Module 2. Intro To Animal Anatomy and Physiology [PDF]

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Introduction to Animal Science

  Chapter 2

Introduction to Animal Anatomy and Physiology

Chapter 2

Introduction to Animal Anatomy and Physiology   Anatomy is the study of the forms and structure of the body. It notes the position and structure of organs. On the other hand, physiology deals with the functions of the body or any of its parts. Its underlying goal is to explain the fundamental mechanisms that operate in a living organisms and how they interact. In production of animal and animal products like meat, eggs and milk, some basic principles of animal physiology must be learned to fully comprehend the intricacies or complexities of the process. It is also inevitable that animal functions and processes be learned in a holistic approach encompassing other disciplines in animal reproduction, breeding, nutrition and disease control. This course provides the basic knowledge in understanding the anatomy and physiology of farm animals. For better understanding, topics such as external and internal parts of the farm animals as well as their body measurements are discussed thoroughly in this module. Procedures in taking the vital signs of farm animals are explained and are related to animal’s health condition. Farm animals were classified according to their digestive system. Parts and function of the reproductive system were discussed. Specific Objectives At the end of the lesson, the students should be able to: -

 Identify the external and internal parts of the farm animals and learn the functions of each part; Estimate bodyweight using body parts of farm animals; Explain the procedures in taking the vital signs of farm animals and relate these to the animal’s health condition Classify farm animals according to their digestive system and; Discuss and appreciate the parts and functions of the reproductive system.

Duration Chapter 2:

Introduction to Animal Anatomy and Physiology

= 4.5 hours (1.5 hours discussion; 3 hours laboratory exercise)

Lesson Proper A. EXTERNAL PARTS 1. Integumentary System Integument is the outer protective covering of the body and is continuous at the natural openings with the mucus surfaces of the digestive, respiratory and urogenital tracts. It consists of the skin, hair, hooves and claws, horns, feather and other epidermal derivatives. Associated with the common integument are sweat and sebaceous glands and numerous sensory nerve endings. Functions of Integuments a. As a protective envelop b. As a secretory mechanism c. As a sense organ d. As temperature regulating device e. As a respiratory structure SKIN. It is the largest organ of the body. It is tough, resilient and highly elastic. The skin is attached to the underlying structure by the sebaceous tissue. This consists mainly of fascia (a form of fibrous connective tissue) and fatty tissue. Layers of the Skin a. Epidermis – it is the avascular superficial layer, which is subdivided into corneum (a hard, dead, cornified external layer of the skin) and the deeper stratum germinativum (moist and contains pigment of the skin) b. Corium – it is the deep skin layer and consists of superficial feltwork of white elastic fibers. Appendages of the Skin a. Hair – it covers almost the entire surface body. Special hairs include: tactile hairs around the nose and lips, eyelashes, vibrissae in the nostril and tragic in the ears. b. Horns – these are epidermal derivatives bound together into a solid mass by keratin. It is supported for a variable distance by the horn core or process cornus, (which is a bony outgrowth of the frontal bones of the skull) c. Hoof or claw – it is the horny covering of the distal end of the digit. d. Chesnut – A horny mass found in the medial aspect of the forearm about halfway between the carpus and the elbow, and on the media; aspect of the hind leg just below the hock of the horse. e. Ergot – A horny mass found in all four legs, embedded in the hair on the posterior aspect of the fetlock joint.

f. Beak – Projecting mouthpart of the chicken consisting of the upper and lower beak g. Bill – Projecting mouthpart of water fowl consisting of the upper and lower bill h. Muzzle – Projecting part of the animal head including the mouth, jaw and nostril. It is seen among cattle, carabaos, goat and sheep. i. Snout – Projecting mouthpart of swine. j. Wattle – Fleshy lobe appendage hanging down from the throat or chin k. Wool – Coat covering of sheep l. Feather – Body covering of poultry species Glands of the Skin a. Sweat glands. (Sudoriferous glands) They secrete watery fluid containing various salts and waste products of metabolism. These serve as organs of excretion and temperature regulation. b. Sebaceous glands. These furnish an oily secretion for lubrication of the skin and hair. Modified sebaceous glands exist in the form of scent or musk gland found in the anal region (mink, civet cat) and around the hock (deer). Also the Meibomian or tarsal gland in the eyelids to prevent overflow of tears. B. INTERNAL PARTS 1. Skeletal System The basic material of the skeleton is bone and cartilage. In adult mammalian skeleton, bone is by far the largest component an served as the framework of the body. Classification of bones according to gross appearance a. Long bone – consists of a relatively cylindrical shaft and two extremities; their function are to act as levers and aid in support, locomotion and prehension. Eg. Humerus, radius, ulna, tibia, fibula b. Short bone – somewhat cuboid or approximately equal in all dimensions. There is no marrow cavity and it acts as absorbing concussion. Eg. Carpus and tarsus c. Flat bone – relatively thin and expanded in two dimensions and it function as protection of vital organs and in muscle attachment. Eg. Scapula and pelvic bone d. Sesamoid bone – resemble a sesame seed and are developed along the course of tendons to reduce friction or change the course of tendons Eg. Patella e. Irregular bone – unpaired bones located on the median plane and serves for protection, support and muscle attachment Eg. Vertebrae

Figure 1. Skeletal System of Cow

Figure 2. Skeletal System of a Bird

Figure 3. Skeletal System of Goat

Figure 4. Skeletal System of a Pig

Division of the body skeleton a. Appendicular skeleton – consists of the bones of the limbs 1. Forelimb Shoulder – scapula Arm – humerus Forearm – radius and ulna Wrist (knee) – carpals Manus (forefoot) – matecarpals amd phalanges 2. Hindlimb Hip – (composed of ilium, ischium and pubis) Thigh – femur Kneecap – patella Leg/shank – tibia and fibula

Ankle (hock) – tarsals Pes (hindfoot) – metatarsals and phalanges b. Axial skeleton – consists the following: 1. Skull 2. Vertebrae Cervical – neck Thoracic – chest Lumbar – waist Sacral – rump Caudal/coccygeal - tail 3. Ribs c. Visceral skeleton – consists of such bones as maybe developed in the soft tissue of certain organs or parts 1. Os rostri (snout of pig) 2. Os cordis (heart of cattle and sheep) 3. Os penis (penis of the dog) Functions of bones a. Provide protection of vital organs b. Give rigidity and form to the body c. Act as levers d. Storage of minerals e. Provide site for blood formation 2. Muscular System The muscular system is the most prominent and extensive anatomical feature of the body. It is specialized for contractility. All muscle tissues have the ability to contract or shorten their normal length. Three major group of muscles a. Striated (skeletal or striped) muscle - Long unbranched, multinucleated fibers - Under the microscope each muscle is crossed traversedly by dark bands or “striations” - Attached by tendons at one or both ends to some part of the skeleton - It is voluntary or under direct control of the will - Capable of sudden and violent contraction - Eg. Muscle of the limbs and trunk b. Smooth (unstriped or visceral) muscle - Smooth in structure, no cross striations - It is not attached to the skeleton, and is not under the control of the will - Under the microscope, the muscle fiber appears to be spindle-shaped with centrally located nucleus - Found in the muscular layer of the stomach and intestines; in the urogenital system, walls of the blood vessels and smooth muscle fibers around the alveoli and alveolar duct of the lungs c. Cardiac (striated involuntary and heart) muscle

