ANIMAL NUTRITION

1.0 DIGESTION IN RUMINANTS AND NON-RUMINANTS

1.1 INTRODUCTIONProduction potential of an animal is determined by;The genetic make-up of the animal fixed at the time of conception,The environment, including feeding (nutrition), management and climate.Feeding ensures that an animal is supplied with nutrients which are required for various purposes within the body such as:Maintenance: physiological processes for survival of the animal are facilitated e.g. respiration, circulation, restoration of tear and wear, etc.Production: growth, reproduction, milk, eggs, wool e.t.c,Work.Definition of termsFood/feed- Is any material which, after ingestion by animals, is capable of being digested,         absorbed and utilized in the animal’s body.             NB. Not all their components are digestible.Nutrients-These are components of feed that are capable of being utilized by the animal.            -Examples- carbohydrates, minerals, vitamins e.t.cNutrition-Is a science that deals with a series of processes whereby feed is consumed, digested and absorbed into the body of an organism for the purposes of maintenance, production and work.1.2 DIGESTIONDigestion is the breakdown of large insoluble food molecules into simple molecules in the animal’s digestive system. Their passage through the wall of the alimentary canal into the blood and lymph is termed as absorption.Digestion can be mechanical, chemical or microbial.Mechanical Digestion: mastication and muscular contraction of the alimentary canalChemical digestion: brought about by enzymes secreted by the animal in the various digestive juicesMicrobial digestion: is brought about by the action of bacteria and protozoa. This is of special significance in ruminants.1.2.1 DIGESTION IN NON-RUMINANT ANIMALSAssignment: draw the digestive tract of a non-ruminant animalThe various parts of the digestive tract of a non-ruminant are: mouth, pharynx, oesophagus, stomach, duodenum, small intestines, caecum, colon, rectum and anus.The movement of the intestinal contents along the tract is produced by peristaltic waves, which are contractions of the circular muscles of the intestinal wall.Digestion in the mouthMastication helps to break up large particles of food and mix it with saliva which:Lubricates (mucin)Moisten the food (water, 99%)Contain an enzyme- salivary amylase which breaks down starch into maltose and dextrinBuffer the food material-alkaline.Digestion in the stomachThe stomach acts as an organ of digestion and storage.The inner surface of the stomach is increased in area by an in folding of the epithelium and contains a variety of secretory cells which collectively secrete the gastric juice.Gastric juice contains:-     waterpepsinogensinorganic saltsmucushydrochloric acidrennin/chymosin (in young)Hcl activates pepsinogens into pepsin and lowers the P. H to between 2.0-2.5.Pepsin breaks down proteins into polypeptides of various chain lengths.Rennin coagulates the milk proteins.Mucus protects the wall of the stomach from digestion.Digestion in small intestinesDuodenum The duodenal glands produce an alkaline secretion which acts as a lubricant and protects the duodenal wall from HCL entering from the stomach.Bile secreted by the liver contains sodium and potassium salts which emulsify fats and provide an alkaline condition.The pancreatic juice secreted by the pancreas contains bicarbonate ions and the following enzymes:Trypsinogen : is activated into active trypsin by enterokinase. Trypsin then breaks down proteins into peptides. Chymotrypsinogen: is activated into active chymotrypsin which then breaks down proteins into peptides.Carboxypeptidase: breaks down peptides into amino acids.Pancreatic amylase: breaks down starch into maltose and glucose.Pancreatic lipase: breaks down triacylglycerol into fatty acids and monoacylglycerol.Ileum and jejunumThe villi on the walls of the Ileum and Jejunum secrete intestinal juice which contains:Sucrase: breaks down sucrose into glucose and fructose,Maltase: breaks down maltose into two glucose molecules,Lactase: breaks down lactose into glucose and galactose,Oligo-1,6-glucosidase: breaks down dextrin into glucoseAmino peptidase and dipeptidase: break down peptides and dipeptides into amino acids,Intestinal lipase: breaks down fat droplets into fatty acids and glycerol.The small intestine is the main absorption site of the hydrolyzed nutrients.Digestion in the large intestinesCellulose and hemicelluloses are not attacked by any enzyme present in the digestive secretions in the pig.Extensive microbial activity occurs in the large intestine especially the caecum.The bacteria present in the caecum include; lactobacilli, streptococci, coliforms, bacteriodes, clostridia and also yeast.The products of this microbial breakdown of polysaccharides are mainly the volatile fatty acids such as acetic, propionic and butyric acid. Large quantities of water is absorbedThe waste material is voided via the anus. NOTE: digestion of cellulose and hemicelluloses is less compared with that taking place in the ruminants.1.2.2 DIGESTION IN RUMINANTSFood is digested with large amount of saliva (typically 150 ltrs in cattle and 10ltrs in sheep per day) firstly during ingestion and again during rumination.The stomach of a ruminant is divided into four compartments;Rumen -pouchReticulum –honey combOmasum –many pliesAbomasum-true stomachIn young suckling ruminants, the rumen and reticulum are underdeveloped and they form a tube-like fold of tissue known as the oesophageal or reticular groove.Milk on reaching the cardia, triggers an oesophageal reflex so that the tissue fold to form a tube to convey the milk through to the Omasum.RumenThe breakdown of food is accomplished partly by physical and partly by chemical means.The contents of the rumen are continually mixed by the rhythmic contractions of its walls. During rumination, material at the anterior end is drawn back into the oesophagus and to the mouth. In the mouth, coarse material is thoroughly chewed (40-50 times) before being returned to the rumen. Rumination in cattle lasts about 8hrs a day. The chemical breakdown of food in the reticulo-rumen is brought about by enzymes secreted by microorganisms. The reticulo-rumen provides a continuous culture system for anaerobic bacteria, protozoa and fungi. Food and water enter the rumen and the food is partially fermented to yield principally VFAs, microbial cells, and the gases methane and CO2.  The gases are lost by eructation (belching) and the VFAs are absorbed through the rumen wall.Homeostasis in the rumenLike other continous culture systems, the rumen requires a number of homeostatic mechanisms. The acids produced by fermentation are theoretically capable of reducing the pH of rumen liquor to 2.5-3.0, but under normal conditions, the pH is maintained at 5.5-6.5. Phosphate and bicarbornate contained in saliva act as buffers; in addition, the rapid absorption of the acids as well as production of ammonia from microbial digestion of proteins help to stabilize the pH. The osmotic pressure of rumen contents is kept near that of blood by the flux of ions between them. Oxygen entering with the food is quickly used up and anaerobiosis is maintained. In the absence of oxygen, carbon is the ultimate acceptor of hydrogen ions hence the formation of methane. The temperature of rumen liquor remains close to that of the animal (38-42°C). Finally the undigested components of the food together with soluble nutrients and bacteria, are eventually removed from the rumen by the passage of digesta through the reticulo-omasal orifice.OmasumAfter rumination, ingesta travels to the omasum. 60-70% of water entering is absorbed, ~ 100L/d. Also VFAs (though mostly absorbed in rumen). Omasum has leaf-like projections that increase SA for absorption.Abomasum The microbial cells together with undegraded feed components pass to the abomasum and small intestines; there they are digested by enzymes secreted by the host animal and the products of digestion are absorbed. In the large intestines, there is a second phase of microbial digestion. The VFA produced in the large intestines are absorbed, but microbial cells are excreted with undigested feed components in the faeces.Digestion of carbohydratesThe diet of ruminants contains considerable quantities of cellulose, hemicelluloses, starch and water soluble carbohydrates, mainly in the form of fructans. In mature herbage and in hay and straw, the proportion of cellulose and hemicelluloses is much higher and that of water soluble carbohydrates is much lower. Carbohydrates (cellulose) are partially fermented to yield volatile fatty acids (acetic, butyric, propionic and isobutyric), gases (carbon dioxide, 60% and methane, 40%).The gases are lost by eructation (belching) and the VFAs are absorbed through the rumen wall.Digestion of proteins-Feed protein are hydrolyzed to peptides and free amino acids by rumen microbes but some amino acids are degraded further to organic acids, ammonia and carbon dioxide.