Proximate Analysis

Question 1

Who devised the Weende System of Proximate Analysis?

Answer 1

Wilhelm Henneberg and Friedrich Stohmann.

Question 2

When and where was the Weende System developed?

Answer 2

In 1865 at Weende Experiment Station near the University of Goettingen, Germany.

Question 3

What is another name for the Weende System?

Answer 3

Proximate Analysis.

Question 4

What are the six groups of nutrients analyzed in the Weende System?

Answer 4

Water (Moisture), Ether Extract (Crude Fat), Crude Fibre, Total Ash, Crude Protein, Nitrogen-Free Extract (NFE).

Question 5

Why is proximate analysis important?

Answer 5

It standardizes feed classification, helps assess feed quality, aids diet preparation, and is the foundation for detailed analysis.

Question 6

Who developed the method for crude fibre estimation and when?

Answer 6

Henneberg and Stohmann in 1860.

Question 7

Who introduced the crude fat analysis method and when?

Answer 7

Soxhlet in 1879.

Question 8

Who introduced the crude protein analysis method and when?

Answer 8

Johann Kjeldahl in 1883.

Question 9

How is moisture content in feed determined?

Answer 9

By drying the sample in a hot air oven at 100°C until a constant weight is achieved.

Question 10

What is the significance of moisture content in feed?

Answer 10

It determines dry matter, affects storage safety, and helps classify feeds into succulent or non-succulent types.

Question 11

What is the ideal moisture content for silage?

Answer 11

60–65%.

Question 12

What is the ideal moisture content for hay?

Answer 12

Approximately 15%.

Question 13

What is the ideal moisture content for air-dried feeds?

Answer 13

Approximately 10%.

Question 14

What risk is associated with feeds containing more than 14% moisture?

Answer 14

Increased risk of bacterial and fungal growth during storage.

Question 15

How does moisture content affect feed classification?

Answer 15

Higher moisture levels classify feeds as succulent; lower moisture levels classify feeds as non-succulent.

Question 16

What is crude fibre composed of?

Answer 16

Cellulose, hemicellulose, and lignin.

Question 17

How is crude fibre content determined?

Answer 17

By boiling fat-free residue with 1.25% H₂SO₄ and 1.25% NaOH, then drying and igniting the residue.

Question 18

What is the significance of crude fibre content in feed classification?

Answer 18

Feeds with ≥18% CF or >35% cell wall are roughages, and those with <18% CF or <35% cell wall are concentrates.

Question 19

What is lignin’s role in crude fibre?

Answer 19

Lignin is indigestible and reduces the digestibility of cellulose and other carbohydrates.

Question 20

What is total ash in feed?

Answer 20

Residue left after burning organic matter.

Question 21

What are the components of total ash?

Answer 21

Acid-Soluble Ash (indicates mineral content) and Acid-Insoluble Ash (AIA, indicates silica levels).

Question 22

What is the limitation of analyzing total ash?

Answer 22

It does not provide detailed mineral composition.

Question 23

How is crude protein calculated?

Answer 23

Nitrogen content × 6.25.

Question 24

How is ether extract (crude fat) determined?

Answer 24

By extracting the portion of feed soluble in petroleum ether.

Question 25

What does ether extract represent?

Answer 25

Lipids and fat-soluble vitamins.

Question 26

How is nitrogen-free extract (NFE) calculated?

Answer 26

NFE = 100 − (Moisture + Crude Fibre + Crude Protein + Crude Fat + Total Ash).

Question 27

What does NFE represent?

Answer 27

Digestible carbohydrates, including pentoses, hexoses, starches, and some soluble hemicelluloses.

Question 28

What is a limitation of NFE estimation?

Answer 28

NFE is overestimated by ~30% due to inclusion of soluble hemicelluloses and lignin.

Question 29

What are the limitations of crude fibre analysis in the Weende system?

Answer 29

Crude fibre is underestimated, and it does not represent a specific chemical group.

Question 30

What are the ideal ranges of NFE in cereals and legumes?

Answer 30

Cereals: 60–70%; Legumes: 30–40%.

Question 31

What are the limitations of the Weende System?

Answer 31

Overestimates NFE, underestimates crude fibre, excludes vitamins, and does not specify mineral composition in ash.

Question 32

What is the first step in Weende analysis?

Answer 32

Measuring moisture content by drying the feed sample.

Question 33

What is dry matter (DM)?

Answer 33

The residue left after removing moisture from the feed sample.

Question 34

How is acid-insoluble ash (AIA) significant?

Answer 34

High AIA levels indicate poor feed quality or adulteration.

Question 35

What percentage of dry matter (DM) do green fodders typically contain?

Answer 35

Green fodders contain 5–20% dry matter.

Question 36

What does the residue left after ether extraction represent?

Answer 36

It is used to determine crude fibre content.

Question 37

What is the purpose of igniting feed residue after boiling with acid and alkali?

Answer 37

To measure crude fibre content by determining weight loss.

Question 38

What is the foundation of the Weende analysis process?

Answer 38

Analyzing feed components as a percentage of weight, commonly on a dry matter basis.

Question 39

What is the primary role of NFE in animal nutrition?

Answer 39

To provide energy through easily digestible carbohydrates.

Question 40

What is a common limitation of the ash content measurement in the Weende System?

Answer 40

It does not specify the chemical composition of the minerals.

Question 41

What was the primary assumption behind dividing crude fibre and NFE?

Answer 41

Crude fibre is less digestible, and NFE is more digestible.

Question 42

What are the ideal moisture levels for good-quality silage and hay?

Answer 42

Silage: 60–65%; Hay: ~15%.

Question 43

How does the oxidation of macronutrients produce water?

Answer 43

1g fat produces 1.07ml, 1g carbohydrate produces 0.6ml, 1g protein produces 0.42ml of metabolic water.

Question 44

What is the importance of metabolic water in desert animals like camels?

Answer 44

It can fulfill their total water requirement.

Question 45

What percentage of metabolic water is available in domestic animals?

Answer 45

Approximately 5–10%.