This document discusses anti-nutritional factors and toxic elements found in animal feed. It classifies these substances into four groups based on their chemical properties: proteins, glycosides, phenols, and miscellaneous. Within each group, it provides examples of specific anti-nutritional compounds and describes their negative effects, such as inhibiting nutrient digestion or utilization. Common toxic elements mentioned are protease inhibitors, lectins, saponins, cyanogens, gossypol, tannins, phytic acid, and various antivitamins. The document stresses that these anti-nutritional factors can reduce feed utilization, lower production, and negatively impact animal health if consumed in large amounts.

1. Anti-Nutritional Factors and Toxic
Elements in Animal feed
Presenter
Sabal Pokharel

2. Anti-nutritional factors in feeds
Anti-nutritional factors (ANFs) are those
substances present in the diet which by
themselves or their metabolic products arising
in the system interfere with the feed
utilization, reduce production, or affects the
health of animal.
These anti-nutritive substances are referred to
as "toxic factors" because of the deleterious
effects they produce when eaten by animals.

3. Classification according to their
chemical properties
• Group I: Proteins
Protease inhibitors, Haemagglutinins (Lectins).
• Group II: Glycosides
Saponins, Cyanogens, Glucosinolate,
• Group III: Phenols
Gossypol, tannins,
• Group IV: Miscellaneous
Anti-metals, Anti-vitamins

4. On the basis of nutrients they affect
directly or indirectly
Substances depressing digestion or metabolic
utilization of proteins
 Protease inhibitor ( trypsin or chymotrypsin inhibitor)
 Haemagglutinins ( lectins )
 Saponins
 Polyphenolic compounds
Substances reducing solubility or interfering with the
utilization of minerals
 Phytic acid
 Oxalic acid
 Glucosinlates (thioglusides)
 Gossypol

5. On the basis of nutrients they affect
directly or indirectly
Substances increasing the requirements of
certain vitamins
Anti-vitamin A,D, E,K
Anti –vitamin B1, B6, B12 and nicotinic acid
Substances with a negative effect on the
digestion of carbohydrates
Amylase inhibitors
Phenolic compounds
Flatulence factors:

6. Contd..
Flatuence factors
Flatulence factors are the oligosaccharides
which are fermented by intestinal bacteria
in the large intestine.
The monomers of these sugars are
converted into VFA, carbon dioxide,
hydrogen, methane resulting in flatulence,
diarrhea, nausea, cramps and discomfort.

7. Contd..
Substances that stimulate the immune system
(antigenic proteins):
Effect of feed antigens:
Increased endogenous protein secretion.
Lowered apparent protein digestibility.
Decreased utilization of feed proteins
Inactivation of feed antigens: heat is not
appropriate; chemical or enzymatic treatments
are preferred; a hot ethanol extraction may be
used.

8. Group I: proteins
Protease inhibitors
Substances that have the ability to inhibit the
proteolytic activity of certain digestive enzymes
E.g. legume seeds (soybean, kidney bean, mung
bean)
Haemagglutinins (lectins)
 Soybean, castor bean and other legume seeds
contain hemagglutinins.
These toxic substances are able to combine with
the glycoprotein causing agglutination of the cells

9. Group II: Glycosides
Saponins
These are glycosides characterized by bitter
taste, foaming in aqueous solution and
haemolyse RBC.
Found in Lucern, soybean.
Upon excess feeding of green lucern etc.
legume forage saponins lower the surface
tension of ruminal contents leading to
accumulation of gas in the digesta. This
condition is known as "bloat".

10. Group II: Glycosides
Cyanogens
It occurs mainly in the form of cyanogenetic
glycosides.
These glycosides can be hydrolysed to prussic
acid or hydrocyanic acid (HCN) by the
enzymes usually present in the same plant or
as they are being digested by the animals
glucosides.
Eg. Almonds, Jowar, Pulses, Linseed, Cassava

11. Group –III Phenols
Gossypol
• In genus Gossypium , gossypol is present in pigment
glands of leaves, stems, roots, and seeds.
• It is highly toxic to monogastric animals.
• Ruminants are more resistant due to the formation of
stable complexes with soluble protein in rumen which
are resistant to enzymatic breakdown.
• Gossypol form complex with metals like iron and the
toxic effect can be overcome by supplementing iron as
ferrous sulphate.
• The physiological effects of free gossypol are reduced
appetite, loss of body weight, accumulation of fluid in
the body cavities, cardiac irregularity, reduced
haemoglobin etc.

12. Group –III Phenols
Tannins
• It is a polyphenolic substance with molecular weight
greater than 500. Tannins are of two types:
• Hydrolysable tannins:
 These can be readily hydrolyzed by water, acids, or
enzymes and yield gallotannins and ellagitannins.
• Condensed tannins:
 These are flavonids –polymers of flavonol.
Chlorogenine is a polyphenolic compound present
in sunflower seed meal.
• Found in SORGHUM, Salseed meal, Mangoseed kernel,
Mustard oil cake, Lucerne meal etc.

13. Group –IV
Antimetals
Phytic acid
 Seeds of cereals, dried legumes, oilseeds, and nuts are
rich in phytic acid.
 Phytic acid also depresses the utilization of several
mineral elements such as Ca, Mg, Fe, Zn, etc. it forms
insoluble compounds which are eliminated in the
feces.
• Oxalic acid:
 Plant feedstuffs have much oxalic acid.
 Oxalate –poisoning in cattle and sheep are
characterized by rapid and labored respiration,
depression, weakness, coma, and death.

14. Group –IV
Antivitamins
Antivitamin A: Raw soybean contains enzyme
lipoxygenase which Lipoxygenase catalyses
oxidation of carotene, the precursor of vitamin A.
Antivitamin E: Present in kidney bean.
Antivitamin K: Eating sweet clover cause fatal
haemorrhagic called sweet clover disease
conditions in cattle.
Antivitamin D: Rachitogenic activity of isolated
soya protein (unheated) has been found with
chicks and pigs

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