L1- L11 (UNIT 1)
butyric acid (butyrate)
- VFA derived from acetic acid - water soluble
acetic acid (acetate)
- VFA that comes from cellulose - important to milk fat in dairy cows - water soluble
propionic acid (propionate)
- VFA that mostly comes from starch - water soluble
CHO digestion in allo-enzymatics
- CHO digestion in ruminants is largely the result of microbial fermentation in the rumen - fermentation is anaerobic respiration - dietary CHOs are fermented, mainly by rumen bacteria, and the absorbed energy sources for the animal are the bacterial waste products, the VFAs
saturated FAs
- FAs that are fully saturated with hydrogen - solid at room temperature
human vs. rabbit digestive system
- both have monogastric digestive systems - rabbit (herbivore) has an enlarged small intestine and cecum to allow more time to digest plant material, which allows more surface area for absorption of nutrients
H.pylori
- cause of most peptic ulcers - survive the acidity of the stomach due to the secretion of urease
urease
- enzyme that changes urea into ammonia and carbon dioxide - neutralizes acid in the stomach
VFA metabolism in ruminants (allo-enzymatics)
- in contrast to simple, non-ruminants, runimants absorb very little glucose - their major absorbed energy source are the VFAs, the end products of microbial fermentation in the rumen - thus, 3 B-complex vitamins (pantothenic acid, biotin, and B12) are involved in propionate entry into the citric acid cycle - propionate metabolism is consequently impaired with B12 deficiency
glycocalyx
- a capsule made up of a fuzzy coat of sticky sugars (rich in carbohydrates) - projection of microvilli - function in trapping nutrients for completion of digestion
metabolic water
- source of water to animals - result of oxidation of organic nutrients in the tissues - water is produced by chemical reactions in the cells
emusification
- the dispersal of lipid in water in the form of very small droplets - increases the surface area of lipids over a 1,000 fold, making them more accessible to the digestive enzymes
acetic acid (C2)
- the major VFA produced by cellulolytic bacteria - high roughage diets result in a high molar proportion of this acid as a percentage of total VFAs
intermediate
- type of ruminant - consume a mixed diet based on season and opportunity - prefer concentrate protions of plant parts and will select shrubs and browse - also possess ability to digest cellulose ex. goat
vitamin A functions
- vision - gene transcription - immune function - embryonic development & reproduction - bone metabolism - haematopoiesis - skin & cellular health - teeth - mucous Membrane
peroxidation
- a chain reaction occurs, in which the peroxidation processes generate free radicals which initiate further peroxidation - other sources of free radicals and lipid oxidants (reactive oxygen species; ROS) are the superoxide free radical anion and hydrogen peroxide - the superoxide ion is a by-product of normal metabolism - free radicals have an unpaired electron and are very electrophilic (i.e. they react to gain another electron) - superoxide is detoxified by the enzyme superoxide dismutase, producing hydrogen peroxide - hydrogen peroxide is also a potent oxidant, and is detoxified by the reaction with reduced glutathione (GSH) catalysed by glutathione peroxidase and with catalase
CHO metabolism
- a fundamental biochemical process that ensures a constant supply of energy to living cells - cellular metabolism of CHO is based on the catabolsim of glucose, which involves the sequential degredation of the molecule through a series of enzymatic rxns - the end result is the conversion of glucose to CO2 and water with the release of energy as ATP and heat - the total energy released is equivalent to the solar energy required to synthesize glucose from CO2 and water via photosynthesis
thirst
- a result of increased concentration of electrolytes in corporal fluids - controlled by the thalamus - can be caused by temp., water quality, disaeses, etc.
absorption of AAs
- absorption from the lumen of small intestine by transepitelial transport - semispecific Na+ dependent transport sysmte - Na+ dependent carriers transport both Na+ and an AA
mastication
- aka "chewing" - physically breaking down food into smaller particles
frugivores
- aka "fruit eaters" - generally have a dietary requirement for vitamin C - these animals have lost the ability to synthesize vitamin C because it is normally present in adequate amounts in their diets
other ruminants
- aka "pseudo-ruminants" - camels and other camelids are considered to be ruminants, but have substantially different stomach anatomy than other ruminants - the stomach has three compartments, roughly comparable to the rumen, omasum, and abomasum
short-chain fatty acids (SCFA)
- aka "volatile fatty acids (VFAs)" - ruminants meet their protein needs by digesting rumen microbes - ruminants meet their energy needs by absorbing the waste products (VFAs) of rumen bacterial fermentation
carotenoids
- an abundant group of plant pigments (over 600 individual carotenoids are known) - contain a long chain of conjugated double bonds, and most (e.g. beta-carotene) but not all (e.g. lycopene) have a beta-ionone ring (which is necessary for vitamin A activity) - the chain of conjugated double bonds has antioxidant activity - in plants, carotenoids are found in the chloroplasts and function in photosynthesis - part of skin and feather pigments - contribute to the antioxidant defenses of animals
glucose
- an essential metabolite in mammalian metabolism - not a dietary essential because other products can be metabolized to produce energy
MUFA (monounsaturated fatty acid)
- an unsaturated fatty acid with one double bond - plant sources that are rich in this type of fatty acid include vegetable oils that are liquid at room temperature, avocados, and nuts
dietary protein
- animal nutritionist have to be careful to provide adequate dietary protein and AAs in the feed formulations - in the comparative standpoint, there are great differences in protein utilization - ruminant animals are largely insulated from specific dietary AA requirements because of the activities of rumen microbes - carnivores have some distinct differences from omnivores in AA needs
selenium
- antioxidant actions (participates in selenium proteins) - in animal production, the use of organic selenium (seleniomethionine) reduces mortality and improves feed efficiency, meat and milk quality - selenium is a key nutrient in animal nutrition and is crucial for an optimal antioxidant status and immune function
selenium
- antioxidant trace element that prevents the peroxidation of unsaturated fatty acids in cell membranes - helps protect against auto-oxidation of cell membranes by virtue of being a component of an enzyme, glutathione peroxidase, that reduces (by providing hydrogen) peroxides, thus converting them to innocuous products - glutathione peroxidase functions mainly in the cytosol and reduces peroxides before they can attack cell membranes, whereas vitamin E acts within the membrane itself as a second line of defense - also functions as a component of a deiodinase that converts the thyroid hormone thyroxine (T4) into its metabolically active form (triiodothyronine) by the removal of one of the four iodines in thyroxine
