Animal Feedstuffs Classification PDF
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This document provides a comprehensive overview of animal feedstuffs, covering classification methods, nutritional value assessment, and antinutritional factors. It delves into various aspects of feedstuffs, such as their origin, nutrient composition, physical form, and digestibility. This guide also discusses the importance of additives and supplements to enhance feed quality and efficiency in animal husbandry.
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CHAPTER IV Classification of animal feedstuffs Nutritional value of different feedstuffs Classification of Anti-nutritional and toxic factors Classification of animal feedstuffs Feedstuffs Definition- any component of a diet ( ration) that serves some useful function Functions...
CHAPTER IV Classification of animal feedstuffs Nutritional value of different feedstuffs Classification of Anti-nutritional and toxic factors Classification of animal feedstuffs Feedstuffs Definition- any component of a diet ( ration) that serves some useful function Functions - Provide source of nutrients and energy* - Combined to produce rations - Modify characteristics of diet* * Denotes a primary functions Feedstuffs can be classified based on various criteria, including their origin, nutrient composition, Digestibility, Use and physical form. 1) By Origin Plant-Based Feedstuffs Cereal Grains: Corn, wheat, barley, oats. Legumes: Soybeans, peas, lentils. Forages: Grass, hay, silage. Byproducts: Bran, meal (e.g., soybean meal, corn gluten meal). Animal-Based Feedstuffs Meat and Bone Meal: Rendered animal byproducts. Milk Products: Whey, casein. Fish Meal: Rendered fish products. Mineral-Based Feedstuffs Mineral Supplements: Limestone, salt, trace minerals. Synthetic Feedstuffs Vitamins and Additives: Synthetic vitamins, amino acids. 2) By Nutrient Composition Energy Feedstuffs High in carbohydrates and fats, e.g., grains and oils. Protein Feedstuffs High in protein content, e.g., soybean meal, fish meal. Mineral Feedstuffs Sources of essential minerals, e.g., salt, calcium carbonate. Vitamin Feedstuffs Sources of vitamins, e.g., vitamin premixes. 3) By Physical Form Concentrates High in energy and protein; low in fiber, e.g., grains and protein meals. Roughages High in fiber; lower in energy, e.g., hay, silage, straw. Complete Feeds Formulated to provide a balanced diet in a single feed, often pelleted. 4) By Digestibility Highly Digestible Feedstuffs Easily broken down and absorbed, e.g., processed grains. Less Digestible Feedstuffs Higher fiber content, e.g., mature forages. 5) By Use Maintenance Feeds: For maintaining body condition without growth or production. Production Feeds: For growth, milk production, egg production, etc. Supplements: Added to base diets to improve nutrient balance. International Feed ID System System for classifying feedstuffs based on descriptive characteristics Based on the primary nutrient provided by the feedstuff Each feedstuff is assigned an International Feed Number ( IFN) The international naming system has been adopted by the International Network of Feed Information Centers (INFIC), of which the National Feed information Center is a member. Under this system, feeds are classified into eight classes. These classes place feeds into groups having similar chemical and/or physical properties and the way they are used in formulating feed mixtures and diets. Eight Classes of Feedstuffs 1. Dry roughages 2. Pasture and range grasses 3. Ensiled roughages 4. High energy concentrates 5. Protein sources 6. Minerals 7. Vitamins 8. additives 1. Dry Roughages Bulky feed that has low weight per unit volume High crude fiber content, low protein and fat digestibility A feed is classified as a roughage if it contains >18% crude fiber and 20% crude protein Animal, avian, marine sources Milk and by-products Legume seeds Brewery and distillery by-products Urea, ammonia 6. Mineral supplements Minerals essential for animal life include common salt (sodium chloride), calcium, phosphorus, sulfur, potassium, magnesium, manganese, iron, copper, cobalt, iodine, zinc, molybdenum, and selenium. The last six of these can be toxic to animals if excessive amounts are eaten. 