Dr. Jacquie Jacob Ph.D., University of Kentucky
NOTE: Before using any feed ingredient, make sure that the ingredient is listed in your Organic System Plan and approved by your certifier.
Amaranth has been cultivated for grain for thousands of years (Kauffman and Weber, 1990). 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; therefore, the genetic base was maintained. This allowed for the rediscovery of amaranth's potential as a food and as a feed ingredient. Technically, amaranth is not a true cereal grain and is sometimes called a pseudo-grain, an herb, or even a vegetable. There are about 60 species of amaranth. Some are grown for their spinach-like leaves, eaten as a salad. Other species are grown for ornamental or decorative purposes, and some are grown for the small seeds.
In a two-year study, Pullins et al. (1997) looked at the potential of five cropping systems in which amaranth was paired with small grains and brassicas. This study concluded that net returns were high for wheat-amaranth and canola-amaranth croppings on the basis of average yield levels. Such combinations may also decrease the incidence of pests and diseases by breaking pest cycles. The use of a winter cover crop may also reduce soil erosion with little or no added equipment costs.
Commercial cultivars of grain amaranth became available in the late 1970s (Hackman and Myers, 2003) but its production has been limited. Increased demand for gluten-free flour has spurred more recent interest in amaranth. Amaranth is adaptable to different climates, including drought-tolerant cultivars suitable for production in the Midwest.
Amaranth seeds are unusually high in protein for a non-legume (12–18% crude protein) (Kauffman and Weber, 1990). 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 other cereals. Corn, the most commonly used energy source in poultry diets, is rich in leucine but poor in lysine and tryptophan. Amaranth seeds have nearly twice the lysine content of wheat and three times that of corn. 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 that is low in most grains—but is low in leucine.
The fat content of amaranth is higher than most cereal grains with 6-10% ether extract (Kauffman and Weber, 1990). 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 liver of deep sea fish and other marine species. Squalene has been shown to reduce cholesterol synthesis. Research has shown that dietary squalene may improve the reproductive performance of broiler breeder males (Li et al., 2010). In a study using artificial insemination, supplementation with squalene increased serum testosterone level and semen collection volume but had no effect of egg fertility rate. Supplementing males in a natural mating environment, however, did increase the egg fertility rate.
Use in Poultry Diets
Use of amaranth seeds in poultry diets is limited because they contain anti-nutritional 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 (Lorenz and Wright, 1984). Tannin levels in amaranth are typically similar to those found in sorghum and millet (Lorenz and Wright, 1984). Presence of the anti-nutritional factors requires that amaranth seeds be heat-treated before they can be effectively included in poultry diets—much the same as is done with soybeans, which contain anti-nutritional factors as well. Raw amaranth cannot be included in broiler diets above 20%. However, heat-treated amaranth can be included at up to 40% in broiler and layer diets with no adverse effect on production performance (Tillman and Waldroup, 1988). Untreated amaranth grain can be used at low levels in the diet as a replacement for meat and bone meal.
Some amaranth cultivars are grown specifically for leaf production. In China, for example, amaranth is grown specifically as forage for cattle with several cuttings occurring each season. Some types of amaranth have been shown to accumulate oxalate(s) and nitrates when grown under stress conditions (Saunders and Becker, 1984). Care should be taken, therefore, when choosing an amaranth cultivar for forage production.
Dried amaranth leaves can also be fed to chickens. They are relatively high in protein (23%) and methionine. The leaves need to be dried first to destroy heat-labile anti-nutritional factors that may be present. Enzyme supplementation (cocktail of cellulase, glucanase, and xylanase) has been shown to increase the level of dried amaranth leaves that can be included in broiler diets (Fasuyi and Akindahunsi, 2009).
Amaranth grain has the potential to partially replace corn and soybean meal in poultry diets. Unfortunately, the presence of anti-nutritional factors require that the seeds be heat-treated before being included in poultry diets. Amaranth leaves are a potential source of protein and methionine for chickens but, as with the grains, they must be heat-treated first, typically by drying.
References and Citations
- Fasuyi, A. O., and A. O. Akindahunsi. 2009. Nutritional evaluation of Amaranthus cruentus leaf meal based broiler diets supplemented with cellulase/glucanase/xylanase enzymes. American Journal of Food Technology 4:108-118. (Available online at: http://docsdrive.com/pdfs/academicjournals/ajft/2009/108-118.pdf) (verified 23 April, 2013)
- Hackman, D., and R. Myers. 2003. Market opportunities for grain amaranth and buckwheat growers in Missouri. Final report to the Federal-State Marketing Improvement Program.
- Kauffman, C. S., and L. E. Weber. 1990. Grain amaranth. p. 127-139. In J. Janick and J.E. Simon (eds.), Advances in new crops. Timber Press, Portland, OR.
- Li, S., Z. Liang, C. Wang, Y. Fend, X. Peng, and Y. Gong. 2010. Improvement of reproduction performance in AA+ meat-type male chicken by feeding with squalene. Journal of Animal and Veterinary Advances 9:486-490.
- Lorenz, K., and B. Wright. 1984. Phytate and tannin content of amaranth. Food Chemistry 14:27-34. (Available online at: http://dx.doi.org/10.1016/0308-8146(84)90015-3) (verified 23 April, 2013)
- Pullins, E. E., R. L. Myers, and H. C. Minor. 1997. Alternative crops in double-crop systems for Missouri. Fact sheet published by the University of Missouri-Columbia. (Available online at: http://extension.missouri.edu/p/G4090) (verified 23 April, 2013)
- Saunders, R. M., and R. Becker. 1984. Amaranthus: a potential food and feed resource. In Advances in Cereal Science and Technology 6:357-396. American Association of Cereal Chemists, Inc., MN.
- Tillman, P. B. and P. W. Waldroup. 1988. Performance and yields of broilers fed extruded grain amaranth and grown to market weight. Poultry Science 67:743-749. (Available online at: http://dx.doi.org/10.3382/ps.0670743) (verified 23 April, 2013)