Anti Nutritional Factors

Question 1

What are the 3 Feed evaluation techniques?

Answer 1

1) Chemical analysis
2) Enzymatic analysis
3) Biological analysis

Question 2

Why do you use enzymatic evaluation?

Answer 2

Predict the nutritive value of feed ingredients

Question 3

How do enzymatic evaluative techniques differ? 3

Answer 3

1) pH
2) Temperature
3) time

Question 4

3 Examples of enzymatic evaluation include:

Answer 4

1) Pepsin cellulase
2) neutral detergent cellulase
3) proteases, lipases and amylases

Question 5

What are the four advantages of enzymatic evaluations?

Answer 5

Don’t require fistualted/ canulated animal
Mimic conditions of feed digestion
Better predictors than chemical analysis
Generate values comparable to in Vivo digestion

Question 6

What are the 5 livestock feed resources?

Answer 6

1) Natural pasture
2) Browse
3) Stover
4) Argo-industrial by-products
5) Animal derived feed resources

Question 7

Discuss natural pastures (4)

Answer 7

An example of natural pasture is grass which contains dietary energy, RUCP and MCP. It is seasonal which results in the quality and quantity being implicated and there is a loss due to urbanization and land cropping

Question 8

Discuss Browse 4

Answer 8

Browse includes leaves, pods and twigs and has a better crude protein content than grass. It is important during the dry season, however ANFs can be a challenge.

Question 9

Discuss residues/ stover (3)

Answer 9

Mostly grazed after harvesting and generally have a low nutritive quality. It requires supplementation with legume hays

Question 10

Discuss ago-industrial by products (4)

Answer 10

These consist of industrial by-products:

1) Grain
2) Oilseed (Soyabean, corn, sunflower)
3) Brewing

These items are hard to access and expensive

Question 11

What are the 3 animal -derived feed resources?

Answer 11

1) Blood meal
2) Bone and meat meal
3) Fish meal

Question 12

What is feed composed of?

Answer 12

Water and Dry matter

Question 13

What is dry matter composed of ?

Answer 13

Organic and inorganic matter

Question 14

What are the constituents of organic and inorganic matter?

Answer 14

1) Carbohydrates
2) Lipids
3) Proteins
4) Nucleic acids and
5) organic acids and vitamins

Inorganic: minerals

Question 15

Describe proximate analysis:

Answer 15

Quantitative method the divide feed resources into 6 categories:

1) Ash (minerals)
2) Moisture
3) Crude protein (CP)
4) Crude fiber (CF)
5) Ether extract (EE)
6) Nitrogen free extractives (NFE) = 1000 - Ash - moisture - CP - CF - EE

Question 16

Describe the pros and cons of proximate analysis

Answer 16

Pros:
Easy to execute, save time

Cons:
Environmentally unfriendly and has technical flaw as this process deems CF a major nutrient and thus digestibility which is estimated by NFE is often overestimated

Question 17

What are fiber assays?

List 3 fiber types:

Answer 17

Fiber assays compensate for proximate analysis and include:

1) Neutral detergent fiber (NDF)
2) Acid detergent fiber (ADF)
3) Acid detergent lignin (ADL)

Question 18

What are the constituents of fiber for NDF?

Answer 18

1) Cellulose
2) Hemicellulose
3) Lignin

Question 19

What are the constituents of fiber for ADF?

Answer 19

1) Cellulose fractions
2) Crude lignin
3) Silica

Question 20

What are the constituents of fiber for ADL

Answer 20

1) Lignified N
2) Lignin
3) Silica

Question 21

What are biological feed evaluation techniques designed to do?

Answer 21

They are designed to simulated parts of GIT in order to provide information about feed potential.

Question 22

Describe the in vitro two-stage technique developed by Tilley and Terry, 1963

Answer 22

The feed sample is fermented for 48 hours in the buffered rumen liquor (maintains pH and anaerobic conditions) and is followed by pepsin digestion in acid conditions

Question 23

What are the 3 advantages of in vitro two stage technique?

Answer 23

1) Allows for controlled experiments
2) Saves time compared to in vivo experimentation which requires an adaptation period.
3) It is repeatable and allows for accurate prediction of nutritive value.

Question 24

Describe the in situation degradability technique:

Answer 24

The rumen of the animal is cannulated. The feed is placed within special nylon bags and incubated in the rumen for specified periods of time. The disappearance of feed from the bag is measured over specific time periods.

Question 25

How does in the in situ degradability technique predict feed value?

Answer 25

The time based measurement of the disappearance of feed gives information about the kinetics of feed degradation, predicting feed value.

