my experience with cows is that they can be really curious. I don't think I have been chased by one on a bike though.
We did back to back 200k rides last week. It was really hot and the first 200k had a lot of climbing in the middle section. I cramped pretty badly and didn't think I would finish the first day, but fortunately the course levels out at the end and I limped home. The second day was even hotter. I didn't have any trouble with cramping, I think because there weren't any steep hills. But there was a headwind for 3/4 of the ride, and I got really slow because of the heat. Fortunately, someone gave me water when I asked about stores. When I did get to a store, I bought a bag of ice and that made things a lot better. Also, one of the locals pointed out they had ice cream in the back so I got a giant serving, which was the small size. Don't order a large ice cream cone in Central Pennsylvania, you will not finish it.
I plan on riding a couple of 100k rides a week until I leave for France.