rumen fermentation of CHO (allo-enzymatics)
- bacteria secrete enzymes that split the bonds linking sugars together in oligosaccharides and polysaccharides resulting in the release of free sugars - these free sugars are taken up immediately by the bacteria and metabolized as energy sources - because the rumen is primary anaerobic, the bacteria cannot oxidize sugars completely to CO2 and water - they excrete carbon fragments in the form of VFAs, CO2, and methane (CH4) - small amounts of O2 may enter the rumen as air swallowed during feeding - although O2 is toxic to anaerobic bacteria, it is quickly utilized by faculative anaerobes
fatty acids (FAs)
- basic unit of lipids - acids differ in the number of carbon atoms and in the amound of hydrogen they contain - include saturated and unsaturated FAs - contain a carboxyl group (-COOH) at the carbon chain
vitamin E deficiency
- birds: encephalomalacia, exudative diatheses (severe edema of the subcutaneous tissues), muscular dystrophy - swine: exudative diatheses, muscular degeneration, liver necrosis - bovines: fetal reabsorption, metritis, testicular degeneration
vitamin D deficiency
- birds: rickets & eggs with bad shells - mammals: rickets, enlargments of metacarpal and metatarsal bones & other bone deformities
caecotropes (caecotrophy)
- caecal material produced in caecal fermenters by goblet cells - this material, known as "soft feces" is consumed by the animal directly from the anus - consumtion of this material provides the animal with a means of more efficienctly digesting the products of caecal fermentation, digesting the microbial protein, and obtaining microbially synthesized B vitamins
goblet cells
- cells on the villi of intestines that produce and secrete mucus - mucus protects the intestinal lining and provides lubrication to facilitate movement of digesta through the gut
rumen fermentation of cellulose (allo-enzymatics)
- cellulolytic bacteria attach to fiber particles and the cell walls of fibrous plant material consumed by the animal - there is little or no free cellulase in the rumen contents - cellulolytic bacteria invade the plant cells and tend to digest them from the inside, which protects them from predatory protozoa
salivation in ruminants
- compared with non-ruminants, ruminant animals secrete copious qauntities of saliva - the saliva is rich in Na+, K+, phosphate, and bicarbonate ions, serving to buffer the rumen VFAs - saliva is also high in mucin, serving as an antifoaming agent in the rumen to prevent bloating - urea is a component of ruminant saliva, functioning in urea recycling - salivary flow is influenced by the amount of time spent eating and ruminating
ATP (adenosine triphosphate)
- compound used in animal metabolism as the energy source for biochemical reactions - animals are not capable of converting all of the available energy in carbs to ATP because a large part of the energy is lost as heat
coprophagy
- consumption of feces - some caeco-colonic fermenters engage in this act - ex. on low protein diets, horses will consume their feces, presumably as a means of conserving nitrogen (wild horses in N.America often practice this)
magnesium
- correlated with calcium and phosphorus, in the metabolism and distribution in the body - participates in the metabolism of carbohydrates, and lipids
water intake requirements
- dairy cow: 40 to 65 L /day, + 1.5 to 2 L/ for each liter of milk produced - beef cattle: 8 to 9 L / 100 kg of body weight - sheep: 3.5 to 4 L/ day - horses: 30 to 45 L / day, Work horse 60 L/ day - chicken: 2 times the amount of feed intake, special requirements in thermic stress - dogs and cats: around 30-60 mL / kg BW / day
phosphorus absorption
- decreased by: phytates, magnesium, calcium - increased by: vitamin D
vitamin deficiency
- deficiency causes a specific disease, which is cured or prevented only by restoring vitamins to the diet - in most cases, these roles are in regulation of enzyme function
nutrition
- defined as applied biochemistry - commonly referred to as "nutritional science"
lipids
- defined as those constituents of plants and animals tissue that are soluble in organic solvents like diethyl ether - function as components of cell membranes and as the insulation of nerves
vitamin B6 deficiency (water soluble)
- dermatitis - skin disorders - kidney stones - nausea - cracks at the corners of mouth
dietary protein in allo-enzymatics
- dietary protein can either be fermented in the rumen or it can bypass rumen fermentation and be digested in the small intestine - several factors influence the rumen degradability of proteins, such as their solubility and nature of their physical structure
minerals and vitamins
- dietary requirements are unequivocal - have specific metabolic roles which cannot be replaced by other nutrients
protein digestion in allo-enzymatics
- digestion in ruminants can be subdivided into 3 phases: 1. alloenzymatic digestion in the stomach (reticulorumen) 2. autoenzymatic digestion in the abomasum and small intestine 3. alloenzymatic digestion in the hindgut
crop
- diverticulum of the esophagus in avian species between the beak and proventriculus - functions as a food storage area (some microbial digestion) - mucus glands in the upper esophagus secrete mucus, which aids in the movement of ingested fede to the crop
cholesterol metabolism
- due to its amphipathic property, cholesterol is a constituent of cell membranes and the outer layer of lipoproteins - all carbon atoms in cholesterol are derived from acetyl CoA - synthesized in many tissues, particularly the liver, and is the precursor of all other steroids in the body (vitamin D, bile acids, androgens, oestrogens, corticosteroids)
cellulase
- enzyme that breaks down cellulose - produced by rumen microbes - permits the digestion of firbous feeds containing cellulose
taurine
- essential amino acid in the cat that is exclusively found in animal-based protein - critical for normal vision, normal digestion, normal heart muscle function, to maintain normal pregnancy and fetal development, and to maintain a healthy immune system
nutrients
- essential for the normal functioning of the human body - dietary essential for one or more species of animals - not all animals require all nutrients - some nutrients can be omitted in the diet if appropriate adjustments are more and for a short period of time (i.e. there is not a requirement for carbs per se)
steroids
- fat-soluble lipids that contain the steroid nucleus - cholesterol is the best-known steroid, and is the ultimate precursor of many others, including vitamin D, bile acids, sex hormones (testosterone, oestrogen, progesterone), corticosteroid hormones (cortisol, corticosterone, aldosterone), anabolic steroids, etc
