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).
Most herds count on their kids gaining about 10 to 15 lbs. per month from birth to weaning and from 8 to 12 lbs. per month from weaning on. It is good to know the average weight gains for kids in your herd (or lambs in your flock) because average gains can vary widely depending on breed and management.