalianexperiment.com to answer a lot of questions because most times the comments confuse me even further.
In the realm of possibilities, the author could be talking about a group of female cats. The compact way the lessons are presented preclude the accompaniment of lengthly or compact context. We need to imagine a context where the English equivalent could indeed be correct, so we can learn the lesson quickly and efficiently and choosing the most simplistic explanation of context is I feel counter productive to learning a language in the shortest amount of time.
Normally Italians would use the masculine word gatti and not the feminine gatte if the gender of the animals is unknown. You use gatte only if you know the gender and if all the cats in the group are females. So essentially it's quite rare to hear about gatte, usually you use gatti. Also if there's a male cat in a group of female cats... it's still gatti and not gatte since gatti is considered to be more general, like neutral.
What if you are talking about a group of male and female cats or don't know the gender of them?