-

Found in the heart Cross striations of striped muscle

Figure 5. Muscular System of a Cow

Figure 6. Muscular System of a Chicken

Figure 7. Muscular System of a Goat

Functions of the muscle a. Pumping of blood around the body b. Movement of extremities c. For respiration d. Movement of nutrient material along the gastrointestinal tract e. Transport of urine to the urinary bladder from the kidneys and emptying of the bladder 3. Nervous System The nervous system is the most highly organized system of the body. It is concerned with the reception of stimuli, transmission of impulses, interpretation of sensations and the integration of sensations that arise from both the internal and the external environment. The information received must be organized and stored, as well as used in the initiation of activity in effectors. The nervous system is responsible for all the complicated processes that make up the animal’s adjustment to both the external and the internal environment. It acts as a control system. Basic unit of the Nervous System 1. Neuron (nerve cell) – is the anatomic and physiologic unit of the nervous system. It consists of the cell body and all its processes, the dendrites and axon. 2. Dendrite – is a nerve cell process that conducts impulses toward the cell body 3. Axon – conducts impulses away from the cell body. The axon (and its myelin covering if present) is called a nerve fiber The continuity of one neuron to the next is provided by the synapse. It is the point of contact between the neurons.

Figure 8. The Neuron

Divisions of the Nervous System a. Central Nervous System – composed of the brain and the spinal cord. The brain id enclosed in the skull while the spinal cord is enclosed in the vertebral canal. The brain is subdivided into three parts. The forebrain is the largest part and fills most of the cranial activity. The midbrain extends caudally from the forebrain. The hindbrain is beyond the midbrain. The spinal cord is the direct continuation of the brain into the vertebral canal. b. Somatic Nervous System – is part of the peripheral nervous system (PNS) associated with the voluntary control of the body movements through the action of skeletal muscles. This system includes all neurons connected with skeletal muscles, skin and sense organs. It is composed of the spinal nerves and cranial nerves. Spinal nerves – are those that arise from the spinal cord and emerge from the vertebrae (transmit nerve impulses to) muscles and organs throughout the body Cranial nerves – supply innervations to structures in the head and neck. Cranial nerves carry information from general sensory receptors in the body, mostly from the head region and this information is processed in the CNS; the resulting orders travel back through the cranial nerves to skeletal muscles. c. Autonomic Nervous System – is a portion of the peripheral nervous that works automatically and without voluntary input. Its parts include receptors within viscera (internal organs). The major role of the autonomic nervous system is to maintain a relatively stable internal body environment or a state of homeokinesis or homeostasis.

Figure 9. Brain of different species of farm animals

4. Cardiovascular System The cardiovascular system functions to meet the needs of distant cells for nutrition and excretion. The system consists of a network of joined vessels (arteries, veins and capillaries) for circulating the nutrient fluid (blood) and a pump (the heart) to propel the fluid through the vessels. Functions of the cardiovascular system 1. To transport the nutrients absorbed from the digestive tract to the tissues 2. To carry oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs 3. To transport hormone from one part of the body to another 4. To help maintain the water equilibrium of the body 5. To assist in keeping the normal temperature of the body 6. To regulate the hydrogen ion concentration in the bod 7. To assist in overcoming diseases. Heart. The heart is a cone-shaped, hollow, muscular structure located in the thorax. The opposie end of the cone id known as the apex. It is contained in a serous sac called the pericardium.

Figure 10. The Heart Pulse rate. Pulse rate determines the rate, rhythm and amplitude of the heart and can be taken using our ears and fingers or stethoscope or electrocardiogram (ECG). The following are the sites for taking the pulse rate in animals: Horse – submandibular artery (face) Cattle – facial artery (face) and coccygeal artery (tail) Pig – femoral artery (thigh) and coccygeal artery (tail) Goat/sheep – femoral artery Dog/cat – femoral artery Some term associated with the pulse rate: a. Bradycardia – marked slowing of the heart rate b. Tachycardia – increased pulse rate c. Arrhythmia – no heart beat Blood Vessels a. Arteries – are tubular structures that carry blood away from the heart. The walls of arteries tend to be thick and elastic. b. Veins – are larger in diameter than the arteries and they carry blood towards the heart Blood Circulation The blood vascular system is further divided into four circulations: a. The cardiac which involves the heart b. The pulmonary which involves the lungs c. The systemic which involves the general body area d. The portal which involves the intestines and the liver Blood. Blood is the fluid carried by the arteries and veins. It is somewhat sticky and viscous, having five times the viscosity of water. Specific gravity: 1/20 greater than water (1.06) pH: 7.4 color: ranges from bright red of oxygenated blood to dark red of unoxygenated blood. It is slightly alkaline in reaction and has a distinctive odor and a salty taste, and makes up from 6-10% of the total body weight. Cellular Elements of Blood 1. Red blood cells (erythrocytes) - Non-nucleated biconcave disc-shaped cells specialized in the transportation of oxygen - It is composed of water and hemoglobin, an iron-containing pigment which is the principal oxygen transport medium Abnormalities: Anemia – red blood cells are reduced in number and or hemoglobin content Polycythemia – excessive number of RBC are found in the circulating blood 2. White blood cells (leucocytes) - Nucleated cells that is capable of independent movement

Divided into 2 groups: a. Granulocytes – those leucocytes that contain granular material within their cytoplasm a.1. neutrophils – these are highly phagocytic and increase in number during acut bacterial infections a.2. eosinophils – become numerous during parasitism and allergic reaction a.3. basophils – simiar to mast cell and mediate during allergic reactions b. Agranulocytes – those leucocytes that contain very little granular material in their cytoplasm b.1. monocytes – largest leucocytes, involved in phagocytosis and increased in numner during chronic infection b.2. lymphocytes – involved in immune responses Abnormalities: Leucopenia – decrease in the number of red blood cells Leucocytosis – increase in the number of white blood cells 3. Platelets (thrombocytes) – cells responsible for blood clotting Abnormalities: Thrombus – a clot that remained fixed in the lumen of the blood vessel Embolus – a clot that floats freely in the bloodstream -

Fluid Elements 1. Plasma – is the liquid part of the blood and it provides the medium of exchange between the blood vessels and the cells of the body. The major component of plasma is water which is about 92%. 2. Serum – the fluid that remains after the blood has clotted 5. Lymphatic System The lymphatic system includes the lymphoid tissues and the lymphatic vessels distributed throughout the body. It drains tissue fluid (called lymph within the lymphatic system) and is a framework for the circulation, production and maturation of immune cells. Lymphoid tissue consists of accumulations of lymphocytes trapped in the spaces between fibers of reticular connective tissue. Eg of lymphoid organs are lymph nodes, spleen, thymus and tonsils. a. Spleen – largest lymphoid organ - Act as blood reservoir - Act as lymphatic organ - Act as blood forming organ in young animals - Act as graveyard for old red blood cells - Site for antibody production b. Thymus – a lympho-epithelial organ that serve as source of lymphocytes c. Tonsils and Peyer’s patches – they primarily act as regional lymph nodes Functions of Lymphatic System a. Returns tissue fluid to the bloodstream from the extracellular spaces

b. c. d. e.