-The ammonia produced, together with some peptides and free amino acids, are utilized by the rumen microbes to synthesize microbial proteins and form new bacterial cells.-The new bacterial cells are eventually killed and digested in acidic Abomasum and later in small intestines to provide the animal’s requirement of amino acids. Ribonucleases and deoxyribonucleases in pancreatic juice digest the nuclear materials of the microbial cells. -The excess Ammonia is absorbed into the blood and transported to the liver, where it is converted to urea (a less toxic compound).-Urea can either be:Transported through blood to the salivary glands where it is secreted together with saliva and returned to the rumen where it is converted to microbial protein.Returned to the rumen directly through the rumen wall (from blood).Excreted into urine.RDP,RUDP AND NPNProtein →              RDP→                peptides→           amino acid↓ ↓RUDP               urea (NPN)           ← liver              ←ammonia   →    Co2 + H2O + Urea↓ ↓    ↓ ↓ 0Amino acids      Saliva or rumen  Kidney               Microbial protein                                                   ↓ ↓                        Urine                  Amino acidsRDP- Ruminally degradable ProteinRUDP- Rumen Undegradable ProteinNPN- Non Protein NitrogenLow producing animals are able to meet their requirement from microbial proteins but high producing animals cannot meet their requirement from these. Therefore they require the high RUDP and NPN such as urea, ammonium salt or biurate to supplement microbial proteins.Protection of high quality proteins from degradation in the rumen is either by treating chemically (formalin) to reduce their solubility or by giving them liquid suspensions that can be made to by-pass the rumen.UREA provides a source of N (NPN) to ruminants. This is of great importance because urea, which can be cheaply synthesized, can be added to the feed of ruminants in order to increase protein synthesis.NOTE that too rapid conversion of urea to ammonia in rumen may lead to toxicity.Digestion of lipidsLipids are hydrolyzed by rumen microbes to glycerol and fatty acids.                                             The glycerol produced is further fermented to propionic acid. Most of the unsaturated fatty acids derived from hydrolysis of lipids are usually hydrogenated to produce saturated fatty acids.2.0 MACRO AND MICRO NUTRIENTS & THEIR UTILIZATIONThe main components of foods (diet), plants and animals are: 2.1 WATER- The water content of the animal body varies with age.- Water makes up 65-85% of the total body weight of the young animal.- It is vital to the life of the organism that the water content of the body be maintained. An animal will die rapidly if deprived of water than if deprived of feed.Types of waterIntracellular water- within the cell (muscles, skin)Extra cellular water- outside or between the cells of the body (blood, synovial, digestive system, cerebral/spinal fluid).FunctionsMany of the chemical reactions brought about by enzymes take place in solution and involve hydrolysis.Solvent in which nutrients are transported about the body and in which waste products are excreted.Maintain constant body temperature.(high specific heat of water, high latent heat of evaporation)Maintain shape of the cells within the body.Lubricate various joints and organs within the body cavity.Major sources of waterDrinking waterWater intake will depend on: environmental temperature and humidity,dry matter intake, more food more water,physiological state of the animal, lactating.FeedVary with the type of feedstuff offered to the animal, example silage (80%), hay (10%). Because of this great variation in water content, the composition of feeds is often expressed on dry matter basis, which allows a more valid comparison of nutrient content. The water content in a growing plant is related to the stage of growth.Metabolic waterArise during metabolism by the oxidation of the hydrogen- containing organic nutrients within the bodyIt accounts for about 5-10% of the total water requirement of the animal.Example Glycerol + Fatty acid => Triacylglycerol + WaterWater lossExpired airEvaporationPerspirationFaeces/urineAbnormal retention- oedemaEffects of water lossInitial thirst,Dehydration,Anorexia- when water deficiency reaches 4-5% bwt,Reduced production,Death.DRY MATTERORGANIC COMPONENTSCarbohydratesAre organic compounds with the general formula (CH2O) n where n ranges between 3-7.Most of it is produced during photosynthesis in plants. Some CHOs contain N, P and S.Classification of CHOsUsually divided into two major groupsSugars; Restricted to those carbohydrates containing less than ten monosaccharide residues.Non-sugarsSugars:i) Simple sugarsMonosaccharide – vary in their number of carbon atoms (3-7)SubgroupsTrioses (C3H6O3)- Glyceraldehyde & dihydroxyacetoneTetroses (C4H8O4)- ErythrosePentoses (C5H10O5)- xylose, riboseHexoses (C6H12O6)- glucose(grape sugar), fructose(fruit, honey)Heptoses (C7H14O7)-SedoheptuloseThese monosaccharides linked together, with elimination of one molecule of water at each linkage produce a disaccharide, trisaccharide or polysaccharide.ii) Complex sugars/OligosaccharidesExample: Disaccharides, trisaccharides and tetrasaccharides.The most nutritionally important disaccharides are sucrose, maltose, lactose and cellobiose which on hydrolysis yield two molecules of Hexoses;C12H22O11 + H2O→2C6H12O6Sucrose – glucose + fructose when hydrolyzed by sucraseSugarcaneLactose – glucose + galactose when hydrolyzed by lactaseMilkMaltose – glucose + glucose when hydrolyzed by maltaseBarley – malt sugarCellobiose- repeating units of cellulose.Non-sugarsPolysaccharidesThese are higher molecular weight carbohydrates containing many simple sugar molecules.Starch-It is present in many plants as a reserve carbohydrate.It is most abundant in seeds like grain of maize or tuber and roots of potatoes and cassava respectively.Made up of many glucose units linked together.glycogenmain carbohydrate storage product found in animal tissue.celluloseMost abundant plant constituent, forming the fundamental structure of plant cell wallsMade of glucose units linked togetherTend to form chemical linkages with lignin and this bond is hard to breakLignin reduces digestibility of cellulose and its availabilityNOTE -Mature hay and straws are rich in lignin and unless treated chemically to break bonds between lignin and cellulose, the feeds are low in digestibility.HemicelluloseMade up of many monosaccharides like glucose, galactose, mannose, xylose, rhamnose and arabinose units.Dissolved in alkaline solution to improve digestibility; feeds like straw can be treated with alkaline solution.Hemmicellulosses include – xylans, arabinoxylans, glucuronoxylans, glucomannan and xyloglucan.LIPIDS-These are substances that are insoluble in water but soluble in organic solvent like ether, chloroform and benzene.FunctionsSupply of energyServe as  carriers of the fat soluble vitamins (ADEK)Form components  of various biological membranes- cell membraneInsulation.Lipids are either oils or fats.Oils are liquid at room TºCFats are solid at room TºCLipids are made up of two components:Glycerol moleculeFatty acids   The type of lipid varies with the type of fatty acid it contains.Properties of fatty acidsContain carboxyl group (-COOH)Are straight chainCan either be saturated or unsaturatedExamples Saturated – stearic acid (C18), no double bondPalmitic acid (C16) Unsaturated – oleic   (C18) 1 double bondlinoleic (C18) 2 double bondslinolenic (C18) 3 double bondsEssential Fatty AcidsCannot be synthesized within the body of an animal.They are essential for chicken, pigs, goats and cattle.Examples- linolenic                      -linoleic                     - Arachidonic (C20), 1 double bond Deficiency symptomsScaly appearance of the skin,Increased permeability to water and increased water consumption,Increased susceptibility to bacterial infections,Sterility,Less stable biomembranes,Capillary fragility,Kidney damage, haematuria and hypertension,Decreased visual acuity,Decreased myocardial contractility,Decreased ATP synthesis in liver and heart,Decreased nitrogen retention.The membranes of various body cells contain unsaturated fatty acids and to maintain their integrity, maintaining the level of the unsaturated fatty acids is important.Derived lipids These are compounds related to fatty acids and are involved in physiological reaction processes.Examples- steroids, cholesterol, bile acids, vitamin D, prostaglandins.PROTEINProteins are the principle constituent of the organs and soft structures of the animal body.Contains- C, H, and ONDepending on the type of protein S, PAmino acids are the basic building units of proteins and are final products when proteins are hydrolyzed. Amino acids NH2 (amino gp)            │        R– CH │ COOHR- Side chain. May be a H atom as in glycine, or may be a complex radical containing e.g. a phenyl gp (cyclic group of atoms with the formula C6H5).Proline is the only amino acid with an imino gp (-NH) instead of an amino gp.Although over 200 amino acids have been isolated from biological materials, only 20 of these are commonly found as components of proteins.Amino acid are usually linked together by the peptide bond between the carboxyl and amino group to form the proteinsComponents of different proteins depend on arrangement and type of amino acid within the chain.Animals cannot synthesize the amino group but can only be synthesized by plants and microorganisms from simple nitrogenous compounds such as nitrates.Certain amino acids can be produced from others by a process of transamination.Those amino acids that are not synthesized through the process of transamination are called essential or indispensable amino acids because they must be provided in the diet since animals require them.Essential amino acidsPhenylalanineValineThreonineTryptophanIsoleucineLeucineMethionineHistidineArginineLysineNon-essential amino acidsThe body has the capacity to synthesise these amino acids hence not required in the dietAlanineAsperagineCystineGlutamineCysteineGlycineGlutamic acidHydroxyprolineProlineSerineTyrosineProtein functions1. Antibodies - are specialized proteins involved in defending the body from antigens (foreign invaders). One way antibodies destroy antigens is by immobilizing them so that they can be destroyed by white blood cells.2. Contractile Proteins - are responsible for movement. Examples include actin and myosin. These proteins are involved in muscle contraction and movement. 3. Enzymes - are proteins that facilitate biochemical reactions. They are often referred to as catalysts because they speed up chemical reactions. Examples include the enzymes lactase and pepsin. Lactase breaks down the sugar lactose found in milk. Pepsin is a digestive enzyme that works in the stomach to break down proteins in feed. 4. Hormonal Proteins - are messenger proteins which help to coordinate certain bodily activities. Examples include insulin, oxytocin, and somatotropin. Insulin regulates glucose metabolism by controlling the blood-sugar concentration. Oxytocin stimulates contractions in females during parturition. Somatotropin is a growth hormone that stimulates protein production in muscle cells.5. Structural Proteins - are fibrous and stringy and provide support. Examples include keratin, collagen, and elastin. Keratins strengthen protective coverings such as hair, quills, feathers, horns, and beaks. Collagens and elastin provide support for connective tissues such as tendons and ligaments.6. Storage Proteins - store amino acids. Examples include ovalbumin and casein. Ovalbumin is found in egg whites and casein is a milk-based protein.7. Transport Proteins - are carrier proteins which move molecules from one place to another around the body. Examples include hemoglobin and cytochromes. Hemoglobin transports oxygen through the blood. Cytochromes operate in the electron transport chain as electron carrier proteins.VITAMINS-These are organic compounds which are required in small amounts for normal growth and maintenance of an animal’s life.- Some compounds function as vitamins only after undergoing a chemical change. Example, β-caroteneThey are described as provitamins or vitamin precursors.Many vitamins are destroyed by oxidation. This process is speeded up by the action of heat, light and certain metals such as iron.Classification of vitaminsVitamins are chemically heterogeneous and are not related.They are classified according to their solubility.Fat soluble vitamins- ADEKOccur in plants as provitamins.Vitamin precursor chemical nameA Carotene retinolE α-tocopherol tocopherolD---D2 (ergocalciferol)      Ergocalciferol ergocalciferol        D3 (cholecalciferol)        K----K1 (phylloquinone)        phylloquinone phylloquinone         K2 (menaquinone)                  K3 (menadione) Usually absorbed in the presence of fats in the intestines.Stored within the fats in the body.Excreted only in faeces and not in urine.Not synthesized by the rumen microbes except the vitamin K.            (b) Water soluble vitaminsChemical name VitaminThiamine B1Riboflavin B2Niacin/ Nicotinamide B3Pantothenic acid B5Pyridoxine B6Biotin B7Folic acid/ Folacin B9CholineCyanocobalamin B12Ascorbic acid C Vitamin A                                                                   Does not exist as such in plants, but is present as precursors/provitamins in the form of certain carotenoids which can be converted into the vitamin, the most important being β-carotene.The source of β-carotene are carrots, sweet potatoes, yellow maize, grass, legume hay, grass silage, pumpkins e.t.cVitamin A is manufactured synthetically and can be obtained in pure form.FunctionsMaintenance of normal functioning of epithelial cells especially of the respiratory, reproductive, eye nerve and genital/urinary systems.Essential in regeneration of rhodopsin (maintain normal vision).Essential for growth and reproductionPrevent xerophthalmia(drying of conjunctiva)Deficiency symptomsNight blindnessImpaired reproductionRetarded growthLow egg production and hatchabilitySlow bone growthExcessive xerophthalmiaRough dry scaly skinVitamin DErgosterol and 7-dehydrocholesterol are the precursors of vitamins D2 and D3 respectively. These precursors are converted into the vitamins in the presence of energy, usually from UV rays of the sun, but artificially produced radiant light can also be used or certain kinds of physical treatment.Source- sun-dried roughages, dead leaves of growing plants. Most feeds of pigs and poultry, with the possible exception of fishmeal, contain little or no vitamin D, and the vitamin is generally supplied to them, if reared indoors, in the form of fish-liver oils or synthetic preparations. FunctionsHormonal function: 1,25-dihydroxycholecalciferol, a secondary derivative of vitamins D2 and D3 in the kidney, acts in a similar way to a steroid hormone, regulating DNA transcription in the intestinal micro-villi, inducing the synthesis of mRNA, responsible for production of calcium binding protein.Enhance the absorption/utilization of Ca and P from the intestines.Deficiency symptomsLeads to rickets in young animals osteomalacia (reabsorption of bone), swollen joints and bone sickness in adult animals.Soft and rubbery bones and beaks in birds.Retarded growth in poultry. weak legs in poultryThin egg shells poor egg production reduced hatchability.ToxicityHypercalcaemia- increased calcium absorption.Symptoms  -   Excessive thirstvomitingconstipation with alternating diarrhealoss of appetiteslow growth and weight lossfrequency of urination.Vitamin EA group of eight naturally occuring compounds, existing in two forms; saturated and unsaturated. The saturated include δ-,γ-,α- and β-tocopherols, with α form being most biologically active. The unsaturated include δ-,γ-,α- and β-tocotrienols. Unlike Vitamin A, Vitamin E is not stored in the body in large amounts, therefore a regular dietary source is important.Sources- cereal grains, green vegetables, vegetable oils, green fodder especially young grass (good source of α-tocopherol). Synthetic α-tocopherol is available as a commercial preparation. FunctionsAs a biological antioxidant( prevent oxidation of cells/fatty acids)Maintain the integrity of cellular structures of lipids and their products(prevent rancidity).Proper growth.Component of enzymes.Cellular respiration of the muscles.Important in the development and function of the immune system.Deficiency symptomsReproductive failures.Encephalomalacia (softening of brain tissue) in chicks; crazy chick disease; inability to walk or stand; hemorrhages and necrosis of brain cells.Myopathy (muscle degeneration)/Muscular dystrophy (Nutritional myopathy): Cause myocardial degeneration in cattle and sheep; Skeletal muscle degeneration in young goats and sheep (stiff lamb disease); weak legs, difficulty in standing, trembling and stagerring gait, inability to rise, weakness of neck muscles hindering raising of head. Myopathy and cardiac disease in pigs; uncoordinated staggering gait and inability to rise. Heart muscles are most affected resulting to death (cardiac failure).Slow growth and poor hatchability in chicken.Reduced feed intake and slow growth in pigsCause oxidative diathesis- a vascular disease resulting in accumulation of fluids in the subcutaneous fat tissues due to an abnormal permeability of capillary walls.Vitamin KIt is an anti-haemorrhagic vitamin in chicks.Bacteria have the ability to synthesise Menadione/vitamin K in the small intestine and colon.It is stored in the liver.Source- Phylloquinone (the form in plants) is present in green leafy material, Lucerne, cabbage, kales.It is relatively stable at ordinary temperatures but are rapidly destroyed on exposure to sunlight.FunctionProduction of prothrombin in liver used in blood clotting.Deficiency symptomsProlonged blood clotting time,Generalized haemorrhages,Pale anaemic appearance in birds- comb, wattles.WATER SOLUBLE VITAMINSVitamin B1 (thiamine)Thiamine occurs naturally in the outer seed coats of many plants and cereal grains, brewers’ yeasts.In animal tissue, it occurs as a coenzyme called “Thiamine pyrophosphate” that is required in energy metabolism.Deficiency symptomsPolyneuritis i.e. degeneration of peripheral nerve systems,Anorexia, loss of weight, unsteady gait,Blue comb in adult chicken,Slow growth.VITAMIN B2 (riboflavin)Synthesized in all green plants and in some bacteria (except lactobacilli).      