Animal Nutrition Prelims PDF

Introduction to Animal Nutrition(Zootc 57) ANIMAL NUTRITION 1. Terms Nutrition- the series of processes by which an organism replacing in the assimilates food for promoting growth and replacing worn-out or injured tissues -encompa...

Introduction to Animal Nutrition(Zootc 57) ANIMAL NUTRITION 1. Terms Nutrition- the series of processes by which an organism replacing in the assimilates food for promoting growth and replacing worn-out or injured tissues -encompasses several fields of discipline like biochemistry, chemistry, physiology, endocrinology, microbiology, genetics Nutrients- any food constituent, or a group of food constituents at same general chemical composition that aids in the support of life -may include synthetically produced vitamins, chemically produced inorganic salt or biogenically synthesized amino acids Digestion- a breakdown of feed particles into suitable products for absorption; may include: mechanical forces, chemical action, enzyme activity Absorption- transfer of substance from gastro-intestinal tract (GIT) to the circulatory (blood or lymph) system Metabolism- combination of anabolic and catabolic reactions occurring in the body with the liberation energy Enzymes- a complex protein produced in living cells that causes changes in other substances within the body without being changed itself (organic catalyst) 2. Classes of Nutrients and their components 1. Water A. General a. Cheapest and most abundant nutrient b. Makes up to 65-85% of animal body weight at birth and 45-60% of body weight at maturity c. Percentage of body water decreases with animal age and has an inverse relationship with body fat. d. Accounts for 90-95% of blood and many tissues contain 70-90% water e. Found in the animal body as: 1. Intracellular water- mainly muscles and skin 2. Extracellular water- mainly interstitial fluids, blood plasma, lymph, synovial and cerebrospinal fluids 3. Water present in urinary and gastro-intestinal tract B. Functions and Deficiencies a. Functions 1. Transport of nutrients and excretion 2. Chemical reactions and solvent properties  3. Body temperature regulation 4. Maintain shape of body cells 5. Lubricates and cushion joints and organs in body cavity b. Deficiencies or restrictions 1. Reduced feed intake and reduced palatability 2. Weight loss due to dehydration 3. Increased secretions of nitrogen and electrolytes such as Na and K. C. Sources of Water in the Animal a. Drinking water- consumption affected by many factors b. Water contained in or on feed- about 8-30% water c. Metabolic- may account for 5-10% total water intake D. Water Loses from the Animal Body a. Urine b. Feces c. Vaporization from lungs d. Sweat from the sweat glands 2.2. Carbohydrates A. General a. Made up of C(40%), H(7%), and O(53%) by % molecular weight b. Include sugar, starch, cellulose and gums c. Very little occurs as such in animal body d. CHO make up approximately ¾ of plant dry weight and thus the largest part of animals food supply e. Formed by photosynthesis in plants B. Structure a. Structure consists of C atoms, arranged in chains to which H and O are attached b. May contain an aldehyde or a ketone group in their structure C. Classification (based on number of sugar molecules) a. Monosaccharides or simple sugars 1. Hexoses- gluecose, fructose, galactos, mannose 2. Pentoses- xylose, ribose, araoinose b. Disaccharides (two sugar molecules) 1. Sucrose, maltose, lactose, c. Polysaccharides (many sugar molecules) 1. Starch- amylase, amylopectins, glycogen 2. Cellulose- glucose molecules in B-linkage 3. Mixed polysaccharides- hemicellulose, pectins 4. lignin D. Functions and Deficiencies a. Functions in the animal body 1. Source of energy  2. Source of heat 3. Building stores for other nutrients 4. Stored in the animal body by converting to fats b. Deficiencies of abnormal metablolism 1. Ketosis 2. Diabetes mellitus 3. Fats/Lipids(Ether Extract) A. General a. Made up molecular weight of C (77%), H(12%) and O(11%) b. Insoluble in water but soluble in organic solvents c. Fat will yield 2.25x more energy that carbohydrates or proteins B. Classification a. simple lipids- wax, fats, oil b. Compound lipids 1. Phospholipids-contain phosphoric acid and N. ex. Lecithins, cephalins, sphingomyelin 2. Glycolipids 3. Lipoproteins c. Derived lipids 1. Steroids-porgesterone, testosterone, estrogen 2. Terpenes 3. Fat soluble vitamins – ADEK C. Structure of fats a. Glycerol and fatty acids b. Saturated fatty acids c. Unsaturated fatty acids d. D. Functions and Deficiencies a. Functions 1. Dietary supply 2. Source of heat, insulation and protection for animal body 3. Source of essential fatty acids – linoleic, linolenic and arachidonic 4. Serve as a carrier for absorption of fat soluble vitamins  b. Deficiency and abnormal metabolism 1. Skin lesions, hair loss and reduced growth rate 2. Ketosis 3. Fatty liver – abnormal metabolism of liver E. Location and Natural Sources of Fat a. Animal Body 1. Subcutaneous 2. Surrounding internal organs 3. Marbling and milk b. Natural sources – most feeds have less than 10% fat except oil seeds(20%) 4. Proteins