You'll note that TXshowmom didn't say anything about WHAT you finish them on. Just that you fatten them up before butchering, as opposed to taking them to auction. Calves can get fat on grass, OR feed OR a combination of both. The "traditional" method of finishing out calves is to put them on some type of grain based feeding program; and, there are many different types of feeding programs. Grain fed finishing is what the commercial feed lots do and where your supermarket beef generally comes from. In recent years "Grass Fed" finishing has increased. Grass fed finished calves are typically finished out on pasture only and typically by ranchers themselves. I'm not aware of any large commercial feed lots that provide a grass fed service or product. There is also another growing classification I'll call "All natural beef". Although I'm not currently aware of any offocials guidelines for this I think this is really just grass fed beef that has been grazed on pasture that has not had fertalizer, pesticides, or herbicides on it for some required amount of time, AND, the calves typically have never been treated implanted, wormed, or injected with anything.
There is strong debate between the "traditional grain fed" and the "grass fed" finishers. Without getting to detailed, and not wanting to start/re-start that debate here I'll just touch the main arguments I'm aware of in this debate.
Arguments FOR Grass Fed Finished Beef vs. traditional grain fed
- Its more healthy beef for the consumer (BIG debate on numerouse aspects of this topic)
- It requires lower cost input to finish-out the calf and hence is easier for ranchers to participate in direct marketing to the consumer (not much debate here)
Arguments AGAINST Grass Fed Finished Beef vs. traditional grain fed
- The beef is typically more lean and may require longer feeding periods to attain a USDA choice level grade.
- The fat can be, (but is not always) yellow vs. the white fat you see on supermarket beef. Genetics of calf and type of pasture play big here.
- The beef can have (but not always) what is refered to as a grassy taste. Genetics of calf and type of pasture play big here.
- Grass fed is a niche market