Animal Science Review Materials PDF 2021

STATE UNIVERSITIES AND COLLEGES – ASSOCIATION OF COLLEGES OF AGRICULTURE IN THE PHILIPPINES (SUC-ACAP) REVIEW MATERIALS FOR THE LICENSURE EXAMINATION FOR AGRICULTURISTS Animal Science Edited by ROMMEL C....

STATE UNIVERSITIES AND COLLEGES – ASSOCIATION OF COLLEGES OF AGRICULTURE IN THE PHILIPPINES (SUC-ACAP) REVIEW MATERIALS FOR THE LICENSURE EXAMINATION FOR AGRICULTURISTS Animal Science Edited by ROMMEL C. SULABO, PhD Core Subject Area Specialist With the assistance of KAMLA ZYRA G. LAVADIA Technical Assistant 2021 i ISBN # 978-971-592-104-6 All rights reserved. No part of this module may be used or reproduced in any manner without written permission from the State Universities and Colleges- Association of Colleges of Agriculture in the Philippines (SUC-ACAP). ii  TABLE OF CONTENTS PREFACE iv FOREWORD vi Unit I: ANATOMY AND PHYSIOLOGY OF FARM ANIMALS 1 Unit II: ANIMAL NUTRITION 25 Unit III: GENETICS AND LIVESTOCK IMPROVEMENT 50 Unit IV: SLAUGHTERING, PROCESSING, AND MARKETING OF FARM ANIMALS 60 Unit V: POULTRY PRODUCTION 76 Unit VI: SWINE PRODUCTION 86 Unit VII: RUMINANT PRODUCTION 96 REFERENCES 143 iii  PREFACE Republic Act 8435 or the Agriculture and Fisheries Modernization Act of 1997, simply known as AFMA, was enacted on December 22, 1997. It is a policy instrument defining measures to modernize Philippine agriculture for the country to compete in the global market. A basic human resource development framework in modernizing agriculture under the Act is to enhance the professional competency of agriculturists by upgrading the standards of the agriculture and fisheries education that will ensure to similarly upgrade the quality and sustainability of, and promote global competitiveness, at all levels. One strategy for professionalizing the agriculture sector is the Licensure Examination for Agriculturists (LEA). First implemented in 2003, LEA serves as a standardized evaluation tool to identify graduates of Agriculture and Agriculture-related degree programs who are academically and technically fit to be admitted in the agricultural profession. The three-day examination consists of multiple-choice type questions in the following component subjects: Crop Science, Soil Science, Crop Protection, Animal Science, Agricultural Economics and Marketing, and Agricultural Extension and Communication. The COVID-19 pandemic has been a major concern of all higher education institutions. When review sessions for licensure board exams are already supposed to be grinding, SUCs are confronted by the reality that face-to-face review is undeniably not possible. Under the circumstance, universities face new pressures to provide an engaging, motivating, and effective teaching and learning experiences for both reviewees and reviewers. Following this, the SUC-ACAP, with its goal of advancing the agriculture professional competency among their member-institutions, and the College of Agriculture and Food Science, UP Los Baños embarked on a joint initiative to enhance the capability of the SUC faculty particularly those engaged in the conduct of review classes in preparation for the Licensure Exam for Agriculture (LEA). To achieve this, the joint initiative conducted three online lectures, namely, 1) Innovative Teaching Methods and Tools Designed for Online Review Classes by no less than the Chancellor of the UP Open University, Dr. Melinda dP. Bandelaria. This online course aimed at introducing the faculty participants to the particularities of conducting review classes online with the use of innovative methods and tools; 2) Test Construction: the Multiple-Choice Type Test from a seasoned UP faculty, Dr. Blanda R. Sumayao, which gave the faculty-participants the opportunity to review the principles and rules for constructing multiple-choice type tests; and 3) Design and Development of Review Materials for LEA, again with Dr. Bandelaria with the objective of providing the faculty-participants the necessary knowledge and skills in designing and developing review materials and planning for the delivery of online review sessions. iv  The Project initiative also gave the faculty-participants the opportunity to review their course syllabus viz-a-viz CMO #14 S. 2008 or the CHED-prescribed outline which enabled them to design and develop this harmonized syllabus for each of the six core subject matter area. The review materials are thus a product of many minds and talents, that is, of faculty- participants from the different SUCs. I would like to acknowledge all the writers/contributors who willingly presented themselves to the initiative and for strictly following deadlines in submitting drafts; to all University Presidents and the Deans of the Colleges of Agriculture who have been highly committed to the objective of this Project initiative and for the support provided to the faculty-participants; to all Cluster and Sub-Cluster Coordinators for the constant reminders and follow-ups; and to the SUC-ACAP Secretariat for the untiring administrative support. And lastly, we are grateful to the College of Agriculture and Food Science, UP Los Baños for being true to its commitment of being a public service University, providing scholarly and technical assistance to its sister and brother SUCs. Specifically, we thank the faculty of CAFS who served as Subject Area Coordinators/Specialists who unselfishly guided our faculty participants throughout their journey in the project, as well as the Technical Assistants and Administrative Staff who have lend full support to attaining the objectives of the joint initiative. As I have always reiterated in many occasions, let us be reminded that student preparation for the licensure is just one of the factors that would determine performance. It is still incumbent upon us SUCs or higher educational institutions to ensure that we will be able to provide the necessary prerequisite services and institutional support in order for students to ultimately pass successfully and help advance the students’ professional careers post licensure exam. The preparation for publication of these review materials was supported by the SUC- ACAP. EDGARDO E. TULIN, PhD University President Visayas State University and President, SUC-ACAP December 2021 v  FOREWORD Unlike in Lord of the Rings and Harry Potter films, there are no wizards, Balrogs, Voldemort, precious rings, or elderly wands, on the journey to becoming a professional agriculturist. But there are narrow bridges and mazes that you must travel and cross over. One of these challenges is the Professional Licensure Exam. In the current climate where globalization, changing natural conditions, production, and social composition; migratory movements, among others, have significantly impacted most agricultural landscapes in the developing world, more than ever, the Licensure Exam for Agriculture has become all the more relevant as it prepares graduates of Agriculture to embrace the tasks ahead of them with utmost professionalism by way of recognizing their expert knowledge and practice. The Licensure Examination for Agriculture was established to recognize the expert knowledge and practice of aspiring professional agriculturists. This Review Material produced by the faculty participants of the joint initiative of the UPLB College of Agriculture and Food Science (UPLB-CAFS)- State Universities and Colleges- Association of Colleges of Agriculture in the Philippines (SUC-ACAP) is a comprehensive resource that covers all relevant subject areas in the field of agriculture which hopes to serve as a valuable review tool to students of SUC-ACAP member institutions. I wish you the best in your journey and beginning your career as a professional agriculturist. ELPIDIO M. AGBISIT JR., PhD Dean College of Agriculture and Food Science UP Los Baños December 2021 vi  LIST OF WRITERS/CONTRIBUTORS Dina B. Tadeo Abra State Institute of Science and Technology Riosahlie Y. Madrid Aurora State College of Technology Jim Boy G. Asoy Bohol Island State University Altea S. Romero Capiz State University Carmel Khrisna W. Moreno Cebu Technological University Maribel R. Raguindin Ilocos Sur Polytechnic State College Hazel H. Achuela Mariano Marcos State University Joan R. Rarogal Mariano Marcos State University Banisa S. Jumawan Negros Oriental State University Milagros Isidra Q. Velarde Negros Oriental State University Lyngielo Panes Northern Iloilo Polytechnic State College Elmer G. Ruedas Occidental Mindoro State College Esteward Jones M. Estabillo Tarlac Agricultural University Arvin D. Subillaga University of Antique Flordeliz S. Obrino University of Eastern Philippines Hyde D. Nadela University of Southeastern Philippines Angie R. Poliquit University of Southeastern Philippines Roger Roque E. Bustamante Visayas State University Jonnie F. Huervana Western Visayas State University vii  Unit I ANATOMY AND PHYSIOLOGY OF FARM ANIMALS ANIMAL PHYSIOLOGY Study of function of the parts or organ systems of the body Explains the physical and chemical factors that are responsible for the origin, development and progression of life It provides knowledge on the structure and function of the body and constantly, the care of the body I. NERVOUS SYSTEM Network of specialized cells that communicate information about animals’ surroundings and itself Composed of neurons and other specialized cells called glia, that aid in the function of t the neurons Controls the rapid activities of the body such as muscular contraction, secretions of some endocrine glands, heart rate, respiration rate, gastrointestinal motility and rapid reflex action o Basic units of NS: Brain, Spinal Cord and Nerves o Nerve Cells or Neurons - specialize in impulse conduction or the relay messages from effector organs to the nervous system and vice versa. Consist of a cell body (soma) and nerve fibers, namely axon ( a single process that extends from the cell body and ends up on a synapse or an effector organ) and one or more dendrites (has distal end called receptors that receive stimuli that initiate conduction of impulses to the cell body of neurons). o Neurons may be classified according to the direction of impulse conduction as follows: ▪ Afferent (sensory) neuron - transmits nerve impulses from effector organs to the spinal cord or brain. ▪ Efferent (motor) neuron - transmits nerve impulses from the spinal cord or brain to the effector organs ▪ Interneuron - conducts impulses from an afferent neuron within the Central Nervous System (CNS) Two separate divisions of the Nervous System 1) Central Nervous System (CNS) – command center of the body; contains the majority of the nervous system and consists of the brain and the spinal cord. It interprets incoming sensory information 2) Peripheral Nervous System (PNS) – part of the nervous system outside of the CNS. It resides or extends outside the limbs and organs. It is not protected by bone, leaving it exposed to toxins and mechanical injuries. 