Functions of the basic nutrients in dry dog foods

Proteins are very important in structural development and the immune system. They are necessary for all aspects of dog’s growth and also provide an important energy source.
  
Fat is the most important energy source. Fats contain approximately two-and-one-fourth times the energy as an equivalent weight of protein or carbohydrates. They contribute to palatability, influence the texture of foods, and carry fat soluble vitamins. They are also source for beneficial fatty acids.

Fiber: dogs do not derive any energy from fiber (insoluble carbohydrates), but having fiber in the diet improves colon health and is good for digestion. In dry food they are essential in keeping the kibbles together.

Ash is actually not added as an ingredient. It is an indicator of mineral (mainly potassium and phosphorus with smaller amounts of calcium, iron, magnesium, sodium and zinc, and trace amounts of many others) content.

Carbohydrates are an easy-digestable energy source and they are also essential in the formation of dry pet food. The starchy carbohydrates are used to add structure, texture, and form to kibbled food helping to create a product that is stable and easy to feed.   
  
Minerals work together with vitamins, enzymes, and other minerals in the body. They are necessary for many different functions such as formation of bone and cartilage, function of muscles and nerves, maintaining fluid balance, transportation of oxygen in the blood, and production of hormones.

Vitamins are indispensable for thousands of different chemical reactions in the body. They work together with minerals and enzymes to assure ia. normal digestion, cell reproduction, growth and function of muscle and bones, and healthy skin and fur.
  

Functions of micronutrients

Biotin is important for maintaining healthy skin and hair and necessary for growth, digestion, and muscle function.

Calcium: Of all the minerals, calcium is required in the greatest amount. It is necessary for many functions including bone formation, blood coagulation, muscle contraction, and nerve impulse transmission.

Choline is a structural component of fat and nerve tissue. Choline may also aid in brain and liver function and it helps other micronutrients to function to their full potential.

Cobalamin (vitamin B12) is a water soluble vitamin. It is necessary for the bone marrow to produce red blood cells.

Copper is essential for ia. the formation of collagen, bone and connective tissues, absorption of iron, development of red blood cells and development of pigment in hair. It also functions as a cell protecting antioxidant.
   
Folic acid is necessary for the bone marrow to produce red blood cells.

Iodine is necessary for the proper functioning of the thyroid gland and the production of thyroid hormones that regulate the rate of metabolism in the body and play an important role in normal growth.

Iron combines with copper (Cu) and protein to form hemoglobin, the molecule in red blood cells that carries oxygen. Iron also is necessary for certain enzymes in the body to function normally.

Magnesium is necessary for the absorption and use of certain vitamins and minerals (including Vitamin C, Vitamin E, calcium and phosphorus, sodium, and potassium) and production of protein. It is necessary for bone growth and the functioning of many enzymes.

Manganese is an essential mineral that enables the proper use of protein and carbohydrate by the body, reproduction, and the action of many enzymes in the body.
   
Nicotinic acid (niacin) is a B group vitamin that plays a role mainly in helping enzymes to function properly.

Pantothenic acid enables the body to create usable energy from macronutrients (carbohydrates, fats, and proteins).

Phosphorus: Calcium and phosphorous work together in the body to maintain the growth and structure of the skeletal system.    

Potassium is necessary for the proper functioning of muscles, nerves and enzymes, and maintaining a proper fluid balance throughout the body.

Riboflavine (vitamin B2) is a water soluble vitamin that has been proven to be essential to normal growth, muscle development and energy metabolism.    
Pyridoxine (vitamin B6) is a water soluble vitamin, that is absolutely essential for life.   
It is necessary for the utilization of amino acids, and it is essential to the immune system, nerve system and development of red blood cells.

Selenium is an antioxidant which functions in conjunction with Vitamin E and certain enzymes to protect cells.

Sodium + chloride (salt): Sodium and chloride help maintain the balance between fluids inside and outside individual cells of the body aiding transfer of nutrients and removal of waste products. Chloride helps maintain the right acid-alkali balance in the body. Chloride is also necessary for the production of hydrochloric acid (HCl) in the stomach which helps in the digestion of protein.   
   
Thiamine (vitamin B1) is a water soluble vitamin that converts glucose to energy, and is necessary for normal function of muscles and nerves.

Vitamin A is a fat soluble vitamin. It is important for the whole immune system, and it functions as an antioxidant that effects the mucous membranes, skin, skeletal system and eyes.
   
Vitamin C is a water soluble vitamin. Dogs and cats can manufacture vitamin C in their system, but adding it to the food can be beneficial especially for growing, pregnant, lactating, stressed, and working dogs.  

Vitamin D3 is a fat soluble vitamin. It is necessary for proper formation of bones, it helps absorbing phosphorus and calcium, and regulating the calcium level in blood.

Vitamin E is a fat soluble vitamin. It is an important antioxidant that prevents polyunsaturated fatty acids from becoming rancid. It is important for the immune system, proper functioning of the heart, blood system and fertility. Some studies suggest it also prevents cancer.
   
Zinc is important for the condition of skin and coat.