Filters out and phagocytize bacteria and other foreign material Helps maintain homeostasis and tissue health Produces antibody and lymphocytes Absorbs and transports fat from the intestine to the bloodstream

6. Respiratory System Respiration is most simply defined as the process by which gas exchange between a living cell and its environment is affected. Respiration involves more than the act of breathing. The circulatory system could not carry oxygen and carbon dioxide to and from the cells unless the respiratory system performs its function of making oxygen available to the blood relieving it of carbon dioxide. The major functions of the respiratory system are the delivery of oxygen and removal of carbon dioxide. Secondary functions include assistance in temperature control and phonation (voice production). The respiratory apparatus The external respiratory system is essentially a series of passages and tubes that commence at the exterior of the animal and end blindly in a multitude of tiny, thin-walled, closed sacs or alveoli. a. Nasal cavity – includes the following structures: External nares and nasal hairs, nasal septum, turbinates, sinuses, olfactory region and the nasal mucous membrane b. Pharynx –a funnel-shaped musculomembranous organ, which is a common passageway for food and air. c. Larynx – connects the pharynx and the trachea. It supports the epiglottis, which regulates the passage of air and prevents the aspiration of food or other foreign bodies. It also serves as the voice box. d. Trachea- a non-collapsible tube formed by a series of adjacent cartilage rings. It is a passageway to the duct system of the lungs e. Lungs- two elastic membranous sacs whose interior is in free communication with the outside air via a system of passages The general scheme of the duct system of the lungs is as follows: a. Trachea b. Primary or stem bronchi c. Secondary bronchi d. Bronchioles e. Alveolar sacs f. Alveolar ducts g. Alveoli – smallest subdivision of the air passages and the true respiratory structures where the exchange of gases between the bloodstream and the inspired air takes place. Pleura. It is a serous membrane which covers the inner wall of the thorax and the thoracic structures. Diaphragm. It is a musculomembranous partition that completely separates the thoracic from the abdominal cavity. It is a muscle for respiration.

Thoracic cavity. It surrounds the heart and its structures, the lungs and part of the trachea and esophagus, mediastinal structures and the great vessels entering and leaving the heart. Mechanism of respiration (Inspiration/Expiration) 1. External respiration – it includes the movement of air into and out of the lungs (breathing), the passage of oxygen from the lungs to the blood, and the passage of carbon dioxide from blood to the lungs, the means by which oxygen is carried to the cells and the means by which carbon dioxide is carried from the cells back to the lungs. Breathing – is the act of bringing air and blood into intimate relationship within the lungs and consists of two phases: inspiration and expiration. The inspiration is when air is brought into the lungs and expiration is when air is expelled from the lungs. 2. Internal respiration – is concerned with the utilization of oxygen and production of carbon dioxide by the cells ad is often referred to as cellular respiration. Types of Breathing/Respiration 1. Costal (thoracic) – involves considerable movements if the ribs 2. Abdominal (diaphragmatic)- diaphragm contraction produces visible movement of the abdomen 3. Eupnea – normal quiet respiration 4. Dyspnea – difficult breathing 5. Apnea – absence or cessation of respiration 6. Hyperpnea – increase in depth or rate of breathing or both 7. Polypnea- rapid shallow breathing 7. Digestive System The digestive system consists of a musculomembranous tube extending from the mouth to the anus. Its functions are ingestion, grinding, digestion and absorption of food and elimination of solid waste. Anatomy of the Digestive System a. Mouth – is the beginning of the digestive system. This includes the lips, tongue, teeth and salivary glands. It is responsible for the breakdown of food materials and serves as a prehensile (grasping) mechanism and as a defensive and offensive weapon. b. Pharynx – is a funnel-shaped musculomembranous organ which is a common passage for food and air c. Esophagus – is a musculomembranous tube extending from the pharynx to the stomach d. Stomach – is a hollow, pear-shaped, muscular digestive organ; the organ of storage of ingested feed Types of Stomach

a. Simple Stomach – It is located just behind the left side of the diaphragm. It is divided into cardia (entrance), fundus (body) and pylorus (termination). It produces the hydrochloric acid and pepsinogen b. Compound Stomach – It is composed of four stomach compartments c. Reticulum (honeycomb) – is the most anterior and smallest section of the forestomach. It receives heaby matter in food and acts as a liquid reservoir to soften these materials d. Rumen (paunch) – is the largest part of the forestomach. It serves as a fermentation vat, organ of maceration, site of bacterial digestion and organ of absorption. e. Omasum (manyplies) – is a spherical organ filled with muscular laminae. Laminae are studded with short, blunt papillae that grind roughage before it enters the abomasum. f. Abomasum (true stomach) – secretes gastric enzyme and hydrochloric acid. g. Small intestine – is a tube connecting the stomach to the cecum and large intestine. It is suspended from the dorsal part of the abdominal cavity by a fold of peritoneum called the great mesentery. Three segments of the small intestine: g.1. Duodenum – is a fixed part of the small intestine and closely attached to the stomach. It contains the pancreas g.2. Jejunum – is about 90% of the total length of the small intestine g.3. Iluem – is the last part of the small intestine h. Large intestine – extends from the termination of the ileum to the anus h.1. Cecum – cul-de-sac situated between the ileum and the great colon. It is somewhat comma-shaped and lies to the right of the median plane h.2. Colon – differs from the small intestine in that is larger, succulated and has longitudinal bands and more fixed position. i. Rectum – is the terminal part of the intestine. It is the organ storage. j. Anus – is the terminal part of the alimentary canal k. Accessory glands k.1. Pancreas – is a gland found in the first loop of the duodenum. It produces sodium bicarbonate and digestive enzyme K.2. Liver – is the largest gland in the body Function of liver: k.2.1. Storage and formation of glycogen (animal starch) k.2.2. Secretion of bile k.2.3. Detoxification of poisons k.2.4. Breakdown of uric acid k.2.5. Formation of urea k.2.6. Desaturation of fatty acids k.3. Gall bladder – is a storage place for bile. It is absent in horse, deer, elk, moose, elephant, giraffe, rhinoceros, camel, tapir and rat. k.4. Salivary glands

