Vitamins are primarily involved metabolic activities within the body. Water should be offered free choice. It is the most limiting of all the nutrients listed. Water requirements increase with lactation, exercise, increasing ambient temperature, and increasing protein and salt intake. Water deprivation produces death faster than any other nutrient.
Sunlight is turned into energy by plants.
These storage forms of energy include carbohydrates, proteins, and fats. When storage forms of energy are burned carbon dioxide, water, and heat are generated completing the cycle. Energy in feeds is measured in Calories. A Calorie is the amount of energy required to raise 1 kilogram of water 1 degree Celsius. NE is very difficult to measure.