Cows have two lungs, just as humans do.

For dairy cows it is around two months. For beef cows, it can range from two months to at least four.

There would have to be still six cows, because the number didn't change, since two died and were consequently replaced by two cows on the same day. Here's how the logic should play out:

You start with six cows. Two die of that six, leaving you with only four cows. However, two more cows "came" (or were bought) the same day that the initial two passed on, bringing the number back up to six.

If you want to do it by numbers, then it would go like this: 6 - 2 + 2 = 6.

Yes....Short bred and long bred cows are two types.

Other two types are dry bred cows and 3-in-1's.