Ushi No Tane Forum

So my cow is at productivity lvl 5 and is now giant with 10 hearts but I still only get normal 5 star milk from her. What more do I need to do?

You have to take the cow to Animal Sanctuary for 50 in game hours.

Simply talk to Neil when his shop is opened and choose "Animal Sanctuary". You can choose more animals to join (I think it is 100G/animal). And then you simply have to wait, you can't do anything there... Neil will take you back at 9 pm. So you need several visits until your cow meets the 50 hour goal. The game won't tell you when you have reached it, so it is better to keep notes for how many hours you have been there.

To add on, it's pretty easy if you just go an dedicate a week and a day to bringing your barn animals to the sanctuary. Go in at 10 and walk away from your DS for a while. I wound up with like three cows and a sheep giving me great products within an hour or two.