A. General a. Made up by molecular weight of C(53%), H(7%), O(23%), N(16%) and P (1%) b. Proteins are the principal constituents of the organ and soft structures of the animal body c. Dietary requirement (%) is highest in the young growing animals and decline gradually to maturity d. Proteins are basically large molecules B. Structure of Proteins a. All proteins have one common property , their basic structure is made up of single unit, amino acids. b. Twenty two amino acids are commonly found in proteins, they are linked together by peptide bonds. c. The arrangement of amino acids in the chain helps determine the composition of the protein. d. The classification of amino acids depends on the number of acidic and basic group that are present C. Classification of proteins a. Simple (globular proteins) – those yielding only amino acids or their derivatives upon hydrolysis, ie. Albumins, histones, protomins, globulins, glutelins, prolamins b. Fibrous protein – constitute about 30% of total protein in animal body , connective tissue, i.e. collagen, elastin, keratins c. Conjugated proteins – those in which simple proteins are combined with non-protein radical, i.e. nucleoproteins, glycoproteins, phsophoproteins, hemoproteins, lecithoproteins, lipoproteins, metalloproteins. D. Protein terminology a. True protein – composed of amino acid b. Non-protein Nitrogen(NPN)-compounds that are not true protein in nature but contain N and can be converted to protein by bacterial action i.e. urea c. Crude Protein – composed of true proteins and nay nitrogenous products; Crude Protein=%N x 6.25 d. Essential amino acids – those amino acids which are essential to the animal and must be supplied in the diet because the animal cannot synthesize them fast enough to meet its requirement. 1. phenylalanine(phe) 6. Methionine(meth) 2. valine (val) 7. Histidine (His) 3. threonine(thr) 8. Arginine (Arg) 4. tryptophan(trp) 9. Leucine (Leu) 5. isoleucine (ile) 10. Lysine (Lys) e. Non-essential amino acids – amino acids which are essential to the animal but are normally synthesized or sufficient in the diet and need not be supplemented 1. Alanine (ala) 7. Glutamine (gln) 2. Asparagines (asn) 8. Glycine (gly) 3. Aspartic acid (asp) 9. hydroxyproline 4. Cysteine(cys) 10. Proline (pro) 5. Cystine 11. Serine (ser) 6. Glutamic acid(glu) 12. Tyrosine (tyr) f. Protein quality – refers to the amount and ratio of essential amino acids present in protein E. Functions and deficiencies a. Functions  1. Basic structural unit of the animal body, i.e. collagen, elastin, contractile protein, keratin proteins, blood proteins 2. Body metabolism – enzymes, hormones, immune antibodies, hereditary transmission b. Deficiencies and abnormalities 1. Symptoms of protein deficiencies: reduced growth rate and feed efficiency, anorexia, infertility 2. Amino acid deficiency – a lack of an important amino acid which result to deamination 5. Minerals A. General a. Inorganic solid, crystalline chemical elements b. The total mineral content of plants or animals is often called ash c. Make up to 5% of animal body on dry weight basis B. Classification a. Major minerals – normally present at greater level in animal body or needed in relatively large amounts in the diet. include Ca, P, Na, Cl, K, Mg, S. b. Trace minerals – normally present at low levels in animal body or needed in very small amount in the diet. Include Cu, Zn, Co, F, I, Fe, Mn, Se, Cr, and are toxic in large quantities C. General Functions a. Skeletal formation and maintenance – Ca, P, Mg, Cu, Mn, F b. Function in protein synthesis - P, S, Zn c. Oxygen transport – Fe, Cu d. Fluid balance(osmotic pressure) – Na, Cl, K e. Regulating acid-base balance of the entire systems – Na, Cl, K f. Activators and/or components of enzyme systems –Ca, P, K, Mg, Fe, Cu, Mn, Zn g. Mineral-vitamin relationship – Ca, P, Co, Se 6. Vitamins A. General a. Organic components of natural food but distinct from carbohydrates, fat, protein and water  b. Present in foods in minute amounts and effective in the animal body in small amounts c. Essential for development of normal tissue necessary for metabolic activity but do not enter into structural portion of the body d. When absent from the diet or not properly absorbed or utilized, results in a specific deficiency disease or syndrome e. Cannot be synthesized by the animal. f. Related substances 1. Provitamins or precursor, i.e. carotene 2. Antivitamins – vitamin antagonists or pseudovitamins B. Classification and Structure a. Fat soluble - ADEK b. Water soluble vitamins – thiamine, riboflavin, niacin, pyridoxine, pantothenic , folic acid C. Functions and Deficiencies a. Play role as regulators of metabolism; necessary for growth and maintenance b. Vitamin requirement may also increase in old age due to difficulties in absorption and utilization Digestion, Absorption and Metabolism Digestion – Digestion it involves the processes, used to prepare food for absorption. Absorption includes the processes that move small molecules through membranes of the gastro-intestinal tract (GI tract ) into blood so the molecules maybe used for their specific