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Calculating Methionine

Are there restrictions on the use of natural sources of methionine, or is only synthetic methionine restricted?

By Annie Amos

Methionine is an essential amino acid necessary for poultry growth and feathering. Poultry can not produce it biologically, so it must be obtained through diet. Birds can get methionine from natural sources including whole wheat, oats, alfalfa, fish meal, earthworms and sunflower meal, or from a synthetic additive.

The National Organic Program (NOP) regulations allow three forms of synthetic DL-methionine as feed additives for use only in organic poultry production. Use is currently restricted to the following maximum levels of synthetic methionine per ton of feed: Laying and broiler chickens—2 pounds; turkeys and all other poultry—3 pounds.

The limits in the NOP regulations only refer to synthetic methionine. Nonsynthetic (natural) sources of methionine are not restricted, although agricultural forms must be organic. Feed product labels guaranteeing methionine do not always distinguish whether the methionine in the product is from a natural or synthetic source. This can make it difficult to calculate the synthetic methionine feeding rates, especially if the product contains both synthetic methionine, and ingredients with natural methionine levels. An OMRI Listed product containing synthetic methionine will always carry the methionine use restriction, even if it also contains natural sources. If a product guaranteeing methionine is in a non-restricted OMRI category, we have determined that all methionine sources are nonsynthetic. If a product contains both natural and synthetic sources, the operator or certifier may want to contact the feed manufacturer to determine how much of the guaranteed methionine is synthetic.

Revised and updated in April 2018 by OMRI Technical Director Johanna Mirenda. This article was originally published in the Summer 2012 edition of the OMRI Materials Review newsletter.