Question 26

What is digestibility?

Answer 26

The proportion of consumed feed which is not excreted in the farces and therefore is assumed to be absorbed by the animal. Dry matter intake - faces output/ dry matter intake

Question 27

What are the requirements for a digestibility trial?

Answer 27

1) Must have the feed under investigation 2) the test species should be of the same species, breed, age and preferably male 3) The animals need to be appropriately housed 4) harness and farces collection bags need to be fitted to the animals

Question 28

Describe the mechanics of the in vivo digestibility trial (5)

Answer 28

1) An adaptation period is required: 1 week for mono gastric animals and 2 weeks for ruminants 2) the meal must be mixed properly and given at the same time 3) Collection must include total feed consumed and face all output (and urine output in the case of Nitrogen balance urea) 4) Quantify the input and output 5) This will determine apparent digestibility as there is an assumption that the difference between input and output has been absorbed and it does not take into account the metabolic outputs increasing the mass of the farces.

Question 29

What are the criticisms of the in vivo digestibility trial?

Answer 29

The assumption that feed not excreted is absorbed. 1) Methane that is produced during the fermentation of CHO in ruminants is lost via eructation which leads to an overestimation 2) Faeces contains more than just undigested food e.g. endogenous enzymes, cells from the GIT wall and unabsorbed GIT secretions’ 3) Faeces contains metabolic byproducts such as ether extracts and minerals

Question 30

What is an anti nutritional factor?

Answer 30

Secondary plant metabolite that protects plants against herbivory

Question 31

How do ANFs causes their effects? (7)

Answer 31

1) Decrease the palatability of feed 2) Bind to dietary proteins in the GIT 3) Bind to digestive enzymes in the GIT 4) Chelate minerals 5) Precipitate nutrients 6) Cause tissue toxicity 7) Erode the the absorptive enterocytes in small intestine

Question 32

What is the mechanism and effect in the animal of: Arabinoxylans?

Answer 32

Increases digesta viscosity which reduces the mixing of the digesta with digestive enzymes, thereby decreasing absorption and digestion impairing animal performance

Question 33

What is the mechanism and effect in the animal of: Beta fly and

Answer 33

Increases digesta viscosity leading to reduction in mixing with digestive enzymes. Furthermore there is a decreased passage of digesta resulting in colonization of clostridium perfringes resulting in necrotic enteritis.

Question 34

What is the mechanism and effect in the animal of: L-Canavanine

Answer 34

Results in arginine substitution leading to non-functional proteins. Causes toxicity in animals especially chickens.

Question 35

What is the mechanism and effect in the animal of: Lectins/ Phytohaemagluttinins

Answer 35

Lectins bind to carbohydrates on cellular membranes resulting in agglutination. They are thermolabile. This can result in agglutination of erythrocytes and atrophy of the microvilli as well as a decrease in epithelial cell viability.

Question 36

What is the mechanism and effect in the animal of: Phytates/ phytic acid?

Answer 36

Phytates form insoluble salts with Ca, Fe, Mg and Zn, phytases will ameliorate these effects. This results in the blockage of P, Zn, Mg, Ca and Fe resulting in decreased protein and lipid absorption

Question 37

What is the mechanism and effect in the animal of: Protease inhibitors

Answer 37

Inhibit proteolytic enzymes decreasing protein absorption impairing growth. Furthermore, there is a increased secretion of pancreatic proteases resulting in pancreatic hypertrophy

Question 38

What is the mechanism and effect in the animal of: Saponins

Answer 38

They are bitter resulting in a decreased feed intake leading to poor growth performance.

Question 39

What is the mechanism and effect in the animal of: Tannins

Answer 39

Bind to dietary proteins and digestive enzymes inhibiting the activity of trypsin, chymotrypsin, amylase and lipase. This resulting in poor growth performance.

Question 40

What is the mechanism and effect in the animal of:oxalates

Answer 40

Chelates Ca, Fe, K and Mg ions resulting hypocalcemia and hyperoxaluria which is associated with kidney stones, this causes toxicity.

Question 41

How are trypsin inhibitors deactivated?

Answer 41

Heat treatment

Question 42

How are lectins deactivated?

Answer 42

Heat treatment

Question 43

How are phytates destroyed?

Answer 43

Heat

Question 44

How are oligosaccharide destroyed?

Answer 44

Heat

Question 45

Name the thermolabile ANFS 4

Answer 45

1) Trypsin inhibitors 2) Lectins 3) Phytic acid 4) Oligosaccharides

Question 46

What is the formula for crude protein?

Answer 46

Nitrogen content x 6.25