function. Digestion includes the mechanical and chemical processes. Mechanical forces include chewing (mastication) and muscular contractions of the GI tract. Chemical processes include action of acids produced in the GI tract, and enzymatic activity from enzymes produced in the GI tract or enzymes produced by microorganisms located in various parts of the GI tract. There are many types of GI tracts in animals. Three types, non-ruminant, ruminant and avian are common in farm animals. Non-ruminants – Nonrumiants include the pig (Figure 11) , horse, rabbit, dog and cat. Humans also have a nonruminant digestive tract. The following is a description of the functions of the various parts of the nonruminant GI tract: Mouth – the mouth is composed of 3 accessory organs Tongue – grasping food Teeth - mastication of food Salivary glands – produce saliva which contains *water to moisten food *mucin to lubricate food for easy swallowing *bicarbonate salts to buffer (regulate pH) *salivary amylase to start carbohydrate digestion Esophagus – The esophagus, a muscular tube allows passage of food from mouth to stomach Stomach – The stomach is a muscular digestive organ that has 3 major functions: storage of ingested feed, mechanical breakdown, and production of HCl, enzymes and mucus. The stomach has three major regions: cardiac, peptic gland and pyloric. Cardiac region – cells produce mucus that protects the stomach lining Peptic gland region – cells produce HCl, pepsin (proteolytic enzyme) and mucus Pyloric region – primarily mucus producing cells Figure 11. Digestive system of pig Small Intestine – the small intestine has 3 divisions : Duodenum – an active site of digestion that receives secretions from the pancreas, liver and intestinal walls Jejenum – middle section that is involved in nutrient absorption Ileum – last section which is also involved in nutrient absorption Large Intestine - the large intestine also has 3 sections: Cecum - first section which is relatively large in the horse and rabbit – when well developed as in horse contains many bacteria which produced enzymes that digest fiber Colon - middle section which is involved in reabsorption of water – length is related to amount of water reabsorption i.e., the colon is very long in the desert rat Rectum – last section Ruminants – Ruminants such as cattle (Figure 12) and sheep also have only one true gastric stomach, but with additional compartments which evolved for fiber digestion Rumen – the rumen(paunch) is a large muscular compartment which fills the left side of the body cavity. The muscular walls secrete no enzymes and are covered by projections called papillae which are required for absorption of nutrients. Functions of the rumen include the following: *provide favorable environment for protozoa and bacteria. A milliliter of rumen fluid contains 25-50 billion bacteria. These bacteria are responsible for a significant pregastric fermentations which produces 1. Enzymes that breakdown fiber as well as, starch and protein. The digestion which occurs produces volatile fatty acids (propionic, butyric and acetic) which are absorbed via the papillae and used as a source of energy for the animal 2. Water soluble vitamins and vitamin 3. Bacterial synthesis of amino acids and protein. The bacteria will pass out of the rumen and become a source of amino acids for the host animal. Thus, low quality dietary protein (protein which is low in the dietary essential amino acids ) may become high quality protein which is high in the dietary essential amino acids during rumen digestion. Favorable conditions which are provided in the rumen include:  *anaerobic environment *constant warm temperature *constant food supply *mixing *removal of toxic end-poducts Additonal functions of the rumen include : *storage *soaking *physical mixing and breakdown Reticulum – the reticulum(honeycomb) and the rumen are not completely separated: they are not distinctly separate compartments. But they do have different functions. The reticulum has two functions (1) to move food into the rumen or omasum and (2) collection of dense particles of food and in regurgitation of ingesta during rumination (the process of movement of ingesta back up the esophagus to the mouth for additional mechanical breakdown(chewing the cud) Omasum – The omasum is a round muscular organ which contains many muscular laminae (sometimes called manyplies). The function of the omasum is not clearly understood. Possible functions included (1) controlling passage of ingesta to lower tract i.e. acts pump, (2) reduce particle size of ingesta and (3) absorption. Abomasum- The abomasum is considered to be very similar to the true gastric stomach which was described for non-ruminants. In general, the characteristics of the abomasums are identical to the gastric stomach of the nonruminant i.e. gland regions of the abomasums correspond to gland regions of the non-ruminant stomach. Figure 12. Digestive system of a cow Small intestine and large intestine – These areas in the ruminant are very similar in form and functions as in the nonruminant. Additonal unique features of the ruminant