ANTI-NUTRITIONAL FACTORS IN FEEDS AND FODDERS & ITS ROLE IN ANIMAL NUTRITION
Compiled, & shared by-DR. RAJESH KUMAR SINGH, (LIVESTOCK & POULTRY CONSULTANT), JAMSHEDPUR Post no 1379Dt 30/08//2019
JHARKHAND,INDIA 9431309542, rajeshsinghvet@gmail.com
Anti-Nutritional Factors in Animal feed stuffs:
Antinutritional factors are substances that when present in animal feed or water reduce the availability of one or more nutrients. It is important to have knowledge of antinutritional factors because they can adversely affect the health of your poultry flock.
Plants contain starch polysaccharides and nonstarch polysaccharides (NSPs). A polysaccharide is a chain of sugar molecules (also known as monosaccharides) linked together. Polysaccharides are identified based on the carbon atoms of each sugar involved in the bond and the orientation of the hemiacetal oxygen atom (alpha/α or beta/ß). Some polysaccharides are antinutritional factors.
It is well known that nutrition is one of the main factors driving the functioning efficacy, efficiency and evolution of livestock system. The main challenges nowadays in ruminant production are to reduce feeding cost, improve products quality and diminish the impact of production on environment. The use of unconventional feedstuffs may contribute to decrease feeding cost and environmental impact through reduced methane emissions as well. Not only that, but shrubby plants can be used to combat desertification, mitigating the effect of drought, allowing soil fixation an enhancing the restoration of the vegetation and the rehabilitation of rangelands.
Anti-nutritive substance are defined as “those generated in natural feedstuffs by the normal metabolism of the species from which the material originates and by different mechanisms exerting effects contrary to optimum nutrition”.
Type of Anti-Nutritive substances
On the basis of the type of nutrient affected and the biological response produced in the animal of the toxic factors can be classified into five major groups as follows:
1) Substance depressing digestion or metabolic utilization of protein:
a) Protease inhibitors
b) Lectins or Ricin (hemagglutinins)
c) Saponins
d) Polyphenolic compounds (TANNINS)
2) Substance reducing the solubility or interfering with the utilization of mineral elements:
a) Phytic acid
b) Oxalic acid
c) Glucosinolates
d) Gossypol
3) Substance inactivating or increasing the requirements of certain vitamins and hormones:
a) Antivitamins A, D, E, K and anti-pyridoxine
b) Minosine (Anti hormone)
4) Cyanogens
5) Nitrate and Nitrate
6) Moulds and mycotoxins in animal feedstuffs
Substance depressing digestion or metabolic utilization of proteins:
a) Protease inhibitors:
Substance that inhibit proteolytic enzymes and thereby growth and non-ruminants are
distributed throughout the plant kingdom but are particularly abundant in seeds and legumes. In the case of soyabeans identification of two main groups or protease inhibitors have recently been made namely: (1) Kumitz inhibitors have few disulphide bonds and a specificity towards trypsin
(2) Bowman-Brik inhibitors have a high proportion of disulphide bonds, inhibiting both trypsin and chymotrypsin. Feeding raw soyabeans to pigs, chicks and rats have resulted growth rate pancreatic hyperplasia and low production. Although ruminants are capable of utilising raw soyabeans without suffering any deleterious effects, a better response in milk production and growth rate in obtained on diets containing treated soyabean. The inhibitory substances are mostly heat labile and thus before feeding any leguminous grain to non-ruminants, the situation is generally corrected by proper heat treatment. Since overheating can damages some nutrients, such as amino acids and vitamins, quality control tests have been developed to assess the adequacy of heat treatment. These includes trypsin inhibitor and unease assays, cresol red absorption, protein dispersibility (index) PDI) and nitrogen solubility index (NSI).
b) Lectins or ricin (hamagglutinins):
This important group of anti-nutritional factor are found in both plant and animal tissue. At first, while studying the toxicity of castor been cakes (after the oil had been extracted) a toxic fraction capable of agglutinating human red blood cells was noted as “ricin”. Subsequently, similar active extracts from other edible legume seeds were obtained. Lectin are protein in
nature, resistant to digestion by pancreatic juice. Although very resistant to destruction by dry heat, lectins are destroyed by the same conditions as those used to inactive protease inhibitors.
