Defferetiate the 3 system of beef cattle production?

The three main systems of beef cattle production are the Cow/Calf productions: the farmer will raise the calf from birth to 6-10 months of age (approximately 400-600 lbs). Then the Stocker/Yearling operation: the farmer then grows the calf to approximately 600-180 lbs feeding mostly roughage's. Finally, the feed lot operation: the farmer now will feed the calf a high energy feed ration to "finish" the cattle to the desirable slaughter weight (usually about 900-1,300 lbs). Most cattle are slaughtered between the ages of 15-24 months.