vitamin B12 deficiency (water soluble)
- fatigue - anemia - neurological disorders - bone barrow problems
microvilli
- fingerlike extensions of plasma membrane of apical epithelial cells - increase surface area of villi - aid in absorbtion - have projections called glycocalyx - exist on every moist epithelia, but most dense in small intestine and kidney
glycolysis
- first step in the catabolism of glucose to CO2 and water in CHO metabolsim - enzymes are located in the cytosol of the cell - can function either aerobically or anaerobically - pathway involves the breakdown of glucose (C6) to 2 molecules of pyruvate (C3) (pyruvic acid in aerobic metabolism and lactic acid in anaerobic metabolism) - small amounts of ATP is generated
stomach (autoenzymatic digesters)
- food is consumed, chewed, and swallowed, moving down the espohagus into the stomach - the stomach functions in digestion, absorption, food storage and mixing, and secretin - consists of four functionally distinct zones (image) - ingesta exit the stomach from the pyloric region, entering the duodenum of the small intestine
calcium functions
- formation of bone matrix - essential factor in the coagulation of the blood - participation in the muscle contraction process - act as adjuvant in the process of neural signaling transmission - enzyme regulation (calmodulin, muscle contraction) - act as a second message to some hormones
ruminant herbivore
- four-chambered stomach with large rumen - long small and large intestines - ex. deer
young ruminant digestive tract
- functions as a mongastric system - no fermentative digestion (rumen & reticulum are non-functional) - reticular groove or esophageal groove allows suckled milk to go to omasum - suckling is important because it helps groove to function - bucket-fed calves spill milk into rumen & reticulum
vitamin C (ascorbic acid)
- functions as an antioxidant, in addition to its role in vitamin E recycling - synthesis involves formation of L-gulonolactone from glucose, which is converted to ascorbic acid by the enzyme L-gulonolactone oxidase - most animals have this enzyme - a few, including humans, other primates, guinea pigs, fruit-eating bats, some fruit-eating birds and some fish lack this enzyme and so have a dietary requirement for vitamin C - also required in collagen synthesis
gastrin family
- gastrin - cholecystokinin (CCK)
digestive hormones in the GI tract
- gatric secretions are controlled by GI tract hormones, with the process initiated by the nervous sytem - a large number of GI tract hormones have been discovered (image)
thiamin deficiency
- glucose metabolism is impaired at this step and pyruvate accumulates - blocks energy metabolism at the decarboxylation rxns invovled in formation of acetyl CoA and succinyl CoA, causing symptoms of energy deficiency, including polyneuritis, anorexia, and hypothermia
polyphenolic antioxidants
- great deal of interest in polyphenolics in fruits and vegetables - believed to have beneficial effects on human health by functioning as tissue antioxidants - contain aromatic rings with hydroxyl groups - have more than one hydroxyl group - function as antioxidants by providing hydrogen to reduce oxidants (Note that this is how vitamin E functions) - ex. resveratrol
vitamin E
- group of 8 fat soluble vitamins that include four tocopherols and four tocotrienols - deficiency is rare and usually due to an underlying problem with digesting dietary fat rather than from a diet low in vitamin E
vitamin K
- group of structurally similar, fat-soluble vitamins found in foods and in dietary supplements - the human body requires vitamin K for complete synthesis of certain proteins that are needed for blood coagulation or for controlling binding of calcium in bones and other tissues - synthesis of this vitamin is in the rumen by bacteria in allo-enzymatics - synthesis of this vitamin is in the large intestine in auto-enzymatics (can only be used via coprophagy)
amphipathic
- having both polar and non-polar properties - soluble in both water and lipids
ADH (arginine vasopressin)
- hormone made by the hypothalamus in the brain and stored in the posterior pituitary gland - tells your kidneys how much water to conserve - constantly regulates and balances the amount of water in your blood
cholecystokinin (CCK)
- hormone secreted primarily by the small intestine - mediates stomach emptying via the presence of unabsorbed lipids in the intestine - promotes satiation (fullness)
hindgut fermenters
- horses, rhinos, elephants, rabbits, & koalas - digestive system in which microbial fermentation occurs in the digestive organs that follow the small intestine: the large intestine and cecum
vitamin C deficiency (water soluble)
- improper wound healing - loose teeth - bleeing and swollen gums - muscle weakness
fat and FA metabolism
- in general, because lipids are insoluble in water, they are transported in blood in association with serum proteins, forming lipoproteins - main lipoproteins include chylomicrons, VLDL, LDL, and HDL
crop milk
- in some birds, such as pigeons, doves, parrots, penguins, flamingos and pelicans, the crop produces "milk" which is regurgitated into the crops of the young - the milk consists largely of lipid-rich epithelial cells plus ingested feed - the production of this milk is stimulated by the hormone prolactin
CHO digestion in chickens (auto-enzymatics)
- in the chicken, the chick at hatching has full development of its CHO digestive enzymes, whereas this is not the case for species that consume crop milk (i.e. pigeons) - in contrast to the chicken, these crop-milk species develop digestive enzyme activity and diet shifts over the first few weeks of life
CHO digestion in pigs (auto-enzymatics)
- in the pigs and other mammals, the neonate initially consumes only milk, so at birth has low acitivity of amylase, sucrase and other carbohydrases involved in digestion of plant-origin CHO - only lactase is needed by the newborn mammal - development of digestive enzyme activity is stimulated by the consumption of solid feed by the young animal
polyneuritis
- inflammation of many nerves - ataxia, opisthotonus or star gazing - convulsions
minerals
- inorganic components of plant and animal tissues - classified as macro or micro (trace) minerals
chromium
- known to enhance the action of insulin , a hormone critical to the metabolism and storage of carbohydrate, fat, and protein in the body - refer to image for symptoms of chromium deficiency
protein
- large molecules composed of AAs joined together by peptide bonds - plant and animal proteins are composed of about 20 AA, arranged in various sequences to form specific proteins - a few other AA do not occur in protein synthesis but have specific functions and are known as non-protein AA (i.e. citrulline)
rumen
