The science of nutrition involves providing a balance of nutrients that best meets the animals needs for growth, maintenance, egg production, etc. For economic reasons, this supply of nutrients should be at least cost, and so we must supply only enough for requirements, without there being any major excesses. It is very difficult and very expensive to supply all nutrients at the exact nutrient needs - rather we have to oversupply some nutrients in practical situations, in an attempt to meet the limiting nutrients. In poultry diets these limiting nutrients are usually energy and some of the essential amino acids, such as methionine and lysine. In formulating diets the following nutrients are considered:

  • energy
  • protein
  • fat
  • vitamins
  • minerals
  • water

With the exception of water, these nutrients are provided by the ingredients that make up the diet. Ingredients are classified as:

  • cereals
  • animal proteins
  • vegetable proteins
  • vegetable fats
  • animal fats
  • micro minerals
  • macro minerals
  • vitamin premixes

Each of these separate types of ingredient provides a specific quantity and quality of nutrients to the diet. Balancing these ingredients to produce the diet formulation (recipe) relies on the skill of the nutritionist.

In order to produce a diet, the nutritionist must know the birds needs and the composition of the ingredients.

Formulation = balance needs vs ingredients vs costs.

The following nutrients are considered both for the birds needs and for the composition of the various ingredients:


Measure as crude protein, which is simply nitrogen x 6.25. Component amino acids are the important part of protein. There are 10 amino acids that are essential to the bird:

  • methionine
  • lysine
  • tryptophan
  • threonine

Protein and amino acids are supplied by ingredients such as:

  • soybean meal
  • canola meal
  • cottonseed meal

All contain toxins that must be destroyed by heat treatment. Other protein sources are from animals, and are generally of better amino acid content, but are expensive:

  • meat meal
  • poultry by-product meal
  • fish meal


The most expensive nutrient in a diet, but is difficult to measure and there is no guarantee with the feed.

Energy is important because it governs feed intake.

  • high energy = low feed intake
  • low energy = high feed intake

Sources of energy: everything in the diet other than minerals.

Units: calorie, or kilocalorie

Metabolizable energy = Energy intake as feed minus energy appearing in urine and feces. Therefore can only measure with a chicken trial, therefore expensive ($1,000/assay).


  • corn
  • soybean meal
  • fat
  • wheat
  • meat meal
  • barley

Fiber largely indigestible - cecal microbes?

  • Influences manure consistency.
  • Problem with some ingredients such as wheat, barley - enzymes.


All supplied as synthetics.

  • Fat soluble: A, D3, E, K.
  • Water soluble: B vitamins (for example, Riboflavin, biotin).

Cost about $2-5/tonne.

Exception is choline, which is added separately.

Generous safety factor 2-10x requirement.

Storage loss: time, temperature, humidity


  • Macro: calcium, phosphorus.
  • Micro: copper, zinc, manganese, iron, iodine, selenium.
  • Salt: sodium, chloride.


Not really an essential nutrient, other than linoleic acid (fatty acid).

  • Animal fats: hard, inexpensive. Problems with digestion by young birds.
  • Vegetable oils: liquid, expensive.

Pellet quality, dustiness of feed.