1  Divided into: Somatic nervous system - innervates striated or skeletal muscles, controls the voluntary movements of skeletal muscles. Autonomic nervous system - innervates glands and visceral musculature, control involuntary or automatic activities in the body Two subdivisions of Autonomic nervous system 1) Sympathetic nervous system – regulates involuntary activities that help the body respond to stressful conditions 2) Parasympathetic nervous system – regulates involuntary activities that help the body run smoothly under normal conditions Brain = Important Central Regulation Feed intake regulation o Ventromedial = Satiety center (voracious eating) o Lateral = Feeding center (loss of appetite) o Preoptic Area = Thermoregulatory Center o Suprachiasmic Nuclei = Center for sleep and wakefulness Neuroendocrine – involvement of nerve cells that releases chemical messengers, especially neurohormone, directly into the bloodstream Forms of energy converted by receptors Mechanical (touch-pressure) Thermal (degrees of warmth or cold) Electromagnetic (light) Chemical energy (odor, taste, O2 content of blood) Sensory modalities Smell Vision Hearing Rotational and linear acceleration Taste Cutaneous senses with receptors in the skin to monitor touch-pressure Cold Pain 2 II. ENDOCRINE SYSTEM Endocrinology - branch of physiology which deals with the coordination of various body tissues by chemical mediators (hormones) produced by restricted area of the body (endocrine glands) and transported through the circulatory system to the target organ or tissue Hormone – substance or chemical messenger produced by an endocrine glands and carried in the blood to distant parts of the body to exert its effect Functions: ▪ Regulating growth and development ▪ Mood ▪ Tissue function ▪ Metabolism (catabolism and anabolism) ▪ Sexual function and reproductive processes Endocrine glands are sometimes called ductless glands because they have no ducts connecting them to specific body parts Hormones may be classified as simple protein, glycoprotein and steroids but they all have common characteristics and functions: (1) Hormones appear to regulate rather than initiate reactions; (2) Hormones are effective in biocatalytic amounts; (3) Hormones are not secreted in uniform rates; (4) Hormones are inactivated rapidly either at the site where it exerts its effect or at some other glands or organs; and (5) Hormones are transported through the circulatory system or blood stream. Not all hormones have specific target organs, like growth hormone or somatotropin (STH); but for those with specific target organs, the cells in the target organ contain receptors that specifically recognize the hormone. Hormone receptors bind specific hormone and directly or indirectly trigger a metabolic effect. Pituitary gland or Hypophysis Located at the base of the brain in a concavity of the sphenoid bone called sella turcica which protects it from outside pressure. It has three lobes: o Anterior Pituitary Lobe or Adenohypophysis; o Intermediate Lobe or Pars Intermedia; and o Posterior Pituitary Lobe or Neurohypophysis 3 The Adenohypophysis secretes the following hormones: (1) Growth hormone or Somatotropic hormone (STH) - promotes growth of the long bones before the epiphyseal – diaphyseal plate is fused together in adulthood. Over secretion of STH results in Gigantism when this happens before adulthood and Acromegaly when this happens after adulthood in human. Dwarfism occurs when there is a deficiency of STH during growth development (2) Adrenocorticotropic Hormone or ACTH – stimulates the adrenal cortex to produce glucocorticoids such as cortisol, cortisone and corticosterone (3) Thyroid Stimulating Hormone or TSH – stimulates the thyroid gland to produce thyroid hormones (T4 and T3) (4) Prolactin or Luteotropic Hormone (LTH) – stimulates milk secretion in lactating mammary gland (5) Follicle Stimulating Hormone (FSH) – stimulates the ovary to produce grafian follicle; in the male, it maintains the integrity of the seminiferous tubules of the testis (6) Luteinizing Hormone (LH) – stimulates ovulation in maturing follicle and the formation of corpus luteum in ovulated follicle as well as the production of progesterone by the corpus luteum. Also called Interstitial Cell Stimulating Hormone (ICSH) in males, it stimulates the cells of Leydig or insterstitial cells to produce testosterone, a male sex hormone The neurohypophysis secretes two hormones: (1) Oxytocin – stimulates milk-ejection in lactating females; and (2) Vasopressin or Antidiuritic Hormone (ADH), which is important in conserving body water by reducing urine formation. It promotes water reabsorption in the kidney tubules Thyroid gland Located in the neck area just below the larynx. Has two lobes connected by a bridge called isthmus It is not essential to life but in its absence, there is poor resistance to cold, mental and physical slowing and in children, mental retardation and dwarfism Maintains the level of metabolism in the tissues that is optimal for their normal function. It secretes the hormone: ▪ Thyroxine (T4) and Triiodothyronine (T3) which increase the metabolic rate of the cells of the body ▪ Functions: Stimulates O2 consumption of most of the cells 4  Helps regulate lipid and carbohydrate metabolism Necessary for normal growth and maturation Increase the basal metabolic rate of an individual ▪ Disorders: Thyrotoxicosis – over activity of the gland (high T4 secretion) Hypothyroidism – lack of the T4 Secretion, due to lack of iodine (TSH is stimulated resulting to enlargement of the gland) Parathyroid gland Located behind the thyroid gland Two distinct types of cells in parathyroid: 1) chief cells, and 2) oxyphil cells Secretes hormone: ▪ Parathyroid hormone (PTH)- secreted by chief cells; mobilizes calcium from bone reserves and increases urinary phosphates, thus increasing blood calcium level ▪ Oxyphil cells – less abundant cells with large amounts of mitochondria; function unknown ▪ Calcitonin or Thyrocalcitonin = the hormone that lowers calcium level in the blood (opposite of PTH) by increasing urinary calcium excretion and preventing bone resorption through activation of osteoblasts which stimulate bone formation, secreted by thyroid gland upon stimulation by a secretion coming from the parathyroid gland in response to high blood calcium level ▪ Disorders: o Rickets (in adult)/Osteomalacia (in young) = characterized by a failure of normal mineralization of bone in young or adults; under- mineralization of cartilage and bone results in retardation of growth and development of skeletal deformities o Hyperparathyroidism = hypersecretion of PTH, resulting to hypercalcemia, hypophosphatemia, hypercalciuria, and hypophosphaturia o Hypoparathyroidism osteoclerosis = may occur due to increased amount of calcified bone, symptoms include hypocalcemia, hyperphosphatemia, hypercaliurea and hypophosphaturia Adrenal gland There are two endocrine organs 1) Adrenal cortex and 2) Adrenal medulla Outer adrenal cortex secretes steroid hormones Three types of cell making up three zones: 1) Zona glomerulosa – secrete Aldosterone 5  2) Zona fasciculata – secrete Glucocorticoids 3) Zona reticularis – secrete Glucocorticoids Aldosterone – regulates sodium metabolism by reabsorbing sodium from the kidney tubules; secretion is stimulated by extra cellular fluid volume (ECF) and/or blood pressure Glucocorticoids- include Cortisol, Cortisone and Corticosterone; important for carbohydrate metabolism, mobilizes glucose via glycogenolysis and gluconeogenesis; secretion is controlled primarily by ACTH from anterior pituitary Inner adrenal medulla secrete 1) Epinephrine = Adrenaline and 2) Norepinephrine = Noradrenaline. These secretions are not essential for life but help cope for emergencies Pancreas Both an exocrine and endocrine gland. Located at the duodenal loop of the small intestine It functions as exocrine gland when its acinar cells secrete pancreatic juice containing digestive enzymes. The endocrine function is limited to the cells of the islets of Langerhans which are found throughout the pancreas. The alpha cells of the islets of Langerhans secrete glucagon which is responsible for increasing blood sugar level; and the beta cells secrete insulin which is responsible for lowering blood glucose level by facilitating entry into target cells, thereby increasing its utilization and to the adipose cells (stored fats) Types of diabetes o Type I – Insufficient insulin secretion o Type II – Tissues resistance to insulin action Somatostatin – third hormone, secreted by delta cells. Regulate islet cell secretion. Pineal Gland Also called epiphysis cerebri Located at the epithalamus near the center of the brain Source of melatonin – hormone that plays a major role in the regulation of daily and seasonal rhythms for many vertebrates; associated with different behavioral and physiological responses in animals Examples: seasonal breeding for livestock, effect of daylength in stimulating egg production III. CARDIOVASCULAR SYSTEM 6  Includes the heart, blood and blood vessels through which blood flows in circulation Functions: o Conveys nutrients absorbed from the digestive tract to tissues o Carries O2 from lungs to tissues and CO2 from tissues to lungs o Removes waste product of metabolism and take them to excretory organs for disposal o Transports hormones from one part of the body to another o Helps in maintaining water equilibrium in the body o Regulates hydrogen ion concentration in the body o Increases the flow of blood to meet increased energy demands during exercise and regulates body temperature o Conveys disease-fighting elements of immune system, such as white blood cells and antibodies o