include:  Esophageal groove – The esophageal groove begins at the base of the esophagus and when stimulated by sucking forms a tube which empty into the abomasums. The function of the esophageal groove is to direct milk obtained from sucking to escape microbial digestion in the rumen. Rumination – Rumination can be described as controlled vomiting. In rumination, a controlled set of contractions of the esophagus, reticulum and rumen allow ingesta to be regurgitated back up to the esophagus where fluids are swallowed again and additional remastication and reswallowing of solid occurs. Eructation – Eructation (belching of gas) allows for removal of large volumes of gas produced in the rumen. In eructation, contraction of the upper part of the rumen force the gas up the esophagus and from there the gas penetrates into the trachea and lungs. Avian GI tract – The avian GI tract(Figure 13) is very different from the nonruminant and ruminant tracts. Mouth – does not contain teeth but the bird’s beak is used to collect particles of feed and to break some large particles into smaller pieces. A tongue and salivary glands are present and the saliva does contain salivary amylase. Esophagus – The esophagus of most birds include an enlarged area called the crop. Functions of the crop include (1) temporary storage and moistening of food. (2) place for salivary amylase to work and (3) microbial fermentation in some species Proventriculus – The proventriculus corresponds to the true stomach as described for the nonruminant and the abomasums of the ruminant. Therefore, the proventriculus is the site of HCl and pepsin production in the bird. It is very interesting to note that ingesta passes through the proventriculus very rapidly (14 seconds) Ventriculus – The ventriculus commonly called the gizzard is a muscular area which contains grit. The muscular contractions which are involuntary aid in the mechanical breakdown of food ; similar to the mastication by the teeth in the non-ruminant and ruminant Small intestine – The small intestine of the bird is similar to the small intestine of the non-ruminant and ruminant Large intestine – The large intestine of the bird contains 2 areas which are very similar in forma and function to the cecum of non-ruminant and ruminants. In the bird these are called cecum.  Figure 13. Digestive system of chicken Nutrient Digestion As indicated previously, digestion is simply the preparation of food for absorption. For absorption to occur, nutrients must be broken down to very small molecules. The basic unit of a nutrient is the form of the nutrient which maybe absorbed. The following is a list of the nutrients and their basic units: Nutrients Basic Unit Protein -Amino acid Starch -Glucose (nonruminant) Volatile fatty acids and lactic acid(ruminant) Cellulose -Volatile fatty acids Sucrose -Glucose and fructose Lactose -Glucose and galactose Lipids -Fatty acids and glycerol Minerals -Any soluble form Vitamins -Any soluble form Following mechanical breakdown, the action of enzymes is required to break nutrients down to their basic units. Enzymes are organic catalysts which produce changes in the  structure of nutrients which result in the reduction to basic units. The following outline summarizes the site of production and the end-products of the key enzymes Saliva *salivary amylase – starch to maltose Rumen *microbial cellulose – cellulose to volatile fatty acids *microbial amylase – starch to volatile fatty acids and lactic acid *microbial proteases – protein to amino acids and NH 3 *microbial urease – urea to CO and NH 2 3 Stomach, Abomasum and Proventriculus *Pepsin – protein to polypeptides Pancreas enzymes produced by pancreas are secreted into the duodenum *Trypsin - protein to peptides and amino acids *Chymotrypsin – protein to peptides and amino acids *Amylase – starch to maltose *Lipase – lipids to fatty acids and glycerol Small Intestine *Aminopeptidase – protein to peptides and amino acids *Dipeptidase – peptides to amino acids *Maltase – maltose to glucose *Lactase – lactose to glucose and galactose *Sucrase - sucrose to glucose and fructose Absorption – absorption occurs primarily in the small intestine and large intestine. The villi (very small projections which line the small intestine) are essential for absorption. A large amount of absorption of volatile fatty acids occurs in the rumen and depends greatly on many healthy papillae (projections which line the rumen). In general, absorption occurs as the result of diffusion or active transport. Diffusion involves the movement of the basic units from areas of high concentration(the GI tract) to area of lower concentration (the blood). Metabolism – Metabolism can occur only after the basic units of the nutrients have been absorbed in the blood. Metabolism involves all the chemical reactions performed by the cells to use the basic units of the nutrients for their specific functions i.e. glucose for energy or amino acids for protein synthesis. Generally, the reactions function in series and are described as pathways or cycles i.e., the Embden-Myerhof pathway of glucose metabolism or the Krebs cycle.