c) Saponins
The important common forages which have caused saponin poisoning of livestock are Lucerne, White clover, red clover and soyabean Saponins or Sapogenins are either steroids or
triterpenoids, which are the break down products of certain glycosides found in soyabean, peas, alfalfa and certain varieties of beans. They are bitter in taste, lather forming and inhibit the
action of proteolytic enzymes and cholinesterase. They also causes haemolysis of red blood cells. Water soaking and rinsing will remove them components in the feedstuffs. Chemically saponins are glycosides which on hydrolysis yield surgars such as pentoses, hexoses and uronic acids and aglycaons (Derivatives of polycyclic ring system.) Among forages saponins occur mainly in legumes such as alfalfa, clovers and Leucaena. Alfalfa and Leucaena saponins are present in leaves, stems, roots and blossoms of the plant to an extent of 2 to 3 per cent.
Adverse Actions upon Excessive Eating:
1) In ruminant saponins have been suggested as being involved in formation of bloat by altering the surface tension of the ruminant contents due to entrapment of countless bubbles of fermentation gases throughout the ingesta.
2) It also increases the respiratory rate which later on becomes irregular.
3) Saponins also have found to inhibit the actions of certain enzymes. E.g., x-chymotrypsin.
4) The compound has got the ability to lyse red blood cells.
5) In general the effects of ingestion of saponins include excessive salivation, increased respiratory tract secretion, gastroenteritis, vomiting, diarrhoea, haemolysis, haematuria,
damage to livers and kidney tissues, cystitis, bloating, reduction of gastric motility, reduction of cholesterol absorption from the gut, lowering of blood and liver cholesterol levels, reduction of food intake, reduction of growth rate.
d) Polyphenolic compounds (tannins):
Definition:
Also known as tannic acid, gallotannin and gallotannic acid. It is now defined to include those naturally occurring compounds having high molecular weight (500-3000) and containing a sufficiently large number of phenolic hydroxyl groups (1 to 2 per 100 molecular weight) to enable them to form effective cross-links between proteins and other macromolecules.
Types of Tannins:
Vegetable tannins
Chemically tannins may be grouped
Hydrolysable
Condensed
two broad categories:
(1) Hydrolysable
1. Carbohydrate
2. Gallotannins
3. Ellagatannin
Acid or alkali or tannase enzyme
1. Sugar
Dehydrogenased
1. Proanthocyanidins tannin and (2) Condenced tannins. Most(Flavan-3,4-diois) tannins extracts appear to contain mixture of Catechins (Hydeoxyflavan 3 ols) both the types of tannins but generally one or the other predominates at least in any given
Heating part of the plant.
2. Gallic acid
3. Ellagic acid
enzyme or in acid diluted mineral solution acids at room
temperature
Flavonoid Anthocyanidinis Amorphous
tannins and brown phlobaphenenes
phlobaphene like or tannin-reds
Properties of Tannins:
1. The most important property of tannins is undoubtedly their capacity to bind proteins;they are thus inhibitors of enzymes.
2. The low palatability of some herbage plants such as cotton grass (Imperata cylindrica) and of some grains as has already mentioned have been attributed to their high tannin content.
3. They are also markedly astringent – that is they cause a dry or puckery sensation in the mouth, probably by reducing the lubricant action of the glycoproteins I the saliva.
4. The presence of tannins in a feedstuff has been assumed to affect voluntary intake as it cause a dry or puckery sensation in the mouth, propably by reducing the lubricant action of the glycoprotein in the saliva. High tannin content also depress cellulose activity and thereby affects digestion of crude fibre. Besides, tannins may cause loss of mucus, epithelial edema, irritation and damage of alimentary canal tissue, which in turn facilitate greater tannin absorption, thus causing toxicity.
Substance reducing the solubility or interfering with the utilization of mineral elements:
a) Phytic acid:
Phytates are the salts of phytic acid. Phytic acid is formed due to combination of six phosphate molecules with Inositol, a cylic alcohol with six hydroxy redicals like that of hexose sugar.The anionic character of phytase makes it ideal for forming complexes with mineral elements particularly the transitional element such as zinc, iron and manganese resulting the minerals insoluble in the intestinal tract. Solubility of these complexes mainly varies with pH, and calcium ion concentration, eg. Calcium enhance the formation of Zn-phytate complex. The effect of pH on solubility is particularly significant as because pH 6 is the approximate pH of the duodenum and upper jejunum the size of absorption of heavy elements including zinc. Neither phytate nor the zinc-phytate or calcium-Zn-phytate complex are absorbed under this pH range.