Sources-    milk-whey,green leafy crops,good quality hay,N.B.: Cereal grains are poor sources of vit. B2.FunctionComponent of two enzymes- Flavin mononucleotide (FMN)                           - Flavin adenine dinucleotide (FAD)They are important in                 -   Carbohydrate and amino acid metabolism,Fatty acid synthesis and metabolism,Deamination of amino acids,ATP production.Deficiency symptomsCurled toe paralysis in chicken,Ocular abnormalities,Dermatitis in pigs,Slow growth,Impaired RBCs.Pantothenic acid (Vit B5 )This is a derivative of butyric acid and pentoic acid which are normally joined to amino acid, β-Alanine.Sources- groundnuts, peas, yeasts, molasses, cereal grains.FunctionsImportant in metabolism of carbohydrate, fats and amino acids as it is a constituent of coenzyme A.Deficiency symptomsDermatitis in chicks- mouth and eyes,Growth retardation in pigs,Still gait,Poor appetite,Diarrhea,Reduced reproductive performance,Alopecia,Rough feathers.Biotin (B7)Occurs linked to amino acid Lysine.Sources- most feeds including milk, vegetables and rumen synthesis.FunctionsRequired in enzyme reactions like in the case of carbondioxide fixation, fat synthesis, amino acid deamination, protein synthesis, and carbohydrate metabolism.Deficiency symptomsDermatitis,Perosis- bone deformities in chicken,- cracked hooves in pigs and feet in chicks.Nicotinamide (nicotinic acid)It is a component of enzyme NAD (Nicotinamide adenine dinucleotide) and NADP.FunctionNAD and NADP are important enzymes in carbohydrates, proteins and lipids metabolism.Deficiency symptomsskin and nervous system disorders,Perosis, retarded growth and feathering disturbances in chicken,Dermatitis, loss of appetite and enteritis in pigs.Vitamin B6 (pyridoxine)3 forms which are interconvertible in body tissues: Pyridoxine (parent substance), Pyrodoxal (aldehyde derivative) and Pyridoxamine (amine). Amine and aldehyde derivatives are less stable and destroyed by heat. Source- present in plants as pyridoxine. Animal products may also contain pyridoxal and pyridoxamine. Sources include cereal grains, milk, pulses, yeasts. FunctionPyridoxal phosphate is the most actively functioning, playing a central role as a coenzyme in amino acid metabolism.Believed to play a role in absorption of amino acids from the intestines.Deficiency symptomsA wide variety of biochemical lesions, affecting animal’s growth rate,Convulsions- epileptic conditions, muscle twitching,Chicks show jerky movements,Reduced egg production and hatchability in adult chicken,Anorexia and Anaemia in pigs.N.B. : Deficiency unlikely to occur in practise in farm animals due to wide distribution of the vitamin.Folacin (folic acid)The chemical name is pteroylmonoglutamic acid. Several active derivatives occur, containing up to 11 glutamate residues in the molecule. The monoglutamate form is readily absorbed from the git but the polyglutamates must be degraded by enzymes to the monoglutamate form before they can be absorbed. Source- green leafy vegetable materials, cereals, extracted oil seeds and animal protein meal. It is reasonably stable in foods stored under dry conditions but is readily degraded by moisture, particularly at high temperatures. It is also destroyed by U.V. light.FunctionAfter absorption is converted into tetrahydrofolic acid, which functions as a coenzyme in the metabolisation and utilization of single-carbon groups (e.g. formyl, methyl) that are added to or removed from such metabolites as histidine, serine, glycine, methionine, and purines. Involved in the synthesis of RNA, DNA and neurotransmitters. Deficiency symptomMegaloblastic anaemia- large and immature RBCs anaemia. Poor growth, Poor bone development,G.i.t disorders,Poor egg production and hatchability,Stiff neck paralysis in turkeys.CholineIt is normally synthesized in the liver from Methionine. The exogenous requirement for it is therefore influenced by the level of methionine in the diet. Source- , green leafy materials, yeast, cereal and legumes.Functions: unlike other B vitamins, is not a metabolic catalyst. A methyl donor especially in lipid metabolism-transmethylation reactions-which involve folic acid or Vit B12. A component of acetylcholine, responsible for the transmission of nerve impulses.Component of Lecithins, which play a vital role in cellular structure and activity. plays important role in lipid metabolism in the liver  where it converts excess fat into lecithin or increases the utilization of fatty acids, thereby preventing the accumulation of fat in this organ.Deficiency symptoms-Perosis/slipped tendon in chicks.- Fatty liver- fatty infiltration of the liver in chicks and pigs.- Slow growth in chicks and pigs. (CAT 25/3/19 @ 3.50PM)Vitamin B12 (Cyanocobalamine)Occur in animals and microorganisms (microbial vitamins). Intestinal synthesis occurs in pigs and poultry and rumen synthesis in ruminants.Functionsred blood cell production, production of DNA and RNA, energy metabolism and proper nerve function.Deficiency symptomsLead to pernicious anaemia.Retarded growth and high mortality in young animals.Poor feathering and kidney damage may occur.Poor growth in piglets and lack of coordination of hind legs.In older pigs, dermatitis, a rough coat and suboptimal growth.In ruminants, reduced appetite, emaciation and anaemia.Neurological disorders.Reduced hatchability.N.B. : Deficiency of cobalt will result in deficiency since it is a component of the Vitamin.Vitamin C (ascorbic acid)Produced from D-glucoseDestruction is accelerated by exposure to lightSources- green leafy vegetables, citrus fruits.FunctionsEnergy production.Important in maintenance of normal collagen metabolism.Important in storage of iron in bone marrow, liver and spleen.Biological antioxidant.Deficiency symptomsNot yet seen in livestock because they synthesize this vitamin.Inorganic components of dry matterMINERALSThey occur all over in the environment- soils, plants, animals, and atmosphere.There are two categories:Minor/trace elements.Major elements.The trace elements are those required in small quantities in the body because of their concentration. Examples- copper, cobalt, iodine, iron, manganese, molybdenum, selenium, zinc, fluorine, nickel, silicon and chromium.Major elements are required in larger quantities for the roles they play. They include calcium, phosphorus, sodium, potassium, magnesium, chlorine and sulphur.Minerals are found in cells and tissues of the body in different chemical composition and concentrations. The concentrations of these elements have to be maintained within narrow range to avoid either deficiency or toxicity. This is referred to as normal ranges.Maintaining the concentration at normal range is important in the maintenance of the functional and structural integrity of different tissues of the body, so that the growth, productivity and health of the animal are not impaired.Variations of minerals in the bodyThis is contributed by the level of elements in the feeds or plants consumed by the animal.The level of elements in the feed or plants consumed depends on:Soil – mineral availability in the soil vary from one area to anotherClimate- mineral elements are low during dry season hence deficiency.Species of plant consumed by the animal- shrubs, legumes, browse(high), grasses(low).Interaction of the various mineralsExample- Fe, Zn, Mn, Co, and Pb share same absorption and transport pathways within the bodyHigh intake of Zn leads to Cu deficiency,High concentration of Pb in Fe deficient animal lead to Pb toxicityCu-Mo-S interaction: high intake of Mo leads to deficiency of CuFormation of insoluble complexesExample- Phosphorous form Phytate   - Oxalates inhibit absorption of Ca.SOURCES, FUNCTIONS AND EFFECTS OF DEFICIENCY OF MINERALSMAJOR ELEMENTSCALCIUMMost forages are good sources of calcium, although some, like oat forages and corn silage, are marginal to low in this mineral. Grain is a poor source of calcium. Other sources, particularly for non-ruminants; ground limestone, Dicalcium phosphate, defluorinated rock phosphate, steamed bone meal.FunctionsImpulse transmission- regulate neuromuscular transmission.Muscle contraction- reaction between actin and myosin