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Animal Science Final

by: Callie windham

Animal Science Final 1113

Marketplace > Mississippi State University > 1113 > Animal Science Final
Callie windham

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These notes cover everything covered after the midterm to the final. For Dr. Rude's class, this will be the only material on the final.
Animal Science
Brian Rude
Class Notes
Animal Science, animal, Science, nutrition, lactation, reproduction
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This 18 page Class Notes was uploaded by Callie windham on Friday April 29, 2016. The Class Notes belongs to 1113 at Mississippi State University taught by Brian Rude in Summer 2015. Since its upload, it has received 21 views.


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Date Created: 04/29/16
Animal Science— 4/4/16 Info for exam 4 Graph for progesterone and lh/estrogen will be on exam 4! Study production characteristics sheet. Lactation 3/28/16-4/4/16 ● Composition of Milk and factors affecting composition ○ Cow ◆ fat- 3.6 ◆ protein 3.3 ◆ Lactose 4.6 ◆ Solids 12.5 ○ Ewe ◆ fat- 5.4 ◆ protein- 4.8 ◆ 4.6 ◆ 15.7 ○ Sow ◆ 6.8 ◆ 5.1 ◆ 5.5 ◆ 17-18 ○ Mare ◆ 1.3 ◆ 2.2 ◆ 5.9 ◆ 9.8 ○ Woman ◆ 4.5 ◆ 1.1 ◆ 6.8 ◆ 12.6 ○ Baby animals get most of their energy from the lactose in the milk, and then from the fat ● Dairy Cows ○ Holstein ◆ Milk fat, %: 3.3-3.6 ○ Ayrshire ◆ 3.9 ○ Brown swiss ◆ 4.0 ○ Guernsey ◆ 4.6 ○ Jersey ◆ 5.0 ◆ Dairy producers are paid per every 100 lbs of milk Physiological and environmental factors affecting milk composition/ production ● Season ○ Higher fat in winter vs. Summer ◆ It takes more energy to cool themselves than to heat themselves. ○ Related to diet? (Hay vs. lush grazing) ● Stage of Lactatin ○ Percent of milk fat content increases during a lactation. (May ~0.5%) ● Time of sampling during milking ○ First-drawn milk (fore-milk) is lower in fat content than last-drawn milk (hind- milk) ○ “Fat leaves last” (~0.2% change) ● Age ○ Heifers have higher milk fat content than mature cows (~0.3%) ○ The fat amount usually does not change ● Calving (Colostrum) ○ Greatest variation in milk composition occurs after calving ● Colostrum ○ Milk present in udder at parturition ○ Transition from producing colostrum to producing normal milk takes 3-5 days; milk usually not salable until after the 11th milking (milk not salable until “normal”) ○ Composition ◆ Contains more… antibodies, vitamins A & D, fat, protein, most minerals (imunoglobins) ○ Why is it important? ◆ Newborn has no (or very low) immunity ◆ Transfer of immune globulins via colostrum is important ◆ Intestinal absorption of immune globulins lasts only 24-36 hr. Newborn must receive colostrum early to acquire disease resistance. ◆ Should have frozen colostrum on hand Udder development ● Starts early in growth of fetus ● At birth: teats, cisterns, and glands already exist ● Birth to puberty: little mammary change. Have isometric growth ● At puberty: ○ Estrogen stimulates growth of the duct system ○ Progesterone stimulates growth of the secretory tissues ○ Visible enlargement of udder is not apparent ● Final growth (visible enlargement) occurs when colostrum is secreted prior to birth of first calf Structure of the udder ● Species differences ○ Cow: 4 glands, terminate in 4 teats ○ Mare: 4 glands served by 2 teats ○ Cheap and goat: 2 glands and @ teats ○ Multiparous animals (Sow, bitch): ◆ 10-18 glands along abdominal wall. ● Udder of the cow ○ Suspension ◆ Median suspensory ligament— runs front to back ◆ Lateral suspensory ligament— runs left to right ◆ Mature cow: udder weighs 25-60 lb. ◆ Holds 50 or more lb milk ○ Four glands or quarters ◆ Separate from each other— Milk cannot move between quarters ◆ Rear quarters—> 60% of milk ◆ Rear ones usually produce more milk than the fore teats ○ Teats ◆ Hollow tubes of skin, muscle & erectile tissue hanging from udder. ◆ Valves close top and bottom; sphincter muscle closes bottom. ◆ Bottom opening = “streak canal” ○ Milk collecting system ◆ Teat cistern (cistern- a storage tank for water/liquid) ◆ Gland cistern ◆ Many collecting ducts (large & small milk ducts) ○ Alveolus ◆ Bulb-shaped with hollow center ◆ Basic milk-producing unit in udder ◆ Very small… ~1 million/cu. in. ◆ Lined with single layer of epithelial cells which synthesize milk from blood circulating through udder ◆ Milk is stored in cavity of alveoli until forced out by hormone action on small muscle tissues around the alveoli at time of milking ◆ Oxytocin stimulates milk to leave the alveoli Milk Secretion ● General ○ Each alveolus can independently synthesize new milk ○ Not dependent on the help of specialized cells. ○ Very efficient ○ ~400 lb. blood pass through user to supply nutrients need for 1 lb. milk (80 lb. milk produced/day = 16 tons of blood passing through.) ○ Synthesis is a continuous process ◆ Slowed and finally stopped by build-up of intramammary pressure (pressure on the alveoli) caused by accumulation of newly-made milk ◆ Essentially all the milk that can be obtained at milking is present in udder ◆ when milk evacuation begins. (Get only ~70% of milk present.) ○ Milk let-down (prior to milking, milk is stored in milk cavity of the alveoli.) when the udder (especially the teats) stimulated by calf or milker ◆ Impulses are conducted via nerves to pituitary gland ◆ Posterior pituitary- releases oxytocin (stimulates smooth muscle contraction around alveolus to let milk out) ◆ Anterior pituitary- releases prolactin (causes lactation/the synthesis of milk) ◆ Blood transports hormones back to udder ◆ Oxytocin causes contraction of smooth, muscle-like cells surrounding each alveolus (myoepithelial class), forcing milk into duct system and finally to cisterns ◆ Prolactin stimulates… ○ Milk hold-up ◆ If cow is disturbed, upset, frightened, or angry, let-down may not occur ◆ Epinephrine (adrenalin) is released into blood and can override action of oxytocin. (Reduced blood circulation to alveoli) ◆ A new work can cause anxiety in a cow and reduce milk let-down ○ Lactation curve ***Very important graph*** ◆ Peak= 6-8 weeks (42-56 days) ◆ Persistency normally = 90-92% (milk production this month as a percentage of last month.) ◆ Dry period: 2 months is ideal to give her enough time to store up nutrients to use again after she gives birth again Mastitis ● Inflammation of the udder ● Most costly disease of dairy cattle ○ Losses avg. ~$100/cow/year ○ ~$1.1 billion/year to industry ● Usually caused by streptococcus $ staphylococcus bacteria. ○ Infection usually is chronic. ● Three main causes: ○ Dirty or poorly adjusted milking equipment ○ Poor milking practices (dirty animals) ○ Injuries to cows because of their surroundings (teat got stepped on, teat got cut by fence etc.) Growth —4/6/16 If we are going to improve the efficiency of food conversion in livestock production, we must have a knowledge of how animals grow. Feed efficiency is highly associated with the body composition of the animal and the particular stage of growth for bone, muscle, and fat deposition (The three things we get from animals essentially). It takes 2.25% the amount of feed for an animal to give muscle than fat ● What is growth? ○ True growth- Increase in weight due to protein and bone deposition and fat deposition which is part of the developmental process ◆ True growth happens up until puberty ◆ After puberty there is no increase in bone, and there is virtually no increase in muscle ◆ After puberty, mostly what is being deposited is fat ○ Composition of a typical steer vs an over-finished steer ○ *insert graph here* ○ The fatter they get, the more is discarded ○ Yield grade is the proportion of that animal that will wind up