- largest compartment of a foregut fermenter's (ruminant's) stomach - functions as a fermentation vat for ingested feed - rumen microbes are primarily anaerobic bacteria that secrete enzymes which digest the consumed feed
sphingolipids
- lipid that contains glycerol - contain a long-chain alcohol, sphingosine - are phospholipids containing ceramide, the fatty-acid derivative of sphingosine - major constituents of nerve tissue (cerebrosides and gangliosides) and they occur in cell membranes in general
phospholipids
- lipid that contains glycerol - contain one or more phosphate groups - important consituents of cell membranes and nerve tissue - ex. lecithin
waxes
- lipid that contains glycerol - the surfaces of plants are often covered in a protective layer of wax or cutin - waxes are lipids with FAs esterified to an alcohol other than glycerol
lipid digestion in auto-enzymatics
- lipids are hydrophobic (not water-soluble) - fundamental aspect of lipid digestion is to "dissolve" fat in water - accomplished by emulsification - bile contains bile salts, lecithin, and substances derived from cholesterol so it acts as an emulsifier
eicosanoids
- lipids derived from 20-C and 22-C FAs - include prostaglandins, prostacyclins, thromboxanes and leukotrienes - have hormone or hormone-like roles in vasoconstriction and blood
HDL (high density lipoprotein)
- lipoprotein that transports cholesterol back to the liver from the cells - composed primarily of protein
LDL (low density lipoprotein)
- lipoprotein that transports cholesterol to cells - "bad" cholesterol
pseudo-ruminants
- llamas, camels, alpacas - eat a lot of plant material and roughage - have 3-chambered stomachs in the digestive system - have a large cecum and it is the site where the roughage is fermented and digested
limiting amino acids
- lysine, threonine, methionine, tryptophan - these AAs are found in the shortest supply from incomplete proteins
carbohydrates (CHO)
- macronutrient that contains carbon, hydrogen, and oxygen - basic energy source of almost all animal life - produed in the end of the products of photosynthesis by green plant tissue
calcium (Ca2+)
- main element in bone tissue, that include 99% of the corporal calcium, and around 75% of all phosphorus in the body (bones and teeth) - adult cow has 6 kg of calcium, and 2.8 kg of phosphorus in the body, the correlation of Ca:P is 2:1 - in the milk the correlation is 1:1 (can cause deficiency of P) - in sheep the correlation of Ca:P is 3:1
volatile fatty acids (VFAs)
- main end-product of anaerobic rumen fermentation - primarily absorbed energy sources of ruminants - the rumen is lined with projections called papillae, which absorb VFAs (similar to absorption of nutrients via the villi of small intestine in autoenzymatics)
dietary importance of lipids in animal nutrition
- mainly fat and oils, which are energy-rich compared with carbohydrates - have about 225% the energy content to carbohydrates on an equal weight basis - lipid component of animal products (body fat, cholesterol) are important in human nutrition and is implicated in various human health pathologies
ruminants
- mainly herbivores like cows, sheep, and goats - entire diet consists of eating large amounts of roughage fiber
vitamin D functions
- major function is to maintain normal blood levels of Ca2+ and phosphorus - aids in the absorption of Ca2+ and helps to form & maintain strong bones - promotes bone mineralization in concert with a number of other vitamins, minerals, and hormones - maintains normal cellular growth and function - maintains healthy immune function and preventing excessive inflammation - inhibits PTH secretion from the parathyroid gland
development of nutrition
- many species have different requirements - different physiologyical and anatomical characteristics - different growh due to human interference
exclusively meat-based diet
- members of the cat family have this type of diet - results in a substantially different protein and amino acid metabolism than other animals
methane production
- methane production by ruminants is nutritionally significant - methane, aka "natural gas", represents a major loss of energy in rumen metabolism - 4 to 10% of the gross energy intake is lost to the animal as a result of rumen methane production - development of ways to reduce ruminal methane would increase the efficiency of ruminant production - the amount of methane produced in ruminants is determined in large part by diet
urine
- method of ridding water from the body - 15-21% of the intake water (feed and metabolic water) - correlated with feed intake - correlated environment (if its available or not) - correlated with the content of K+ and Na+ in the feed and urine - correlated with the dry matter of the diet (low DM% = high intake of water)
milk
- method of ridding water from the body - correlated with around 30% of the total water intake (free and metabolic water) - milk has around 13% of solids and 87% water
feces
- method of ridding water from the body - dependent of the intake of water - dependent of the % dry matter in the feed - succulent diets with high concentration of minerals = excretion of more water in the fecal matter - represent around 30 - 35% of the ingested water (free water and metabolic water)
skin evaporation
- method of ridding water from the body - very important way to lose water in the body, can be more then the urine excretion; - correlated with physical activity - correlated with environmental temperatures - represent around 18% of the total water lost in the animal body
macrominerals
- minerals required in relatively large quantities - Ca2+, phosphorus, and Mg2+ are major components of the skeletal system and thus function in a structural role - Na+, K+, and Cl- function as electrolytes in regulating fluid balance between the gut, blood, cells, tissue spaces and body cavities - sulfur is not a dietary essential, but is a component of many organic constituents of tissue such as the sulfur containing AAs and the vitamins biotin and thiamin
microminerals ("trace minerals")
- minerals required in very small amounts - function primarily in regulatory roles - can regulate enzyme activity either as integral components of enzymes or as cofactors (ex. selenium is an integral component of the enzyme glutathione peroxidase) - copper is a cofactor of cytochrome oxidase - other minerals (i.e. vanadium, silicon, boron, & nickel) only show a dietary need in lab animals fed with purified diets
vitamin A
- more common as pigments (carotenoids) in the feed - most storage in the liver - horses, cattle, and chickens can absorb more carotenoids than swine, sheep and rats - cats cannot convert carotenoids to vitamin A
foregut fermenter (ruminant)
- multi-chambered stomach - adapted to digesting cellulose - fermentation occurs before digestion in the stomach in a specialized rumen (1st stomach chamber)
vitamin B7 deficiency (water soluble)
- nausea - vomiting - muscle pains - anemia - fatigue - loss of appetite - heart abnormalities
colostrum absorption