proteins.Blood clotting process.Secretory process- example insulin.proper bone and teeth formation.Deficiency symptomsrickets  - Enlarged joints,- Lameness and stiffness, - Disorder of bones.Osteomalacia- occur in mature animals- Ca is withdrawn from bones hence cause weak and brittle         bones            - Thin egg shell.Milk fever(Parturient Paresis)Mainly occurs in dairy cows shortly after or before calving,High producing animals tends to divert all Ca to the production of milk hence low level of Ca in the plasma (serum Ca) – hypocalcaemia.Impairment of nerve impulse transmission hence the animal gets weak and lies down (lateral recumbency).PHOSPHORUSSource- milk, cereal grains, FM and meat products containing bones.Note- content in hay and straws are very low.P deficiency is common during dry season and this also depends on age of the plant example, old and mature plants have low P.FunctionsBone formation,Component of phospholipids, phosphoproteins, DNA, and RNA,Important in energy metabolism in the formation of sugar-phosphates and adenosine di- and triphosphates-ADP and ATP,Has buffering effect in various tissues of the body like in saliva and urine.Deficiency symptomsRickets,Osteomalacia (softening of bones),Depraved appetite/pica- abnormal appetite and chew bones, wood, rags etc.,Chronic P deficiency leads to stiff joints and muscular weakness,Poor fertility- irregular oestrus and low conception rate,Subnormal growth in young animals and low live weight gains in the mature,Reduced milk yield in cattle,Reduced egg yield, hatchability and egg shell thickness in hens.Calcium:phosphorus ratioWhen giving calcium supplements to animals it is important to consider the Ca:P ratio in the diet, since an abnormal ratio may be as harmful as a deficiency of either in the diet.The Ca:P ratio considered most suitable for farm animals other than poultry is generally within the  range 1:1 to 2:1.The proportion of Ca for laying hens is much larger.MAGNESIUMIt is closely associated with Ca and P because 70% of the total Mg is found in skeleton and remainder in soft tissues and fluids.Sources- wheat bran, dried yeast, most vegetables (e.g. clovers), protein concentrates like CSC and linseed cake, soya bean meal.FunctionsEnzyme activator,Involved in cellular respiration,Regulation of neuro-muscular transfer of nerve impulse.Deficiency symptomsGeneral loss of appetite,Hypomagnesaemic tetany- affect animals which have been introduced to rapidly growing pasture especially during rainy season,Transit tetany- stress during transit especially horses.Tetany- nervousness, tremor, twitching of facial muscles, staggering gait and convulsions.SODIUMSource- animal products- meat meals, foods of marine origin           - Sodium chloride (common salt)FunctionsAcid base balance and osmotic pressure regulation of body fluids,Absorption of sugars and amino acids from digestive tract,Transmission of nerve impulses.Deficiency symptomsDehydration of the body,Poor growth and reduced utilization of digested proteins and energy,Reduced egg production.POTASSIUMPotassium content in plants generally is very high especially in grass hence deficiency symptom are rare.FunctionsOsmotic regulation of the body fluids,Acid- base balance in the animal,Nerve and muscle excitability,Energy metabolism.SULPHUR FunctionsIt is a component of:Protein containing amino acids- Cystine (wool is rich in Cystine), Cysteine, Methionine,vitamins biotin and thiamin- important in lipid and carbohydrate metabolismhormone insulin.Deficiency symptomsWool production is reduced,Reduction in weight gain/poor growth and Reduced egg production and growth in hens.IRONSource- seed coats, green leafy vegetables, most leguminous plants, meat, blood, and fish meals.Note: milk is a poor source.FunctionsComponent of proteins- Haemoglobin- Transferrin- transfer of iron from one part of the body to anotherin oxidative enzyme systems involved in energy metabolism.Deficiency symptomsAnaemia -piglet anaemia characterized by- Poor appetite and growth           - Difficult breathing    - pale mucus membranes.COPPERSources- seeds and seed by-products, straw, forage.FunctionsFormation of normal RBCs,Proper formation of bones,Normal pigmentation of hair, fur and wool.Deficiency symptomsAnaemia, poor growth, bone disorders, scouring/diarrheaLow fertility rate,Enzootic ataxia/sway back characterized by the inability to co-ordinate the movement of the hind leg and walk by staggering/swaying-lambs.COBALTFunctionsConstituent of vit.B12: Cobalt is required in synthesis of vit.B12  by microorganisms in the rumen.Deficiency symptomsReduced appetite,Reduction in growth rate- emaciation,Anaemia- Megaloblastic anaemia.IODINEFunctionsConstituent of thyroxin- stimulate various metabolic reactions in the body.Deficiency symptomsPoor growth of the animalReproductive failureGoiter- enlargement of the thyroid glandMANGANESEFunctionsEnzyme activator in carbohydrate and lipid metabolism,Essential for normal bone formation.Deficiency symptomsSkeletal abnormalities,Poor growth,Uncoordinated movement/ataxia in young animals,Reproductive failure- Spermatogenesis and libido,           - Oestrus cycle,          - High rate of abortion.Reduced hatchability,Egg shell thickness is reduced.ZINCFunctionsHealing of wounds,Activator of several enzymes.Deficiency symptomsDelayed wound healing,Depressed appetite,Scabs on the skin,Reproduction is affected.SELENIUMFunctionsConstituent of the enzyme glutathione peroxidase which catalyses the removal of hydrogen peroxide in the cells hence it maintain the integrity of cellular membranes.Deficiency symptomsNutritional muscular dystrophy in lambs- weakening of muscles,Generalized oedema in poultry because of increased permeability of capillary walls,Encephalomalacia (crazy chick disease) because of haemorrhages in brain,Reduced hatchability and egg production.EVALUATION OF FEEDSMethods of feed evaluationPhysical/sensory evaluationBiological evaluationChemical evaluationLab/invitro evaluationPhysical/Sensory evaluationTouch, smell, sight, can be initially used to assess feed quality issues. Physical/Sensory evaluation may suggest further chemical or physical characterization of the feed is necessary. Initial visual evaluation of a feed would include:1. Stage of Maturity: refers to the growth stage of the plant at the time of harvesting.More mature plants will have larger and thicker stems and either seed heads or blooms. Too young and too old plants are less nutritious than plants that have just reached maturity.2. Leafiness: is an important factor in evaluating hay since most of the digestiblenutrients reside in the leaf, especially protein. As the plant matures the leaf to stem ratio will decline. If the plant is not cured and handled properly many leaves will be lost due to leaf shatter. This is especially important in alfalfa hays.3. Color: e.g color of hay can indicate when the plant was cut and how well it was cured and stored. Bright green color indicates high vitamin A content and generally high quality. Yellowing color to the hay may indicate excessive sun curing, overly mature forage or both. Brown to black hay usually indicates heating from fermentation and moisture damage. These hays have the highest potential for molding and are unacceptable feeds.4. Odor: Odor of good quality hay should be similar to new-mown hay. Feed should nothave a musty, mildew or rotten smell. Heat-damaged feeds will often have a caramelized or tobacco smell.5. Foreign Material: is anything that does not belong in feed. Harmless foreign material would include certain weeds, other plants, sticks or dirt. Foreign materials of concern may include poisonous plants, awns, metal objects, insects and molds. Good quality feed should be free of foreign material. Biological evaluationInvolves the use of animalsFeeding trialsDigestibility trialsDegradabilityInvitro evaluationDone in the lab using machine that mimic the digestive system functions.Chemical evaluationDone by analyzing the various chemical compositions of the feedstuffs.This is achieved by carrying out proximate analysis of feedsProximate feed analysis give the following fractions:Moisture contentCrude protein (CP)Ash contentCrude fibre extract (CF)Ether extract (E.E)Nitrogen free extract (NFE)MoistureIt is determined as the loss in weight which results from drying a known weight of food to a constant weight at 100-115ºCIt is satisfactory for most food but such feeds like silage; there are significant losses of volatile material.Procedure: Measure the weight of a dry empty crucible (A)Place a sample of the feed on the crucible and measure the weight (B)Subtract A from B to get the weight of the feed sample (C) Place the sample on the crucible in the oven and dry 24-48hrs at temperatures between 100-115 ºC i.e. to a constant weight.Remove the sample and place in a dessicator to cool.Measure the weight of the sample (D)Subtract A from