What are the methionine requirements of slow-growing meat chickens?

Answer: In the United States, maximum protein accretion is the goal both in conventional and most organic poultry production. The fast-growing Cornish Cross broiler is used in both conventional and organic production because of its high growth capacity when raised on a high supply of amino acids. In contrast, slow-growing meat chickens are used in the European Union organic program, the French Label Rouge program, and American producers of heritage breeds. In contrast to harvest of birds at eight weeks typical of fast-growing birds, these birds have a growing period of about 12 weeks. Small farms in the United States typically use Cornish Cross broilers. However, some are interested in slow-growing breeds such as Red Broilers or New Hampshire.

The nutrient requirements of high-yielding broilers raised in controlled indoor environments are well-known. In contrast, the nutrient requirements of lower-yielding meat chickens raised in less-controlled housing with access to the outdoors and a high level of activity are not as well-known. Peter et al. (1997) found that a protein level of 20% is adequate as a starter for slow-growing birds. After six weeks, protein content can be reduced to 17.5%. U.S. research was conducted to determine the MET requirements of slower-growing meat chickens. Fanatico et al. (2006) raised three genotypes with different growth rates (fast, medium, and slow), using graded levels of MET, and found that, based on feed efficiency and weight gain responses, the MET and SAA requirements of the various genotypes are similar during the starter and grower phases.

Han and Baker (1991) found that slow-growing meat chickens require the amino acid lysine at the same concentration as fast-growing broilers. However, the fast-growing broilers required more than twice as much daily lysine as the slow-growing meat birds; the increased need was supplied by greater daily feed intake.

The body composition of meat chickens may come into play when considering amino acid requirements. If the protein-to-fat ratio of the bird is greater in a fast-growing chick than in a slow-growing chick, then dietary amino acid requirements may be higher for the fast-growing chick.

You’ll benefit from reading the ATTRA publication Organic Poultry Production: Providing Adequate Methionine, which discusses synthetic methionine, natural methionine supplement, methionine requirements and deficiency problems, and feeding strategies.

Also check out the Poultry section of ATTRA’s website, where you’ll find a host of useful poultry resources.


Peter, W., S. Danicke, H. Jeroch, M. Wicke, and G. von Lengerken. 1997. Influence of intensity of nutrition on selected parameters of carcass and meat quality of French Label type chickens. Archiv fur Geflugelkunde. Vol. 61, No. 3. p. 110-116.

Fanatico, A.C., P. B. Pillai, T. O’Connor-Dennie, J. L. Emmert. 2006. Methionine requirements of alternative slow-growing genotypes. Poultry Science. Vol. 85, Supplement 1. Abstract.

Han, Y., and D.H. Baker. 1991. Lysine requirements of fast- and slow-growing broiler chicks. Poultry Science. Vol. 70, No. 10. p. 2108-2114.