Prof. Hassen: Classification of feedstuff

Question 1

Why do we analyse feedstuffs

Answer 1

• To ID the chemical composition and nutrient conc of substrates
• Characterizing the digestibility and bioavailability of the substrate to the animals

Question 2

Although the basic (proximate analysis gives a general indication of the value of a feed, it does not really____

Answer 2

Deal with specific nutrients

Question 3

Define organic matter (OM):

Answer 3

• Difference between dry matter and crude ash
• It represents the content of compounds that contain C
• according to the Weende analysis OM consists of crude protein, ether extract, crude fibre and nitrogen free extractives.

Question 4

Define crude protein: CP

Answer 4

• Total N-content determined according to Kjeldahl method X by 6.25.
• Made up of true protein and non protein nitrogen substances.
• Includes peptides, free amino acids, amides purines.

Question 5

Define crude ash (CA):

Answer 5

• Inorganic fraction of feed determined by its ignition until there is no carbon left.
• Represents the minerals in feed
• Main component is silica

Question 6

Define crude fat: (ether extract)

Answer 6

• Fraction of the feed that is soluble in non-polar solvents
• Fraction is determined by subjecting the feed to a continues extraction with petroleum ether. (Soxhlets method)
• Includes fats, oils, waxes, organic acids and pigments

Question 7

Define crude fibre: ( CF)

Answer 7

• organic residue after feed sample successive treatment with boiling acid and alkali of defined concentrations.
• includes cellulose, lignin and hemicellulose

Question 8

Define nitrogen free extractives (NFE) :

Answer 8

• Fraction of all components not included in the other fractions
• Include: starch, sugars, fructans, pectins, organic acids, pigments, some amount of cellulose, lignin and hemicellulose.

Question 9

How is the content of nutrient expressed?

Answer 9

% or in g/kg

Question 10

What are the criticisms for the proximate analysis procedure

Answer 10

Imprecision of:

• Crude ash content
• crude fiber content
• Nitrogen free extract fractions

Question 11

What was an alternative procedure developed for fiber analysis?

Answer 11

Van Soest Method

Question 12

The Van Soest (DETERGENT) method is divided into 4 classes, name and shortly describe them:

Answer 12

1) Neutral detergent solubles (NDS), include soluble proteins, NPN, lipids, sugars, starch, organic acids, pectin, some soluble minerals.
2) Neutral detergent fraction (NDF): consist of plant cell wall material including lignin, cellulose, hemicellulose.
3) Acid detergent fraction: (ADF), consists of lignin, cellulose, lignified nitrogen and silica
4) Acid detergent Lignin(ADL): Residue after treatment with 72% sulpheric acid, consists of lignin and silica

Question 13

NDF - ADF =?

ADF- ADL =?

Answer 13

1) hemicellulose

2) cellulose

Question 14

Which 2 AA’s are insufficient in young or high milk yielding animals?

Answer 14

Lysine and methionine

Question 15

What are the 2 diffirent levels of protein requirements?

Answer 15

• Requirements to meet the need of rumen microbes

- Requirements to meet the need of the host animal

Question 16

What are the categories that feedstuffs are categorized into?

Answer 16

• Roughages
• Energy feeds
• Protein supplements
• mineral supplements
• Vitamin supplements
• Feed additives

Question 17

Energy feeds and protein supplements are termed as ____,

Answer 17

concentrates, which usually means high quality, low fibre feeds like cereal grains, protein sources and fats

Question 18

Define roughages

Answer 18

More fibrous and bulky with >20% ADF or >30% NDF.

Question 19

What does AFCO stand for?

Answer 19

American Feed control Officials

Question 20

According to AFCO, feedstuffs are broadly classified into :

Answer 20

• Animal protein products
• Forage products
• Grain products
• Plant protein products
• Processed grain by-products
• Roughages product
• Molasses product.

Question 21

The AFCO method is :

Answer 21

• intended to ID the sources of the feed ingredients

- is a common method when dealing with manufactured and by-product feedstuffs.

Question 22

What are the 2 major criteria used to classify feedstuffs?

Answer 22

• Major nutrients provided

- Origin/source of feedstuffs