It's just that keeping your heart rate in the target range during regular aerobic exercise has been shown to be safe and effective for increasing your aerobic fitness. Exercising above this range can be very uncomfortable and may increase your risk of injury.
Typical daily weight gains for feedlot animals ranges between 0.5kg to 2.5kg per day, while grass fed animals are somewhat lower than this. The following data was collected from a small beef cattle company in Dallarnil in Queensland (approximately 300km north of Brisbane).
Target Market Weight. Target market weight will affect the number of days on feed. If cattle have a 750-pound target market weight, calves gaining 1 lb/d with the high roughage diet will require 275 days to reach their target weight, whereas the low roughage diet will require 110 days. Market timing is just as important as market weight.