Figure 11. Digestive System of a Cattle

Figure 12. Digestive System of Chicken

Anatomy and physiology of the avian digestive system a. Beak- it is adopted for rapid picking up of small particles of feeds. b. Esophagus – most birds (except insect0eating species) have an enlarged area in the esophagus referred to as the crop. Its functions: b.1. To serve as na ingesta holding and moistening reservoir b.2. To allow breakdown reaction of salivary amylase b.3. For fermentation c. Provetriculus – The site of gastric juice production (hydrochloric acid and pepsin) d. Gizzard (ventriculus) – thick muscular walled area acting to physically reduce particle size of ingesta. Gizzard lining normally contains grit (small stone or hard particles? Which aid in grinding ingested seeds and grains) e. Small intestine – Most of the enzymes found in mammalian species are present, with the exception of lactase. f. Ceca and Large Intestine – it contains two blind pouches (ceca) as compared to mammals (cecum). The ceca and the large intestine are site for water resorption. Fiber digestion and water soluble vitamins synthesis occur because of the bacterial fermentation. g. Cloaca/Vent/Anus – eliminates waste products. 8. Excretory System The principal function of the urinary system is the extraction and removal of waste products from the blood. It consists of two kidneys, two ureters, the bladder and urethra. Structures of the Excretory System a. Kidney – most domestic animals have somewhat bean-shaped kidneys and located in the dorsal anterior portion of the abdominal cavity on both sides of the median plane and slightly posterior to the liver. This is the primary organ for the urine formation. b. Ureters – is a muscular tube that conveys urine from the pelvis of the kidney to the bladder c. Urinary bladder – is a hollow muscular organ that varies in size and position with the amount of urine it contains.

d. Urethra – is a relatively long usually curved common passageway for urine and semen in male and a short relatively straight and solely urinary function in the female. The nephron is the unit of structure and function of the kidney. Urine Formation Secretion moves substances out of the blood and into the collecting tubules where they mix with the water and other wastes and are converted into urine. Micturition – the term for the expulsion of urine from the bladder.

Figure 13. Excretory System of a Cattle

9. Reproductive System Forms of Reproduction a. Asexual reproduction – does not require the sex organs to facilitate the perpetuation of the species b. Sexual reproduction – the union of sex cells, ovum and sperm cell are involved to form a new individual Reproductive System of the Female The female reproductive system includes: the pair of ovaries and the reproductive duct system. a. Ovaries – the primary sex organs of the female attached by the broad ligament (mesovarium) to the dorsal wall of the sub-lumbar region of the body cavity. Two main functions: (1) production of egg cells or ova and; (2) production of female sex hormones: estrogen and progesterone. b. Oviduct or fallopian tube – tube (left and right) extending from the ovaries to the uterus. The portion of the oviduct nearest the ovary is modified into a thin, funnelshaped fimbriated membrane known as infundibulum, which partially surrounds the ovary. Mesosalpinx, a fold in the anterior portion of the broad ligament suspends the oviduct. Oviduct reserves the ova during ovulation and it is the site of fertilization. c. Uterus – known as the site of implantation for the fertilized egg. This is divided into a body and two horns. The proportion, shape and arrangement of the parts

d.

e. f.

g.

vary with species. Bicornuate like swine have horns which are folded and convoluted while the body is short or not prominent. Bipartite (cattle, sheep, goat and horses) are with prominent uterine body and a septum that separates the two horns. Uterus receives blood and its nerve supply through the support of the broad ligament (mesometrium) Cervix – it is considered as the neck of the uterus. Its opening, os uteri close when the animal gets pregnant to protect the uterine contents. Cervix acts as sperm receptacle in certain animals. It also facilitates transport of viable sperm through the cervical mucus to the uterus. Vagina – the primary organ of copulation. It serves as the sperm depository area in many species. Also comprises a part of the birth canal at parturition. Vulva – is the common passage for the products of reproduction and urine. The vulva is comparable to the cloaca of the birds. It is also homologous to the scrotum of the male, since both are derived from the same embryonic structure (vestibular folds) Clitoris – small rudimentary organ homologous to the glans penis of the male

Figure 14. Male Reproductive Tract of Ruminant

Figure 16. Male Poultry Reproductive Tract

Reproductive System of the Male

Figure 15. Female Reproductive Tract of Ruminant

Figure 17. Female Reproductive Tract of Chicken

a. Testes – is the primary organ of the male. In birds, the two testes are located within the body cavity. In livestock, testes are located outside the body cavity within the scrotum. b. Scrotum – is a cutaneous sac that serves as the external covering of the testes. Protects the testes from direct mechanical injuries and provides an environment which is cooler (6-9°C) than the body temperature required for normal sperm production. The cremaster and tunica dartos are the thermoregulatory muscles of the testes. Testes have two main functions: (1) production of sperm cells; (2) production of sex hormone – testosterone. Testosterone is responsible for the development of male secondary characteristics such as muscular development, aggressiveness and libido. c. Seminiferous tubules – are found inside the testes and responsible for the production of spermatozoa. Leydig cells are embedded between the seminiferouns tubules of the testes that produce testosterone. Descent of the Testes At fetal stage, the initial development of the testes starts inside the body cavity. As fetus grows, testes start to descend to the scrotum through the inguinal canal. Descent is completed at birth soon after birth. Bilateral cryptorchid – when both testes failed to descend to the scrotum sac (sterile) Unilateral cryptorchid – when only one of the testes failed to descend, but capable of fertilization d. The duct system d.1. Epididymis – the seminiferous tubules join together to form the rete testis and come out of the testis as vas efferens. The vas efferens converged to form the head, then the body and tail of the epididymis. Epididymis is a convoluted tube that serves as site of sperm maturation. d.2. Vas deferens – found at the end of the tail of epididymis which is straightened and enlarges to form the ampulla. Was deferens carries sperm from epididymis to the urethra. Ampulla koins with the urethra. d.3. Urethra – where spermatozoa and accessory fluids are mixed. It has a loop called sigmoid flexure (bull, boar, ram and buck) d.4. Penis – male organ of copulation. It is divided into three general areas: the glans, the body and the roots which are attached to the arch of pelvis.

Figure 13. Reproductive Organ of a Bull

Male Accessory Glands a. Seminal vesicle – paired, hollow and pear shaped in stallion, lobulated in bull, ram and boars, absent in dogs. Secretions include ascorbic acid, citric acid, acid soluble phosphorus, seminal fructose and ergothionene. Secretions neutralize urine residues. b. Prostate gland – unpaired, more or less completely surrounds the pelvic urethra. In adult it may become enlarged and interfere with urination. It produces alkaline secretion which gives characteristic odor of semen. Secretes substances to nourish and stimulate activity of the sperm. Example of secretion: antagluttin. c. Cowper’s gland or bulbo-urethral gland – small paired glands located on either side of the pelvic urethra. Found in all domestic animals except in dogs and are extremely large in boars. Secretions add volume to ejaculate. Sialoprotein is a secretion responsible for the formation of gelatinous fraction of semen (sometimes called tapioca). In boar, gel blocks the cervix to prevent back flow of the semen during copulation

Semen Semen consists of the sperm cell plus the secretions of the accessory glands. In vasextomized animal, the vas deferens is severed, thus the semen consists only of the secretions of accessory glands (sterile male without losing libido). Castrated animal, when both testes removed, render the male sterile with loss of libido.