7. Vitamin supplements Must be added by sources that animal is able to absorb Vitamin concentration in plants and animal tissues varies greatly Plants: vitamin concentration affected by harvesting, processing and storing Animals: liver and kidney are good sources of most vitamins 8. Additives Non-nutritive ingredients added to stimulate growth or performance or improve the efficiency of feed Added in very small quantities Antibiotics, antifungals, antimicrobials Probiotics, buffers Colors, flavors Hormones, enzymes Are materials that are administered to the animal to enhance the effectiveness of nutrients and exert their effects in the gut or on the gut wall cells. Types of Feed Additives 1. Additives that influence feed stability, feed manufacturing and properties of feeds 2. Additives that modify animal growth, feed efficiency, metabolism and performance 3. Additives that modify animal health 4. Additives that modify consumer acceptance 5. Suppliments, Additives that influence feed stability, feed manufacturing and properties of feeds Name Descriptions 1. Antifungals Agents used to prevent fungal (mold) growth in stored in feed ingredients and mixed feeds. Molds reduced palatability and may produce mycotoxins. Aflatoxin and Fusarium toxins are among those most concern The used of mold inhibitor is strongly recommended when the moisture content of grain exceeds 13%to 14%, the relative humidity is above 80 to 85%, the temperature is 55% or above, or the grain is damaged, broken, or insect infested. Examples: propionic acid, sodium diacetate, sorbic acid, gentian violet Name Descriptions 2. Preservatives that prevents the auto-oxidation of fats (rancidity) Antioxidants These synthetic anti-oxidation are very effective in preventing deterioration of stored feeds and are commonly used for this purpose. Besides protecting against peroxidation in feeds, synthetic antioxidants also prevent these reactions in animal tissues, thus having a sparing effect on Vit E and selenium requirements Sparing effect means that when one nutrient or substance reduces the requirement for another nutrient, usually replacing it in some aspect of its metabolic function. Natural antioxidants are Vit E and C Synthetic antioxidants are ethoxyquin santoquin, Butylated Hydroxytoluene (BHT) and Butylated Hydoxyanisole (BHA) Name Descriptions 3. Pellet Used to give firmer, stronger pellets with a reduced tendency to crumble. Binders Advantages: increases the density of feed resulting in increased feed intake and improved growth and feed efficiency; reduces feed wastage and eliminates sorting of ingredients by animals; and reduces dust and increases ease of feed handling Disadvantages: added cost, which may add up to 10% or more to the cost of the feed; pelleting may hide a multitude of sins in terms of the quality of the ingredients used; The presence of fines ( small feed particles) and the tendency of pellets to crumble and break apart. Bentonites are mostly used, Hemicellulose extracts and higher sulfonate, by products of the wood-processing industry. Additives that modify animal growth, feed efficiency, metabolism and performance Name Descriptions Feed Used to increase the acceptance of diets of low palatability, increase the intake of diets flavors during periods of stress such as weaning and increase the intake of palatable feeds. Digestion modifiers a. Provide the sources of beta-glucanase to swine and poultry to increase the digestion of β- Enzymes glucans. Glucans are important source of CHO in barley and Oats. b. Buffers Is a salt of a weak acid or base that resists a pH changes, whereas an alkalizing or neutralizing agent neutralizes acid but also increases pH. Examples of true buffers are: sodium bicarbonate, Potassium bicarbonate, magnesium bicarbonate, calcium carbonate,bentonites. Examples of alkalizing agents are sodium carbonate, potassium carbonate, magnesium oxide, sodium hydroxide, calcium hydroxide Limestone has also a buffering effect Name Descriptions c. ion-exchange Zeolites are the principal ion-exchange compounds used in feeds. compounds They are clay minerals consisting of hydrated aluminum silicates of various cations. They can gain and lose water reversibly and exchange their constituent cations d. Ionophores Ionophores are a class antibiotics that are extensively used as feed additives for and methane cattle inhibitors Methane production reduces hydrogen formation represents a “hydrogen sink” by which hydrogen formed in fermentation is removed. So with inhibition of methane production, the efficiency of ruminant production will increase, as well as reducing methane emissions which have been linked to global warming. Examples are chloroform, iodoform and other halogenated methane analogs. Name Descriptions e. Isoacid Has been produced commercially to allow the addition of volatile fatty acids compounds to the diets It includes VFAs: Isobutyric acid, 2-methylbutyric acid, isovaleric acid and valeric acid f. Probiotics Is a term coined to describe microbes used as feed additives It is defined as live microbial feed supplements which beneficially affect the host animal by improving its gastrointestinal microbial balance Most enteric pathogens, such as E. coli and Vibrio Cholera, cannot produce disease without attachment to the host intestinal cells, so attachment of probiotic organisms to the intestinal cells could be very important in increasing