Like some other people, cattle think about sex and food, mainly. Food all the time. Then every three weeks cows think about sex (until they are in calf), bulls think about it all the time, and steers hardly ever...
When thinking about food, most cows think about how dull it is eating the same one kind of grass, all day, every day -- except in the winter when they just east silage, made from the same grass. Apart from that, dairy cattle dream of the AI man.
Our own "proper" cattle think about how lovely it is eating flowers, grasses, sedges, trees and rushes, or heather in the winter. When they graze, they get all excited, like a dog with a special treat.
When it's time for our girls to think of other things, they have a very convenient and cooperative bull handy...