A normal spermatozoon consists of head, neck or mid-piece and tail. Shape varies with species from flattened ovoid in bull, ram, boar and rabbit and rounded in man. Age of animal when sperm is produced: Boar – 117 days Bull – 224 days Buck – 110 days Ram – 147 days The life span of ejaculated spermatozoa in the female reproductive tract is about 24 hours (20-30 hours) in most mammals and about 14 days in chicken. Few thousand from the so many millions of spermatozoa will reach the oviduct and only one sperm cell enters the ovum and accomplishes fertilization. Puberty and Estrus Cycle The production of ova starts early in the prenatal period. When ovum is formed, it is enclosed in a structure called ovrian follicle or graafian follicle (GF) consisting of: (1) epithelial cells around the ovum (2) folliculi (theca internal and external); and the antrum which is filled with brown or yellowish, alkaline, albuminous fluid. The female reproductive tract starts to function at age of puberty. Puberty indicates that the female has reached sexual maturity – varies between breeds and among females of the same breed. At puberty, follicle stimulating hormone (FSH) secreted from the anterior pituitary gland causes growth and development of the GH in the ovary. The developing follicle secretes estrogen which causes estrus in female. Estrogen stimulates the production of luteinizing hormone (LH). At the peak of estrogen production, LH production increases which coincides with the production of inhibin from the ovary which inhibits production of FSH. Luteinizing hormone is the hormone that causes ovulation of matured follicle at the ovarian surface. It also initiates the formation of a yellow body (filled with lutein cells) called corpus luteum (CL) at the site of ovulation. The Cl secretes progesterone (as long as the CL is secreting progesterone, estrus is inhibited). Progesterone is responsible for (1) preparation of the endometrium of the uterus for implantation of the fertilized egg; (2) maintain normal pregnancy until birth. If there is no pregnancy, CL will regress to form corpus albicans, while the uterus secretes prostaglandin F2 alpha (PGF2α) which could destroy the Cl. Animals may be classified based on the occurrence of estrus cycle: 1. Monoestrus – if animal comes in heat only once a year 2. Polyestrus – if animal comes in heat all throughout the year (example: swine, cattle)

Phases of Estrus Cycle 1. Proestrus – characterized by follicle growth and thickened uterine mucosa which become congested with blood

2. Estrus – under the influence of estrogen wherein the female accepts the male for mating (standing heat). Ovulation takes place during this phase. 3. Metestrus – characterized by the formation of CL develop in the ruptured follicle and the uterine mucosa are prepared to receive fertilized egg. CL will produce progesterone. If fertilization occurs, metestrus is followed by the period of pregnancy (conception). If not diestrus will follow. 4. Diestrus – when CL cease to function, the uterus goes into a period of quiescence (resting stage) in order that a new cycle can begin Signs of Estrus 1. Reddening and swelling of vulva 2. Frequent urination 3. Restlessness 4. Mucus secretion from the vagina that can be seen in the vulva (watery at first and towards end of the estrus becomes sticky) 5. Mounting other animals 6. Stands still when mounted by a male Silent heaters can be detected by breeding male through the smell of pheromones, a hormone like substance secreted by the female. Term related to estrus: Anestrus – absence of estrus in an animal Nymphomania – animals with estrogen primed ovary and always in heat (may be due to cystic ovary). Fertilization and Pregnancy During mating, the sperm cells deposited in the vagina of most farm animals reside in the female reproductive tract before becoming capable of attaching to and penetrating the ovum. This process is known as sperm capacitation and believed to start in the uterus. Final capacitation occurs in the oviduct or fallopian tube. a. Fertilization – takes place in the upper part of the fallopian tube. The following are the stages involved: a.1. Sperm migration from the site of deposition to the oviduct and convergence of the spermatozoa towards the ovum a.2. Sperm attachment and penetration through the zona pellucida a.3. Fusion of the sperm and ovum nuclei The transport of the sperm from the place where they are deposited in the female genital organ to the fallopian tube takes only a short time (2-15 minutes) aided by the rhythmic contractions of the vagina, cervix and uterus. The viability of the sperm in the female reproductive tract of the cows, ewes and sow is about 24 hours (in mares, 2-3 days). The fertilized egg is called a zygote and undergoes its first division within 24 hours and repeated cell divisions occur. b. Pregnancy

When the zygote travels from the oviduct to the horn of the uterus, cleavage continue to progress. Cleavage divisions give rise to an embryo that has developed into the 8- to 16-cell stage (morula) which is transported into the uterus where it will continue to proliferate. Stages of Pregnancy 1. Nidation or implantation – trophoblastic cells of the blastocyst attach themselves between the epithelial cells of the uterus. In the maternal recognition of pregnancy, implantation allows the conceptus and uterine endometrium to achieve intimate contact for nutrient exchange and endocrine communication. At appropriate time, the conceptus produces steroid hormones and/or protein to signal its presence to the maternal system necessary to maintain the CL for continuous production of progesterone 2. Embryonic period – extends from the time of attachment of the fertilized egg to the wall of the uterus until the form of new individual is laid down. During this period three extra embryonic membranes are developed. 3. Fetal period- period which extends from the end of the embryonic period to the time of birth. Placental Development Three Extra Embryonic Membranes 1. Allantois – formed as an outpouching of the hind gut of the digestive tract. Fuses with chorion to form the allantoic cavity hat serve as urinary receptacle for the embryo and also collects some solid waste. The allantois which fuses with the chorion becomes the fetal placenta. Placenta is an apposition or fusion of the fetal membranes to the endometrium of the uterus to permit physiological exchange between the fetus and mother. 2. Chorion – outer layer which is in contact with the maternal tissues. Completely surrounds the embryo, amnion and allantoic cavity. 3. Amnion – innermost membrane which surrounds the embryo. It encloses the embryo in a double layered sac that forms the water bag (amnion). This is filled with a clear watery fluid in which the embryo is suspended. The water bag provides a protective cushion against external shocks and pressure of the adjacent body organs and prevents adhesion between the surface of the embryo and the surrounding membranes. At parturition. The amnion acts as wedge to dilate the cervix. Two General Types of Placentation among Farm Animals 1. Diffuse placenta – consists of a simple apposition of fetal and maternal epithelia. Sow and mare have diffuse placenta. 2. Cotyledonary placenta – cotyledons from the fetal placenta are attached to the caruncles of the maternal placenta through which the uterine blood flows. A caruncle with attached cotyledon is called placentome. Sheep, goat, cattle and carabao have cotyledonary placenta.

