Yield, Growth Characteristics, and Forage Quality of Amaranth and Conventional Small-Grain Crops as Forage in Southern Kyushu

Amaranth (Amaranthus hypochondriacus) is a potential C4 food and forage crop with high yield and quality, which is expected to improve quality forage supply in southern Kyushu region. However, the use of amaranth as a forage crop is limited in southern Kyushu, Japan. Amaranth was seeded in early May 2020 and 2022 to test its adaptability, yield, and forage quality. These characteristics were compared with those of four typical small-grained forage species that is foxtail millet (Setaria italica), Japanese barnyard millet (Echinochloa esculenta), proso millet (Panicum miliaceum), and forage sorghum (Sorghum bicolor). In both years, the highest yield and the rate of crop growth were observed in the first harvest plants in the amaranth. In addition, amaranth also had the highest in vitro dry matter digestibility (IVDMD) and crude protein (CP) content in addition to the lowest neutral detergent fiber (NDF) content in 2020. Both IVDMD and CP content were lower in 2022, due to the fact that the crops were more mature at harvest, although NDF content was the lowest. Among small-grained forage plants, forage sorghum had the second highest yield after amaranth and the highest IVDMD in first-cut plants. The amaranth crop was extensively damaged in 2020, when 31.7% of the crop was lodged by a strong wind from typhoon No. 5. Compared to conventional small grain forage species, amaranth has the potential for high forage yields and quality. However, protecting amaranth plants from typhoon damage requires further study.