Sends clotting cells and proteins to the affected site, which quickly stop bleeding and promote healing Heart - located in the middle mediastinal space o A muscular organ located at the chest (thoracic) cavity and enclosed in a fibrous sac, the pericardium. The walls of the heart are composed primarily of cardiac muscle, the myocardium o Divided into four chambers: upper 2 chambers are the left and right atrium, and the lower 2 chambers are the left and right ventricle o Atrio-ventricular valve (A-V valve) – prevents backflow of blood from the ventricle to the atrium during ventricular systole; valve on the right side is the tricuspid valve and the one on the left side is the bicuspid (or mitral) valve o Aortic valve (valve at the aortic orifice) and Pulmonary valve (valve at the pulmonary orifice) – prevent backflow of blood from blood vessels (aorta and pulmonary artery) into the ventricles during diastole Blood o Thick suspension of cellular elements in an aqueous solution of electrolytes and some non-electrolytes o Separated into two categories of plasma and cells by centrifugation o Plasma ▪ the fluid portion of the blood containing a number of ions, inorganic molecules and organic molecules which are in transit to various parts of the body or which aid in the transport of other substances ▪ Contains water, gases, proteins, non-protein nitrogen substances, inorganic salts and minerals, enzymes, hormones, vitamins, immune substances, etc. ▪ Normal plasma volume is about 3-5% of BW 7  o Blood cells – suspended in the plasma ▪ White Blood Cells (Leukocytes) - act to defend body against infection; phagocytic, produce antibodies and counteract toxins Three types 1) Granulocytes ▪ Neutrophils – affinity to neutral dyes ▪ Eosinophils – affinity to acidic dyes ▪ Basophils – affinity to basic dyes 2) Lymphocytes 3) Monocytes ▪ Red Blood Cells (Erythrocytes) - are biconcave disks manufactured in the bone marrow; these non-nucleated cells are soft and contain hemoglobin, a complex iron-containing conjugated protein Hemoglobin binds O2 to form oxyhemoglobin by attaching to Fe2+ in the heme; reacts with 4 molecules of O2 to form Hb4O8 (reaction is called oxygenation) In muscles, O2 is taken up by myohemoglobin ▪ Platelets (Thrombocytes) – small oval disk-like granulated bodies; when blood vessels walls are injured, platelets collect at the site, sticking to the vessel wall and liberating serotonin, which leads to local vasoconstriction. They also liberate thromboplastin which aids in blood clotting o Blood coagulation – conversion of soluble plasma protein fibrinogen to insoluble protein fibrin, a reaction catalyzed by enzyme thrombin. ▪ Thrombin is formed from its inactive form called prothrombin in the presence of calcium ions by the action of activated thromboplastin ▪ Prothrombin is synthesized in the liver with vitamin K involved in the hepatic synthesis Blood Vessel o Artery - blood vessel that carries blood away from the heart o Vein - blood vessel that carries blood back to the heart o Artery - blood vessel that carries oxygenated blood (exception: pulmonary artery) o Vein - blood vessel that carries unoxgenated blood (exception: pulmonary vein) Pulse rate (rate of heartbeat) may be taken by feeling the artery o Horse -external maxillary artery or about the middle of the lower jaw o Cattle and Carabao – similar location as the horse but slightly in the outer surface; coccygeal artery at the base of the underneath of the tail o Sheep and Goat – femoral artery o Pigs and others – auscultation method using stethoscope at the cardiac or chest region 8  Average pulse rate per minute o Horses – 38 o Cattle and Carabao – 54 o Goat – 78 o Chicken – 200-400 Systemic Circulation – carries oxygenated blood from the heart to all the tissues in the body except the lungs and returns deoxygenated blood carrying waste products, such as carbon dioxide, back to the heart. Includes the following systems of blood circulation: ▪ Coronary circulation – supplies blood to the heart itself ▪ Hepatic circulation – supplies arterial blood to the liver ▪ Cerebral circulation – supplies arterial blood to the brain ▪ Renal circulation – supplies arterial blood to the kidney ▪ Splanchnic circulation – supplies arterial blood to the digestive tract Pulmonary circulation – carries this spent blood from the heart to the lungs. In the lung, the blood releases its carbon dioxide and absorbs oxygen. The oxygenated blood then returns to the heart before transferring to the systemic circulation Lymphatic System - is composed of lymph nodes, lymph vessel and the lymph. o Lymph nodes - function for the production of lymphocytes. Another function is to stop foreign materials that come to them in the lymph. They become swollen or inflamed during severe bacterial infections o Lymph capillaries - more permeable walls than the blood capillaries, all metabolites of big molecular size which cannot be absorbed by the lymph capillaries. Eventually, the lymph fluid will enter the circulatory system through the right lymphatic duct and the thoracic duct o Lymph vessels - contain thin-walled valves which prevent the back flow of its content IV. RESPIRATORY SYSTEM Main function is to provide oxygen to the cells of the body and to remove excess carbon dioxide from them Interruption for more than a few minutes can lead to serious, irreversible damage to tissues followed by the failure of all body systems, and ultimately death Important functions: o Intake of oxygen and removal of carbon dioxide o Helps regulate the balance of acid and base in tissues, a process crucial for the normal functioning of cells o Protects the body against disease-causing organisms and toxic substances inhaled with air 9  o Houses the cells that detect smell Makes use of two systems that cooperate to supply the needs of the tissues 1) a blood circulatory system – carry to and from tissue cells large quantities of O2 and CO2 with the help of hemoglobin 2) a respiratory system (gas exchanger) – load blood with O2 and remove excess CO2 Respiratory Apparatus Air passages leading to the lungs o Nasal Cavity – passage of air; line with epithelial cells with microscopic cilia; between epithelial cells are goblets that produce mucus; the role is to filter the air to remove potentially disease-causing organisms o Pharynx – a short, funnel-shaped tube about 13cm (5 in) long that transports air to the larynx; lined with a protective mucous membrane and ciliated cells that remove impurities from the air o Larynx – a structure about 5cm (2in) long located approximately in the middle of the neck; transport air to the trachea; its mucous membrane and cilia-bearing cells help filter air o Trachea, Bronchi, and Bronchioles ▪ A tube about 12 to 15cm (about 5 to 6 in) long located just below the larynx ▪ Formed of 15 to 20 C-shaped rings of cartilage that keeps it open ▪ Trachea branches into two tubes, the left and right bronchi, which deliver air to the left and right lungs, respectively ▪ Within the lungs, the bronchi branch into smaller tubes called bronchioles o Alveoli – Each bronchiole branches into several subdivisions producing about million terminal tubes, at the end are the alveoli or alveolar sacs; gas exchange occurs at the alveoli Lungs o Tidal Volume - the amount of air that moves into the lungs with each inspiration or that moves out with each expiration Thorax Pleura Respiratory Muscles o Inspiratory muscles ▪ Diaphragm ▪ External intercostal muscles o Expiratory muscles Internal intercostal muscles Muscles of the anterior abdominal wall 10  Respiratory Centers o The flow of air in and out of the lungs is controlled by the nervous systems o The brain respiratory centers include: ▪ Medullary center ▪ Pneumotaxic center ▪ Apneustic center Regulation of respiratory center activity – controlled by sensory receptors particularly chemoreceptors sensitive to chemical changes in the environment such as 1) medullary chemoreceptors, 2) carotid bodies, and 3) aortic bodies Mechanism of inspiration and expiration Inspiration – active process; contraction of diaphragm that increases longitudinal diameter of the chest and contraction of external intercostal muscles elevating the ribs resulting in increased diameter of the thorax Intrapleural pressure is about -2.5 mmHg at start of inspiration which then decreases to -6 mmHg when chest volume is increased. Air flows into the lungs as pressure in the airway becomes slightly negative. Expiration – enlarged thorax returns to resting position by purely passive forces following inspiration. Pressure in airways become slightly positive and air flows out of lungs. Labored breathing is accompanied by active expiration Regulation of respiration Spontaneous respiration is completely dependent upon discharge of respiratory center in the medulla oblongata V. SKELETAL SYSTEM BONES A highly specialized supportive tissue which is characterized by its rigidity and hardness Four main functions are to provide mechanical support (e.g. ribs) to permit locomotion (e.g. long bones) to provide protection (e.g. skull) to act as metabolic reservoir of minerals Composition 1. Cells: the bone is composed of four cell types 11  a. Osteogenic Cells Mesenchymal cells Located in the inner layer of the periosteum (fibrous membrane that covers the surface of the bone) and by differentiation, they give rise to osteoblast b. Osteoblasts These are bone secreting cells During bone formation, they first secrete the amorphous and fibrous (collagen) components of unmineralized bone, and later they deposit their stored calcium to mineralize or harden the bone They line the trabecular (bone material) surfaces of the bone c. Osteocytes Mature bone cells that stop secreting the bone substance They are actually osteoblasts which have been trapped in spaces called lacunae in the bone substance during mineralization Their main function is to maintain the integrity of the bone by supplying nutrient derived from the blood vessels in the canaliculi d. Osteoclasts Believed to rise from the fusing of osteocytes Remodeling cells which are multinucleated in the structure and located in a concavity called the Howship's lacuna at the bone surface 2. Osteoid: a non-mineral matrix of collagen and glycosaminoglycan 3. Inorganic mineral salts deposited within the matrix Types of Bones Bone is classified