A grazing system needs to meet the nutritional requirements of the livestock.
Animals require water, energy, protein, vitamins and minerals.
These nutrients are used to meet the requirements for reproduction, body growth, wool or hair growth, lactation, and general body maintenance. Environmental conditions, such as hot and cold weather, can increase maintenance requirements. Consequently, reproduction is the first to go and the last to return in cases of inadequate nutrition. As forage plants mature, energy availability and protein content decrease. Forage intake decreases as nutrient availability or digestibility decreases.