At parturition, the chorionic villi of both types of placentation are merely withdrawn and there is no extensive destruction of the uterine tissue. Parturition Parturition is a physiological process by which the pregnant uterus delivers the fetus and placenta from the maternal organism. Signs of Approaching Parturition a. Enlargement of the vulva b. Obvious enlargement of the mammary gland, teats become swollen c. Presence of milk is a strong indication of approaching parturition Parturition may be divided into three stages: a. Dilation of the cervix – with uterine contractions which are painful causing restlessness and adominal discomfort, fetus progresses to the cervix b. Expulsion of the fetus –fetus exclosed in amnion is propelled c. Expulsion of the placenta – rhythmic contractions continue after birth and cause the expulsion of the placenta Male Fowl Reproduction System The two testicles in bird are located inside the abdominal cavity, along the backbone and near the front end of the kidneys. The body temperature of the fowl (about 104°F) does not inhibit spermatogenesis as it does in most mammals. In the bird, production and maturation of the large numbers of spermatozoa occur rapidly within the seminiferous tubules. The quite small epididymis on the side of each testicle provides limited storage. Thus, the vas deferens which lead from the testicles to the cloaca are the main storage site of sperm cells. There are no accessory glands in the bird. As sperm cells leave the testicle, they are carried by seminal fluid produced by the testicle. Also, transparent fluid is ejaculated with the sperm derived from the cloacal wall. Pappillae or small projections in the cloacal wall serve as the copulatory organ. Caponization is a process of removing the testicels by making an incision on one side of the back of the cock (capon) Female Fowl Reproductive System During embryonic development, both left and right ovaries and their respective oviducts are present in mammals. In birds, the right side atrophies, leaving the left ovary and its oviduct to function in the production of the ovum within the yolk. The eggs produced by birds are much larger than ova produced by most of the mammals. Avian embryo develops inside the egg receives nourishment for embryonic development until hatch.

Egg Formation 1. Ovary – forms the ovum (yolk). When fully formed ovulation will occur (stimulated by LH). The yolk moves into the duct system of the female reproductive system. 2. Oviduct a. Infundibulum/funnel – picks up ovum ir yolk from the ovary. Should the hen have been inseminated (natural or artificial) fertilization likely to occur in the infundibulum b. Magnum – secretes albumen, a high protein and viscous (thick white) secreted from magnum glands deposited around the yolk. c. Isthmus – the developing egg moves through the isthmus, where thin membranes are secreted to surround and contain the albumen (shell membrane) 3. Uterus – known as the “shell gland”. In this portion, protein, calcium and other materials including pigments are secreted to form the shell. Egg shell is comprised of largely calcium carbonate (CaCO3) but the very thin outer layer called the cuticle is largely protein. 4. Vagina – inverts to expel the egg from uterus. Stimulated by oxytocin, causes vigorous contraction of the uterus moves the egg through the vagina and cloaca depositing the egg externally of the bird. 5. Cloaca – there is no cervix in female fowl but there is sphincter between the uterus and vagina, and vagina opens directly into the cloaca which serves as common passage of egg and feces. The smaller pointed end of the egg is generally the leading end during egg formation process, but before the egg is laid it is usually rotated 180° in the lateral manner. Anatomy of the Mammary Gland 1. Exterior of the udder Udder – skin gland not connected with abdominal cavity except through the inguinal canal. Udder contains large amount of secretory tissues and small amount of connective tissue. s 2. Supporting system – median and lateral suspensory ligament - Fibrous elastic connective tissue 3. Duct and secretory system - Teat - Teat cistern - Sphincter muscles - Gland cistern - Secretory tissue Alveolus – tiny structure resembling a balloon, lined with simple layer of epithelial cells (active in milk secretion)

The tissue covering the surface of the alveoli has been identified as myoepithelium, a contractive tissue which forces milk from the gland after a sustainable stimulus. The number of alveoli is highly correlated with the production capacity. Physiological Mechanism of Lactation The mammary glands are the distinguishing characteristics of all mammals. Classified as exocrine glands, these modified skin glands secret milk for the nourishment of the young. These glands grow during pregnancy and start to secrete milk after parturition. Lactation is the production of milk by mammary gland in mammals like cattle, sheep, swine, horse, goats, buffaloes and rabbits. Young mammals at first feed solely on milk from their mothers. The milk produced for human consumption usually comes from cow and goat, including buffalo/carabao. Development of Mammary Gland  At birth, a female mammal has a mammary gland with the characteristics number of teats: 2 for sheep, horse, donkeys, 4 for cattle, 10-18 for swine.  Development of udder is not remarkable until puberty (sexual maturity). At puberty, estrogen stimulates the udder to develop a duct system. Progesterone stimulates alveolar development at the end of the duct development.  At estrus, development of udder progresses when estrogen level is high and regresses when low. At pregnancy, further development of udder continues due to estrogen/progesterone secreted from the placenta. Hormones form pituitary gland (lactogen or prolactin and growth hormone or somatotropin) are necessary for proper udder development and milk secretion. Secretion of Milk  Milk is made and secreted by the single layer of cells in the alveoli.  Precursor for milk is the plasma from the blood. Large blood vessels can be seen in the udder. Milk Let-Down  Most animals do not “let the milk let down” until they are stimulated; young nudges or applies pressure to the udder and teat  Nervous impulse causes the posterior pituitary to release oxytocin causing contraction of smooth muscle of the udder.  Contraction forces the milk into the teat and gland  Dairy cows respond to being milked by a person or a machine  Injection of oxytocin can be given to effect milk letdown Factors Affecting the Level of Milk Production  Genetics o fat is most variable o minerals and lactose – least variable

 Nutrition – ration that increase milk production usually reduces fat percentage  Stage of lactation and persistency Colostrum – secretion produced by udder after parturition (3-5 days); rich in gamma globulin (antibodies); rich in calcium, magnesium, phosphorus and chlorine, iron, Vitamins A and D.  Milk secretion rate Milk ejection rate is maximal immediately after milking and lowest just before and during milking.  Environment o High temperature will decrease appetite of cow resulting in reduced milk yield o Heat stress affects high-producing cows more than low producers.  Disease and drugs o Diseases like mastitis, ketosis, milk fever and digestive upsets affect milk production and milk composition. o Pesticides are also excreted into the milk (discarded) aside from antibiotic residues. 10. Endocrine System Hormones – are groups of chemical substance with very diverse structure. They are produced by the glands in the body and travel through the blood stream (ductless) to affect distant target organs that contain specific receptors on which the particular hormones act. Some hormones are proteins or polypeptides (oxytocin, TSH, insulin). Others, neither proteins nor polypeptides, are derivatives of amino acids (thyroxine, epinephrine). Others (steroids) are produced in lipid as derivatives of cholesterol. Hormone-producing glands a. Pituitary gland a.1. Anterior lobe – growth hormone, gonadotropic hormones (acting on the gonads.sex organs) like Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), Thryoid Stimulating Hormone (TSH) and Adrenocorticotrophic Hormone (ACTH). a.2. Posterior lobe – oxytocin, vasopressin a.3. Intermediate lobe – melanophore hormones b. Thyroid gland – thryroxine, calcitonin c. Parathyroid gland - parathormone d. Adrenal glands – cortisol, adrenaline e. Pancreas – insulin (Islets of Langerhans), glucagon f. Testicles – Testosterone g. Ovaries - Estrogen h. Corpus luteum – progesterone (placenta), estrogen, relaxin Specific hormones Specific hormone a. Growth hormone (Somatotrophin)

Origin Anterior pituitary gland

Functions Promotes growth, gluconeogenesis, lipolysis, protein synthesis

b. Prolactin

Anterior pituitary gland

c. Adrenocorticotrophi c hormone (ACTH) d. Luteinizing hormone (LH) & Follicle stimulating hormone (FSH)