into two types based on the frequency of appearance of interosseous spaces o Interosseous space - is the space between adjacent trabeculae o Trabeculae - a portion of the bone substance which is also called the bone spicule 1. Cancellous Bone (Spongy Bone) - consisting of few trabeculae and many of the interosseous spaces 2. Compact Bone (Lamellar Bone) - consists of extensive lamellae and fewer interosseous spaces. This bone develops into existing trabeculae to form layers called lamellae Osteon or Haversian System Basic unit structure of a compact bone Circular structure composed of a central canal called the Haversian canal surrounded by concentric layers (lamellae) of bone substance 12  Embedded in the lamellae are the bone cuniculi containing the cytoplasmic process of the osteocytes The Haversian canal connects a transversely positioned Volkmann's canal Osteogenesis The process by which bone is formed through the secretory activity of the osteoblasts In embryo, it occurs in two ways: 4. Intramembranous Ossification: bone develops in pre-existing mesenchymal connective tissue (bones of this type are called membrane bones) 5. Endochondral Ossification: bones that developed from pre-existing cartilage (e.g. long bones like femur and humerus). This type of bone growth is responsible for the longitudinal growth of bones Epiphyseal Plate (Epiphyseal Line) Site of bone growth as seen in long bones Composed of different zones a. Zone of growth b. Zone of cartilage transformation c. Zone of ossification CLASSIFICATION OF BONE BASED ON GROSS APPEARANCE 1. Long bones - great dimension - e.g., Forelimb = humerus, radius, ulna, metacarpals, phalanges Hind limb = femur, tibia, fibula, metatarsals, phalanges Functions: a. act as levers b. for support, locomotion 2. Short Bones - cuboids or equal shape - e.g. carpals, tarsals Function: absorbs concussion 3. Flat Bones - thin and expanded - e.g. skull, ribs, scapula, pelvic bones Functions: a. protect vital organs e.g. brain, lungs b. provide areas for muscle attachment 13 4. Sesamoid Bones - sesame-seed shape develops along the course of tendons - e.g. patella Functions: a. reduce friction b. change the course of tendons 5. Irregular Bones - unpaired bones in median plane - e.g. vertebral column, some bones of the skull Functions: a. for protection and support b. for muscle attachment 6. Pneumatic Bones - presence of air spaces or sinuses that communicate with the exterior - e.g. flying birds, maxillary and frontal bones Axial Skeleton - includes all bones except those of the limbs or appendages composed of the skull, vertebrae and ribs Appendicular Skeleton - made up of bones of the limbs bones of the front (pectoral) limbs and bones of the hind (pelvic) limbs VI. DIGESTIVE SYSTEM Simple Stomach (Monogastric animals) Mouth Esophagus Stomach Duodenum Jejunum Ileum Cecum Colon Rectum Vent Modified simple stomach (Poultry Species) Beak Esophagus Crop Proventriculus Gizzard 14  Duodenum Jejunum Ileum Ceca Colon Rectum Anus/Vent Herbivorous monogastric (horse/rabbits) Mouth Esophagus Stomach Duodenum Jejunum Ileum Cecum (large and functional) Ruminant animals Mouth Reticulum Rumen Omasum Abomasum Small intestine Large intestine Accessory glands - not part of the digestive system but plays important roles in digestion process Salivary glands Pancreas Liver Gall bladder Digestion in Monogastric Animals Ingestion of food comes salivation Chewing reduces the particle size and increases surface area for enzyme action Swallowing Stomach secretes HCl, mucus, digestive enzyme, pepsin and gastrin (pepsin= protein to polypeptide; gastrin=hormone that stimulates secretion of HCl) Chyme passes through the duodenum (pancreas secretes, lipases, trypsin and chymotrypsin and other enzymes; duodenal cells secrete secretin, pancreozymin, CCK) Fibrous materials pass and fermented at cecum 15 Digestion in Ruminant Animals Predigestive fermentation occurs in the rumen and reticulum Bacteria and protozoa use the roughages consumed by animals as nutrient sources for their growth and multiplication The rumen environment is ideal for microorganism growth because it is anaerobic, pH 6.9-7 and warm (39-41C) Excess microbes are continuously removed from rumen and reticulum along with the small feed particles through the omasum and abomasum Abomasum is acidic and functions similar to monogastric stomach, the small intestines then digest the microbes as source of nutrients. Pancreas secretes enzymes into the duodenum similar to what is happening in monogastric animals The rumen fermentation process produces VFA (acetic, propionic and butyric acids). The ruminants use this as major source of energy In the process of fermentation, the animal releases methane gas, ruminants release this gas by belching. When the gas releasing mechanism fails, the gas accumulates in the rumen and causes bloating A young, suckling calf consumes little or no roughages. Largest compartment of a young ruminant stomach is abomasum Milk is directed immediately into the abomasum in the young ruminants by esophageal groove, allowing milk to bypass fermentation in the rumen Complete development of the rumen, reticulum and abomasum requires about 2 months in sheep and goat and 3 to 4 months in cattle. The development is influenced by the type of feed the animal consumes VII. EXCRETORY SYSTEM Kidney - the main organ of excretion; the kidneys are commonly described as excretory organs, but actually, they are organs which primarily regulate volume and composition of the internal fluid environment. Their excretory function is incidental to their regulatory function. each kidney is composed of over a million units of nephrons Kidney aids in keeping blood plasma composition constant by: o Excretion of urea and other nitrogenous waste products of metabolism o Excretion of excess inorganic salts o Excretion of excess water o Excretion of non-volatile, soluble foreign substances that are in blood Structure of the kidney o Paired bean-shaped organ against the rear wall of the abdomen, on other side of the spine 16  o Supplied with blood by renal artery, branches on the pelvis, pass between calyxes and penetrate parenchyma o Outermost layer of the kidney is the cortex o Beneath the cortex lies the medulla, an area that contains between 8 and 18 cone-shaped sections known as pyramids, which are formed almost entirely of bundles of microscopic tubules o The center of the kidney is a cavity called the renal pelvis o Approximately one million nephrons compose each bean-shaped kidney A nephron consists of several parts: o Glomerulus – the filtration unit of the nephron that regulates the concentration within the body of important substances, and removes substances not needed by the body such as drugs and food additives o Bowman’s capsule and glomerulus are collectively called as renal corpuscle or malphigian o Proximal tubule – is joined to Bowman’s capsule by a short connecting segment. o Loop of Henle (descending limb and ascending limb) – becomes extremely narrow, extending down away from Bowman’s capsule and then back up again in a U shape o Distal convoluted tubule o Collecting ducts The renal pelvis drains into the ureter and the latter enters the urinary bladder. Urine Production Begins with the process of filtration that goes on at renal corpuscles or nephron Glomerular filtration = as blood courses through the glomeruli, much of its fluid, containing both useful chemicals and dissolved waste materials, soaks out of the blood through the membranes (by osmosis and diffusion) where it is filtered and then flows into the Bowman’s capsule Urea is formed in the body to eliminate the very toxic ammonia formed in the liver The total glomerular filtration rate of both kidneys is 125ml/min ▪ 125 ml/min x 60 min/hr = 7.5L ▪ 7.5L/hr x 24/hrs/day = 180L.day Re-absorption – the movement out of the renal tubules back into the blood capillaries (peritubular capillaries) o Reabsorption starts at the proximal convoluted tubules and continues in the loop of Henle, distal convoluted tubules, and collecting tubules o Descending loop of Henle = permeable to water 17  o Ascending loop of Henle = salts are extruded o In water diuresis, blood ADH is low, the epithelium of the distal tubules and collecting ducts are impermeable to water Secretion – is the process by which substances move into the distal and collecting tubules from blood in the capillaries around these tubules. In short, secretion is the reverse of absorption o Re-absorption moves substances out of the tubules and into the blood o Secretion moves substances out of the blood and into the tubules where they mix with the water and other wastes and are converted into urine Vasopressin or ADH Conserves body water by: o ADH is a vasoconstrictor which reduces medullary and papillary blood flow in the renal interstitium, thus increasing hypertonicity of the interstitium; reabsorption of water by osmosis would increase o ADH stimulate sodium pump in ascending loop of Henle - ↑ rate of sodium transport from the lumen of the tubule to the interstitium and concentration gradient of sodium between interstitium and fluid in the lumen of the tubules o ADH may dilate the “pres” of the collecting duct – facilitates water reabsorption VIII. REPRODUCTIVE SYSTEM Forms of Reproduction Sexual – male and female sex organs are involved in the process of propagation; union of sex cells (ovum and sperm) needed to form individual Asexual – does not require the sex organ Cloning o Dolly from mammary cells (Roslin Institute, Edinburg) o Mouse from a mouse tail (University of Hawaii) o Cow from reproductive tract (cumulus cells) (Kinki University, Nara, Japan) Female reproductive system Ovaries-primary sex organs o Functions: (a) the production of sex cell or ovum and (b) production of female sex hormones – estrogen and progesterone Accessory reproductive tract includes 18  o Infundibulum – funnel-shaped structure which picks up the egg when released by the ovary o Oviduct – tubular structure connecting the infundibulum to the horn of the uterus; serves as the passageway of the egg on its way to the uterus o Uterus - site of fertilization o Horn of uterus - site of implantation for the fertilized egg o Cervix – neck of the uterus; serves as the sperm receptacle in certain animals. Its opening called os uteri