- newborn animals of many species (auto- and allo-enzymatics) absorb large, intact protein molecules, permitting the absorption of antibodies from colostrum - this can be for several hours to several days depending on the species
normal GIT (gastrointestinal tract)
- not adapted to digesting cellulose - no fermentation chamber
anaerobic fermentation
- occurs in the rumen of foregut fermenters (ruminants) - because the rumen is an anaerobic environment, microbial fermentation cannot result in the complete oxidation of carbohydrates to CO2 and water - this type of fermentation is basically the glycolysis pathway by which glucose is broken down into pyruvic acid - in the rumen, the microbes convert pyruvic acid to several short-chain organic acids, called volatile FAs (VFAs)
antiperistalsis
- occurs when the material is moved "backwards" - occurs primarily in the hindgut as a means of moving material from the colon to the caecum - this action is important in small herbivores, such as the rabbit - in chickens, this movement occurs in the colon (digesta mixed with urine from the cloaca refluzes small particles and fluids into the caeca)
methane (CH4)
- one of the main gases produced in allo-enzymatic fermentation - methane in the rumen is a hydrogen sink - the rumen is a reducing environment with excess hydrogen - rumen methane production has several adverse consequences - because methane is eliminated from the rumen by eructation, it represents a loss of energy (about 10% of gross energy intake) - methane is also a "greenhouse gas", which accumulates in the upper atmostphere contributing to the greenhouse effect and global warming - ruminant methane males a small but significant contribution to the global methane pool
vitamin E
- only metabolic function of vitamin E is as a cellular antioxidant, responsible for stabilizing cell membranes - all symptoms of vitamin E deficiency are manifestations of peroxidation of cell membranes - associates with lipid micelles in the intestine, and is absorbed with fat absorption - transported in the blood in association with lipoproteins and within cells is associated with tocopherol-binding proteins
stomach ulcers
- open sores or lesions found in the stomach or duodenal lining - carbohydrate fermentation by bacteria in the esophageal region - most cases of peptic ulcers are cause by a bacterial infection by Helicobacter pylori
acifiers
- organic acids such as citric and fumaric acids - sometimes used in diets for baby pigs in an effort to avoid colonization of the gut with pathogens
vitamins
- organic compounds other than porteins, carbs, and lipids that have specific roles in metabolism and are required in the diet in very small amounts - term was created in 1912 by polish chemist, casimir funk
amino acids (AAs)
- organic molecules that are composed of carbon, hydrogen, oxygen, and nitrogen - link together via peptide bonds to form proteins - some can have sulfur - divided into 4 parts: amino group (NH2) & carboxylic group (COOH), hydrogen, alpha carbon, and side chain (characteristic of each AA)
fat-soluble vitamins and cholesterol
- other types of lipids - cholesterol is an important metabolite necesary for the synthesis of steriod hormones and bile acids and is an essential component of cell membranes
pyloric sphincter
- part of autoenzymatic digestion - controls release of food from the stomach - regulated hormonally, so as not to overload the digestive capacities of the small intestine
phosphorus functions
- part of the bone matrix - part of the nucleoproteins, phospholipids, and nucleic acids (important in the growth) - participates in acid-basic intracellular homeostasis - part and activation of the coenzymes (NAD, and NADP) - is extremely necessary in the metabolism and growth of rumen bacteria (Celluloliticas)
FA metabolism
- pathways of FA metabolism involve fatty acid biosynthesis, oxidation, and metabolism of essential FAs - these processes, especially FA biosynthesis and degradation, are intertwined with pathways of carbohydrate metabolism because of the central roles of acetyl CoA in both fat and carbohydrate metabolism
caecal fermenter digestion
- peristaltic action propels the fiber particles through the colon rapidly, whereas antiperistaltic contractions of the haustrae of the proximal colon move the soluble nutrients and fluids "backwards" into the caecum - the digestive strategy of small caecal fermenters is to minimize the digestion of fiber and to concentrate on the digestive action of more nutritionally valuable non-fiber constiuents - after the colon is emptied of hard faecal pellets, consisting primarly of fiber, the caecum contracts and its contents are squeezed into the proximal colon - mucin is secreted by goblet cells, producing caecal maerial covered with a mucilaginous membrane
synthetic antioxidants (preservatives)
- phenolic compounds - include: ethoxyquin, BHT, & BHA - very effective at preventing oxidation (rancidity) of stored feeds and are commonly used for this purpose (ethoxyquin is not actually a phenolic)
rumen fungi
- play a role in fiber digestion of ruminants - they invade highly lignified mature plant fiber (i.e. straw) and aid in its penetration by cellulolytic bacteria - these four genera of rumen fungi have been identified: neocallimastix, caecomyces, pyromyces, and orpinomyces
cecum
- pouch within the peritoneum that is considered to be the beginning of the large intestine - contains many microorganisms that are necessary for the digestion of plant materials in ruminants
digestion (autoenzymatic digesters)
- preparation of ingested nutrients for absorption - normally, only small molecules are absorbed - proteins are hydrolyzed into small units (peptides and AAs) - complex carbs turn into simple sugars (monosaccharides) - fat turns into monoacylglycerides and FAs - minerals and vitamins do not undergo digestion and are absorbed as such
cholesterol
- present either as free cholesterol or combined with a longchain fatty acid (LCFA) as cholesterol ester - both forms are transported with lipoproteins in plasma - amphipathic, so it's soluble in both water and lipids - derived from both dietary sources and de novo synthesis in the liver and other tissues
antioxidants
- prevents lipid peroxidation - a number of antioxidants are used as preservatives to prevent auto-oxidation of lipids in foods and feeds - include butylated hyroxyanisole (BHA), butylated hydroxytoluene (BHT) and ethoxyquin - naturally occurring antioxidants include vitamin E and vitamin C - selenium has antioxidant activity by way of its role in glutathione peroxidase - polyphenols from plant sources also have antioxidant activity - the phenolic group(s) of antioxidants is the active site; most antioxidants are phenolics, including vitamin E
photosynthesis
- process that consists of the reduction (gain of hydrogen) of CO2 in plants to produce carbohydrate - requires an energy input - plant tissue contains pigments (such as chlorophyll and carotenoids) that trap solar energy to provide electrons to accomplish the reduction of CO2