About half of more of the phosphorus in cereal grains is in the form of phyrin. The availability of phytin phosphorus to all non-ruminants is influenced by the level of vitamin D, calcium, the calcium to phosphorus ratio, amount of zinc in the feed, alimentary tract pH and other factors. How vitamin D specifically acts in improving the utilization of phytin phosphorus is not clear. In ruminants, the selected ruminal microbes are in a position to hydrolyse phytates by secreting the enzyme phytates so that it no longer binds are mineral as mentioned. Thus ruminants can utilize phytin phosphorus satisfactorily. For non-ruminants supplementation with adequate minerals (which are affected by phytates) is the useful practice followed to-day in livestock feeding to overcome the adverse effect of phytates.
b) Oxalic acid:
In both the vegetable and animal kingdoms oxalic is found as free and in salt forms. Plants which are particularly rich in oxalates include beet, spinach and a number of agro-industrial by-products used as livestock feed ingredient.Oxalic acid (oxalate) poisoning of livestock household pets and people is of important throughout the world. Oxalic acids is an organic dicroboxylic acid that readily forms insoluble salts with calcium ad magnesium.Oxalate
is apparently split to carbon dioxide and formate and the hydrogen from formic acid is used to synthesis methane. Oxalate degrading aerobic bacteria have been isolated from rumen content.
Bacterial degradation of oxalate to a non-toxic form and this tolerance for oxalate are acquired by gradually increasing the quality of oxalate-containing plant material. Increased degradation rates were also induced by intra-ruminal infusion of sodium oxalate. When the dietary amount exceeds certain level, normal degradation is interrupted and the excess oxalate combine with feed calcium to form insoluble calcium oxalate and then become unavailable for absorption or excess oxalate (20-30 mg per cent) may be absorbed from the rumen into the blood stream where it can combine with calcium to produce hypocalcomia. The insoluble calcium oxalate may then crystalise in various tissue, specially kidneys and rumen wall.
c) Glucosinolates (Thioglucosides):
Glucosinolates are responsible for the pungent flavour found in some cultivated plants belonging to the Cruciferae, specially the genus Brassica, which includes cabbage, turnips, rapseed, mustered seed. Their main biological effect is to depress the synthesis of the thyroid hormine (Tryroxine and Triiodothyronine), thus producing goitre, although the later is not caused by the glucosinolates per se but by their products of hydrolysis.The glucosinolates occur in the root, stem, leaf and seed and are always accomplished by the enzyme thioglucosidase, which is
capable of hydrolysing then to glucose, acid sulphate and either thiocyanates, isothiocyanates or nitrate. Some of the isothiocyanate are subsequently cyclised to oxazolidine-2-thiones (OZT). It is intersting to note that thioglucosidase is also present in some intestinal bacteria and is important when intact glucosinolates are fed to animals.In contrast, ruminants appear to be less susceptible to the toxic effect of glucosinolates compared with pigs and poultry. This is probably the result of the glucosinolates being relatively unhydrolysed in the rumen.When feed containing goitrogenic substance are fed in excessive quantities but are soaked or cooked in water, the disease (goiter) is much less likely to develop as the cooking process eliminates the enzyme. An adequate supply of iodized salt in another preventive measure specifically in areas where non-ruminants consume goitrogenic substances in a large dose. For treatment a daily injection of thyroxide @ 0.1 to 0.3 mg is advocated.
d) Gossypol
Gossypol pigments are polyphenolic compounds found exclusively in the pigment glands of cottonseed. At least 15 such pigments have been identified in extract of both cottonseed meal
and oil, but the most predominant is the yellow (C30H30O8). These pigments can exist either in a free from or as gossypol-protein complex. Whole seeds contain a total of 1.09-1.53 g/100g, of
which an average of 0.19 g/100 g exists in the free form. Decorticated seed contain a total of approximately 2 g/100 g, of which 0.15 g/100g is in the free form.The physiological effects of
free gossypol,. In addition to reduced appetite and loss or body weight, include accumulation of fluid in the body cavities, cardiac irregularity, reduced oxygen carrying capacity of the blood and
an adverse effect on certain liver enzymes.Pigs and rabbits appear to be more sensitive than poultry where 0.06 per cent gossypol in the diet can depress growth in young chickens. In laying
birds, 0.15 per cent of free gossypol reduce egg production. In the case of pigs a dietary level of 0.01 per cent reduces growth rate. The toxic effects of gossypol can be overcomes by supplementing the diet with iron in the form of ferrous sulphate.
