Evaluation of modifications to the neutral-detergent-fiber analysis procedure for corn and distillers grains plus solubles1

Six experiments were conducted to evaluate methods for measuring NDF in corn and distillers grains plus solubles. Methods included using sodium sulfite, α-amylase (AMY), amyloglucosidase, heat and steam with an autoclave, grinding methods, and a pre-fat extraction to decrease factors that interfere with measuring NDF accurately. Using sodium sulfite and AMY resulted in decreased (P < 0.01) corn NDF values, but these decreases were different dependent on dry-rolled corn or high-moisture corn (interaction P < 0.01). Two doses of AMY (0.5 mL each) was optimum at decreasing dry-rolled corn, high-moisture corn, and steam-flaked corn NDF, but using amyloglucosidase, heat and steam with an autoclave, or both did not aid in decreasing corn NDF. Grinding corns through a 1-mm Tecator Cyclomill, compared with a Wiley mill, resulted in decreased corn NDF (P < 0.01). Using a pre-fat extraction method before the traditional NDF method resulted in decreased NDF values for distillers grains plus solubles (P < 0.01) compared with using 100 or 200 mL of NDF solution. The recommended methods for obtaining accurate NDF concentrations include using cyclo grinding and adding two 0.5 mL of AMY doses and 0.5 g of sodium sulfite for corn and pre-fat extraction for distillers grains plus solubles.