closes when the animal gets pregnant to protect the uterine contents o Vagina - primary organ for copulation; serves as sperm receptacle in many species o Vulva - common passageway for the products of reproduction and for urine; comparable to the ventral portion of the cloaca of birds and homologous with the scrotum of the male Male reproductive system Testis - main sex organ Scrotum - serves as the external covering of the testes Birds – two testes are located within the body cavity in the dorsolumbar region Farm animals – testes are located outside the body cavity within the scrotum Testes - have 2 main functions: 1) the production of sperm cells and 2) production of male sex hormone - testosterone Testosterone – responsible for development of secondary sex characters (e.g. muscular development, aggressiveness, libido) Seminiferous tubules – site of spermatozoa production in the testis Penis is the male organ of copulation and serves to introduce spermatozoa into the female reproductive tract Three accessory glands that contribute to bulk of the semen 1) Seminal vesicles or vesicular glands 2) Prostate gland 3) Cowper’s glands or bulbo-urethral gland Semen – consists of sperm cells plus secretions of the three accessory glands Secretions serve as vehicle for transport of spermatozoa from vagina to the oviduct, stimulates spermatozoa activity, serve as lubricating substance during copulation Life span of ejaculated spermatozoa in the female reproductive tract o Most mammals – about 24 hrs (20-30 hrs) o Chickens – about 14 days 19  Both Follicle stimulating hormone (FSH) and Luteinizing hormone (LH) are required for normal spermatogenesis o FSH – stimulates germinal epithelium lining the seminiferous tubules to initiate spermatogenesis o LH) – stimulates interstitial cells or Leydig cells to secrete testosterone Puberty and Estrous cycle Puberty is defined as the first estrus accompanied by ovulation in animals Indicates that the female has reached sexual maturity-capable of producing offsprings. The age of puberty varies between breeds of animals and among female animal with same breed Species Male Female Bovine 11 mo. (7-19) 11 mo. (9-24) Ovine 7 mo. (6-9) 7 mo. (4-14) Porcine 7 mo. (5-8) 6 mo. (5-7) Equine 14 mo. (10-24) 18 mo. (12-19) Estrous Cycle The period from estrus to the next estrus In many farm animals such as carabao, cattle, pigs, and horses, estrus comes every 21 days if the female animal is cycling regularly, although it could vary from 12 to 30 days Animals may be classified based on the occurrence of their estrus cycle as: (1) Monoestrus - the animal comes in heat only once a year, such as dogs/bitch (2) Seasonally Polyestrus - if it comes in heat at certain seasons only, such as sheep (3) Polyestrus - if it comes in heat all throughout the year, like cattle, swine and carabao An estrous cycle may be divided into four portions: (1) Proestrus - which is characterized by follicular growth (2) Estrus - which is under the influence of estrogen (3) Metestrus - characterized by the formation of CL (4) Diestrus - which is under the influence of progesterone secreted by the CL Estrogen Hormone which causes estrus in females 20  Production is greatest when developing Graafian follicle (GF) in the reaches largest size; growth and development of GF in the ovary is caused by FSH secreted by the anterior pituitary glands Presence of estrogen stimulates LH production At peak of estrogen production, LH increases which coincides with the production of inhibin in the ovary (hormone that inhibits FSH production) Causes behavioral changes (Signs of Heat) o Stands for mounting other animals o The female stands still when mounted by the male o Reddening and swelling of the vulva o Mucus discharged from vagina o Nervousness and restlessness o Frequent urination o Increase in body temperature o Loss of appetite o Bellowing LH is the hormone that causes ovulation of GF; initiates formation of corpus luteum (CL) Summary of sequence of events in an estrous cycle 1) Anterior pituitary secretes FSH which causes development og GF in the ovary 2) GF secretes estrogen which stimulates LH production and at the same time causes heat or estrus in the female animal (best time to breed) 3) Surge of LH released by anterior pituitary causes ovulation 4) LH will also initiate development of CL and causes production of progesterone by CL 5) Progesterone will prepare uterus for implantation of fertilized egg, if fertilization has taken place 6) Progesterone maintains pregnancy if animal is pregnant 7) The uterus will produce prostaglandin that causes destruction of the CL resulting in the cessation of the production of progesterone 8) When this happens, FSH production would again continue and a new cycle begins When to best breed or inseminate Cattle and carabao Ovulation takes place 15-18 hrs from the end of estrus; best time is toward the end of estrus Duration of estrus is variable – 5-36 hrs, average is 18 hrs 21  It is recommended to breed (or inseminate) immediately once the animal is in standing heat Swine Duration of estrus – 2-3 days Best time to breed (or inseminate) is on the second or third day of estrus Mares Duration of estrus – 6-7 days Best time to breed (or inseminate) is on the fourth or fifth day of estrus Fertilization and Pregnancy Fertilization means the sperm joins the egg, creating the zygote which is the first cell of the new individual Require three critical events a) sperm migration from site of deposition to oviduct and convergence of spermatozoa towards the ovum b) sperm attachment and penetration through the zona pellucida c) Fusion of sperm and ovum plasma membranes In polytocous species such as pigs, embryos undergo uterine migration and equidistant spacing prior to implantation. Pig blastocysts begin to attach to the uterine surface on day 13 and completed between days 18 to 24 In ruminants, initial placentation occurs at day 22 in cattle and day 15 in sheep. Placental attachment is through caruncles or cotyledons, which are finger-like villi or papillae that allow nutrient intake by the developing conceptus. Gestation period (days) o Cattle – 278-290 o Horse – 335-345 o Sheep – 145-155 o Swine – 112-115 Placental development Two general types of placentation 22  Sows and mare – have diffuse placenta, which consists of a simple apposition of fetal and maternal epithelia Sheep, goat, cows and carabao – have cotyledonary placenta, cotyledons from fetal placenta are attached to the caruncles of the maternal placenta through which uterine blood flows Parturition and lactation Parturition (or labor) is defined as the physiological process by which the pregnant uterus delivers the fetus and placenta from the maternal organism Signs of approaching parturition o Obvious enlargement of mammary glands o Teats become swollen o Presence of milk in the mammary gland Triggered by the fetus and is completed by complex interaction of endocrine, neural and mechanical factors Parturition is divided into three stages 1) Dilation of the cervix (1st stage) 2) Expulsion of the fetus (2nd stage) 3) Expulsion of the placenta (3rd stage) Onset of milk secretion follows parturition Prolactin initiates milk secretion in the mammary gland IX. BODY TEMPERATURE REGULATION Classification of animals based in their ability to regulate body temperature 1. Homeotherms (warm-blooded animals) – body temperature is largely independent of environment 2. Poikilotherms (cold-blooded animals) – body temperature directly varies with environment Homeotherms attain body temperature constancy by 1. Chemical regulation ▪ Altering metabolic rate by adjusting production of hormones such as thyroxin and/or epinephrine ▪ Shivering and changing muscle tension 2. Physical devices and activities ▪ Sweating with evaporation of water from the skin ▪ Changing rate of breathing to alter vaporization of lungs ▪ Altering volume of blood flowing to the body surface by vasodilation or vasoconstriction 23  ▪ Changing amount of internal or external thermal insulation such as subcutaneous fat, feathers, fur or hair ▪ Changing “free” body surface area by lying down and huddling when it is cold or by standing in stretched position when it is hot ▪ Locating more favorable environment such as shade, dry or wet areas, shelter from wind, etc. Normal rectal temperature range (Body temperature) Horse, ruminants – 36-39°C Pigs, rabbit – 38-40°C Chicken, turkey, goose, duck – 40-41°C Quail – 41-43°C Different processes of heat dissipation 1) Conduction 2) Convection 3) Radiation 4) Vaporization Thermal Neutrality Thermoneutral zone, environmental temperature at which the heat loss is equal to minimal heat production (Basal Metabolic Rate/metabolism at rest) At this point, body temperature is normal without much regulation Heat Stress As environmental temperature rises, body temperature is maintained until the upper critical temperature (UCT) UCT depends on species, ranges from +3 to +6°C of thermoneutral zone Beyond UCT, animal is unable to maintain its body temperature even with thermoregulating devices “Critical” body temperature refers to body temperature at which 50% of species dies Cold Stress As environmental temperature decreases, thermogenesis begins to increase until it reaches lower critical temperature (LCT) to balance thermolysis Beyond LCT, animal is unable to maintain its normal body temperature, hence body temperature goes down correspondingly as ambient temperature declines LCT is -20°C of the normal body temperature of the animal 24 25  Unit II ANIMAL NUTRITION Definition of Terms Nutrition - is a science that deals with the series of processes by which an organism takes in and assimilates food for promoting growth and replacing damaged or injured tissues; it encompasses several fields of discipline Nutrients - any feed constituent or a group of feed constituents that aids in the support of life Digestion - process of breaking down of feed particles into suitable products for absorption Absorption - transfer of substance from gastro-intestinal tract (GIT) to the circulatory system Metabolism - combination of anabolic and catabolic reactions occurring in the body with the liberation of energy Catabolism - also known as destructive metabolism; and is the process that produces the energy required for all activity in the cells; i.e. cells break down large molecules (mostly carbohydrates and fats) to release energy Anabolism - also called constructive metabolism; is all about building and storing; small molecules are changed into larger, more complex molecules of carbohydrate, protein and lipids, etc. Enzyme - a complex protein produced in living cells that causes changes in other substances within the body without being changed itself (organic catalyst) Classes of Nutrients Water 1. Cheapest and most abundant nutrient. 