Topic 12 - Anti-nutritional compounds in forages → biosynthetic pathways

Question 1

Adverse effects of forages

Answer 1

Contamination with inorganic compounds

Mouldy forage (fungi, bacteria)

Narrow range of forages

Non-optimal dosage

Non-optimal nutrient and energy supply

Secondary plant metabolites

Question 2

Anti-nutritional factors

Answer 2

Substances that when present in animal feed reduce the availability of one or more nutrients

Interfere with the utilisation of dietary nutrients in a variety of ways

No major role in primary metabolism (non-essential compounds)

Mainly secondary metabolites

Taxonspecific metabolites

Question 3

Effects on animal species

Answer 3

Decrease voluntary feed intake

Reduce digestibility

Changes in metabolism

Poisonous effects → decreased production (or quality)

Question 4

Classification

Answer 4

Animal nutrition: based on their effect on the nutritive value of feedstuffs and on biological responses in animals

Botany: biosynthetic pathway of plant metabolites

Question 5

Carbohydrates with anti nutritive effects

Answer 5

Non-starch polysaccharides

Non-digestible oligosaccharides

Question 6

Non-starch polysaccharides (NSP)

Answer 6

Major structural elements in the cell wall - mainly i forage legumes

Cellulose → low digestibility

Beta-glucans and arabinoxylans → high water absorption capacity → increased viscosity → sticky faeces syndrome

Question 7

High proportion of NSP

Answer 7

decreased energy value and digestibility of the forage → decreased production

Question 8

Prevention of NSPs

Answer 8

Application of forage mixtures or specific enzymes

Question 9

Non-digestible olgiosaccharides

Answer 9

Raffinose, stachyose and verbascose

Most of the species do not have enzymes to digest them → pass unchanged to the colon → intestinal bacteria ferment them to gases →bloating effect

Mainly in fabaceous plants as stored nutrinets

Question 10

Prevention of non-digestible oligosaccharides

Answer 10

Application of beta-glalactosidase enzyme

Question 11

Phytic acid

Answer 11

A primary product of carbohydrate metabolism

Can form complexes with basic residues of proteins → interfere with the activity of enzymes and digestibility of other nutrients

Occurrence: cereals, pulse crops, and oil plants

Question 12

Phytate

Answer 12

Can form complexes with a variety of minerals → reducing the availability of these nutrients

Phosphorous and inositol in phytate form → not bioavailable to non-ruminant animals

Occurrence: cereals, pulse crops, and oil plants

Poultry and pigs: low feed conversion

Ruminant: tolerant → phytase enzyme produced by rumen microorganimsms

Question 13

Prevention of phytic acid and phytates

Answer 13

Application of phytase supplementation

Question 14

Phenolics with anti nutritive effects

Answer 14

Tannins

Isoflavonoids

Question 15

Tannins

Answer 15

Hydrolyzable and condensed tannins

Natural occurrence: field pea, field bean, sainfoin

Major effects astringent taste (depresses feed intake), precipitate proteins water insoluble complexes (decreased protein conversion rate), bounds with iron (iron deficiency)

Susceptible species: poultry, pig, horse

Tannin content of forage plants is generally low, no poisonous, but mild antinutritive effect

Question 16

Isoflavonoids

Answer 16

Coumestrol, genistein, formononetin

Natural occurrence: soybean, lucerns, clovers

Susceptible species: cattle, horse

Question 17

Effects of isoflavonoids

Answer 17

Similar to animal estrogen

Bind irreversible to estrogen receptors

Decreasing fertility – abnormal estrus cycle, abortion, sterility

Question 18

Prevention of isoflavonoids

Answer 18

application of forage mixtures

Question 19

Polyketides with anti nutritive effects

Answer 19

Euric acid

Question 20

Euric acid

Answer 20

General compound in the Brassicaceae family

Mainly stored in the seed

Major effects: myocardial lesions (fatty infiltration)