tocopheroxyl free radical
- product that is reduced back to tocopherol by ascorbic acid (vitamin C) - the ascorbate free radical is converted to ascorbate and dehydroascorbate, which are not free radicals
six types of nutrients
- proteins - carbohydrates - water - fats - vitamins - minerals
cardiac region
- region of the autoenzymatic digester stomach - adjacent to the esophageal region - contains glands which exude mucus - the mucus (consisting of glycoproteins) has an alkaline (basic) reaction and serves to protect the stomach lining from being digested by the proteolytic enzymes and strong acid secreted into the stomach
esophageal region
- region of the autoenzymatic digester stomach - an extension of the esophagus - no gladular secretions in this region - some limited bacterial growth
fundus gland and pyloric regions
- region of the autoenzymatic digester stomach - sites of other gastric secretions, including mucus, HCl, and pepsin (proteolytic enzyme)
importance and function of minerals
- represents 2 to 5% of the weight of the animal tissues - acts as co-factors of enzymatic activity - activate some hormones - correlated with osmotic equilibrium - correlated with the acid basic balance
ammonia (allo-enzymatics)
- rumen ammonia occupies a central role in nitrogen metabolism in the rumen - ammonia is the nitrogenous end product of bacterial fermentation of dietary protein - ammonia is also the starting point for microbial synthesis of bacterial amino acids and proteins - most rumen bacteria synthesize their own AAs from scratch with ammonia as the source of the amino group - thus, rumen bacteria can synthesize protein from any substrate which will yield ammonia in the rumen - non-protein nitrogen (NPN) sources such as urea, biuret, and uric acid (from poultry excreta) may be convereted by RMO into bacterial protein
rumen protozoa
- rumen microbe that makes up a substaintial (about 40%) part of the total microbial mass of the rumen - metabolic contribution appears to be much lower than their mass would suggest - number of these rumen microbes are influenced by the type of diet - concentrate selectors tend to have a simple protozoal pop., while mixed feeders have a more diversified fauna
lipid digestion in allo-enzymatics
- rumen microbes utilize lipids inefficiently - in the rumen, there is a lack of emulsifying agent, pancreatic lipase, so high (above 5%) amounts of dietary fat can cause reductions in fiber digestibility by a physical coating action on feed particles - fats also have an inhibitory effect on rumen microbes - unsaturated fatty acids are toxic to rumen bacteria - fatty acids are neutralized at the rumen pH and converted to soaps, which are salts of fatty acids - K+ soaps are readily absorbed in the small intestine, whereas calcium soaps have lower absorbability - ruminants secrete a high proportion of taurine-conjugated bile acids, which facilitates solubilization of fatty acids in the acidic duodenum of ruminants - in ruminants, the majority of lipid entering the small intestine is in the form of FFAs (80-90%) in contrast to non-ruminants, in which most lipid is in the esterified form
concentrate selector ruminants diet
- ruminant that consumes less lignified (more soluble) fiber parts of herbage, including tree shrub leaves, herbs, fruit, and other, succulent plant parts - this herbage, will a high concentration of cell contents and a low cell-wall content, is more readily digested than diets with similar total fiber but with more lignified and less soluble fiber - starches and sugars in diet do not require fermentation bc they can be digested by the animal itself - tend to nibble of a wide variety of plants rather than feeding on one type of vegetation exclusively
citric acid cycle
- second step in the catabolism of glucose to CO2 and water in CHO metabolism - involves eight steps that completes the metabolic breakdown of glucose molecules to carbon dioxide - occurs within the mitochondrion
secretin family
- secretin - glucagon - glicentin - vasoactive intestinal peptide (VIP) - gastrin inhibitory polypeptide (GIP)
insectivore
- short intestine - no cecum - ex. mole
carnivore
- short intestine and colon - small cecum - ex. fox
nonruminant herbivore
- simple stomach - large cecum - ex. rabbit
avain species (autoenzymatics) digestive system
- simple, non-compartmentalized stomach - differences in the foregut of mammalian type (pigs) and avian species (chickens)
non-ruminant (autoenzymatic) digestive system
- simple, non-compartmentalized stomach - differences in the foregut of mammalian type (pigs) and avian species (chickens)
hindgut fermenter
- single chambered stomach - adapted to digesting cellulose - fermentation occurs after digestion in the stomach in the enlarged cecum and large intestine
villi
- small projections that increase the surface area of the small intestine - very dynamic structures - each villus is lined with a single layer of cells called enterocytes, which form generative areas called crypts of lieberkuhn
free water
- source of water to animals - 70-97% of the water is consumed by the animal
water from food
- source of water to animals - intake of the water with the food (large variation) - grains have about 9-30% of water - pastures of hay have less than 10% of water - fodder has around 65-75% of water
rumen starch fermentation (allo-enzymatics)
- starch is a major dietary consittuent of concentrate-fed ruminants (i.e. dairy cattles) - the rate of degredation of starch depends upon its source and feed processing method - amylolytic bacteria attach to feed particles and starch granules and break down starch - free maltose and glucose units are taken up by saccharolytic bacteria - fermentation of the sugars occurs by glycolysis with production of ATP for bacterial metabolism - the end product of glycolysis, pyruvate, is converted to VFAs, CO2, and CH4
amylolytic bacteria
- starch-digesting rumen bacteria - attach to feed particles and starch granules - secrete amylase at the point of attachment, degrading starch to maltose and free glucose units
abomasum
- stomach chamber in ruminants - considered the "true" stomach - the equivalent of the monogastric stomach chamber where gastric juices are secreted
reticulum
- stomach chamber in ruminants - main function is to collect smaller digesta particles and move them to the omasum - larger particles stay in the rumen for further digestion
saccharolytic bacteria
- sugar digesting bacteria - includes: Bacteroides ruminicola, Butyrivibrio fibrisolvens and Selenomonas ruminantium
water functions
- temp. regulation - transport of nutrients and metabolites - help in the digestion process and metabolism of nutrients - dilutent factor to urea and uric acid excretion - mineral homeostasis - catalysts in biochemical reactions of the body - hydrolysis of proteins, lipids, and carbs - special actions (vision, brain, articulation, etc.)