2. Makes up 65 to 85% of animal body weight at birth and 45 to 60% of body weight at maturity. 26  3. Percentage of body water decreases with animal age and has an inverse relationship with body fat. 4. Found in the animal body as: a. Intracellular water – mainly muscle and skin b. Extracellular water – mainly interstitial fluids, blood plasma, lymph, synovial and cerebrospinal fluid c. Water present in urinary and gastrointestinal tract Functions and Deficiencies of Water in the Animal 1. Functions a. Transportation of nutrients and excretions b. Chemical reactions and solvent properties c. Body temperature regulation d. Maintains shape of body cells e. Lubricates and cushion joints and organs in the body cavity 2. Deficiencies or restrictions a. Reduced feed intake and reduced productivity b. Weight loss due to dehydration c. Increased excretion of N and electrolytes such as Na and K Sources of Water to the Animal 1. Drinking water a. Factors that affect drinking water consumption 1) Environmental temperature and humidity (increased water consumption at heat stress) 2) Dry matter consumption (water consumption directly correlated at moderate temperatures) 3) Dietary factors a) High water content of feed reduces drinking b) High fiber, salt or protein content of the diet increases drinking. b. Function of the animal (lactating sows vs. dry sows) c. Type of urinary system (mammal vs. avian) d. Water quality 1) Good water should have less than 2500 mg/L of total dissolved solids. 2) Water containing over 1 g/L of sulfates may cause diarrhea. 3) Levels above 100-200 ppm of nitrates are potentially toxic. 27  2. Water contained in or on the feed 3. Metabolic water a. Results from oxidation of organic nutrients in the tissues. b. May account for 5 to 10% of total water intake. Water Losses from the Animal Body 1. Urine 2. Feces 3. Vaporization from the lungs and dissipation through the skin (insensible losses). 4. Sweat from the sweat glands. Carbohydrates General 1. Includes sugar, starch, cellulose, and gums. 2. Very little occurs as such in animal body. 3. CHO serve as structural components in the plant. 4. CHO make up approximately ¾ of plant dry weight and thus form the largest part of the animal’s food supply. Classification (by Number of Sugar Molecules) 1. Monosaccharides (1 sugar molecule) a. Hexoses (6 C) 1) Glucose 2) Fructose 3) Galactose 4) Mannose b. Pentoses (5 C) 1) Arabinose 2) Xylose 3) Ribose 2. Disaccharides (2 sugar molecules) a. Sucrose (glucose + fructose) b. Maltose (glucose + glucose) c. Lactose (galactose + glucose) 28  d. Cellobiose (glucose + glucose) 3. Polysaccharides (many sugar molecules) 1. Starch – α-linkage of glucose 1) Amylose – unbranched-chain plant starch 2) Amylopectin – branched-chain plant starch. 3) Glycogen – branched-chain animal starch. b. Cellulose – β-linkage of glucose c. Mixed polysaccharides 1) Hemicellulose – mixture of hexoses and pentoses 2) Pectins – hexoses and pentoses mixed with salts of complex acids. 3) Gums - mixture of hexoses and pentoses d. Lignin 1) Not considered a true CHO as the proportions of C, H. and O are different from the other polysaccharides. 2) Essentially indigestible by all animals and may reduce the digestibility of other nutrients. Function 1. Source of energy 2. Source of heat 3. Building blocks for other nutrients 4. Stored in animal body by converting to fats. Fats / Lipids General 1. Insoluble in water but soluble in organic solvents. 2. One gram of typical fat yields about 9.45 kcal gross energy (heat) when completely combusted, compared with about 4.2 kcal for a typical CHO; thus, fats produce 2.25 times more energy than CHO. Structure of Fat 1. Composed of fatty acids attached to glycerol by an ester linkage. It may have a mono-, di-, or triglyceride, which is an ester linkage of a fatty acid with 1, 2, or 3 hydroxyl groups of glycerol, respectively. 29  2. Fatty acids consist of chains of C atoms ranging from 2 to 24 or more Cs in length and characterized by a carboxyl group on the end. a. Saturated fatty acids are those in which each C atom in the chain (except the carboxyl group) has 2 H atoms attached to it (3 Hs at the terminal C). b. Unsaturated fatty acids have one or more pairs of Ca atoms in their chain attached by a double bond, and H has been removed. Functions 1. Dietary energy supply 2. Source of heat, insulation and protection for the animal body 3. Source of essential fatty acids a. Linoleic acid (C18:2) and linolenic acid (C18:3) apparently cannot be synthesized by animal tissues, or at least not in sufficient amounts to prevent pathological changes, and so must be supplied in the diet. b. Arachidonic acid (C20:4) can be synthesized from linoleic acid, and therefore is required in the diet only if linoleic is absent. 4. Serve as a carrier for absorption of fat-soluble vitamins. Natural Sources of Fat a. Most feeds contain low levels of fat, generally less than 10% (cereal grains, animal products, etc.). Unprocessed oilseeds may contain up to 20% fat (soybean, cottonseed, sunflower, etc.). Proteins General 1. Protein is the principal constituent of the organs and soft structures of the animal body. 2. All proteins have one common property: their basic structure is made up of simple units, amino acids. The essential component is an α-amino group (NH2) on the C atom adjacent to the carboxyl group (-COOH). The R represents the remainder of the molecule attached to the C atom associated with the α-amino group of the amino acid. 3. Twenty-two amino acids are commonly found in proteins: they are linked together by peptide bonds that couple the α-carboxyl group of one amino acid residue to the α-amino group of another residue. 30 Functions 1. Basic structural unit of the animal body a. Collagen b. Elastin c. Contractile proteins d. Keratin proteins e. Blood proteins 2. Body metabolism a. Enzymes 1) Digestion process 2) Degradative process 3) Synthesis process b. Hormones c. Immune antibodies d. Hereditary transmission 3. Source of energy after deamination Deficiencies 1. Symptoms of protein deficiency include reduced growth rate and feed efficiency, anorexia, reduced N balance and serum protein concentration, anemia, fatty liver, infertility, reduced birth weight of newborn, reduced milk production, and reduced synthesis of certain hormones and enzymes. 2. Amino acid deficiency – a deficiency of an individual amino acid results in the animal body deaminating the other amino acids and using the C chains for energy. Symptoms of a deficiency may resemble those described for protein deficiency with certain amino acid deficiencies producing specific lesions. Protein Terminology 1. True protein – protein composed only of amino acids. 2. Nonprotein nitrogen (NPN) – compounds that are not protein in nature but contain N and can be converted to protein by bacterial action (example: urea). 3. Crude protein (or total protein) – protein composed of true protein and any other nitrogenous product. 31  Crude protein = %N x 6.25 4. Digestible protein – the portion of CP which the animal can digest 5. Indispensable (or Essential) amino acids – those amino acids that are essential to the animal and must be supplied in the diet because the animal body cannot synthesize them fast enough to meet its requirement. The following are considered indispensable AA for normal growth. Phenyalanine* Tryptophan Histidine (for poultry) Valine Isoleucine Arginine Glycine Threonine Methionine** Leucine Proline Lysine *About ⅓ to ½ of the requirement can be met (or spared) by tyrosine. **About ½ of the requirement can be met (or spared) by cystine. 6. Dispensable (or Non-essential) amino acids – those amino acids that are essential to the animal but are normally synthesized or sufficient in the diet and need not be supplemented Alanine Cystine Hydroxyproline Asparagine Glutamic acid Proline Aspartic acid Glutamine Serine Cysteine Glycine Tyrosine Vitamins General 1. Organic components of natural food but distinct from CHO, fat, protein, and water. 2. Present in food in minute amounts and effective in the animal body in small amounts. 3. Essential for development of normal tissue; necessary for metabolic activity but do not enter into structural portion of the body. 4. When absent from the diet or not properly absorbed or utilized, results in a specific deficiency disease or syndrome. 5. Cannot be synthesized by the animal and therefore must be obtained from the diet (or microbial synthesis in the digestive tract). 6. General comparison of fat- vs. water-soluble vitamins: 32  a. Chemical composition – fat soluble vitamins contain only C, H, and O, whereas the water-soluble vitamins contain these 3 elements plus either N, S, or Co. b. Occurrence – fat-soluble vitamins differ from the water-soluble B vitamins in that they may occur in plant tissues in the form of provitamin (a precursor of vitamin), which can be converted into a vitamin in the animal’s body. No provitamins are known for any water-soluble vitamins. c. Physiological action – water-soluble B vitamins almost collectively are concerned with the transfer of energy. Fat-soluble vitamins are required for the regulation of the metabolism of the structural units. d. Absorption - fat-soluble vitamins are absorbed from the intestinal tract in the presence of fat. The absorption of water-soluble vitamins is a simpler process because water from the intestine is constantly resorbed into the bloodstream. e. Storage – any of the fat-soluble vitamins may be stored whenever fat is deposited; the storage increases with intake. The water-soluble B vitamins are not stored in the same way or to the same extent. f. Excretion – fat-soluble vitamins are excreted wholly in the feces. Water-soluble B vitamins may be present in the feces, but their chief pathway of excretion following metabolic use is through the urine. Classification 1. Fat-soluble vitamins a. Vitamin A b. Vitamin D c. Vitamin E d. Vitamin K 2. Water soluble vitamins a. Vitamin B1 (Thiamin) b. Vitamin B2 (Riboflavin) c. Vitamin B6 (Pyridoxine) d. Vitamin B12 (Cobalamin) e. Niacin f. Folic Acid g. Pantothenic acid h. Biotin 33  i. Choline j. Vitamin C Functions and Deficiencies 1. Since vitamins play various roles as regulators of metabolism, they are necessary for growth and maintenance of life. Therefore, proper vitamin levels in the diet are not only important from the standpoint of preventing specific deficiency symptoms, but also to promote general health, vigor and the ability to combat stress and disease. For example, most vitamins are apparently involved in antibody synthesis whereby animals acquire immunity to specific infections. 