Substance inactivating or increasing the requirements of certain vitamins and hormones: Cyanogens Cyanide in trace amount is fairly widespread in the form of glucosides and relatively high
levels can be found in certain grasses such as ‘jowar (sorghum) and sudan grass, linseed maize and cassava root. These plants generally contain cyanogenetic glycosides, which can be
hydrolysed to prussic acid by the enzyme usually present in the sample plant under a number of conditions during their growing period, or as they are being digested by animals. Maize linseed,
jowar, sudan grass may develop toxic levels of prussic acid also known as hydrocyanic acid (HCN) in the new growth that follows either a period of drought, or a period of heavy trampling
or physical damage by frost etc. Heavy nitrate fertilisation of the soil followed by an abundant irrigation or rainfall may increase the prussic acid poisoning potential of these crops. Note that the grasses mentioned so far are not abused in any way if growing conditions are favourable. In plants the glucoside is non-toxic in the intact issues and as stated earlier, when the plants are damaged or begin to decay, hydrolytic enzyme from the same plant is released liberating HCN. This reaction can take place in the rumen by microbial activity. The HCN is rapidly absorbed
and some is eliminated through the lungs, but the greater part is rapidly detoxified in the liver by conversion to thiocyanate. Excess cyanide ion can quickly produce anoxia of the central nervous system through inactivating the cytochrome oxidase system, and death can result within a few seconds. Based on the intensity animals show nervousness, abnormal breathing, trembling or
jerking muscles, blue colouration of the lining of the mouth, spasms or convulsions and respiratory failure. Animals which have not shown much evidence of toxicity may be injected
intravenously with 3 g of sodium nitrate and 15g sodium thiosulphate in 200 ml H2O for cattle, for sheep, 1g sodium nitrate and 2.5 g sodium thiosulphate in 50 ml H2O. Ruminants are more
susceptible to HCN poisoning than are horses and pigs, because in the latter two species the enzyme concerned in the release of HCN is destroyed by the gastric HCl.
Nitrates and nitrites
Forages and drinking water when contaminated with inorganic nitrates and nitrites cause an acute toxicosis in cattle resulting from formation of methemoglobin (a true oxidation product
of haemoglobin) which is unable to transport oxygen because the iron is in the ferric (Fe+++) rather than the usual ferrous (Fe++) state. The situation is more common in forages where either
nitrogenous fertilizers have been used at a very high dose or the forages have been harvested at a very early stage of their growth. It appears to be a more serious problem in the ruminant since
nitrates are reduced to the more toxic nitrites in the rumen. If the amount is not much, nitrite is reduced to ammonia. When excess nitrate is ingested, the toxic nitrite may accumulate and
absorbed from the rumen because the activity of nitrate reductase exceeds that of nitrite reductase. The rates of nitrate and nitrite reduction by a given population of ruminal microbes
appears to depend upon the supply of fermentable energy sources which supply hydrogen for the reduction. A high dose of concentrates in the daily ration and adequate feeding or Vitamin A
have a protective effect. Symptoms seen in acute toxicity include laboured breathing (dyspena), grinding of the teeth, uneasiness and excessive salivation.