Susceptible: All livestock species

Question 21

Prevention of euric acid

Answer 21

application of double zero cultivars

Question 22

Terpenoids with anti nutritive effects

Answer 22

Saponins

Glossypol

Question 23

Saponins

Answer 23

Natural occurrence: species of Fabaceae family

Generally molecules have a bitter flavor irritation of mucous membranes

Susceptible species: ruminants, poultry, pigs

Question 24

Effects of saponins

Answer 24

Produce foam in the rumen

Can enter into the lipid bilayer of membranes disintegrated membranes

Decrease rumen motility

Red blood cells are affected → haemolytic effect

Question 25

Prevention of saponins

Answer 25

Application of selected cultivars, forage mixtures or drying

Question 26

Glossypol

Answer 26

A sesquiterpene dimer of cottonseed Absorbed from the GT and highly bound to amino acids, especially lysine, and to dietary iron Susceptible species: all animals, but especially monogastrics, preruminants, immature ruminants, and poultry

Question 27

Effects of glossypol

Answer 27

Renders many amino acids unavailable → affects enzymatic reactions Effects on the cardiac, hepatic, renal, reproductive, or other systems Green discoloration of egg yolk

Question 28

Prevention of glossypol

Answer 28

High intake of protein, calcium hydroxide, or iron salts, and limited dietary glossypol concentrations

Question 29

Azetoids with anti nutritive effects

Answer 29

Non-proteinogenic amino acids Water soluble peptides of low molecular weight

Question 30

Non-proteinogenic amino acids

Answer 30

Natural occurrence in Lathyrus species: Lathyrogenes (ODAP, BAPN, DAB) BAPN can inhibite the collagen synthesis → damage of bones and connective tissue Susceptible species: horse, cattle, poultry

Question 31

Prevention of Non-proteinogenic amino acids

Answer 31

Heat treatment or consumption of foods containing sulphuric amino acids

Question 32

Water soluble peptides of low molecular weight

Answer 32

Natural occurrence: in species of family lucern, clovers Rapid digestion by rumen microbes slime production frothy bloat (distension caused by foam and gases) Susceptible species: horse, cattle

Question 33

Prevention of Water soluble peptides of low molecular weight

Answer 33

drying, ensilage, slow accustoming to fresh forage legumes

Question 34

Protease inhibitors

Answer 34

Natural occurrence in legume seeds (soy bean, beans) and cereals Mainly trypsin and chymotrypsin inhibitors Amylase inhibitors → minor importance → impaired digestion of starch Susceptible species: poultry, pig, carnivores

Question 35

trypsin and chymotrypsin inhibitors

Answer 35

Form stable inactive complexes with the pancreatic enzymes → decreased protein digestion When trypsin and chymotrypsin are reduced → pancreas stimulated to produce more digestive enszymes → hypertrophy of the pancreas

Question 36

Prevention of protease inhibitors

Answer 36

heat treatment but trypsin inhibitors are less susceptible to heat

Question 37

Lectins

Answer 37

Phytoheamagglutinins Proteins that are generally present in the form of glycoproteins → have the ability to bind to specific sugars Natural occurrence: in beans (highly toxic), field bean, pea, lupines (less toxic) Susceptible species: monogastric species

Question 38

Effects of lectins

Answer 38

Binding of lectins to epithelial cells → disorders of nutrient absorption → growth depressions

Question 39

Prevention of lectins

Answer 39

Heat treatment

Question 40

Glycosinolates

Answer 40

Sulphuric compounds from cysteine strong, hot flavor Natural occurrence: species of Brassicaceae If specific proteins → carcinogenic nitriles, or thiocyanates can also be produced It can be excreted in the milk Susceptible species: pig, cattle, poultry

Question 41

Effects of glycosinolates

Answer 41

Isothiocyanates produced → irritation of skin and mucous membranes, goitrogen effect → disrupts the production of thyroid hormones (interferes with iodine uptake) Low iodine uptake losing of weight, haemorrhagic symptoms in liver, enlarged spleen and kidneys, abortion

Question 42

Prevention of glycosinolates

Answer 42

Application of double zero cultivars

Question 43

Poisonous azotoids

Answer 43

Cyanogenic glycosides Poisonous alkaloids

Question 44

Cyanogenic glycosides

Answer 44

Natural occurrence: linseed, Sorghum spp., white clover Inhibition of cell respiration

Question 45

Prevention of Cyanogenic glycosides

Answer 45

Grazing, harvesting in optimal phenological stage, application of limited amounts in mixtures

Question 46

Poisonous alkaloids

Answer 46

Lupinus species: quinolizidine type – Lupinine, pupanine → Lupine poisoning Vicia faba: pyrimidine type – vicine, konvicine → favism

Question 47

Prevention of Poisonous alkaloids

Answer 47

application of selected cultivars