Proximate Analysis Flashcards
Who devised the Weende System of Proximate Analysis?
Wilhelm Henneberg and Friedrich Stohmann.
When and where was the Weende System developed?
In 1865 at Weende Experiment Station near the University of Goettingen, Germany.
What is another name for the Weende System?
Proximate Analysis.
What are the six groups of nutrients analyzed in the Weende System?
Water (Moisture), Ether Extract (Crude Fat), Crude Fibre, Total Ash, Crude Protein, Nitrogen-Free Extract (NFE).
Why is proximate analysis important?
It standardizes feed classification, helps assess feed quality, aids diet preparation, and is the foundation for detailed analysis.
Who developed the method for crude fibre estimation and when?
Henneberg and Stohmann in 1860.
Who introduced the crude fat analysis method and when?
Soxhlet in 1879.
Who introduced the crude protein analysis method and when?
Johann Kjeldahl in 1883.
How is moisture content in feed determined?
By drying the sample in a hot air oven at 100°C until a constant weight is achieved.
What is the significance of moisture content in feed?
It determines dry matter, affects storage safety, and helps classify feeds into succulent or non-succulent types.
What is the ideal moisture content for silage?
60–65%.
What is the ideal moisture content for hay?
Approximately 15%.
What is the ideal moisture content for air-dried feeds?
Approximately 10%.
What risk is associated with feeds containing more than 14% moisture?
Increased risk of bacterial and fungal growth during storage.
How does moisture content affect feed classification?
Higher moisture levels classify feeds as succulent; lower moisture levels classify feeds as non-succulent.
What is crude fibre composed of?
Cellulose, hemicellulose, and lignin.
How is crude fibre content determined?
By boiling fat-free residue with 1.25% H₂SO₄ and 1.25% NaOH, then drying and igniting the residue.
What is the significance of crude fibre content in feed classification?
Feeds with ≥18% CF or >35% cell wall are roughages, and those with <18% CF or <35% cell wall are concentrates.
What is lignin’s role in crude fibre?
Lignin is indigestible and reduces the digestibility of cellulose and other carbohydrates.
What is total ash in feed?
Residue left after burning organic matter.
What are the components of total ash?
Acid-Soluble Ash (indicates mineral content) and Acid-Insoluble Ash (AIA, indicates silica levels).
What is the limitation of analyzing total ash?
It does not provide detailed mineral composition.
How is crude protein calculated?
Nitrogen content × 6.25.
How is ether extract (crude fat) determined?
By extracting the portion of feed soluble in petroleum ether.
What does ether extract represent?
Lipids and fat-soluble vitamins.
How is nitrogen-free extract (NFE) calculated?
NFE = 100 − (Moisture + Crude Fibre + Crude Protein + Crude Fat + Total Ash).
What does NFE represent?
Digestible carbohydrates, including pentoses, hexoses, starches, and some soluble hemicelluloses.
What is a limitation of NFE estimation?
NFE is overestimated by ~30% due to inclusion of soluble hemicelluloses and lignin.
What are the limitations of crude fibre analysis in the Weende system?
Crude fibre is underestimated, and it does not represent a specific chemical group.
What are the ideal ranges of NFE in cereals and legumes?
Cereals: 60–70%; Legumes: 30–40%.
What are the limitations of the Weende System?
Overestimates NFE, underestimates crude fibre, excludes vitamins, and does not specify mineral composition in ash.
What is the first step in Weende analysis?
Measuring moisture content by drying the feed sample.
What is dry matter (DM)?
The residue left after removing moisture from the feed sample.
How is acid-insoluble ash (AIA) significant?
High AIA levels indicate poor feed quality or adulteration.
What percentage of dry matter (DM) do green fodders typically contain?
Green fodders contain 5–20% dry matter.
What does the residue left after ether extraction represent?
It is used to determine crude fibre content.
What is the purpose of igniting feed residue after boiling with acid and alkali?
To measure crude fibre content by determining weight loss.
What is the foundation of the Weende analysis process?
Analyzing feed components as a percentage of weight, commonly on a dry matter basis.
What is the primary role of NFE in animal nutrition?
To provide energy through easily digestible carbohydrates.
What is a common limitation of the ash content measurement in the Weende System?
It does not specify the chemical composition of the minerals.
What was the primary assumption behind dividing crude fibre and NFE?
Crude fibre is less digestible, and NFE is more digestible.
What are the ideal moisture levels for good-quality silage and hay?
Silage: 60–65%; Hay: ~15%.
How does the oxidation of macronutrients produce water?
1g fat produces 1.07ml, 1g carbohydrate produces 0.6ml, 1g protein produces 0.42ml of metabolic water.
What is the importance of metabolic water in desert animals like camels?
It can fulfill their total water requirement.
What percentage of metabolic water is available in domestic animals?
Approximately 5–10%.