D to get the weight of the dried sample (E)Subtract E from C to get the moisture content of the feed. This can be expressed as a percentage as : Crude proteinIt is calculated from the nitrogen content of the food. In this method, food is digested with sulphuric acid which converts to ammonia all nitrogen present except that in form of nitrate and nitrite. The ammonia is liberated by adding NaOH to the digest, distilled off and collected in standard acid (HCL). The quantity so collected is determined by titration.It is assumed that N is derived from protein containing 16%N. The nitrogen value is obtained by multiplying the nitrogen figure by a constant 6.25. The figure obtained is not true protein since it determines nitrogen from other sources other than protein and the fraction is therefore designated CP.AshThe content is determined by ignition of a known weight of the food at 500ºC until all carbon has been removed. The residue is ash and represents the inorganic component of the food. It may contain materials of organic origin such as S and P from proteins. There is loss of Na, Cl, P, K and S hence not truly representative of the inorganic material.Ether extracts (E.E)It is determined by subjecting the food to a continuous extraction with petroleum ether for a defined period. The residue after evaporation of the solvent is the ether extract which contain true fat although it can also contains waxes, organic acids, alcohols, or pigments.Carbohydrate contain two fractions:Crude fibre(CF)It is determined by subjecting the residual food from ether extraction to successive treatment with boiling acid and alkali of defined concentration. The organic residue is CF represented by cellulose, hemicellulose and lignin.Nitrogen free extracts (NFE)When the sum of the amounts of moisture, ash, CP, ether extract and CF (expressed in g/kg) is subtracted from 1000, the difference is designated as NFE. UTILISATION OF FEEDSClasses of feedsThe feed classification is based on:nutrient in itits bulkinessRoughages/foragesconcentratesROUGHAGESAre feeds of plant origin with high CF content and low protein content.They are bulky hence suitable for the ruminants.Nutrient content depend on:Plant speciesPlant PhysiologyAge at which the material is utilizedSoil fertilityConservation methodStorage conditionsTypes of roughagesSucculent roughages- high moisture content and carbohydrate contentDry roughages- low moisture contentExamplespasturesAre of two groupsnatural pasturecultivated pasture- single or mixture of plant speciesFactors that affect nutritive value of pasture forageStage of growth when the material is being utilizedWith advancement in maturity there is an/a:increase in DM production/unit area of landdecrease in protein contentdecrease in mineral contentincrease in CF contentdecrease in carotene contentComposition of plant species- legumes, legume/grass mixture, grass pastureClimate- extreme wet or coldFertilizer applicationFodders- cut and carryConserved foragesHayIt is conserved by reducing the moisture content to a level of ≤15%. This is to inhibit the action of plant and microbial enzymes.For good quality hay, the plant material must be cut at an optimum stage of maturity so as to harvest a maximum amount of nutrients/unit area of land.Losses that occurs during drying and storageMechanical lossesThe leaves loose moisture more rapidly than the stems hence they become brittle and shatter in case of excessive handling. The leaves contain 2-3 times more of the total CP than the stem.LeachingWhen partially dry material is exposed to the rain, the soluble nutrients are leached. The exposure to rain also encourages the enzyme activity and growth of moulds.Plant enzymesThe enzymes are active when the weather is not favourable. They destroy plant nutrients by fermentation and cell respiration.OxidationExposure to sun leads to oxidation of carotene. The material turn brown which means 90% of carotene has been lost.Heat damage/action of microorganismsIf the material is stored with excess moisture the activities of bacteria and fungi are enhanced leading to production of heat which destroy proteins and carotene.Treatment of hayUse preservatives- propionic acid and acetic acid which inhibit the activities of microorganisms.Drying agents- sodium and potassium bicarbonate which disrupt the waxy layer in forage hence enhance rapid dryingAnhydrous ammonia- inhibit Moss, breakdown cell wall, source of N.Characteristics of good hayColour- much of green colour should be retainedLeaf: stem ratio- should be highAbsence of foreign materialsAbsence of mouldsHay materialsGrasses, legumes (Lucerne, clover, soybeans) and cereals (barley, oat, wheat).SILAGEThis is a material produced by the controlled fermentation of a crop of high moisture content. The process is called ensiling or ensilage. The fermentation process is controlled by encouraging the growth of lactic acid bacteria which are present on the fresh herbage or pre-wilted crop. In order to obtain successful preservation, it is necessary to achieve and maintain anaerobic conditions.This is achieved by:Chopping the crop during harvesting into small sizesRapid filling of the siloAdequate consolidation (compaction) and sealingCrops for silage makingGrasses, legumes, whole cereals (especially wheat and maize) and fruit residues.Losses that occur during ensiling and storage processField losses: during harvesting, chopping process and transportationGaseous (CO2, H2, NH3) or fermentation losses: especially due to clostridia and enterobacteria.Surface spoilage through oxidationLoss through seepage especially too wet material ( effluent)Characteristics of good silageSweet and aromaticColour close to naturalNo mouldsNot slimyCROP RESIDUESThey have fewer nutrients and are mainly used during dry season. Consists of the stems and leaves of plants after the removal of the ripe seeds by threshing and are produced from most cereal crops and some legumes.Examples- barley and oat straws, maize stovers, legume strawTreatment methodsBiological: e.g. the use of lignin degrading microorganisms such as white rot fungi- produce ligninolytic enzymes. Physical processingReduce particle size and bulk by grinding, milling, chopping or compaction. This method:Increase the density of material and the capacity of the animal to consume it.Reduce the chewing timeIncrease the surface area Increase the rate of passage of material through the gastrointestinal tractChemical treatment- sodium hydroxide, ammonium hydroxide, ammonia gas, calcium hydroxide, potassium hydroxide or urea.CONCENTRATESEnergy supplementsThese are cereals and their by-products.Contains less than 20%CP & CFExamplesMaizeContains about 80% total digestible nutrients.Poor in calcium but fair in P and good source of thiamineYellow maize has more caroteneFed in different forms- whole grain, maize & cob meal or high moisture maizeHighly digestible and acceptableSorghumAble to withstand heat and droughtResistant to pest like maize stalk borerAdapted to wide range of soil typesTDN-70%Some varieties have high tannin content which limit digestibility of nutrients and acceptabilityOatsLower energy content because of the seed coat which has high CFTDN- 70%Suitable for dairy animals because of its CP and bulkiness and acceptabilityBarleyHas a high energy contentTDN- 75%Highly acceptable to ruminantsThe cost is highWheatHigh energy contentTDN- 80%Not economical for feeding to animalsThe starch in it is broken down more rapidly than starch in maize hence when fed to animal, one has to incorporate sodium bicarbonate to buffer/neutralize the lactic acid produced (to avoid acidosis)MolassesHas high energy contentTDN- 70%A by-product of sugar processingCan either be in liquid or dehydrated formHighly acceptable and digestibleIncluded in feed to reduce dust or increase feed intake for example the crop residuesShould be less than 25% of the total ration because it can cause digestive disturbances like diarrhea because of its high salt content- Ca, K or Cl.For ruminants observe strictly less than 10% level of inclusion.PotatoesGood source of readily available carbohydrateHalf of N in it is contributed by NPN (peptides too small to be precipitated, free amino acids, amides and other nonpolymeric nitrogen cpds).Contain an alkaloid called solanidine which is toxic especially when potatoes are exposed to sunlight (they turn green)Remedy- removes the peel or boils to reduce solanidine and increase digestibilitySuitable for non-ruminantsCassavaTubers- very low in CP (30%)High TDNLeaves- CP 20%Both leaves and tubers contain toxic substance called prussic acidOvercome by: Drying before feedingBoilingHeating in an ovenProtein supplementsProtein is a critical nutrient especially in young and growing animals and high producing adult animals. Protein concentrates are more expensive compared to energy concentrates.The quality of protein concentrates is determined by the types