2. Vitamin requirements may also increase in old age due to difficulties in absorption and utilization. Today, suboptimal vitamin levels in the rations fed to livestock that cause undetected reductions in performance are probably of greater importance than gross deficiencies with the resulting typical deficiency symptom. On the other hand, vitamin supplementation should not be used as a “cure-all” treatment. Natural Sources 1. A – feeds rich in carotene, yellow corn, whole milk, fish oils 2. D – Sunlight 3. E – seed germ or germ oils from plants 4. K – fish meal, menadione (synthetic Vitamin K3) 5. Riboflavin – milk or milk products, meat or fish meal, distillers or brewer’s by- products 6. Pantothenic acid – brewer’s yeast, fish solubles, most feedstuffs fairly good sources 7. Niacin – animal by-products, brewer’s yeast, some present in ingredients but is largely unavailable in grains in non-ruminants 8. Pyridoxine – most feedstuffs fairly good sources, cereal grains and by-products, rice and rice bran, yeast 9. Biotin – widely distributed, esp. rich in egg yolk, liver, kidney, milk and yeast 10. Folic acid – some animal proteins 11. Choline – most commonly used feedstuffs are fair to good sources 12. B12 – animal proteins, fermentation products Minerals 34 General 1. Inorganic, solid, crystalline chemical elements. 2. The total mineral content of plants or animals is often called ash. 3. Make up 3 to 5% of animal body dry weight, depending on species; calcium accounts for nearly ½ of the total body mineral; P, approximately ¼; and all other minerals approximately ¼. Classification 1. Major minerals (macrominerals) a. Minerals normally present at greater levels in the animal body or needed in relatively large amounts in the diet. b. Include Ca, P, Na, Cl, Mg, K, S. 2. Trace minerals (microminerals) a. Minerals normally present at low levels in animal body or needed in very small amounts in the diet. b. Include Co, Cu, F, I, Fe, Mn, Zn, Mo, Se. c. Small amounts of F and SE are considered beneficial in certain geographical areas, but toxic if fed in excess. Functions 1. General functions of minerals a. Skeletal formation and maintenance – Ca, P, Mg, Cu, Zn b. Protein synthesis – P, S, Zn c. Oxygen transport – Fe, Cu d. Osmotic balance – Na, Cl, K e. Activators of enzyme systems – Ca, P, K, Mg, Fe, Cu, Mn, Zn f. Mineral-vitamin relationships – Ca, P, Co, Se Utilization of Nutrients Digestion - 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 may be used for their specific function Types of Digestion o Mechanical Digestion - includes chewing (mastication) and muscular contractions of the GI tract o Chemical Digestion 35  ▪ Includes action of acids produced in the GI tract ▪ Activity from enzymes produced in the GI tract ▪ Enzymes produced by microorganisms located in various parts of the GI tract Types of animals according to structure of their stomach Monogastric o Also called “simple-stomach” animals o Animals with one-compartment stomach, e.g. pigs Modified Simple-stomach o Has crop (for storage of feed), proventriculus (secretion of gastric enzymes for digestion) and gizzard (for mixing and grinding feed) Herbivorous monogastric o Have large and functional cecum that serves as site for microbial fermentation o The well-developed cecum enables them to utilize roughages as energy sources Ruminants o Also called “compound stomach animals” o Have a four-compartment stomach- rumen, reticulum, omasum, abomasum Digestion and Absorption of Different Nutrients 1. Carbohydrates Crude fiber (cellulose, hemicellulose, lignin) - poorly digested CHO Nitrogen-free extract (soluble sugars and starches) - readily digested Carbohydrates must be broken down to monosaccharides for absorption from the digestive system. This requires digestive enzymes elaborated by the host or by microflora inhabiting the digestive system of the host. A high proportion of these monosaccharides will be converted to glucose in the wall of the small intestine. The remainder is modified by the liver or metabolized in other ways. The carbohydrate-splitting enzymes are effective in hydrolyzing most complex carbohydrates to monosaccharides except for those with the β (beta) linkage such as cellulose. Microflora of the rumen of ruminants and the cecum of some nonruminants, such as the horse and rabbit, produce cellulase, so that these 36  species can utilize large quantities of cellulose. Anaerobic fermentation of carbohydrates by these microflora results in the production of large quantities of volatile fatty acids (VFA), mainly acetic, propionic and butyric acids. These acids provide the host animal a large proportion of the total energy supply. 2. Lipids 1. The digestibility of fat is quite high (usually exceeding 80%). The triglyceride molecule undergoes hydrolysis in the small intestine to monoglyceride and free fatty acids. These small units rarely pass into the blood circulatory system directly but normally are absorbed into the lymph system following hydrolysis and resynthesized during the absorption process. 2. Breakdown of long-chain fatty acids proceeds by stepwise removal of two carbons at a time beginning at the carboxyl end. Acetyl-CoA is the form in which the C2 fragments are removed. The acetyl-CoA released in oxidation is available for synthesis of fatty acids, for synthesis of steroids or ketones or for entry into the Krebs cycle. 3. Protein and Amino Acids 1. Dietary proteins must be broken down to amino acid fragments for absorption from the digestive system. An exception to this is in early postnatal life of mammals (in most species during the first 24 to 48 hours), when intact protein is absorbed across the intestinal epithelium. 2. Hydrolysis of dietary proteins is accomplished by proteolytic enzymes elaborated by epithelial cells lining the lumen of the intestinal tract and by the pancreas. The efficiency with which hydrolysis occurs determines the degree of absorption of individual amino acids and thus contributes to the nutritional value of the dietary protein. Another important factor contributing tp nutritional value is the balance of essential amino acids. Even proteins easily hydrolyzed in the intestinal tract do not have a high nutritional value if they have a deficiency or an imbalance of one or more amino acids. 37  3. The fate of amino acids after absorption can be divided broadly into three categories: a. Tissue protein synthesis b. Synthesis of enzymes, hormones, and other metabolites c. Deamination and use of the carbon skeleton and entrance of the carbon skeleton into the Krebs. 5. Minerals 1. Mineral elements are absorbed primarily from the small intestine in the ionic form. 2. Absorption occurs as the result of active absorption (Ca, P, and Na) or diffusion (all other minerals). 3. Factors affecting mineral absorption a. Age of the animal (young more efficient than old in absorbing minerals) b. Form of the element (organic vs. inorganic) – inorganic generally more available. c. pH of the intestinal tract – lower pH enhances absorption. d. Binding or chelating components (oxalates, phytates, fats, etc.) may reduce absorption. 4. Excesses or interactions within minerals. 6. Vitamins 1. Little is known about the digestion of vitamins, but they probably can be used as such within the body without conversion to simpler compounds. 2. Most of the vitamins are absorbed in the upper portion of the small intestine, with the exception of vitamin B12, which is absorbed in the ileum. Water- soluble vitamins are rapidly absorbed, but the absorption of fat-soluble vitamins relies heavily on the fat absorption mechanisms, which generally are slow. Nutrient Digestibility 38 A careful assessment of the digestibility of energy and nutrients is critical for evaluating the nutritional value of feed ingredients and for estimating their energy and amino acid requirements. Methods for estimating nutrient digestibility should be accurate and easy to use in practice and yield values that are additive in mixtures of feed ingredients. Therefore, assessing the value of feed ingredients should be based on their digestible fractions, not their total concentrations. Factors affecting digestibility 1. Age or body weight 2. Feed source and composition - feeds may vary in the type of fiber and/or ether extract material present and thus influence the digestibility. 3. Level of feed intake - as the level of feed intake increases above a certain value, the digestibility of all nutrients tends to decrease. 4. Rate of passage through intestinal tract a. Rapid - lack of time for complete digestive action and complete absorption. b. Slow - may be excessively subject to wasteful fermentations. c. Highly influenced by particle size and degree of feedstuff preparation. 6. Nutrient excess or deficiency - may cause poorer absorption and utilization of other nutrients. 7. Digestibility of a mixture is not necessarily the average of values for its constituents determines separately or indirectly. 8. Disease and/or parasites (worms) Method to measure nutrient digestibility A. Chemical analysis is the starting point for determining the nutritional value of feeds but the actual value of ingested nutrients depends on the use the body can make of them. The first consideration here is digestibility, since undigested nutrients do not get into the body proper. B. A digestibility trial consists chiefly of: 1. Running a proximate analysis of feed 2. Feeding an animal a given amount by use of a marker or collecting feces at a given time on a constant rate feeding. 