Amino Acids in Pig & Poultry Feed Survey 2004

In order for animals to build up body proteins they must have a dietary source of amino acids. These become available either as the end products of digestion, or as the result of synthetic processes within the body. Not all amino acids are capable of being synthesized in the body, and others are not synthesized at sufficient speed to satisfy the needs of the body. Both of these groups are known as essential or indispensable amino acids. It should be noted that all of the 25 amino acids normally found in the body are physiological essentials, of which 10 or 11 are dietary essentials, as defined above.

As may be expected, the actual list of dietary essential amino acids differs from species to species. In the case of ruminants (cattle, sheep) bacterial synthesis of amino acids in the rumen renders the inclusion of any specific amino acids in the diet unnecessary except under conditions of intensive production.

Pigs and Poultry

In addition to a general need for protein, non-ruminant animals have specific dietary requirements for 10 or so essential amino acids. Feeding standards expressed in terms of total protein are normally supplemented by standards for some or all of these amino acids; feed compounders formulate diets accordingly. In practice it is usually found that the amino acid 'blend' provided by the diet is out of proportion when compared with an 'ideal' diet and hence is inefficiently utilized by the animal, because one or two amino acids are markedly deficient. By comparing the requirements for amino acids with the levels provided by typical diets it can be shown that for pigs the acid most likely to be most deficient is lysine; for poultry it is most commonly methionine. The Feeding Stuffs Regulations 2000 take account of this by requiring the levels of these amino acids to be declared in (respectively) pig and poultry feed.

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