of amino acids, the ratio and the amount of different amino acids. The main concern is the non-ruminants.Divided into two:animal originplant originPlant originOil meal- by-product of oil extractionSoya bean mealHighly palatable44%CPPoor source of CaHas trypsin inhibitor which suppress the activity of trypsin enzymeHas a high content of urease enzyme which breakdown urea into ammoniaCotton seed cake40%CP10-15%CFGood source of P but poor in CaHas an anti-nutritive factor, GOSSYPOL which is toxic to animal but its toxicity depends on the animal species and age.Ruminants are less affected and poultry more tolerant compared to pigsYoung animals are more susceptible to the effects.0.005% concentration cause discolouration of the egg yolk- turn greenish especially if stored for longRation for layers should be <5%Include iron sulphate to bind the gossypolSunflower cake24%CF32%CPGood source of PRich in Vitamins BLimited in lysineEnd product is very dusty hence reduced palatabilityHulls have high liquid absorption capacity suitable for ruminantsleguminous seedsBeans, peas and lupinsAnimal compete with man for these food.Animal originAre by-products of meat and fish processingAre expensive hence inclusion in the ration should be between 5-10%Rich in mineral and vitamin B complex.Fish mealDrying and grinding of either whole or certain part of fish>65%CPRich in lysine, Methionine and TryptophanHighly digestible when well prepared- 93-95%High content of minerals(21%)- Ca, P, Mn, I, and FeExcellent source of vitamin BGood source of rumen by-pass protein for ruminantsMeat mealDrying and grinding of carcassesFree from diseases, hairs, hooves, offal, horns and skin60-70%CPMeat and bone mealHigh proportion of bones45-55%CPGood source of minerals- Ca, P and MnGood source of lysineKeeping quality depends on residual oilBlood mealDrying blood from the slaughter housesFerment to improve the quality by adding molassesCP 80%Good source of ironRich in lysineGood source of rumen by-pass proteinMilk and by-productsSlightly deficient in sulphur containing amino acidsBy-products- (i) skim milkWhen cream is removedLow energy contentLow in fat soluble vitamins- A,D,E KGood source of protein for young animals in liquid form and powder(ii) Whey milkby-product of cheese makingmost protein will be removed together with fat and half Ca and PMainly used as a source of energyFACTORS THAT AFFECT FEED UTILISATION(A)Feed intakeThis is the amount of feed an animal consumes per time.General factor that affect feed intakePhysical factorsAccessibility of the animal to the feed resourcesRoughage content dietFeed preparationChemical factorsFibre contentEnergy levelProtein content of the rationPHToxicityPhysiological state of the animalGrowth stage of the animalLactating and pregnant animalBody sizeDiseaseSensory factorshypothalamus has two centers:Hunger centerFound in the lateral side of the hypothalamus. When it is stimulated during hunger (low glucose), the animal starts to eat or search for food.Satiety centerWhen stimulated the animal stop eating. This is brought about by distention effect which stimulates the stretch receptors and chemoreceptors which then transfer the information to the satiety center to inhibit feeding process.Climatic factorsTemperatureDuring cold season, animal consume more food because the animal need to generate heat hence energy requirement is very high.HumidityHigh humidity limit feed intakeSocial factorsThere will be competition hence aggressive animal will tend to have higher feed intake.(B) DigestibilityThis refers to the proportion of feedstuff which is not excreted in faeces and which is therefore assumed to have been absorbed by the animal.Digestibility (%) DM = I – F X 100      IExample:  An animal given 4kg DM/day of food containing 120g protein per kg excreted 0.5kg DM containing 150g protein per kg. Calculate the digestibility of the protein. Factors affecting digestibilityFeed factorsFeed composition- low CP and CFRation composition- readily available carbohydrateFeed preparation- grinding and choppingChemical treatmentLeaf: stem ratioLevel of feedingParasites, worms and diseaseAnimal factorsAnimal species- ruminant and non-ruminantAge of the animal- young and adultParasites and diseasesPhysiological status- lactating animalSYSTEMS OF EXPRESSING FEED ENERGY VALUESEnergy is required by the animal for all functions in the body. The functions involve the transfer and conversion of chemical energy into mechanical or heat energy. The ability of feed to supply energy is therefore of great importance in determining its nutritive value.Gross energy (GE)This is the total energy contained in feedstuff. The quantity of chemical energy present in a food is measured by converting it into heat energy and determining the heat produced. This conversion is carried out by oxidizing food by burning it. Therefore G.E is the quantity of heat resulting from complete oxidation of unit weight of food. It is expressed as MJ/kg DM. Not all GE is available to the animal for use. Some is lost through:FaecesUrineGasesHeat increment-mastication/digestion                              -heat of fermentationDigestible energy (DE)DE = gross energy – energy lost in faeces. Metabolizable energy (ME)ME = DE less the energy lost in urine and combustible gasesME = DE – losses in urine (urea) + gases (methane)Net energy (NE)NE is ME less the energy lost in form of heat (heat increment).NE is therefore the energy utilized by the body to perform various functions like maintenance and production.Starch equivalent (SE) The starch equivalent system (developed by Kellner in Germany) can be considered the first widely adopted net energy system. It expresses the efficiency with which 1 kg of feed is used for lipid deposition relative to 1 kg of pure starch.Partitioning of proteinCrude proteinThis is determined by nitrogen content of feedstuff when it is multiplied by the constant 6.25. CP = N x 6.25Digestible crude protein (DCP)This gives the proportion of CP that is digested and absorbed by the animal.Total digestible nutrients (TDN)The total digestible nutrient value of a feed is calculated as: digestible crude protein +digestible crude fibre + digestible nitrogen-free extract + 2.25 x digestible ether extract. In contrast to digestible energy (DE), which is based on energy values of nutrients, TDN is based on mass with a correction factor for lipids.INDICATORS OF PROTEIN QUALITYProtein quality A term used to describe the relative values of dietary proteins. In concept it is an estimate of how well the amino acid (AA) pattern of a dietary protein or combination of dietary proteins matches the pattern of the amino acids an animal requires. In application, less of a high quality protein (or a mixture of proteins with a highquality) will be needed to meet an animal’s requirement than when proteins of lowerquality are used. Estimates of protein quality can be made by calculation of the chemicalscore of the protein relative to the calculated pattern from the requirement of the animal. Chemical scores have percentage values such as 70%, etc. The chemical score is estimated from the amino acid content of the protein: it does not involve an animal assay. These estimates are the least accurate because they do not involve consumption, digestion and absorption of the dietary amino acids by the animal in question.Chemical score: Here, the quality of a protein is decided by that amino acid which is in greatest deficit when compared with the standard. The standard generally has been egg protein but currently a defined amino acid mixture, the FAO recommended reference amino acid pattern is used. The content of each of the essential amino acids of a protein is expressed as a proportion of that in the standard (the standard pattern ratio) and the lowest proportion taken as the score. In wheat protein for example, the essential amino acid in greatest deficit is lysine. The contents of lysine in egg and wheat proteins are 72 and 27 g/kg respectively and the chemical score for wheat protein is therefore 27/72=0.37 or 37%.The Essential Amino Acid Index (IAAI)Is the geometric mean of the egg, or standard pattern, ratios of the indispensable amino acids. It has the advantage of predicting the effect of supplementation in combinations of proteins. It has the disadvantage that proteins of very different amino acid composition may have the same or a very similar index. Protein efficiency ratio (PER): is the animal’s weight gain (in grams) per gram of protein consumed.A system used to evaluate the quality of dietary proteins. Groups of animals (usually laboratory rats or chicks) are fed diets containing 10% crude protein from the source to be evaluated. PER is calculated as the weight gain in grams divided by the grams of protein consumed over 4 weeks. In theory, the more closely the pattern of amino acids in the protein matches the pattern of amino acids the animal requires, the