## 1 Introduction  
Global climate change is expected to increase the exposure of grain crops to elevated temperatures, by 1-4 \({}^{\circ}\)C by the year 2100, and to increase the prevalence of droughs, at the same time as demand for chicken meat is increasing rapidly to meet the growth in world population and increased affluence in many developing countries [1]. Amaranth is a widespread, dicotyledonous, pseudocreal, some genera of which have been cultivated for thousands of years in Central and South America [2], whereas others are considered weeds. In Aztec culture, amaranth was used as a staple crop and had religious significance, but the Spanish forbade its cultivation in an attempt to suppress their culture [3]. Amaranth responds positively to temperature increases of 4 \({}^{\circ}\)C, up to 32 \({}^{\circ}\)C [4], as well as having high yields and drought resistance by virtue of its C4 photosynthetic pathway [5]. Amaranthhas a water requirement half that of corn and is recommended in areas where sorghum and millet are grown [6]. Moreover, fertilizer prices have more than doubled in the last two years [7], considerably more than grain prices, which means that crops with low nitrogen requirements such as amaranth have to be carefully considered. There are no reliable statistics on worldwide amaranth cultivation; however, it is mainly grown in China and Russia [8], with 300,000 and 100,000 ha reported to be under cultivation around the turn of the century [9]. It is also grown in Central and South America, India and parts of Africa. With international trade worth approximately 1 billion USD, the world's major exporter is China (14% of the global market), followed by the Netherlands (8%) and Austria (7%) [10]. Different amaranth varieties are grown for two main products: grain (_Amaranthus cruentus, A. hybridus_ and _A. hypochondriacus_) and a green vegetable (_A. tricolor_ and _A. lividus_). Both have high-potential and multipurpose usage [11], including as an ingredient in bakery products and as a thickening agent. There are also non-food uses, such as dusting powder in cosme [9]. The starch from amaranth grain has a low gelatinisation temperature and is stable over a wide range of temperatures, making it suitable for use as a thickening agent [9]. Amaranth protein is of better amino acid composition for humans than most major cereals and even cows' milk [9]. Amaranth contains more oil than the other major cereals, with a saturated fat-to-unsaturated fat ratio of about 0.3. Amaranth also has some antimutritive factors as well as polyphenols with antioxidant properties, which are claimed to reduce blood cholesterol [8]. The antioxidant properties are amplified by heat treatment, probably as a result of increased flavonoids, whereas phenolic content is variably affected, depending on variety and type of heat treatment [12]. Viscosity is typically increased by heat treatment; however, protein digestibility declines [12]. Heat treatment may be in the form of autoclaving, popping or roasting. Amaranth has a fast growth rate, and typical yields of amaranth grains per hectare are between 2 and 6 tons [9], providing there is sufficient heat for germination and for the first three months of growth. It can be used in rotation with winter wheat. Amaranths are considered a relatively neglected species that is important for future food security [13; 14; 15]. The main use of amaranth grain in livestock diets has been in China, where it is used extensively, as is silage from green material [9]. As well as a high nutritive value, it has significant antibacterial and antiviral effects [16]. It is recommended as a supplement for humans in developing countries, particularly to reduce the incidence of anaemia by virtue of its high iron content [16]. Fermented amaranth is a good substrate for probiotics [17], but preferentiing prior to feeding to livestock has not yet been evaluated for its effects on the nutritive value of amaranth grain. The nutritive value of amaranth grain (_A. cruentus, A. hypochondriacus_ and _A.