Crude fibre is the indigestible plant material — primarily cellulose and lignin — measured in food and feed samples to assess dietary fibre content and nutritional quality. Enter the Weight Before Ashing, Weight After Ashing, and Sample Weight into the Crude Fibre Calculator to get the Crude Fibre Percentage of your sample. Secondary outputs include Fibre Weight and Ash Weight in grams.
Crude Fibre Percentage
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Fibre Weight
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Ash Weight
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Crude fibre is the portion of plant material in feeds that is indigestible by monogastric animals. It represents the structural carbohydrates like cellulose and lignin after acid and alkali digestion treatment.
The calculation uses the formula: (Weight before ashing - Weight after ashing) × 100 / Sample weight. This determines the organic matter lost during ashing as a percentage of the original sample.
Ashing in a muffle furnace removes all organic matter, leaving only mineral ash. The weight difference before and after ashing represents the crude fibre content.
Samples are typically ashed at 550-600°C in a muffle furnace for 3-4 hours to ensure complete combustion of organic matter while preserving mineral content.
High crude fibre content indicates more indigestible plant material, which can reduce feed digestibility and energy value but may be beneficial for ruminant animals' digestive health.
Weighing should be accurate to at least 0.001g (1mg) for reliable results, as small weight differences significantly impact the final percentage calculation.
Cereal grains typically contain 2-12% crude fibre, while forages like hay can contain 25-40%. Concentrates usually have lower fibre content than roughages.
Yes, this gravimetric method can be applied to analyze crude fibre in human foods, though dietary fibre analysis methods are more commonly used for nutritional labeling.