Most expensive cattle?
Show cattle are the most expensive . but in terms of Market Colby Beef are the most expensive.
It really depends on the animal and the breeder who sells them. Those miniature breeds are quite expensive. However, there are Angus cattle that will sell for quite a lot too: top bulls will go for around $100,000 or more. Even prized Holstein or Jersey cows will cost a producer $200,000 or more to sell.
Beef cattle are usually grazed in pastures, fields or native rangelands. The type of country varies their grazing diet, and they are usually brought in to paddocks in feedlots for fattening up on grains prior to being sold for slaughter. In Japan, cattle are hand fed in stalls and regularly massaged by their owners in order to produce the most expensive and arguably best beef in the world which is called Kobe beef.
You certainly can feed sweet corn ("people corn") to cattle, but farmers don't because it doesn't yield nearly as much as field corn (dent corn). Most cattle feedlots operate on a tight enough margin that they need to feed the least expensive corn they can get, and that's not as cheap as it used to be.