3. Running a proximate analysis of feces 4. The difference is the apparent digestible portion of the feed 5. Computed as follows Nutrient intake – Nutrient in feces Apparent digestibility (%) = x 100 39  Nutrient intake C. Methods Employed for Fecal Collection b. Marker-fed with the diet at beginning and end of the collection period a. Desirable properties of markers (1) Physiologically inert (2) Contain no element under investigation (3) Will not diffuse b. Types of markers (1) Carmine (2) Ferric oxide (3) Chromic oxide c. Use of markers is not desirable in animals with larger and more complicated digestive tracts (ruminants) d. Using the marker method requires accurate measurement of the total amount of feed. c. Indicator method – involves the use of an “inert reference substance” as an indicator a. Ideal specifications of indicators (1) Totally indigestible and unabsorbable (2) Have no pharmacological action on the digestive tract (3) Pass through the tract at a uniform rate (4) Are readily determined chemically (5) Preferably a natural constituent of the feed under test b. By determining the ratio of the concentration of the reference substance to that of a given nutrient in the feed and the same ratio in the feces resulting from the feed, the apparent digestibility of the nutrient can be obtained without measuring either the feed intake or feces output. c. The calculation is made as follows % indicator in feed % nutrient in feces Apparent digestibility = 100 - [ 100 x x ] % indicator in feces % nutrient in feed d. Indicator materials (1) Chromic oxide (2) Titanium dioxide d. Metabolism cages – used to confine the animal for quantitative collection of the feces uncontaminated by the urine. An essential feature of these stalls is that the animals must have freedom of movement, particularly as regards lying down or getting up. Can also be designed to collect urine separately. e. Digestion trials generally consist of two periods: 40  a. Preliminary or adjustment period- to free digestive tract of any prior undigested feed and accustom the animal to the facility. b. Collection period- time period in which measurement of feed and collection of feces occur. c. For pigs, preliminary and collection periods of 3 to 5 days each are commonly used. 5. Errors in a digestibility trial a. The nutrient digestibility is only apparent because the feces may contain portions of nutrients from sources other than from the consumed feed such as (1) Enzymes excreted into the digestive tract. (2) Nutrients of bacterial origin. (3) Nutrients (primarily N) from abraded intestinal mucosa. (4) Some mineral excretion into the digestive tract. b. Feed or fecal spillage or wastage. c. Errors in proximate analysis. Nutrient Requirements Livestock and poultry have daily requirements for absolute quantities of specific nutrients. Various factors affect voluntary feed intake and performance, and thus, these will affect the concentration of nutrients that should be provided in the diet. Underfeeding nutrients can result in suboptimal performance and overfeeding often increases feed cost and nutrient excretion. Thus, understanding the factors involved and adjusting diet formulations accordingly is essential to ensure optimal production at an economical cost. Nutrient needs are influenced by phase of production, genetics, gender, environment, health status, and overall management of pigs, equipment, and facilities. Taking these factors into account and providing allowances for variation in individual animal performance and feed nutrient composition results in nutrient recommendations for diets that should allow for success in the livestock production feeding system. Fate of Nutrients I. Maintenance Maintenance means maintaining an animal in a state of well-being or good health from day to day. It is the amount of nutrients (or feed) required to adequately support an animal doing no non-vital work, making no growth, developing no fetus, storing no fat, or yielding no product. The nutritive requirements for maintenance are the first to be met. The nutritive needs of an animal for other purposes are for 41 the most part over and above those for maintenance. As much as 100% of an animal’s rations may go for maintenance. On the other hand, with full-fed animals as little as ⅓ or even less of an animal’s nutrient intake may be required for maintenance purposes. On the average, about ½ of all feed fed to livestock goes for maintenance. While it is sometimes profitable to hold animals on a maintenance ration from a period of low prices to a period of high prices, generally speaking, only those nutrients fed over and above the maintenance requirements are available for economic production. The requirements for maintenance are as follows: II. Growth A. Growth is largely an increase in muscle, bone organs, and connective tissue. Since meat is basically muscle, then growth is basic for meat production. Also, it is only through growth that an animal is able to attain a mature status. It should be recognized in this connection that the nutritive requirements for growth as outlined below are in addition to those listed above for maintenance. The primary nutritive requirements for growth are as follows: 1. Protein a. The dry matter of muscle and connective tissue, and to a considerable degree also that of bone, is primarily protein. Hence, protein is one of the major nutritive requirements of growth. b. Protein for growth must be of good quality – that is, it must contain the proper proportions and amounts of essential amino acids at the tissue level. 2. Energy a. Animal tissue produced as the result of normal growth ordinarily contains a limited amount of ether extract. Energy in the form of net energy must be provided to meet this need in addition to that in the protein of tissue. Also a certain amount of additional energy is used by the body for growth. 3. Minerals a. Since bone formation is a primary activity of growth and since bone is high in calcium and phosphorus content, these two minerals are especially essential for growth. b. Other minerals are involved in the digestion and utilization of other nutrients needed for growth. 4. Vitamins a. Vitamin D is essential for bone formation. 42  b. Certain other vitamins function in various metabolic processes related to nutrient utilization for growth. 5. Water Fat-free muscle tissue is about 75-80% water. Hence, water is a major requirement for growth. Supplying adequate water for livestock growth, however, is not a major consideration sine the amount needed for growth as compared to maintenance is rather inconsequential. However, it behooves the livestock producer to take advantage insofar as possible of the fact that growth, especially muscle growth, is largely water, and water is cheap. B. Rate of growth 1. Varies in amount per head daily among the different species – more or less in accordance with the mature size of the species. 2. Varies among different breeds largely in accordance with the size of mature animals of the respective breeds. III. Fat Deposition A. Fattening in an animal is simply the deposition of unused energy in the form of fat within the body tissues. Fattening is of two general types. 1. Abdominal, intramuscular, and subcutaneous deposition. This is for the most part undesirable but unavoidable if marbling is to be realized. 2. Intramuscular deposition. Commonly referred to as marbling. This is what is wanted. Difficult to obtain without excessive abdominal, intramuscular and subcutaneous deposition. B. The object of fattening is to make meat tender, juicy and of good flavor. While most people do not like fat meat, they like the lean meat only if it contains a certain amount of fat as marbling. Fat represents the most costly form of gain in livestock. Consequently, livestock are ordinarily fattened only to a point that they will be sufficiently marbled to make their meat acceptable to the consumer. C. Requirements for fattening 1. The primary requirement for fattening is energy. This energy must be in the form of net energy. Net energy for fattening meat come from any of several forms of feed energy such as: Starch Protein Sugars Fat Cellulose 43  2. Fattening increases an animal’s need for protein over and above that required for maintenance and growth only to the extent that additional protein may be necessary to promote good digestion. Fattening increases an animal’s metabolic requirements for protein little, if at all. 3. Fattening may increase the need for certain of those vitamins related to energy metabolism. 4. Fattening animals are usually full fed since only that net energy over and above that required for maintenance and growth is available for fattening. There may be some loss in feed digestibility with full feeding, but this is more that offset by an overall increase in the efficiency of feed utilization for growth and fattening. D. Fattening vs. growth in producing weight gains 1. Weight gains in animals are derived from the following: a. Growth b. Fattening c. Fill or increase in content of feed and water 2. Growth is a much cheaper form of gain than is fattening a. Gain from growth is primarily in the form of protein tissue and bone. Gain from fattening is largely in the form of fat. b. Protein tissue is about 25% protein and 75% water. While protein is one of the more costly nutrients, water is essentially free. Hence, protein tissue is a less expensive form of gain. c. Bone formation in growth requires considerable calcium and phosphorus. Hence, growth utilizes the calcium and phosphorus of feed more completely for weight gain than does fattening. Even if the requirements for growth make it necessary to add calcium and or phosphorus supplements, these are usually an economical source of nutrients for gain. d. Gain from fat is generally relatively inexpensive. Little, if any, water and minerals are laid down in fattening. In fact, during fattening, fat nay actually replace water in the tissues, which makes for a very uneconomical exchange. Also, about 2.25 times as much energy is required to form a kg of body fat as is required to form a kg of body protein. While protein is usually a costly source of net energy, it is seldom 2.25 times as expensive as other sources. e. Since gain from growth is usually more efficient and cheaper than gain from fattening and s