Animal nutrition - anti nutrional factors

Question 1

What are „Anti-nutritional factors“ or „Secondary substances“ in feeds?
Give up to 6 examples.

Answer 1

Anti-nutritional factors can be defined as a substance which, under practical circumstances, can impair some aspects of animal metabolism and produce adverse
biological or economic effects in animal production.

Examples are;
– protease inhibitors
– glycosides such as saponins
– tannins
– lectins or haemaglutinins
– phytin
– indigestible carbohydrates (β-glucans)

Question 2

Protease inhibitors are

Answer 2

are medications/enzymes that act by interfering with enzymes that cleave proteins.

Question 3

Most common Protease inhibitors are (2)

Answer 3

trypsin inhibitors,
also chymotrypsin inhibitors

Inhibitors form complexes with enzymes trypsin
and chymotrypsin -> reduce digestibility

Question 4

Where are Protease inhibitors found?

Answer 4

Trypsin inhibitors are mainly in leguminous plants, like soyabeans, peas, field beans

– for example -> if peas or field beans are fed to pigs or poultry, use varieties containing less trypsin inhibitor, otherwise it will decrease performance

Question 5

Activity of trypsin inhibitors can be reduced by

Answer 5

heating.

During manufacture of soyabean meal
– process the soyabeans in an autoclave for 40 minutes at 110°C
– roast soybeans for 2…3 minutes at 230°C

heat processing inactivates protease inhibitors

Question 6

Glycosides are

Answer 6

crystalline compounds in which the saccharide component is linked to an alcohol or some other group

Are soluble in water, alcohol and acetone

Question 7

Glycosides can be divided into (3)

Answer 7

– cyanogenetic glycosides (linamarin, vicine)

– glycosinolates or mustard oil glycosides

– amphipathic glycosides or saponins

Question 8

Give an example of a Cyanogenetic glycoside

Answer 8

linamarin

from linseed/flaxseeds

Question 9

Cyanogenetic glycoside - linamarin degrades in the presence of

Answer 9

moisture and the enzyme linamarase,
to D-glucose, acetone and hydrocyanic acid (prussic acid).

Question 10

Linamarase is an

Answer 10

extracellular enzyme, and therefore the degradation of linamarin takes place only after
linseed processing, and cell wall breakage.

Question 11

How to treat linamarin to render it safe?

Answer 11

Heating destroys linamarase and will not cause poisoning. Feeding unheated flaxseeds is dangerous!

All linseeds sold in products in grocery stores are heat treated.

Question 12

Give an exmaple of a Cyanogenetic glycoside

Answer 12

vicine (and linamarin and amygdalin)

is present in common vetch (a nitrogen-fixing leguminous plant), also in field beans. tastes bitter and horses and poultry are particularly sensitive.

Affects the nervous system, digestive tract and causes rashes on the skin

Question 13

Mustard oil glycosides are also called?
And are found in?

Answer 13

glycosinolates
contain sulphur, more than 100 are known

present in rape seeds, fodder kale, fodder rape

Question 14

main glycosinolate compound is

Answer 14

progoitrin
content in rapeseeds depends on variety

degrades in the presence of the enzyme myrosinase, and produces mustard oil (isothiocyanate), which is toxic for animals

– inhibits the uptake of iodine by the thyroid gland into thyroxine, thyroid gland increases in size, haemorrhages in udder, urine changes to a red colour

Question 15

The Enzyme myrosinase can degrade glycosinolates in what circumstances?

Answer 15

Enzyme myrosinase is active at 50…60°C, but is destroyed when the temperature is over 80°C.

“glycosinolate progoitrin degrades in the presence of the enzyme myrosinase, and produces mustard oil (isothiocyanate), which is toxic for animals”

Question 16

Amphipathic glycosides also known as?

Answer 16

saponins
produce foam

are surface active and bitter substances, causing bloat in animals
present to some extent in leguminous (clover) leaves and shoots

Question 17

Solanine is a

Answer 17

glycoalkaloid with properties of a fungicide and a pesticide (helpful to the plant)

Question 18

where is solanine found?

Answer 18

is found in young potato sprouts and in potatoes that colour green due to the sun (content can rise up to 0.5%)

is poisonous for animals when the solanine content increases up to 0.05%
a potato normally contains 0.002…0.01%

Question 19

Gossypol is a

Answer 19

yellowish fat-soluble pigment of cotton seeds (0.2%)

For poultry, cotton seeds and meal are dangerous when the content of gossypol is from 0.01%.