higher the quality. A high quality protein has a high PER because a smaller quantity can meet an animal’s needs.A problem with this estimate is that no value is given for meeting the maintenance requirement for protein. If an animal does not grow, PER is zero, even though the protein has provided its maintenance needs.Two other similar animal growth assays have been used to estimate protein quality: Net protein ratio (NPR) In the assay, growing animals (usually rats or chicks) are given a diet containing the test protein (or mixture of proteins) for a set period (commonly 10 days to 4 weeks). NPR is calculated from the weight gain of the test group (T), the weight loss of a similar group of animals given a protein-free diet (C) and the amount of crude protein consumed by the test animals (P) as:NPR = (T + C)/PUnlike protein efficiency ratio (PER), the assay takes account of the use of the protein in meeting the animal’s maintenance requirements.Net protein utilization (NPU) It is defined as the percentage of the dietary protein retained. The value of dietary protein (therefore, not a single protein) is estimated by use of an animal growth trial. This method involves measuring total body nitrogen in a group of experimental animals (groups of 4 or more rats) which have consumed a protein-free diet and another group fed a similar diet containing the test protein. After the animals have consumed the diets for the desired time (10 or more days) the value of the protein is estimated using the formula for NPU:NPU = 100 X ((Body N of test group) – (Body N of protein-free group))/(Nitrogen consumed)It therefore takes account of protein intake and digestibility, which is appropriate as animals have to eat, digest and absorb the amino acids released from the protein in order for it to be of value to them.Biological value (BV) A measure of protein quality. BV is calculated by measuringthe faecal and urinary nitrogen losses of two groups of growing rats: one given a protein free diet, the other a diet containing the test protein at a concentration of 10%:BV = 100 (Ni – (Nu – Nue) – (Nf – Nfe)) /(Ni – (Nf – Nfe))where, for the rats given the test diet, Ni is the nitrogen intake, Nu is urinary nitrogenexcretion, Nf is faecal nitrogen excretion; and, for the rats given the protein-free diet, Nue is urinary nitrogen excretion (endogenous urinary nitrogen), Nfe is faecal nitrogen excretion (metabolic faecal nitrogen). Thus, endogenous urinary nitrogen and metabolic faecal nitrogen are added to the nitrogen retained to give the total amount of nitrogen utilized. This is divided by the nitrogen truly absorbed (i.e. faecal nitrogen is correctedfor endogenous loss) to give the biological value, which is therefore independentof digestibility. BV is related to the simpler measure, net protein utilization (NPU):BV = NPU X true digestibility. Although originally designed and strictly defined as a test with rats, it has also been adapted for use with other animals.PRINCIPLES OF RATION FORMULATION- Ration is the daily apportionment of food for an individual animal.- Formulation is the computation of the daily apportionment.- A well balanced ration is one which has the correct quantities and proportion of the necessary nutrients. The ration should also be palatable and economical.In ration formulation, we consider:The work or role of the animalThe species of the animal- pigs, dairy cattle, beef animal, sheep e.t.cThe specific situations- lactation, rest, pregnancy, growth, environment e.t.cThe requirement of specific nutrients in the bodyTake note that there are also differences among the breeds of animals and ageProcedure Determine the nutrient requirement for a specific group of animalsDetermine the nutrient composition of the feed to ascertain the limiting nutrients in the ration and toxicity/ant nutritive factorsDetermine the cost of feedstuff so in case of substitution you can do itDetermine the feed intake in terms of dry matter of the animal per day for example, cow consumes 3%DM of its body weightDetermine the production level, physiological conditions e.t.cINGREDIENTSMain ingredients---energy – maize         Protein – Soya bean mealSubsidiary ingredients----maize germ, maize bran, rice germ, rice bran, wheat germ,            Wheat bran e.t.cMineralsMaximum allowed level or the limitationExamples Fish meal – in dairy meal < 5% (Palatability) - In broiler starter <10%Salt – poultry , maximum of 1%Limestone – chicks duckling mash 1%layers mash 6%vitamin premix- depend on the manufacturercoccidiostats- as per the manufacturermolasses – ruminants- 3-10%non-ruminants 1%Methods of balancing rationMethods of feed formulation:Pearson square methodComputer programmesTrial and error Algebra method (equation)Computer programmesAdvantagesfaster and accurateeasy to input the limitationsmany combination of feedsDisadvantageslack of powerlack of technical know-how on computer operationsTrial and errorThe formulator keeps trying until the right ration is determined. For example, combination of forages and concentratesAdvantage- Various feeds are involvedDisadvantage- Prone to errors and unsuitable for higher yieldsAlgebra methodUse equationsNot suitable for too many ingredientsPearson square methodIt uses only two feeds at a timeIt is the easiestExample Compute a feed ration of 100kg with CP of 16% containing maize 8%CP and Soya bean meal 50%CP. Include mineral/vitamin premix at 2%. Solution:Mineral/vitamin premix 2% = Proportion left excluding premix = 100kg-2kg=98kg Maize 8%                             34 parts of maize     16% SBM 50%                             8 parts of SBM                                               42 parts           NOTE: 42 parts should always be equivalent to the difference in the level of nutrients in the ingredients like, SBM 50% - Maize 8% = 42 %Proportion of Maize = 34 x 98 = 79.3kg     42Proportion of Soya bean meal = 8 x 98 = 18.7kg          42Formulation of rations using several Pearson squareIn many instances, more than two feedstuffs and for more than one nutrient need to be balanced. A double Pearson square method may be used with four feedstuffs and two nutrients. This is accomplished using three Pearson squares. Example: Make a ration for a lactating cow of 18 % CP and ME of 12.0 MJ/ kg DM of ME using MG (10.6 % CP and 15.5 MJ/ kg DM), Poultry litter (PL) (16 % CP and 10.6 MJ/ kg DM), Cotton seed cake (35 % CP and 13.5 MJ/ kg DM) and Soyabean meal (47 % CP and 12.4 MJ/ kg DM).Normally, two sets of a high energy and a high protein concentrates are chosen. The first two Pearson squares are used to balance for the first nutrient in both sets. The densities of the second nutrient in either mixture are calculated. Then the two mixtures are balanced in the third set for the second nutrient. Note: for ME to be >12.0 MJ/kg DM, MG must be used. For CP = 18 %, either CSC or soybean (SBM) can be used. Compute for ME in mix 1. MG (70*15.5/100) + CSC (30*13.5/100) =14.9 MJ/ kg DM Compute for MEPL (93.5*10.6/100) + SBM (6.5 *12.4/100) = 10.7 MJ/ kg DM Mix 3: CP=18 %, ME=12.0 MJ/ kg DM Mix 1 = 14.9 1.3 = 31.0 % (Mix 1) 12.0 Mix 2 = 10.7 2.9 = 69.0 (Mix 2) Ruminant animal like a cow has a high capacity in the digestive system but it is not able to consume enough forage to satisfy it nutrient requirements hence there is need to supplement with concentrates.Forage intake = f (Quality)Exellent quality – 35% DM intake per day of its body wtGood quality – 2.5% DM intake per day of its body wtPoor quality – 1% DM intake per day of its body wtConcentrates of higher nutrient capacity is needed to supplement for the poor quality forage.Glossary:Rennin, also called Chymosin, protein-digesting enzyme that curdles milk by transforming caseinogen into insoluble casein; it is found only in the fourth stomach of cud-chewing animals, such as cows. Its action extends the period in which milk is retained in the stomach of the young animal. In animals that lack rennin, milk is coagulated by the action of pepsin, as is the case in humans. A commercial form of rennin, rennet, is used in manufacturing cheese and preparing junket.           References: A.A. Safari Sinegani, G. Emtiazi, S. Hajrasuliha, H. Shariatmadari, 2005. Biodegradation of some agricultural residues by fungi in agitated submerged cultures. African Journal of Biotechnology Vol. 4 (10), pp. 1058-1061.FAO, 2004. Assessing Quality and safety of Animal Feeds. FAO Animal Production and Health Paper. Pp. 47. http://vivocolostate.edu/hbooks/pathphys/digestion/herbivores/index.html accessed 15/01/2012http://www.biology.About.com/od/proteinfunction accessed 8/02/2012http://www.infonet-biovision.org/default/ct/287/animalkeeping accesed 8/03/2012.http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex4521  accessed 26/01/2012P. McDonald, R.A. Edwards, J.F.D. Greenhalgh, C.A. Morgan, 2002. Animal Nutrition, 6th Edition. Pearson Prentice Hall, Harlow, London. Pp 693.