as human consumption ● There are many things about growth that we don’t know ○ Why growth starts ○ How it is regulated ○ Why it stops ◆ In the body, genetics (DNA) is the ultimate regulator. Cell size and number are regulated to reach genetically determined values. ◆ Example: Cut out a piece of liver. Liver quickly grows back to original size and stops. Why? Some inhibitory mechanism stops the growth ● Growth occurs in two ways ○ Hyperplasia (increase in cell numbers) ◆ Occurs before birth except for… ◆ Some adipose cells— continue to divide and get new cells for a while after birth ◆ Skin — slough cells; repair wounds ◆ Intestinal lining ◆ Blood cells ◆ Most of these really are not new growth, but more of a replacement. However, cut or destroyed brain and muscle cels are not replaced/ repaired. ○ Hypertrophy (increase in cell size) ◆ Muscle cells— You have all of your muscle cells at birth ◆ Nerve Cells— You have all of your nerve cells at birth ◆ Most adipose cells— Have most of these at birth ● Prenatal growth ○ Sex cells—> embryo —> fetus ○ Endoderm: GI tract, lungs, bladder ○ Mesoderm: Skeleton, muscle, Connective tissues ○ Ectoderm: Skin hair, brain, spinal cord ● Bone growth ○ Structure and areas of growth ◆ All meat-producing animals follow a common pattern of bone development ◆ At the end of a long bone, there is something called an epiphysis. ◆ The middle of that bone is called diaphysis ◆ Plate between diaphysis and epiphysis called the epiphyseal plate cartilage ◆ Sheep: ◆ Break joint= lamb ◆ Spool joint= mutton ◆ Epiphyseal plate (cartilage)— New cartilage is formed as long as bone growth continues. The cartilage is gradually turned into bone. When the cartilage in the epiphyseal plate ossifies and no new cartilage is formed, bone growth ceases ◆ Diameter growth occurs by the periosteum depositing new bone cells (osteocytes). As new bone is deposited, deeper, inner bone is removed causing an increase in the size of the marrow cavity. Inner bone material that is removed is used by the perineum to make new bone. ◆ As bone cells are growing they’re called osteoblasts. When they’re done growing, they’re called osteocytes ○ Amount of cartilage ◆ Amount of cartilage (or lack of it) is used to estimate maturity in carcasses ◆ Maturity is a primary factor in determining carcass quality grade (choice vs. commercial) ◆ Maturity is the best single indicatory of meat tenderness ◆ As muscle gets older, there is increased connective tissue ◆ As muscle gets older, it gets less tender ◆ At 18 months an animal is no longer eligible to be prime, choice or select cut. ○ Frame size of beef cattle ◆ Frame size is determined by 2 factors ◆ Height at the hooks (hips) ◆ Hip height is used because hip height maturity is reached several months before mature height at the shoulders ◆ Age ◆ Frame size is of great importance in identifying the physiological maturity pattern of cattle on the growth curve. If you know the frame size of a bull, you have a good estimate of his eventual mature size. ◆ If you know the frame size of feeder cattle, you will have a good idea what their slaughter weight will be ◆ *insert graph here* ● Embryonic development ○ Adipose development begins during mid-to-late stages of fetal development ○ Differentiation (round-type cell) ◆ Small fat globules start to enter the cell ● Postnatal growth ○ At birth animals have very little fat ◆ Example: Pigs are around 2% fat at birth ○ As animal grows fat deposition occurs by enlargement of individual fat cells, ○ and for a short period of tie new fat cells develop ◆ Enlargement accounts for most of fat development ○ Fat is deposited at specific locations, and as the animals grows, it develops further from these locations ○ Adipocytes— fat cells ———4/8/16——— ○ Lets look at where fat is deposited in the body as an animal grows ◆ Around organs— Kidney, pelvic, and