Give the cow a medal. And fresh hay.
Changing the diet of an ungulate suddenly is BadThing(tm). If you've never dealt with colic before... bring a lunch or two. You might lose one or two.
Wanna do something nice? handful of oats or sweet feed at the bottom of the bag, and figure on squirts for a day or two. Don't approach from aft of abeam.
The cow figured it out. Just leave things alone and keep them the same. I'm sure she'll be happy with standard rats.
Cooks know stuff like that.
/johnny