Mimosine
Mimosine is a toxic amino acid, also called as ‘leucenine’ found in the plants belonging to the genus Leucaena like subabul. This toxic substance mimosine can cause problems when
the forage is eaten in large quantities for a long period. Mimosine is a powerful depilatory agent that cannot be degraded after absorption. But it can be extensively degraded to Dihydroxy
pyridone (DHP) in the rumen. Excess DHP is absorbed into the blood stream, reaches thyroid gland and inhibits biosynthes of the hormone thyroxine. Acceptable safe daily intake of mimosine was calculated to be 0.14% g/kg body weight. Among the various livestock, horses, sheep, pigs and even rabbits are highly sensitive to mimosine and thus subabul should not be fed
to them. The main symptoms are reduced growth and weight loss, excessive salivation, loss of hair, eroded gums, enlarged thyroid gland and poor reproductive efficiency, Sun dried leucaena
leaf meal contains 3.2% of mimosine. Ferrous sulphate supplementation also reduce the minosine toxicity, by forming insoluble red iron complex. Certain strains of rumen microbs at
Australia capable of detoxifying mimosine have been identified and are now being innoculated to livestock of other nation to overcome mimosine toxicity Substance inactivating or increasing the requirements of certain vitamins:
(a) Anti Vitamin A:
Raw soyabean contain an enzyme Lipoxygenase, which catalysis oxidation of carotene, the precoursor of vitamin A. It has been noted that 30 per cent of ground, row soyabeans in the
diet of dairy calves products of sharp lowering of vitamin A and carotene in blood plasma. The enzyme can be destroyed by heating soyabean for 15 minutes with steam at atmospheric
pressure.
(b) Anti-Vitamin B:
Rachitogenic activity of isolated soya protein (unheated) has been founded with chicks and pigs. The effect could be partially eliminated by increasing the vitamin D in the diet by 8-10 fold. Autoclaving eliminates this rachirtogenic activity.
(c) Anti-Vitamin E:
The author while working his Ph.D. programme at Cornell ?University in USA observed that diets containing raw kidney beans (Phaseolus vulgaris) produce muscular dystiophy in lambs by reducing plasma vitamin E. Alcohol extraction of the beans reveals two factors with anti-vitamin E activity, one being alcohol soluble and heat-stable, the other being neat-labile and alcohol-insoluble. By autoclaving beans the anti-vitamin activity is eliminated.
(d) Anti-Vitamin K:
“Sweet clover disease” is characterized by a fatal haemorragic condition in cattle and has been known for over 20 years. The active principle reasonable for this disease is dicoumarol, which reduces the prothrombin level of the blood, thus interfering with the blood clothing mechanism. The effect is due to reducing vitamin KL utilization in the production of thrombin.
(e) Anti-pyridoxine:
It has been demonstrated that the nutritive value of linseed meal for chicks can be considerably improved after extracting the meal with water and autoclaving. An antagonist of
pyridoxine (a member of B Vitamins) from linseed which has been identified as 1-amino-D-proline and occurs naturally in combination with glutamic acid ass a peptide is known as linatine.
Moulds and mycotoxins in animal feed stuffs:
A mycotioxin is a fungal metabolite causing pathological or physiological changes in man or animal. Mycotoxins are highly toxic, small molecular weight, compounds non-antigenic
secondary frugal metabolites that alter physiological response in higher animals regardless the
route of administration. Aflatoxins are the most potent toxic, mutagenic, teratogenic and carcinogenic metabolities produced by the species of Aspergillus flavus and A.parasiticus on
food and feed materials. Aflatoxins B1, B2, G1 produce liver cancer in cats. The occurrence of these toxins in food and feed materials and their consumption has caused not only health hazards
in animals and humans, but also resulted in economic losses, especially to the exporting countries. Other fungal toxins include T2 toxin, Ochratoxin A and Zearalenone.
Methods of reduce the deleterious effect of ANF’s———
A number of methods have been tried to overcome the deleterious effect of such anti-nutritional factors and tannins is came at the head. These are through making hay, silage with inoculants, using PEG;21,22 urea23 or biological treatment with fungi24,25 can be applied to either take off or minimized and decrease anti-nutritional factors concentration. It is will know that alkali treatment includes polyethylene glycol (PEG), which a tannins-binding agent,26 was shown to be a powerful tool for isolating the effect of tannins on various digestive function.27‒29 But it may not be economic. Although the incorporation of polyethylene glycol (PEG), which binds with and inactivates tannins, is quite effective, success of its adoption depends on the cost: benefit ratio.30,31 Russsell & Olley23 suggest feed animals with 1% urea. In that system, urea not only provides extra N but also deactivates the leaf tannins.
For increasing the utilization of dietary nutrients, reducing environmental contamination and decrease feeding cost, the optimum use of unconventional feedstuffs as well as any local sources (shrubs, browsing tree) has big potential.
