Methionine—History and Uses in Organic Poultry Production

By Lindsay Fernandez-Salvador

Methionine (MET) is an essential amino acid that supports complex metabolic processes in poultry, including the synthesis of body proteins that make up muscles, organs and feathers. A lack of methionine nutrition in poultry can lead to reduced immune function and may result in poor feathering, feather pecking, cannibalism and mortality. While birds can obtain methionine from dietary sources such as fish, sunflower meals and insects, it can be difficult to ensure they have sufficient amounts from their natural feed ration. Synthetic MET is derived from propene, sulfuric acid, methanol and ammonia, and has been permitted in organic poultry production since 2003, with various annotations limiting its use. Due to the importance of MET in the diet of organic poultry, significant attention has concentrated on how to find a source that is nonsynthetic and compatible with organic principles, but to date an optimum solution has not been found. The National Organic Standards Board (NOSB) has revisited the allowance for synthetic MET on several occasions. In 2010 they voted to step down the amount of synthetic MET that organic producers can feed their poultry, providing maximums allowed per ton of feed. In 2015, they voted to add flexibility, providing a maximum per ton of feed, averaged over the life of the flock. This nuance was intended to allow producers to adjust the amount of methionine at different stages of life.

Synthetic MET wasn’t included in the USDA organic regulations until 2003. When it was added to the National List, MET was permitted as a feed additive in organic poultry production until October 21, 2005, with no restrictions on the amount that could be fed to the animals. It was considered along with several synthetic amino acids at the time, but it was the only substance from that group that was permitted. Subsequently, the NOSB reviewed a petition submitted in 2005 and voted to extend the allowance until October 21, 2008. According to that petition and NOSB recommendation, no viable alternatives existed, and more time was needed to complete research. In 2007, the NOSB received another petition to remove the expiration date entirely from the allowance for MET, which would have effectively permitted its use indefinitely. However, the NOSB rejected this petition and instead extended the allowance until October 1, 2010, citing their intent to “stimulate further commercial development and management changes to provide methionine to poultry in a nonsynthetic manner.”¹

Prior to the 2010 expiration date, a Methionine Task Force submitted another petition² to specify an average amount of synthetic MET to be fed over the life of the bird. They petitioned to allow synthetic MET until October 2015, and to limit its levels “calculated as the average pounds per ton of 100% synthetic MET in the diet over the life of the bird—Laying chickens, 4 lbs.; Broiler chickens, 5 lbs.; turkeys and other poultry, 6 lbs.” They emphasized the need to use the average amount of MET over the life of the bird, so that more or less methionine could be provided to meet poultry health needs. The NOSB again rejected some portions of that petition, stating that “the pounds of MET requested represents the highest levels normally fed on a daily, per-ton basis. Averaging the pounds fed over the life of the bird would allow even higher levels of MET to be fed at certain times, which is not the direction the committee wants to head.” Instead, the NOSB recommended that synthetic MET be permitted until October 2012, but at maximum levels per ton of synthetic methionine in the feed ration (at any time), instead of a maximum average over the life of the bird. At this same meeting, the NOSB recommended to continue to step down the amount that organic poultry producers can use after October 2012³. The annotation for synthetic MET was changed to permit its use at the following levels per ton of feed: Laying and broiler chickens—2 lbs.; turkeys and all other poultry—3 lbs. per ton. The restriction did not carry an expiration date besides the regular sunset review every five years.

In 2011, the Methionine Task Force again petitioned the NOSB to change the calculation method to average the amount of MET added to feed over the life of the bird, and to approve a slight increase in the amounts allowed. The petition cites the calculation method as important to change, so that feed rations could be better adjusted to the needs of the bird during the stage of life, seasonality, or for different breeds. This petition was considered at the April 2014 NOSB meeting and stimulated a great deal of discussion. Despite the fact that the livestock subcommittee unanimously voted to approve the change to the calculation method in 2013, the full NOSB could not come to a decision, and instead referred it back to the subcommittee to refine its recommendation for consideration at a later date.

The topic returned to the NOSB in 2015. In April of that year, the NOSB recommended amending the annotation to average the rate of MET addition over the lifetime of the flock. This was consistent with what the Livestock Subcommittee had recommended in the past. However, it wasn’t until 2019 that the annotation was actually changed in the USDA organic regulations.

1 https://www.ams.usda.gov/sites/default/files/media/Mth%20NOSB%20Final%20Recommendation%202008.pdf
2 https://www.ams.usda.gov/sites/default/files/media/Methionine%202009.pdf
3 https://www.ams.usda.gov/sites/default/files/media/Mth%20NOSB%20Final%20Recommendation%20on%20Methionine%20Step-Down%20Annotation%20after%20October%202012.pdf

This article was first published in August 2014, and was reviewed and updated in November 2023 by Research and Education Manager Peter Bungum.