Written by: Dr. Jacquie Jacob, University of Kentucky
Amaranth has been cultivated for grain for thousands of years. Amaranth grain was a staple in the diet of the Aztecs and was an integral part of their religious ceremonies. As a result, when the conquistadors arrived in South America, they banned the cultivation of amaranth. Amaranth continued to grow as a weed during this time, so the genetic base was maintained, allowing for the "rediscovery" of the potential of amaranth as a food and a feed ingredient.
There are about 60 species of amaranth. Some are grown for their spinach-like leaves, which are eaten as a salad. Other species are grown for ornamental or decorative purposes. Some species are grown for the small seeds. Technically amaranth is not a true cereal grain. It is sometimes called a pseudograin, an herb, or even a vegetable.
Amaranth seeds are unusually high in protein for a nonlegume (14% to 16% crude protein). The protein also has a well-balanced amino acid profile and is high in lysine. Amaranth seeds are said to have more balanced levels of the essential amino acids than grain options. Corn, the most commonly used energy source in poultry diets, has relatively high levels of leucine but is low in lysine and tryptophan. Amaranth seeds have nearly twice the lysine content of wheat and three times that of maize. In fact, the levels of lysine in amaranth seeds are similar to those in milk. Amaranth is also high in methionine, another essential amino acid low in most grains. Despite high levels of the amino acids lysine and tryptophan, amaranth is low in leucine.
Unfortunately, amaranth seeds also contain antinutritional factors, including saponins, trypsin inhibitors, phytate, and tannins. The phytate content of amaranth is typically higher than that of rice and millet but lower than that of corn and wheat. Tannin levels in amaranth are typically similar to those found in sorghum and millet. Because of the antinutritional factors in amaranth, the seeds must be treated before they can be included in poultry diets in significant amounts. Raw amaranth cannot be included in broiler diets at proportions above 20%. Heat treated amaranth, however, can compose up to 40% of a broiler diet. Treated amaranth can also be included in the diets of laying hens at proportions up to 40% without adversely affecting production performance.
The fat content of amaranth is higher than that of most cereal grains. The fat is also high in unsaturated fatty acids, especially the essential fatty acid linolenic acid. Amaranth also has a high content of squalene, which is usually only found in the liver of deep sea fish and other marine species. Research has shown that dietary squalene might improve the reproductive performance of broiler breeder males. In the context of artificial insemination, supplementing the male diet with squalene increased serum testosterone level and semen collection volume, but had no effect on the egg fertility rate. In the context of natural mating, however, supplementing the male diet with squalene did increase the egg fertility rate.
Dried amaranth leaves can also be fed to chickens. The leaves are relatively high in protein (25%) and methionine. The leaves must be dried before they can be used, to destroy any heat-labile antinutritional factors that might be present.
Alternative crops in double-crop systems in Missouri. Emily Pullins, Robert Myers, and Harry Minor, University of Missouri–Columbia
Market opportunities for grain amaranth and buckwheat growers in Missouri. Deanne Hackman, Missouri Department of Agriculture; Robert Myers, Thomas Jefferson Agricultural Institute.