Question 20

What animal should not be fed feed containing gossypol?

Answer 20

During the manufacturing process of meal, where the fat is extracted, gossypol is also removed.

During extrusion, some gossypol stays in the cake, and therefore should not be fed to non-ruminants.

A reddish-yellow colour of the meal or cake indicates a dangerous content of gossypol.

Question 21

What are Lupine alkaloids

Answer 21

Lupin is a protein-rich grain legume used as livestock feed, containis alkaloids, which are a plant defensive mechanism against herbivores.

Question 22

Examples of lupine alkaloids (4)

Answer 22

angustifoline,
lupinine,
lusitanine,
sparteine

Question 23

Grain legume lupin can be divided into two, called

Answer 23

Bitter lupin and sweet lupin.

Bitter lupin contain alkaloids at more than 1.5…1.8% compared to sweet lupin, at 0.05%

Lupine alkaloids are poisonous.

Question 24

What animals are most sensitive to alkaloids?

Answer 24

Horses and sheep are more sensitive to alkaloids than other animals.

– causes changes in the mucosa and disturbances of the nervous system

Question 25

Tannins are

Answer 25

polyphenolic compounds, found widely in plants such as

– leguminous (field beans, peas), rapeseeds, sorghum (flowering grass), barley

Question 26

Tannins Can be divided into (2)

Answer 26

hydrolysable or condensed tannins

condensed are more important in animal nutrition

Question 27

Condensed tannins are not toxic per se, but they cause problems in animal nutrition. Why? (3)

Answer 27

– they can form complexes with feed proteins and enzymes, with carbohydrates, and with divalent ions, causing reduction in digestibility

– can increase intestinal epithelial erosion
– may reduce forage palatability (and feed intake)

Question 28

How can tannins have a positive effect?

Answer 28

Could have a positive effect at certain levels (<9% DM)

– reduces likelihood of rumen bloat, increases the dietary amount of protein flowing to the duodenum, may reduce methane emission

• We cannot decrease the amount of tannins by processing (except for peeling), but can by plant breeding.

Question 29

Lectins, also known as

Answer 29

haemagluttinins

Question 30

Lectins or haemagluttinins are

Answer 30

glycoproteins named for their ability to agglutinate red blood cells

Question 31

Where are lectins found?

Answer 31

present in leguminous seeds

– ricin**, soya beans **, peas **, field beans*

Question 32

Lectins harm

Answer 32

intestinal wall and microvilli

The intestinal wall contains glycoproteins for which lectins, as they are also glycoproteins, have agglutinate properties and due to this they cling to the gut wall.

– cause bloody diarrhoea & toxicity
– decrease nutrient absorption, organism immunity and production

Question 33

How are lectins destroyed?

Answer 33

Easily destroyed by heating

Question 34

Phytin is

Answer 34

a phosphorous-rich substance in green plants

Question 35

Phytin binds..?

Answer 35

metals (Ca, Co, Cu, Zn etc.), forms salts

Question 36

60…70% of phosphorous in maize, sorghum, wheat, barley, oats, cakes and meals is found in phytin.

To split phytin and release phosphorus, what enzyme is required?

Answer 36

phytase

Question 37

Phytase originates from?

Answer 37

Phytase is need to split phytin to release the phosphorus inside.
Phytase is of microbial origin, but is missing in monogastric animals, incl. poultry.
Due to this P assimilation is less than 25%.

To increase P assimilation, phytase of synthetic or microbial origin must be used in pig and poultry rations -> using supplemental phytase reduces environmental pollution of unassimilated phosphorus (unabsorbed and pooped out).

Question 38

Indigestible carbohydrates, or oligo- or polysaccharides are mainly

Answer 38

β-Glucans

– barley and oats contain 4%, rye 2.5%, wheat 1% (oats hulls 5.5-23%)

Question 39

β-glucans form sticky faeces together with

Answer 39

pentosans, which causes hygiene problems.

Pentosans are water soluble and make intestinal contents viscous, which blocks digesta movement and promotes feed microbial fermentation in the intestine.

Question 40

Pigs and poultry cannot digest β-Glucans due to

Answer 40

a lack of specific digestive enzymes.

To digest β-glucans synthetic enzymes must be used in the rations of pigs and poultry.
– they increase the absorption of energy by about 10%