USDA LTAR Common Experiment measurement: Obtaining quality metrics in forage aboveground biomass v1

Harvesting crops for potential use as livestock forage must include nutritional value measurements to understand how these feedstuffs will meet the consumptive needs of animals. Nutritional value is often called “forage quality.” Nutritional value can change rapidly over hours to days as plants grow, mature, and respond to their environment. Measuring nutritive constituents in forage follows standardized methodologies across commercial and research laboratories. Crude protein (CP) estimates the true protein concentration based on tissue nitrogen analysis and the assumption that most plant protein is 16% nitrogen. Ash measures the total mineral elements present in forage, such as calcium and phosphorus, which do not contribute to its nutritional energy value. Cell wall constituents in forages are quantified using the Van Soest system (Goering and van Soest, 1970), where neutral detergent fiber (NDF) includes cellulose, hemicellulose, and lignin, while acid detergent fiber (ADF) contains cellulose and lignin, and acid detergent lignin (ADL) contains only lignin. This protocol outlines the methodology for analyzing ash, CP, ADF, NDF, and lignin in a forage sample.