The term "ruminating", meaning to muse or ponder, comes from cattle. When they're resting, cattle's four-stomached digestive system, or rumen, permits them to regurgitate partially digested grasses. This wad of partially digested grass is called the cud. Cattle can often be seen resting quietly chewing their cud, otherwise known as ruminating.
The Bull Factor
To keep cows calving within the same timeframe, the farmer limits the exposure that the cows have to herd bulls. Bulls and cows are not pastured together year-round. Rather, bulls are turned out with the cows in early summer and removed from the cow herd a few weeks later. Approximately nine and a-half months later, the calves are born.
Cows that do not become pregnant during that year's breeding season are usually sold for processing. This is what's known as culling the herd. It costs money to feed a cow over the winter, and a cow that is not going to produce a calf is not going to make money for the farmer.