symbiotically associated
- term to describe plant and animal metabolism in terms of carbs - plants require the CO2 and water excreted as metabolic wastes by animals - animals require the oxygen excreted by plants and the organic compounds they synthesize - the whole process is sustained by a constant fusion of solar energy
colonic and caeco-colonic fermenter digestion
- the caecum is often enlarged, but performs as an extension of the colon as a fermentation site rather than functioning in selective retention of small particles as in the caecal fermenters - caeco-colonic fermenters also include new world monkeys, lemurs, and rodents - the digestive strategy of these colon fermenters is similar to that of ruminants
end products of rumen fermentation
- the main end products of rumen fermentation are microbial cell mass, gases, heat (the heat of fermentation) and VFAs - the main gases produced are CO2, CH4, and small amounts of hydrogen and hydrogen sulfide - rumen gas is typically about 65% CO2 and 25% CH4
stomach molility (autoenzymatic digesters)
- the motility is necessary for mixing gastric guices with the ingested feed and for moving the digesta into the small intestine - acidity is highest in the pyloric region of the stomach - the esophageal region has little gastric acid, allowing microbial survival and growth in this area - the small intestine regulates the gastric motility according to the capacity of the intestine to recieve ingesta
water absorption
- the movement of water in the TGI is passive transport (without energy) - always in the direction to keep the TGI content in isoosmotic state
omasum
- the muscular third stomach of a ruminant animal, between the reticulum and the abomasum - where food particles are small enough to get transferred into the abomasum for enzymatic digestion
lipids in allo-enzymatics
- the natural diets of ruminants tend to have a low concentration of lipids - leaf lipids are mainly galactolipids and phospholipids, and miscellaneous substances such as waxes, plant pigments (chlorophyll, carotenoids) and essential oils - seed lipids are primarily triglycerides (TAGs) - therefore, modern feedlot and dairy diets based on grains have a preponderance of dietary lipid as TAGs
rumination
- the process whereby consumed feed is regurgitated and chewed to break it up into smaller particles - muscles at the base of the esophagus form a bolus of fibrous material, which is the propelled by muscular action to the mouth - mastication extracts the soluble cell contents, and mixes the remaining fibrous material with saliva
foregut vs. hindgut fermentation
- the relative efficiencies of ruminant and nonruminant digestion are influced by body size and the abundance of plant material - among herbivores, the ruminants generally dominante in numbers in the intermediate body-size range - very small and very large herbivores are mainly non-ruminant herbivores - with very large ruminants, insufficient fibrous feed can be ingested to meet the energy requirements of a large body mass through fermentation by-products
rumen microbes
- the rumen microbial pop. is responsible for much of the total digestive activity in ruminants, particuarly grazers - the main microbes are bacteria and protozoa, although yeasts, fungi, and phaes are also found in small numbers
Na+, K+, and Cl-
- these 3 minerals works together with phosphate ions, and bicarbonate ions - regulate the osmotic pressure and acid-basic homeostasis - control in the absorption of nutrients in the cells, and the metabolism of water
vegetarian carnivore
- these animals are members of the order Carnivora and has the dentition and digestive tract of a true carnivore, but are vegetarian by feeding strategy - ex. giant pandas
avian digestion (autoenzymatic digesters)
- these animals have some modifications from mammalian digestive systems - the stomach is divided into two parts (proventriculus & gizzard) - also contains the crop
rumen microorganisms (RMO)
- these rumen microbes (mainly bacteria) synthesize proteins that are ultimately used by the host animal when the microbes are digested - it is important to bear in mind that the synthetic activities of the RMO are for their own benefit, there is not a higher calling that they are doing anything to benefit the host
omasum
- third compartment of the ruminant stomach - materials exit the reticulo-rumen and enter this chamber - this is a small comaprtment containing membranous division called omasal leaves - functions in retaining material in the rumen until it has been degraded into small particle sizes
koalas
- this animal is a specialist feeder and has coevolved with particular plant species - this animal and several other australian arboreal folivores have developed dietary preferences for eucalyptus foliage - it is difficult for this animal to be raised on any other diet except eucalyptus leaves, making their exhibition in zoos a challenge (although synthetic diets containing eucalyptus oil have been used successfully)
balance of water in the body
- this balance will be equal to the equilibrium between the intake and amount of water excreted - the ways to keep this balance will depend upon the animal species, management, diseases, and dietary constrains associated with the animal husbandry
colon (avian species)
- this structure has very little digestive activity in chickens - some fermentation in the caeca occurs (reverse peristaltic contractions move fluids and fine particles from the colon into the caecum) - some bacterial vitamin synthesis occurs, which is of nutritional benefit to birds that have access to their excreta and consume them (coprophagy)
reticulum
- this structure is continuous with the rumen in foregut fermenters (often considered the "reticulo-rumen") - lined with honey-comb shaped projections - main function is to collect smaller digesta particles and move them into the omasum, while the larger particles remain in the rumen for futher digestion
monogastric
- this type of digestive system consists of one stomach chamber - humans and many animals have this type of system - the process of digestion begins with the mouth and the intake of food - the teeth play an important role in masticating (chewing)
actions of vitamins in CHO metabolism (refer to image)
- three B vitamins (thiamin, niacin, and pantothenic acid) are involved in these steps - niacin (B3) functions as a component of NAD - thiamin (B1) is a coenzyme for decarboxylation rxns - pantothenic acid (B5) is a component of CoA - deficicnes of these vitamins results in impaired energy metabolism and deficiency symptoms which may reflect this impairment
the ruminant system
- to help digest large amounts of plant material, the stomach of the ruminants is a multi-chambered organ - contains four compartments
abomasum
- true stomach of ruminants - fluids and small particles flow through the omasum to this compartment - this chamber contains large spiral folds in the fundus gland region - gastric secretions, such as pepsinogen and HCl, are secreted here - the acidity kills rumen microbes in the digesta, which are then subject to digestion in the small intestine
foregut fermenters (ruminants)
- type of alloenzymatic digester - animals which ruminate or "chew" their "cud" by regurgitation of ingested material (rumination) - these animals have complex, compartmentalized stomachs, characterized by one large compartment, the rumen, in which microbial fermentation of ingested feed occurs (anaerobic environment)
proventriculus
- type of avian stomach chamber where gastric juices are produced to digest the food before it enters the stomach - gastric or "true" stomach
gizzard
- type of avian stomach chamber where the food is stored, soaked, and mechnically ground - aka "ventriculus"
caecal fermenters
- type of hindgut fermenter - rabbit is the best-known example of this type of fermenter - the hindgut functions to selectively excrete fiber, and retain the non-fiber components of forage for fermentation in the caecum
colonic and caeco-colonic fermenters
- type of hindgut fermenters (alloenzymatic digesters) - in all large hindgut fermenters, the enlarged proximal colon is the primary site of fermentation (i.e. horse, elephant, etc.)