heart fat (KPH) ◆ Fat is important for protecting organs— good for insulation— energy reserve as well ◆ Makes up 3.5% of carcass weight (USDA choice) ◆ Fat surrounds kidneys even in young calves ◆ Increases as weight increases ◆ Dairy breeds have higher kidney fat than beef breeds even with less body fat— genetic difference ◆ Subcutaneous fat (under skin)— for insulation ◆ Largest quantity of fat in the body of hogs ◆ Is deposited in layers and connective tissue separates these fat layers ◆ Outer layer— laid down relatively early in life ◆ Increases very little as animal grows to mature weight ◆ earliest subcutaneous layer ◆ Middle layer— most development during growth to “normal” market weights ◆ Inner layer— (directly over longissiumus muscle) ◆ develops much later ◆ Fat-type pigs— evident at 120 lb ◆ Meat-type pig— very small at 230 lb ◆ In selection for meat-type pig, we have reduced the middle and inner layers of fat, but the outer layer changed little. ◆ subcutaneous fat deposition patterns for angus steers as they grow from 850-1000 lb ◆ Intermuscular fat— (called “seam fat” in the trade industry) ◆ located between the muscles ◆ largest quantity of fat in cattle ◆ Intermuscular fat often surrounds moving muscle parts; fills spaces between bone & points of muscle attachment ◆ Large deposits of intermuscular fat often causes problems for the packer and retailer in the merchandising of cuts ◆ The shoulder (lamb and pork) and chuck (beef) are particularly bad. ◆ Intramuscular fat (marbling) ◆ Located between muscle fibers and within muscle fibers ◆ Called marbling— indicator of palatability ◆ Remember: maturity (age) and marbling are 2 main factors in carcass quality grades ◆ Most deposition is in the later stages of growth (some is even present ◆ at birth) ◆ First to leave if animal is starved ◆ Marketing live animals on full feed: ◆ In cattle: 0.4 to 0.5 inches of back fat= 60-70% Choice (depending on breed) ◆ Measured between 12th/13th ribs, and about 5 inches from the midline ● Relationship b/w sex of animal and fat deposition ○ Young animals grow rapidly and more muscle protein than fat is deposited at this early stage ◆ As the animal matures, a greater portion of the gain is fat ○ Sex of animal makes a big difference in rate of fat deposition as animal matures: ◆ Intact (noncastrated) males are normally the leanest ◆ Cattle: steer normally leaner than heifer ◆ Sheep: wether normally leaner than ewe ◆ Hogs: gilts have more muscle (less fat) than barrows at market weight. ○ Hormones play a major role in sex differences in fat deposition ◆ Testosterone: stimulates muscle development and has an inhibitory influence on fat deposition ◆ Bulls and rams have more efficient weight gains plus more muscular, trimmer carcasses ◆ ALSO— bulls and rams won’t grade at typical market weights ◆ Testosterone also inhibits intramuscular fat. Animals have to be fed to heavier weights ◆ Estrogens: increases rate of closure of epiphyseal plate; therefore, slowing growth. (earlier closure than males) ◆ heifers ready for market about 150 lbs lighter than steers ◆ Why are gilts leaner than barrows? ◆ Who knows. but gilts do have a male pattern of growth hormone secretion ◆ BST— sonadotropine— growth hormone— stimulates milk production, or stimulates growth— ceases produce of estrogen ● Muscle growth and development ———4/11/16——— ○ Contraction is major function of muscles ○ In general: ◆ Loin and postural muscles are the most tender ◆ Sirloin [foreleg] (most tender) ◆ Round [rear leg] ◆ Chuck (least tender) [front shoulder] ◆ Selected muscles within each of the less tender areas have acceptable tenderness ● Prenatal development of muscle tissue ○ Total muscle-cell numbers are genetically established before birth ○ Postnatal development is an increase in size ● Postnatal development ○ Muscle fibers grow in diameter in length ○ Tenderness decreases as the animal ages because of connective tissue ◆ There becomes more connective tissue and more cross-linking ○ Pigs: {about the same for all livestock animals, only thing that differs would be the amount of days} ◆ at 80 days of age: ◆ ~50% of muscle-fiber growth achieved ◆ intramuscular fat starts to increase ◆ Water content decreases ◆ At 120 days of age: ◆ muscle-fiber growth ~75% complete ◆ Fat is increasing rapidly ◆ At 150 days of age: ◆ 95% of maximum fiber diameter is attained ◆ ready for market ◆ additional weight gain is fat Body Composition— tying it all together ● Selection for efficient animal production involves an understanding of the magnitude and sequence of tissue deposition at different stages of development. Not all portions of the body develop equally or at the same time during growth. ● Growth curve ○ Sigmoidal or S-shaped ○ If it’s alive, it has a growth curve. Anything from animals to plants to bacteria ○ Events during growth (Phases of the growth curve) ◆ Relatively little growth before birth and initial increase following birth is slow ◆ Early— rapid growth of the essential organs, skin and bone ◆ Head and legs are proportionally greater than the trunk ◆ Have further development of the organs, skin and bone pus very rapid muscle growth. Some fat is starting to be deposited ◆ Body becomes longer but still lacks depth ◆ Weight gains are rapid and efficient, mostly due to muscle and bone growth ◆ Bone growth is nearly complete by the end of the phase ◆ Some fat is being deposited, even during this period of lean growth ◆ Last phase— increase in growth is nearly all fat ● Growth and development of bone muscle and fat ○ Bone is earliest maturing— becomes rather constant ○ Muscle is next ○ Rapid increase in fat occurs when muscle begins slowing down Nutrition ● Animal Classification ○ Monogastris (also called non-ruminants, simple stomach) ◆ Digestion begins in stomach— only to a small degree. ◆ Most digestion and absorption occurs in small intestine ◆ Pigs, dogs, cats, humans ○ Ruminants ◆ Have one stomach with four compartments ◆ Reticulum, Rumen(largest section), Omasum and abomasum ◆ Feed can go between reticulum and rumen ◆ Microorganisms in the reticulum and rumen account for much of the breakdown of feeds ◆ Cattle, sheep, goats, deer, elk, moose ◆ Do not require amino acids because of the bacteria in the reticulum ○ Non-ruminant Herbivores ◆ Have a simple or mono gastric stomach ◆ But have a cecum {large pouch at the junction of the large intestine and small intestine— contains the microorganisms that digest fiber} ◆ Cecum is an enlarged pouch located at the posterior end of the intestine— this is the difference b/w horse and pig stomach ◆ {animals cannot digest fiber. the microorganisms inside them can digest the fiber} ◆ Horses, rabbits, guinea pigs ◆ Not all herbivores are ruminants! Some animals eat grass and have a single stomach but use other methods to house the bacteria which break down the cell walls. Rabbits, horses, donkeys, zebras, geese, koalas and groundhogs are non-ruminant herbivores. Look for horns, antlers or protuberances of the head, because many of the ruminants have something sticking out of their heads— cattle, sheep, goats, deer, giraffe etc ● Grouped by feeding behavior- what they eat ○ Carnivores. Length of the digestive tract is relatively short. Cats, dogs, and mink ○ Herbivores. Longest of the digestive systems with modified gastric or cecal- colon areas. Cattle, goats, and horses ○ Omnivores. Intermediate length systems. Swine and humans. Anatomy of the Digestive system —4/13/16— ● Animals are like donuts- they have a hole in the middle of them ● A tube from the lips to the anus ● Regions divided into Mouth [acquire food & somewhat chew], esophagus, stomach, small intestine, cecum, large intestine, rectum and anus. ● Attached to the tube