Anterior pituitary gland Anterior pituitary gland

e. Thyroid stimulating hormone (TSH) f. Melanocyte stimulating hormone g. Antidiuretic hormone (ADH or vasopressin)

Anterior pituitary

h. Oxytocin

Middle lobe of pituitary Hypothalamus (stored in posterior pituitary) Hypothalamus

i. Thyroxine

Thyroid gland

j. Calcitonin

Thyroid gland

k. Parathormone

Parathyroid glands

l. Epinephrine

Adrenal medulla

Stimulates mammary development and lactose synthesis in pregnancy Stimulates cortisol secretion in adrenal cortex In males, LH stimulates testosterone synthesis in the testis, whereas FSH stimulates spermatogenesis. In females, FSH is necessary for maturation of ovarian follicle and LH for ovulation and induces subsequent development of the corpus luteum of the ovary. Controls production of thyroid hormone Promotes melanin pigmentation of the skin Acts on the kidney to promote reabsorption of water back into the circulation Stimulates release of milk in lactating animals; stimulates uterine contraction Increases body metabolic rate Decreases plasma calcium. Acts on bone by decreasing the activity of osteoclasts (cells that breakdown bone). Its net effect is opposite to that of parathyroid hormone Maintains the level of calcium in the blood, acting mainly on bone and kidney. Epinephrine stimulates glycogen breakdown, lipid breakdown and gluconeogenesis (the opposite of insulin). Norepinephrine, though, is the predominant neurotransmitter in postganglionic axons of the autonomic nervous system,

m. Glucocorticoids (cortisol being most important)

Adrenal cortex

n. Mineralocorticoids (aldosterone being the most important)

Adrenal cortex

o. Insulin

Pancreas

p. Glucagon

Pancreas

q. Estrogen (Estradiol being the most important)

Ovary

r. Progesterone

Corpus luteum of the ovary

s. Testosterone

Testes

t. Human Chorionic Gonadotrophin (HCG)

Chorion and placenta

Body Temperature Regulation

where it mediates sympathetic, and particularly catabolic (energy-expending flightor-flight) responses Promote gluconeogenesis and protein and fat breakdown; antiinflammatory Stimulates kidney reabsorption of sodium back into the circulation with loss of potassium Clears the blood of glucose; stimulates glycolysis and glycogen synthesis; promotes protein and fat synthesis; inhibits gluconeogenesis; facilitates uptake of glucose by cells. Stimulates glycogen breakdown and gluconeogenesis in the liver Necessary for development of secondary female characteristics; needed for proliferation of the uterine endometrium during the early phase of the estrous cycle Prepares the endometrium to receive the fertilized egg during the post ovulatory phase of the estrous cycle. Development of male genitalia, male secondary sex characteristics, spermatogenesis, and libido. Androgens also promote skeletal and muscular development Prevents corpus luteum from shrinking in pregnancy, allowing a rise of estrogen and progesterone

Homeotherms vs Poikilotherms – animals are grouped according to their reaction to the environment Homeotherms – animals exhibiting constant body temperature irrespective of the environmental changes; also known as warm-blooded animals. Cold blooded or poikilotherms – animals that show changes in temperature following that of the environment Hibernation is a protective mechanism against profound cooling. This is observed in mammoth, ground hog, hamster and hedgehog. Heat Production a. Heat is produced in the metabolic or chemical processes taking place in the protoplasm of the animal body. b. Most of the heat is produced in the skeletal muscles and in the glands  Muscles produce 70% of the body heat  Liver is a gland where most heat is generated  Highest temperature found in the hepatic veil  Rectal temperature is the fair index of internal temperature of animals c. Sudden lowering of temperature causes the body to shiver, thereby producing heat d. Adrenaline and thyroxin cause heat production; also the body gains heat; e. Heat loss or heat dissipation Heat is dissipated through:  Radiation, conduction and convection – 70% of heat is lost by these means  Radiation – 60% of the heat is eliminated from the body  More heat is lost if the surrounding temperature is lower than that of the body  If the temperature and humidity are high, less heat loss can be expected f. Vaporization of water on the skin (sweat) or insensible perspiration  Water is vaporized as fast as it comes out of the skin  Insensible perspiration is important in cattle, sheep and rabbit  Horses sweat  Swine sweat at the snout  External temperature which causes blood distribution and dilution of blood – favors heat loss  Erection of hairs or ruffling of feathers favors conservation of heat as still moist air is trapped g. Vaporization of water in the lungs and respiratory passages  Smoke emitted by animals in cooler temperature of mountainous region  Loss due to heating of inspired air is small  Carabao plants  Dog vaporizes large amount of water from the respiratory passages  Sheep developed heat polypnea (shallow breathing)  25% of the heat of the body of mammals is lost in this way and from the skin

 Chicken – 17% heat loss h. By the feces and urine – insignificant heat is eliminated by this way Comfort Zone or Zone of Thermoneutrality – is a range of environmental temperature within which the animal does not have to adjust to the environment. Critical Temperatures – is the temperature of the environment at which the heatretainning mechanisms of the body are no longer able to maintain constant bod temperature and heat production being increased to meet the requirements of the body. a. Hair, wool, fur, feather, thick layer of subcutaneous fat lower the critical temperature b. Lower in non-fasting than in fasting animals. Cattle and sheep have the lowest crtitical temperature but they are able to withstand cold conditions. The body temperature is the resulting balance of heat production and heat dissipation, influenced by age, sex, season, time of the day, exercise, feeding, drinking and digestion. Hypothermia is the reduction of deep body temperature that develops during pathological conditions. Fever is a rise in deep body temperature that develops during pathological conditions. Physiological Response to Heat a. Circulatory adjustment Cutaneous vasodilation causes a rise in the skin temperature which steepens the thermal exchange gradient for environmental temperature below skin temperature. b. Evaporative heat loss 1. Sweating 2. Panting – is a rapid breathing (polypnea) with open mouth Physiological Response to Cold a. Reduction of heat loss This includes curled-up position of animals and piloerection. Piloerection is increased fur growth and subcutaneous fat deposition. b. Increase heat production by shivering c. Circulatory adjustment Normal Body Temperature of Domestic Animals Animal Range (°C) Stallion 37.2 – 38.1 Mare 37.3 – 38.2 Beef cow 36.7 – 39.1 Dairy cow 38.0 – 39.3 Sheep 38.3 – 39.9 Goat 38.5 – 39.7 Pig 38.7 – 39.8 Dog 37.9 – 39.9 Cat 38.1 – 39.2 Chicken (daylight) 40.6 – 43.0

