Carbohydrates are biochemical compounds composed only of the elements carbon, hydrogen and oxygen, and are the main source of energy for animals. Animals get the majority of their required energy from the carbohydrates in feeds. Carbohydrates are polymers made of basic sugar units, such as glucose (the most abundant), fructose, galactose, etc. T
he two major classes of carbohydrates in plants are known as non-structural and structural. Those that serve as storage and energy reserves and that are available for more rapid metabolism to supply energy (e.g., sugars, starch, and pectin) are referred to as non-structural carbohydrates.
hose carbohydrate fractions that are not used for energy storage and provide fiber and anatomical features for rigidity and even water transport are known as structural carbohydrates (e.g., fibrous cellulose and hemi-cellulose). Non-structural carbohydrates are more available for energy metabolism than the structural carbohydrates.