Effect of Seed Variety and Cutting Age on Dry Matter Yield, Nutritive Values and In Vitro Digestibility of Teff Grass

Abstract

Declining groundwater supplies are among the most pressing issues facing the dairy industry today. The water needed for forage production represents the great majority of total water use on most dairy farms, posing a major challenge in the pursuit of improved drought resilience. The objective of this experiment was to investigate the effect of seed variety and cutting maturity on dry matter yield, nutritive values, and digestibility of teff grass (Eragrostis tef), a warm-season annual grass native to Ethiopia that is well adapted to drought conditions. Eighty pots were blocked by location in a greenhouse and randomly assigned to 4 teff varieties (Tiffany, Moxie, Corvallis, and Dessie) and to 5 cutting ages (40, 45, 50, 55, or 60 d after planting [DAP]). Samples were dried, weighed, and analyzed for crude protein (CP), neutral detergent fiber (aNDFom), and 24 h in vitro NDF digestibility (IVNDFD). It was found that seed variety had no effect on dry matter (DM) yield, CP, aNDFom, or IVNDFD. DM yield increased linearly as cutting age increased from 40 to 60 DAP. Similarly, aNDFom concentration increased quadratically with increasing cutting age. CP and IVNDFD decreased linearly as cutting age increased from 40 to 60 DAP. To assess carryover effects of cutting age on yield and nutritive values, 2 additional cuttings were taken from each pot. It was found that increasing the age at first cutting from 40 to 60 DAP significantly decreased CP concentration in the second cutting. Additionally, increasing DAP significantly reduced DM yield in subsequent cuttings. Across all seed varieties and cutting ages, CP decreased and aNDFom increased linearly with each additional cutting. Results indicate that, under greenhouse conditions, the first cutting of teff should be taken between 45 and 50 DAP to optimize nutritive values and digestibility in that cutting and additional cuttings.