disease resistance g. acidifiers (organic acids) Have shown effects when used as additives in diets for weanling pigs Name Descriptions h. surface active agents such as poploxalene, marketed as bloat guard are effective in Antibloating preventing frothy bloat agent surface active agents prevent the formation of a stable foam by preventing the development of bubble membranes antibloat agents are generally as components of blocks i. Salivation (sialogogues) are substances that increase the production and secretion of saliva. inducers Slaframine and other sialogogues appear to have potential as additives to alter rumen fermentation to favorably influence animal performance j. Defaunating defaunation is the process of treating a ruminant to eliminate its rumen protozoa agents increases the bacterial population density, the efficiency of bacterial protein synthesis and the rate of nitrogen flow to the duodenum, especially when the feed is deficient in protein relative to energy content Sodium lauryl sulfate Name Descriptions Metabolism modifiers a. Hormones b. β-Adrenergic Repartitioning agents, They are NE analogs that stimulate β-adrenergic agents receptors They are called repartitioning agents because they result in a repartitioning of nutrients from fat to protein synthesis, causing increased muscle mass and decreases body fat. Repartitioning agents are believed to act by increasing fat mobilization lipolysis and stimulating protein synthesis Clenbuterol, cimaterol, vatopamine, ractapamine hydrochloride are examples Name Descriptions Growth Promotants a. Antibiotics Are natural metabolites of fungi that inhibit the growth of bacteria like penicillin These antibiotics are given are subtherapeutic levels particularly in swine and in poultry The use of feed additives has sparked controversy as to possible adverse effects of this practice on human health. The major concern is that these antibiotics may lead to the development of antibiotic resistant strains of bacteria, which could make treatment of human diseases more difficult The worse case scenario is that bacteria resistant to all antibiotics could develop and create life-threatening infections in human. Name Descriptions b. These includes arsenical, nitrofurans and sulfonamides Chemotherapeutic Arsenicals are compounds containing arsenic such as arsanilic acid, sodium Agents arsanilite and roxarsone believe to have growth promoting effect similar to that of the antibiotics. Nitrofurans are synthetic compounds with antimicrobial activity. Furazolidone is the best example which acts as a feed additive by controlling enteric diseases Sulfonamides have broad spectrum bacteriostatic effects. “bacteriostatic” means that the agent prevents the growth of bacteria and “bactericidal” means that it kills bacteria. Other examples are carbadox and copper sulfate Name Additives that modify animalDescriptions health Drugs A variety of drugs may be added to the feed for the treatment and/or prevention of disease or internal parasites Some of the drugs commonly used in feeds include worming agents and coccidiostats Example: Phenothiazine, dichlorvos, piperazine, monensin, amprolium and sulfaquinoxaline. Environmentally These products are use for the control of ammonia Active Substance Zeolites are the most widely used and are effective when directly applied to the litter. Saponins are also effective when applied to the excreta directly Immunodulators Instead of antibiotics and other feed additives to help microbes that reduce animal performance, an alternative approach is to use compounds to stimulate the animal’s immune system: enhancing resistance to microbial effects Examples are cytokines like interleukins and interferons and leucocytic origin Additives that modify consumer acceptance Name Descriptions Xanthophylls Are red and yellow carotenoid pigment that are important in poultry nutrition because they are deposited in egg yolk and body fat, producing yellow pigmentation of eggs and the skin and shanks of broilers Sources include: marigold petal meal – 6,000 to 10,000mg/kg; alfalfa – 200 mg/kg; corn gluten meal/Y-corn – 20 mg/kg Lutein is the color found in marigold petal meal Zeaxanthin is found on corn gluten meal and yellow corn Saponins are complex substances with cholesterol and have been shown to have blood- cholesterol lowering properties Supplement a feed used with another to improve the nutritive balance performance of the total feed and intended to be: 1. fed undiluted as a supplement to other feeds 2. Offered free choice with other parts of the ration separately available 3. Further diluted and mixed to produce a complete feed Amino acid Supplements DL –methionine It is a racemate of amino acid-methionine that occurs naturally with at least 99% purity L-Lysine Synthetic amino acid produced by fermentation which is