Forage Nutritive Value of Various Amaranth Species at Different Harvest Dates

Abstract

Complete information on forage quality characteristics of amaranth is unavailable. This study evaluated the forage quality of various amaranth accessions at different harvest dates. Seven accessions from the North Central Plant Introduction Station were established in June 1997 and June 1998 near Boone, IA. Subplots were harvested six times at 2-wk intervals beginning 42 d after planting (DAP). In vitro dry matter digestibility (IVDMD), neutral detergent fiber (NDF), crude protein (CP), nitrate-nitrogen, acid detergent fiber (ADF), acid detergent lignin (ADL), protein and fiber digestion, and undegradable intake protein (UIP) were determined. Averaged over accessions, IVDMD decreased (P < 0.05) from 780 g kg⁻¹ at 42 DAP to 680 g kg⁻¹ at 112 DAP. Digestibility ranged from 590 to 790 g kg⁻¹ Averaged over accessions at 42 DAP, CP was 270 g kg⁻¹ then decreased to 100 g kg⁻¹ at 112 DAP. Neutral detergent fiber increased from 310 g kg⁻¹ at 42 DAP to 430 g kg⁻¹ at 112 DAP. Averaged over harvest date, Amaranthus cruentus (Zimbabwe) had the highest NDF (390 g kg⁻¹), and A. hybrid (Puebla, Mexico) had the lowest (330 g kg⁻¹). Amaranthus cruentus (Zimbabwe), A. cruentus (Rwanda), and A. hybrid (Puebla, Mexico) had UIP averaging 25, 22, and 16%, respectively, of total crude protein after 16 h of digestion. Forage quality of the accessions at most harvest dates was consistent with what would be expected for relatively good quality forage, although high nitrate levels are a concern.