Simple, but nice endless runner with good music and a nice art style. Seeing the highest scores was nice. Controls felt good too.
Suggestion:
It would be nice to spice up the endless runner a bit by having a mini game or boss fight that you have to avoid their attacks for a certain period to progress.
Also more obstacles and maybe like a jump would be cool for going over higher objects.
I do agree on the gradual increase in cows so that it builds up or at least more randomized, that would be nice and help with difficulty too.
Overall though, nice work!