soluble in water with at least 98.5% purity for the hydrochloride from and at least 99% for pure L-lysine L-Threonine Synthetic amino acid produced by fermentation Tryptophan Synthetic amino acid produced by fermentation Acidifying Agents (Acidifiers) Chemical products added to the feeds to decrease pH in the gut, thus improving digestion in the stomach Amino Acids Building blocks of proteins, produced either by microbial fermentation, chemical synthesis or extraction from denatured proteins with chemical characteristics similar to their natural origin. Anthelmintics chemical products used to prevent and treat parasitic warm infections. Anti-caking Agents (dewormers) Drugs used to rid animals of internal parasites and prevent formation of lumps. Antibiotics chemicals produced by microbial fermentation or chemical synthesis, which possesses bacteriostatic or bactericidal properties and are added to the feed at sub therapeutic levels. Antimolds chemical preservatives added to the feeds to prevent mold development. Antioxidants chemical products used to prevent rancidity in feeds; protect the polyunsaturated fatty acids and the fat-soluble vitamins from destruction by peroxidation. Anti-toxins usually inert chemical compounds with large internal surfaces, which can fix or absorb toxins in feeds. Coccidiostats Chemical products added to the feed to prevent and control coccidiosis. Enzymes chemical products which are added to the feed to improve digestibility of certain feedstuffs. Flavorings chemical agents added to the feed to improve flavor, thus improving feed intake. Hormones these are substances used to alter metabolism in the body. Pellet Binders additives used to improve pellet quality Pigmenters chemical agents added to the feed to enhance coloration or pigmentation of skin or egg yolk of poultry. Probiotics beneficial organisms added to feeds to alter the environmental condition in the digestive tract for more favorable growth of beneficial micro flora, which prevent the growth of harmful microorganism in the G I tract. Surfactants chemical agents that facilitate uniform dispersion of molecules in feeds and feed mixtures. Repartitioning Agents are additives used to increase lean-muscle and reduce fat deposition in carcasses when added in the diet during the finishing period. Eg. Clenbuterol CHAPTER IV Classification of animal feedstuffs Nutritional value of different feedstuffs Classification of Anti-nutritional and toxic factors Nutritional value of different feedstuffs nutritivevalue of a feed –”the amount of nutrients contained in a feed that can be utilized by the animal” Assessing the Nutritive Value of Feeds 1.Physical Characteristics 2.Chemical composition Physical Characteristics provides preliminary information on the quality of the material. weight, color, smell and whether the material has suffered from any contamination by other materials. presence of adulterants in feedstuffs and feeds Chemical composition Feeds- Water and dry matter Dry matter- organic and inorganic compounds Organic compounds- carbohydrates, proteins, vitamins and fats and oils Inorganic compounds- mineral elements, also known as ash. Methods of Assessing the Nutritive Value of Feeds Laboratory-based analyses Animal-based analyses Laboratory-based analyses Measure amount of each component (nutrient) in feedstuff Accurate quantitative measurement Proximate analysis, Detergent fiber system, Gross energy (GE), Specialized procedures Proximate analysis- is a way to determine the distribution of products when the samples are heated under specified conditions. 5 categories- Crude protein (CP)-Estimates quantity of protein and nonprotein nitrogen compounds Ether extract (EE)- Estimates quantity of organics; lipids Ash- Estimates quantity of inorganics; minerals Crude fiber (CF)- Estimates quantity of fiber associated components, i.e. cellulose, hemicellulose, and lignin Nitrogen-free extract (NFE)- Estimates nonfibrous carbohydrates Detergent fiber system- More accurately estimates CHO fractions Estimates of fibrous CHO Neutral detergent fiber (NDF) -Primarily: hemicellulose, cellulose, and lignin Acid detergent fiber (ADF) -Primarily: cellulose and lignin Estimates of nonfibrous CHO Nonfibrous carbohydrates (NFC) Gross energy (GE) Estimates total chemical energy Inconsistent measure of available energy Specialized procedures High performance liquid chromatography (HPLC) -Identify amino acids Atomic absorption spectrophotometry -Identify minerals Near-infrared reflectance spectroscopy (NIRS) -Standard analyses Gas-liquid chromatography (GLC) - Identify gaseous compounds and compounds able to be vaporized Animal-Based Analyses Measure utilization efficiency of each component in a feedstuff Used in conjunction with laboratory-based analyses Feeding trials, Digestion trials, Energy value of feedstuff – Energy terms Feeding trials Compare production results between feeding schemes Applied research Preliminary trials Measure production differences Digestion trials Estimate total amount of specific nutrient absorbed from GI tract Two measures Apparent digestibility represents the difference between the amount of feed ingested and amount of feces produced Collection Method, Indicator method, Nylon Bag in vivo technique True digestibility is the proportion of the dietary intake that is absorbed from the GI tract, excluding endogenous contribution endogenous sources- body tissues (sloughed intestinal cells and digestive enzymes and the other substances secreted in the gut that are not absorbed) Fecal N derived directly from ingested food is called exogenous N (not from body tissues) Fecal N derived directly from body tissues is termed fecal metabolic N / endogenous N In Vitro Digestibility Energy value of a feedstuff - total digestible nutrients (TDN) Total Digestible Nutrients is an estimate of the energy content of a feed, and is based on the digestible portion of the nutrients that can supply energy, carbohydrates (crude fiber and NFE), protein, and fat. It can be calculated by the formula: TDN (%) = % digestible crude protein + % digestible crude fibre + % digestible N-free extract + (2.25 x % digestible ether extract). * % TDN = % DCP + % DCF + % DNFE +(2.25 x % DEE) Energy flow diagram Energy terms Gross energy (GE): the amount of energy in the feed. Digestible energy (DE): the amount of energy in the feed minus the amount of energy lost in the feces. Equation: DE = GE – FE Metabolizable energy (ME): the amount of energy in the feed minus the energy lost in the feces and urine. Equation: ME =GE – (FE + UE + GE*) Net energy (NE): the amount of energy in the feed minus the energy lost in the feces, urine, and in heat production through digestive and metabolic processes, i.e. heat increment. Most accurate value Three NE values: maintenance (NEM), growth (NEG), and production (NEP) Calorimetry – estimate HI *Heat increment- Energy loss associated with consumption, digestion, absorption, and metabolism of nutrients for maintenance and productive functions Equation: NE = ME – HI CHAPTER IV Classification of animal feedstuffs Nutritional value of different feedstuffs Classification of Anti-nutritional and toxic factors Antinutritional Factors are: 1. Antinutrients are natural or synthetic compounds that interfere with the absorption of nutrients. 2. Substances which either by themselves or through their metabolic products, interfere with food utilization 3. Affect the health and production of animals 4. Generated in normal metabolism of species, which can produce adverse biological or economic effects in animal production. 5. These substances tends to reduce digestibility, absorption, utilization and increase the requirements from the nutrients needed by the animal. Characteristics of Antinutritional Factors Secondary Products of metabolism Found in virtually all plants to some degree. Bitter Colored Poisonous Odor Antinutritive Immunosuppresive Common in tropical forages. Classification of Factors Affecting Food Value Consumer/Animal – age, nutritional status, disease status Dietary factors – dietary composition, chemical form of nutrients in diet, bioavailabilty and antinutrients Environmental factors – geographical location, climate and management practices COMMON PLANT TOXINS AND ANTINUTRIENTS, AND THEIR EFFECTS ON HUMANS Toxin family Occurrence in plants Effects on humans and animals Cyanogenic Sweet potatoes, stone fruits, lima Gastrointestinal inflammation; inhibition of glycosides beans cellular respiration Glulcosinolates Rape, mustard, radish, cabbage, Goiter; impaired metabolism; reduced iodine peanut, soybean, onion uptake; decreased protein digestion Glycoalkaloids Potato, tomato Depressed central nervous system; kidney inflammation; carcinogenic; birth defects; reduced iron uptake Gossypol Cottonseed Reduced iron uptake; spermicidal; carcinogenic Lectins Cereals, soybeans, other beans, Intestinal inflammation; decreased nutrient potatoes uptake/absorption Oxalate Spinach, rhubarb, tomato Reduces solubility of calcium, iron and zinc Phenols Fruits and vegetables, cereals, Destroys thiamine; raises cholesterol; soybean, potato, tea, coffee estrogen-mimic Coumarins Celery, parsley, parsnip’s, figs Light-activated carcinogens; skin irritation GENERALIZED CLASSIFICATION SCHEME FOR ANTINUTRIENTS AND TOXINS Group Nutrient affected Adverse effects produced Substances Depression of digestion or utilization of Protease inhibitors, lectins, A Protein dietary protein polyphenols Phytic and Oxalic acid, Reduced solubility, absorption or cyanogenic glycosides, B Mineral utilization of element thiocyanates, polyphenols, lectins Ascorbic acid, oxidase, Increased requirement