Average (°C) 37.6 37.8 38.3 38.6 39.1 39.1 39.2 38.9 38.6 41.7

Sense Organs Sensation is the result of afferent impulses from stimuli that eventually reach a conscious level in the cerebral cortex. Special senses include smell, sight, taste, hearing and equilibrium. Organic sensations include hunger, thirst, sensation of bladder fullness and sexual sensation. Tongue: Organ of taste. Three specific taste modalities in man: bitter taste, at the base of the tongue; sour taste, in the lateral sides of the tongue; sweet and salty taste, in the tip of the tongue. Nostril: Organ of smell. Nerve impulses from the olfactory receptor travel to the olfactory bulb of the brain and along the wo olfactory tracts which channel the impulses to interpretive center or cells deeper within the brain. Ear: Organ of hearing and balance. There are three main parts of the ear: a. External ear – it extends from the exterior as far as the tympanic membrane Auricle or pinna – a funnel-shaped outer part composed of skin and elastic cartilage b. Middle ear – it extends from the tympanic membrane into the air-filled excavation within the petrous temporal bone Three auditory ossicles found in the middle ear: malleus or hammer, incus or anvil, stapes or stirrup c. Inner ear – it is also excavated in the petrous temporal bone but is filed with fluid. The inner ear is an essential portion of the organ of hearing and balance or equilibrium. Because of its complex shape it is called labyrinth. Eye: Organ of sight a. Conjunctiva – a thin epithelium which covers the anterior surface of the eyeball and cornea b. Eyelids – two flaps of the skin that serve to close or cover the eye c. Eyelashes – special hairs which act as protective screens and dust filters d. Meibomian or tarsal gland – specialized sebaceous gland located at the base of the hair follicles of the lashes of the upper eyelid e. Third eyelid – transverse sheet of thin translucent membrane located in the median canthus of the eye Major Parts of the Eye a. Fibrous tunic 1. Sclera – an opaque posterior part of the external coat of the eye. It is a dense fibrous membrane which is white but may have a bluish tinge in its thinner part. 2. Cornea – a transparent anterior part of external coat of the eye. It is colorless and non-vascular b. Vascular tunic 1. Choroid – a thin- opaque membrane that lies between the sclera and the retina 2. Ciliary body – the middle portion of the vascular tunic

3. Iris – forms the anterior of the vascular coat. It is a pigmented structure that forms a curtain to control the amount of light entering the eye. c. Nervous tunic Retina – a thin neuroepithelium which is closely attached to the colored and extends from the optic disc to the border of the ciliary ring. It contains the rods and cones, which are receptive to the light stimuli.

References/Additional Resources/Readings Syllabus Manual in ANSCI 100 Introduction to Animal Science, Central Luzon State University, 2015. Lecture Notes in Animal Science 1 Introduction to Animal Science, University of the Philippines Los Baňos, College, Laguna Livestock and Poultry Statistics af the Philippines (2013-2017). Philippine Statistical Authority. 2019. PDF file. LIVESTOCK AND POULTRY STATISTICS of the PHILIPPINES as of 06 Mar 2019_V4_0 Review of High Value Agriculture in the Philippines with Comprehensive Subsectoral Focus: Livestock Industries. Domingo, Sonny N. Philippine Institute for Development Studies. 2018. PDF File. livestock_review_06252018_domingo https://psa.gov.ph/sites/default/files/2017-2016%20CSAC%20Vol1.pdf https://psa.gov.ph/livestock-poultry-iprs/cattle/inventory https://psa.gov.ph/sites/default/files/2015-2016%20CSAC%20Vol2.pdf https://psa.gov.ph/ppa-main/livestock-poultry

Activity Sheet ACTIVITY 2 Name: ______________________Course/Year/Section:

___________ Score: _________

Instruction: Select the nearest correct answer to the following statements. Write the letter of your answer on the space provided. _____ 1. System of the body responsible for the removal of waste products from the blood. A. Cardiovascular

B. Digestive

C. Urinary

D. Lymphatic

_____ 2. Crop in the chicken is responsible for the following functions except: A. B. C. D.

Holding and moistening of feeds Fermentation of feed Grinding of softened feeds Breakdown of some fermentable carbohydrates

_____ 3. Newborn calf, kid and other ruminants are characterized by as follows except: A. A true ruminant B. A non-ruminant

C. Ruminant but not capable of rumination D. All of the above

_____ 4. Gall bladder is absent in some animals except: A. Horse

B. Deer

C. Pig

D. Elephant

_____ 5. Bile is secreted in the ___. A. Liver

B. Gall bladder

C. Small intestine

D. Kidney

_____ 6. The terminal part of the avian digestive system is ___. A. Anus

B. Vent

C. Cloaca

D. Rectum

_____ 7. The organ containing the bile is the ___. A. Urinary bladder

B. Gall bladder

C. Urethra

D. Small intestine

_____ 8. The following are the function of bones except A. Protect vital organs B. Movement of nutrients

C. Storing of minerals D. Act as levers

_____ 9. The color of oxygenated blood is ___. A. Dark red

B. Bright red C. Both A and B

_____ 10. The percent of blood in the total body weight is ___.

D. None of the above

A. 10-20%

B. 6-10%

C. 30%

D. 40%

_____ 11. What are the vessels that carry blood from the heart to the different body parts? A. Veins

B. Arteries

C. Both A and B

D. None of the above

_____ 12. It is the site for taking the pulse rate of a pig. A. Facial artery

B. Femoral artery

C. Sub-mandibular

D. Tibial

C. Liver

D. Stomach

C. Feathers

D. Skin

_____ 13. It is the largest gland in the body. A. Spleen

B. Kidney

_____ 14. It is the body covering of poultry species. A. Hair

B. Wool

_____ 15. It is the breathing which includes movement of air in and out of the lungs. A. External respiration B. Internal respiration

C. Both A and B D. None of the above

Assessment (insert Rubrics) Each question will be graded based on this five (5) point rubric. LEVEL

DESCRIPTION

5 - Outstanding

Well written and very organized. Excellent grammar mechanics. Clear and concise statements. Excellent effort and presentation with detail. Demonstrates a thorough understanding of the topic.

4 - Good

Writes fairly clear. Good grammar mechanics. Good presentation and organization. Sufficient effort and detail.

3 - Fair

Minimal effort. Minimal grammar mechanics. Fair presentation. Few supporting details

2 - Poor

Somewhat unclear. Shows little effort. Poor grammar mechanics. Confusing and choppy, incomplete sentences. No organization of thoughts.

1 - Very Poor

Very poor grammar mechanics. Very unclear. Does not address topic. Limited attempt.

Assignment (if any)

Learner’s Feedback Form   Name of Student: ___________________________________________________ Program : ___________________________________________________ Year Level : ___________ Section : ___________ Faculty : ___________________________________________________ Schedule : ___________________________________________________   Learning Module : Number: _________ Title : ______________________     How do you feel about the topic or concept presented? □ I completely get it. □ I’m struggling. □ I’ve almost got it. □ I’m lost.   In what particular portion of this learning packet, you feel that you are struggling or lost? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________   Did you raise your concern to your instructor? □ Yes □ No   If Yes, what did he/she do to help you? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ If No, state your reason? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________   To further improve this learning packet, what part do you think should be enhanced? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________   How do you want it to be enhanced? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ NOTE: This is an essential part of course module. This must be submitted to the subject teacher (within the 1st week of the class).