are the Liver and the pancreas— they are not digestive organs but are very important ○ Pancrease- enzymes into the digestive tract to help digest & buffers for acidity ● Other than lips, tongue and muscle for swallowing on one end and the sphincter muscle on the other end, the system is smooth muscle ○ Smooth muscle does involuntary work Nutrients and their end products of digestion ● Nutrient: chemical which a body needs for maintenance or production ○ Feed constituents essential to support life ○ Can be: ◆ Simple: Na, Cl, Ca ◆ Complex: protein, fat, carbohydrate ○ Maintenance— it survives, it doesn’t die. ○ Production— Growth, Lactation, Reproduction, Fattening, Work, Eggs, Wool ● Six classifications of nutrients ○ Water ◆ Much of the dietary water is derived from feed 2–4 times as much water consumed as feed. Food moisture ranges from 10%-90%. Dry matter is the term given to the part of a feed or food which is no2 H O ◆ Water helps in Metabolic reactions, transporting nutrients & other things via blood, body temperature regulator, gives/maintains cells their shape. ○ Lipids/fats ◆ Fats: solid at room temperature ◆ Oils: liquid at room temperature ◆ Contain 2.25 times more energy per pound than carbohydrates ◆ 3 essential fatty acids 1. Linoleic 2. Linolenic 3. Arachidonic ◆ Most diets less than 5% ◆ Functions ◆ Essential fatty acids ◆ Insulation ◆ Cushion organs and joints ◆ Protect nerve fibers ◆ Storage of energy ○ Proteins ◆ Animals do not require proteins- they require amino acids. Proteins are made up of amino acids ◆ All proteins have N (NH3 from amino acids) ◆ Feed protein averages 16% N ◆ Two amino acids connected are a dipeptide ◆ Amino acids can connect end to end into long chains, with an assortment of various amino acids ◆ Remember 6.25 proteins are 16% nitrogen ◆ Essential amino acids: Phenylalanine, valine, tryptophan, threonine, isoleucine, methionine, histidine, arginine, lysine, leucine. Acronym: PVT TIM HALL ◆ Ruminants don’t require amino acids because the microbials in their stomach environment— watch out for a trick question on this ◆ cats don’t synthesize taurine so they must acquire them from their diet ◆ Amino acids used for muscle, and other protein synthesis. Amino acids can be used for energy, but CHO are the primary energy source ○ Vitamins ◆ vitamins are needed in very small amounts ◆ Fat soluble vitamins ◆ Absorbed with lipids ◆ Can be stored in the body ◆ A= variable (eyesight) carotenoids ◆ D= Absorption of Ca & P from intestine ◆ E= Variable- serves as an antioxidant ◆ K= blood clotting ◆ Water soluble vitamins [B-complex and C] ◆ Vitamin C is needed by man and guinea pig ◆ Ruminants do not need dietary source ◆ Ascorbic acid (C) ◆ Thiamine (B1) ◆ Riboflavin (B2) ◆ Niacin ◆ Choline ◆ Pantothenic acid ◆ pyridoxine (B6)— discovered during ww2 when it wasn’t in baby milk replacer ◆ Biotin ◆ Folic acid ◆ Cobalamin (B12) ○ Minerals ◆ Not digested like other nutrients ◆ Released from plant cells as part of digestion ◆ Macro: required in large amounts— know these, and any other minerals besides these you’ll know is a micro-mineral ◆ Ca, P, Na, Cl, Mg, K, S ◆ Micro: required in small amounts ◆ I, Co, Cu, Zn, Mn, Fe, Se, Mo ◆ Some are toxic in larger quantities (Se, F) ◆ Functions: too many to attempt to list ◆ Skeletal structure, 99% Ca, and 80% P in body as bone ◆ Metabolism (cofactors for metabolic reactions) ○ Carbohydrates ◆ Simple carbohydrates: glucose, fructose, lactose [building units] ◆ Complex carbohydrates: cellulose, plant cell walls, starch in grain seeds ◆ Make up 65%-80% of grains and roughages ◆ Carbohydrates are the energy source of energy Major feed classifications ● Terms ○ Diet: feed mixture consumed by animals ○ Ration: amount of the diet supplied for a specific time period (24 hrs) ○ Feedstuff: Constituent in the diet or feed material (ingredient) ● Concentrates ○ High in energy ○ Low in fiber ○ Usually are highly digestible by all classes of livestock’ ○ Diets high in concentrates are often referred to as “High-energy” or “high-grain” diets and produce the most rapid gains ○ Include: Grains (corn), oil meals (soybean meal), molasses and dried milk- products. ○ Oil meals in diets as a source of protein ◆ less than 15% of the total diet ● Roughages ○ These are feeds higher in fiber (cellulose) ○ Less digestible ○ Lower in energy ○ Include ◆ Legume hays, grass hays, straws ◆ Silage, stover, fresh grass ○ Animals do not gain as fast as those consuming high-concentrate diets Digestion disassembly process —4/18/16— ● Requires two types of action ○ Chemical breakdown ○ Enzymatic breakdown- occurs in the small intestine ● Complex proteins and carbohydrates must be broken down into simple components ○ Eg glucose, amino acids ○ Then reassembled into animal parts ● Mechanical breakdown ○ Pre-ripping during prehension: crocodiles, chickens, man ○ Mastication: mouth, teeth and tongue ○ Action of grit or stones in chickens (gizzard) ● Chemical breakdown ○ Hydrochloric acid (HCl)— in stomach ◆ HCl stretches the protein chains out for breakdown ● Enzymatic breakdown {this is the bulk of digestion} ○ Amylase: saliva breaks down starches ◆ ONLY in primates and pigs ○ Enzymes break down: ◆ Carbohydrates [amylase (breaks down starch), lactase (breaks down lactose/milk), sucrose (breaks down sugars)] ◆ Lipids (lipase) ◆ Proteins (Peptidases) ● Words to define: ○ Enzyme— an organic catalyst that speeds a reaction without being altered by the reaction ○ Chyme— mixture of food and secretions of the digestive system {entering into the small intestine} ● Three major nutrient classifications of animals— what happens from the mouth to the anus: Monogastrics ○ Mouth 1. Food acquisition 2. Mechanical breakdown (mastication) 3. Saliva: Adds moisture to what the animal has consumed, Acts as a buffer (bicarb), Taste, Amylase (start starch digestion) ○ Esophagus— Mechanism for transporting what the animal consumed to the stomach ○ Stomach (Secretes HCl and pepsinogen) 1. Esophageal region 2. Pylorus— emptying into the intestinal region 3. Cardiac gland region 4. Funds gland region ◆ 2 types of layers in the stomach – Chief cells: produce pepsinogen – Parietal cells: produce HCl ◆ HCl + Pepsinogen = pepsin (capable of digesting protein) ○ Small intestine ◆ Three regions: 1. Duodenum 2. jejunum 3. ileum ◆ Carbohydrates – Starch—> glucose (digested in the SI— not all is digested) – Fiber —> Fiber (not digested) ◆ Fats – Triglycerides—> glycerol & fatty acids (if you can only give one answer, give fatty acids) ◆ Protein – True protein—> amino acids (some not digested) – Non-protein N—> out, ~absorbed ◆ Minerals (absorbed) ◆ Vitamins (absorbed) ◆ Cellulose is not digested Anywhere that water is being absorbed, water soluble vitamins can be absorbed too ○ Large intestine ◆ Water absorption— extract water out of the chyme, therefore a dryer product will be left to excrete as feces ◆ Minerals can be absorbed in the large intestine ◆ Vitamins— water soluble can be absorbed here {Example questions: Where is protein digested in a mono gastric— SI protein absorbed in mono gastric? SI Fat absorbed in mono gastric? SI etc} ———4/20/16——— For this, Remember “where in the GI tract is this happening?” Ruminants ● Digestion in a ruminant animal ○ Mouth ◆ Food acquisition— Tongue is very important for them to acquire food ◆ Mastication— ◆ No upper front teeth ◆ Saliva— Adds moisture; acts as a buffer— this is vital!; NO amylase ○ Reticula-Rumen ◆ The enzymes here are NOT coming from the animal. They are coming from the bacteria in the reticula-rumen ◆ 25-30 billion/mL bacteria ◆ 200-500,000/mL protozoa ◆ Carbohydrates digested to… ◆ Starch—>Microbe nrg—> Volatile Fatty Acids ◆ Fiber—>Microbe nrg—>Volatile Fatty Acids ◆ Volatile fatty acids are absorbed through the wall of the rumen for the animal to make its own glucose and get energy ◆ butyrate, propionate, acetate are the three volatile fatty acids— butyric acid, propionic acid, acetic acid ◆ all carbs should have been digested and absorbed in the reticula- rumen ◆ Fats ◆ Triglyceride—> glycerol and fatty acids ◆ Protein ◆ True protein (chain of amino acids)—> microbial protein some by-pass goes to the small intestine ◆ Non-protein Nitrogen—> microbial protein ◆ escape or bypass protein (because they’re escaping protein degradation in the rumen)—> amino acid ◆ Vitamins ◆ B vitamins are synthesized/made in the rumen by the bacteria ◆ Cobalt, cobalamin (B12) ○ Omasum ◆ Water absorption ○ Abomasum (homologous to the true stomach) ◆ HCL ◆ Pepsinogen—> pepsin ○ Small intestine: major site of digestion and absorption by animal (digest leaving rumen) ◆ Carbohydrates ◆ All of these were digested and broken down into VFA in the reticula- rumen therefore nothing else will happen with carbs in the small intestine ◆ Fats ◆ Fatty acid absorption ◆ Protein ◆ Microbial protein (bacteria)—> amino acids ◆ By-pass protein or escape protein (bacteria)—> amino acid ◆ Minerals (absorbed) ◆ Vitamins (feed and microbial absorbed) ○ Large intestine ◆ Water absorption ◆ Minerals left over can get absorbed ◆ Vitamins left over can get absorbed ● Young ruminants ○ Essentially mono gastric until about 3-4 months old— only the abomasum is functional ○ 3 weeks: rumen begins to become functional ○ 3-4 months: fully functional reticula-rumen ○ Esophageal Groove: muscle, during first 3-4 months of life active. Nursing stimulates it closing— milk by-passes the reticula-rumen and goes straight into the abomasum ● Terms ○ Regurgitate: to cast up “digested” feed from the stomach to the mouth ○ Ruminate: Regurgitation, chewing, re-swallowing ○ Eructate: Elimination of gas via belching ◆ Gas produced by bacteria and protozoa ◆ CO 2nd CH 4 (methane) ◆ They bloat because they’re unable to expel gas— the left side will be more visually bloated ○ Swallow—>Regurgitate —> Chew bolus—> Re-swallow—> Another bolus regurgitated ○ Rumination: Regurgitate—> chew bolus—> Re-swallow ———4.22.16——— Non-ruminant herbivores ● From mouth to small intestine, see mono gastric animal ● Mouth ○ Food Acquisition ○ Mechanical Breakdown (mastication) ○ Saliva ○ They do not vomit. There is no regurgitation actions. ● Stomach ○ HCL ○ Pepsinogen ● Small Intesting ○ Carbs ◆ Starch—> Glucose ◆ Fiber—> not digested ○ Fats ◆ TG—> fatty acids & glycerol ○ Protein ◆ True Protein—> amino acids (some may not be digested here) ○ Minerals (absorbed) ○ Vitamins (absorbed) ● Large Intestine ● Cecum (Pocket) ○ About the same as a rumen ○ Starch does not get digested (very much) in the cecum— this mostly happened in the small intestine ○ Crude protein does not get digested (very much) here— this should have happened mostly in the small intestine ○ Fiber—> VFA (absorption) 70-100% of a horses (maintenance) energy needs can be met just from this fiber. Can live almost entirely on a forage based diet. ○ B Vitamins are synthesized by bacteria in the cecum ● Rest of Large Intestine: ○ Water absorption ○ any minerals that werent absorbed earlier ○ vitamins (B Vitamin) ● A horse will eat 5-8 meals a day— they are called continuous grazers Digestion of Cellulose ● Pre-gastric digestion ● Post-gastric digestion ● Coprophagy— Non ruminant herbivores will eat their own feces ○ More often theyre eating what was expunged from the cecum and not necessarily the nasty part of feces ○ From this, they get protein and B Vitamins ● Giving a ruminant animal protein doesn’t matter. The microbials in the rumen will break down the protein to a lower form of protein ● Horses on the other hand, will break down the protein directly


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