or inactivation of C Vitamins thiaminase, pyridoxine, vitamins antagonists, pyriminase Mycotoxins, mimosine, Retard growth alopecia, reduce feed D Others nitrates, alkaloids, intake and FCE gossypol, isoflavone Common Antinutritional factors A. Protease inhibitors B. Lipase Inhibitors C. Phytic acid D. Glycosides E. Saponins F. Alkaloids G. Tannins A. Protease Inhibitors Inhibit the actions of: Trypsin, Pepsin, Other protease In the gut, they prevent the Digestion and Absorption of protein e.g. legume seeds: soyabean, kidney bean, mung bean. Protease inhibitors are concentrated in the outer part of the cotyledon mass. Protease inhibitors are two types: a. kunitz inhibitor (inhibits only trypsin) b. Bowman-birk inhibitor (inhibits trypsin and Chymotrypsin). The inhibitory substances are mostly heat labile and thus proper heat treatment inactivates the protease inhibitors. Overheating can damage some nutrients such as amino acids and vitamins B. Lipase Inhibitors Interfere with enzymes, such as Pancreatic lipase, that catalyze the hydrolysis of some lipids, including fats. For example Anti-obesity drug orlistat causes a percentage of fat to pass through the digestive tract undigested. Glycosides Generally bitter Structure- Contain CHO and non-CHO groups(aglycone) Mode of action: Toxicity results from aglycone release during enzymatic degradation Sources: Linseed, sorghum, soyabean, clover etc Cyanogens/Glycosides Generally bitter It occurs mainly in the form of cyanogenic glycoside. In plants the Glucoside is non-toxic in the intact tissues. These glycosides can be hydrolyzed to prussic acid or hydrocyanic acid (HCN) by the enzyme usually present in the same plant or as they are being digested by animals. 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 inactivating the cytochrome oxidase system and death can result within a few seconds. There are three distinct glycosides: Glycoside Plant source Amygdalin Almonds Dhurrin Jowar and other immature grasses Linamarin Pulses, Linseed, cassava Ruminants are more susceptible to HCN poisoning than are horses and pigs because the enzyme required for the release of HCN is destroyed in horses and pigs by the gastric HCI. Cattle are most susceptible than sheep C. Saponins These are glycosides characterized by bitter taste, forming in aqueous solution and haemolyse RBC. They are able to form complexes with sterols. Including those associated with the plasma membranes of animal cells. Generally, saponins are less important because their levels are low in most common feed ingredients for monogastric animals. Their toxicity is related to their activity in lowering surface tension in ruminants. The important common forages which cause saponin poisoning of livestock are Lucerne ,soybean etc. Average Saponin content of the leaves are twice as much as those of the stems and that the saponin content declines as the plant become older Excess feeding of green lucerne or legume forages saponins lower the surface tension of ruminal contents leading to accumulation of gas, condition is known as “bloat” This is also know as tympany/tympnitis. The presence of saponins has been cited as one of the factors responsible for formation of foam in the rumen and thereby gas is trapped in the rumen contents with the result of which animals can not eliminate it by belching. The rumen distension impedes the blood flow and asphyxiation develops which is responsible for respiratory or heart failure. Turpentine and paraffin oil are helpful in reducing bloat D. Alkaloids Basic in nature Effects of alkaloids Generally toxic It can cause For example Kidney damage Cocaine Pulmonary damage Nicotine Liver damage Caffeine Diarrhea E. Phytic acid Ithas a strong binding affinity to minerals such as calcium, magnesium, iron, copper, and zinc. Itmakes the minerals unavailable for absorption in the intestine. Phytate has direct anti-nutritional effects for poultry causing reductions in performance by lowering amino acid and mineral absorption. F. Tannins Compounds that tan leather Have beneficial/harmful effects Polyphenolic compounds that can form stable complexes with: Proteins Carbohydrates Minerals Selected Forage Plants with Tannins Lotus species Calliandra calothyrsus Faba beans Leucaena leucocephala Peas Sesbania sesban Sorghum Acacia species Condensed Tannins/ Pro-anthocyanidins (Pas) affect forage utilization by: Forming strong H bonds with other nutrients. Inhibition of digestive enzymes. Inhibition of rumen microbial activity. Concentrations >7% usually reduce nutrient utilization. How to minimize tannic acid toxicity Separate bran fraction from endosperm thru milling (more polyphenols in the subcoat or testa) Chemical treatment, soaking in 1% NAOH Breeding of low tannin varieties Increasing level of protein and methionine in ration containing high-tannin