Translation:The farmer gives the domestic animals food.
'The farmer gives the domestic animals food.' is a literal translation of this sentence and may be marked correct, however, 'The farmer is feeding ( that is: giving food to) the stock.' is a far better translation and should not be marked incorrect! Marking more appropriate translations wrong is a bad move.
Okey, got it. Most language courses that are supposed to lead to translations, are rather particular about not changing words more than necessary, you change between a noun (food) and a verb (feed), and even though the resulting meaning is the same, you have not translated what the author intended. For example, the question "Are not expensive and cheap the same thing?" They need not be exchangable, a house may be 'not expensive', but never 'cheap', and so on. Of course languages differ, and sometimes have their own idiomatic expressions that have to be used, rather than literal translations - but the rule is mostly 'don't change the wording more then necessary to make it idiomatic'
I think you're confusing yourself thinking of the suffix as -rene -erne. the two endings for plural are -er and -e, the -ne after is just the definitive article and it's always the same. as to when to use -er or -e to form the plural, i don't think there are specific rules, you just have to learn it i'm afraid.