VLDL (very low density lipoprotein)
- type of lipoprotein made primarily by liver cells to transport lipids to various tissues in the body - composed primarily of triglycerides
fumonisin
- type of mytoxin in maize - structurally similar to sphingosine - inhibit sphingosine biosynthesis, causing impaired brain synthesis of sphingolipids
hindgut fermenters
- type of nonruminant alloenzymatic digester - the hindgut or large intestine (caecum + colon) is enlarged and has a microbial population performing many of the same digestive functions that take place in the rumen - microbes in the hindgut are not subejct to digestion (unless the feces are consumed) - the passage rate through the hindgut is more rapid than through the rumen, leading to a lower efficiency of fiber digestion
bulk and roughage eaters (grazers)
- type of ruminant - highly developed fermentation system that enables them to digest cellulose fractions of plant cell walls ex. cattle
concentrate selector
- type of ruminant - select diets of plants that are highly digestible - high in starch, proteins, and lipids - low in fiber ex. deer
bulk and roughage eaters (grazers) diet
- type of ruminants that have feeding and digestive strategies based on the utilization of high fiber, low soluble diets - their stomachs facilitates maximal digestibility of fiber - the capacity of the reticulo-rumen is high and thier grazing behvaior permits a rapid intake of a large quantity of fibrous feed - rumination is pronounced, resulting in physical maceration of ingested forage - the omasum is highly developed with many omasal leaves, thus retaining fibrous feed in the rumen until microbial enzymes have degraded it
intermediate feeder diets
- type of ruminants that have feeding and digestive strategies that share properties of both concentrate selectors and grazers - these animals tend to be highly adaptable to varying environments and changing habitats - sheep and goats are domestic animals of this type because they graze on grass but also feed extensively on shrubs and forbs - wild types of these feeders include reindeer, elk, pronghorns, impala, gazelles and eland
neutral lipids
- uncharged lipid that contains glycerol - major type in animal nutrition are triglycerides ("triacyglycerol (TAG)") - triglycerides are fats and oils
immune function (autoenzymatics)
- very important characteristic of the intestine that is not related to the digestive or absorptive functions - the gut has the body's major immunologic defenses - gut-associated lymphoid tissue (GALT), including the peyer's patches and the bursa of fabricius in chickens
fat soluble vitamins
- vitamin A (retinol) - vitamin D (cholecalciferol) - vitamin E (alpha-tocopherol) - vitamin K (phylloquinone)
cobalt in ruminants
- vitamin B12 is a complex molecule containing chelated cobalt - the only known metabolic function of cobalt is its role as a constituent of B12 - ruminants have a relatively high cobalt requirement and may develop wasting disease on pastures that support grazing horses with no sign of deficiency - 2 factors that contribute to the high cobalt requirement of ruminants are inefficiency in ruminal B12 synthesis and low ability to absorb B12
water soluble vitamins
- vitamin C (ascorbic acid) - vitamin B-complex
contents of protein
- 50-55% carbon - 6-7% hydrogen - 20-23% oxygen - 12-19% nitrogen - 0.2-3% sulfur
lysine
- AA with very low endogenous synthesis - transamination does not happen in the body (lysine, threonine, proline, & hydroxyproline) - metabolism is correlated with body protein growth - has slow turnover - illeum digestibility is very correlated with biological availability of lysine - very accurate analysis methods established - the animal requirements are already very well known in all phases of animal growth in many species of animals for production
FA synthesis
- FA synthesis, like beta oxidation, involves metabolism of 2 carbons at a time in the form of acetyl CoA - however, FA synthesis is not simply the reversal of B-oxidation, but involves different enzymes located at a different intracellular site - this separation allows each process to be individually regulated and integrated according to metabolic needs - B-Oxidation occurs in the mitochondria, whereas FA synthesis occurs in the cytosol
FA oxidation
- FAs are oxidized in the mitochondria by being converted to acetyl CoA, which is then catabolized in the citric acid (or TCA) cycle reactions - FAs react with CoA intracellularly to produce activated fatty acids (acyl CoA) (requires ATP) - the activated FAs are transported across the mitochondrial membrane in association with carnitine
unsaturated FAs
- FAs that contain one or more carbon-carbon double bonds that are not saturated with hydrogen - liquid at room temperature - can be either monounsaturated FAs (MUFA) or polyunsaturated FAs (PUFA)
gastric inhibitory peptide (GIP)
- GI hormone secreted by the small intestine musocsa - initiates neural resposnes to inhibit gastrin secretion
gastrin
- GI hormone that is a family of polypeptides - stimulates secretion of gastric juice and is secreted into the bloodstream by the stomach wall in response to the presence of food - ascts by regulating histamine production in gastric mucosa cells - histamine then attaches to membrane receptors on the oxyntic cells of the gastric glands, activating cAMP - cAMP activates carbonic anhydrase, producing H+ ions and ATPase, causing secretion of Cl- in exchange for K+ ions
pigs
_____ are very susceptible to the development of ulcers
false - some animals have single stomachs, while others have multi-chambered stomachs
all animals have a single chambered stomach (T/F)?
proteinaceous
all metabolic reactions are dependent on ______ enzymes
yes
do swines (pigs) have the alpha amylase enzyme in the saliva secreted by the salivary glands?
- urine - feces - skin evaporation - milk - thermoregulation
how do animals excrete water from the body?
ether extract (EE)
lipid content of feeds
rumen
stomach chamber in ruminants in which symbiotic bacteria digest cellulose
start of digestion of CHO in auto-enzymatics
the digestion of CHO can start in the mouth of some animals due to the secretion by the salivary gland of alpha amylase
less
the hindgut is a ____ efficient area for nutrient absorption
rapid
AA with a non polar side chain (Methionine, Leucine, Valine, Iso-leucine, Tryptophan, and Phenyalanine) have a ______ absorption
slow
AA with a polar side chain (Arginine, Glutamic acid, Aspartic acid, and Glycine) have very ____ absorption rates
bacteria
RMO all have roles in CHO digestion, although _______ are the most important
peroxidation (auto-oxidation)
_______ of lipids exposed to oxygen is an important factor in the deterioration (rancidity) of fat-containing feeds and also for damage to tissues in vivo (where it may be important as a cause of cancer, infammatory diseases, atherosclerosis, and ageing)
intermediary
all other AAs (Histidine, Lysine, Alanine, Serine, Threonine, Tyrosine, Cystine, and Proline) have a _________ speed of absorption
pepsin
an enzyme present in gastric juice that begins the hydrolysis of proteins
PUFA (polyunsaturated fatty acid)
an unsaturated fatty acid that has two or more double bonds and may be of two types, based on the position of the first double bond (Omega 3 or 6)
true
animal and poultry nutritionist have played key roles in the development of the nutritional sciences (T/F)?
reverse - when animals eat plants, the energy contained in the the carbs and other organic compounds synthesized from carbs (i.e. AAs and lipids) are made available by metabolic process
animal metabolism is the _____ of photosynthesis
niches
animals have evolved to occupy virtually all ecological _____ and in many cases have developed specialized feeding strategies
absorption; waste
as in other animals, the ruminant small intestine plays an important role in nutrient _______ and the large intestine helps in the elimination of _______
decreases
as the body size of ruminants ________, fermentation of forages can no longer meet the increasing energy requirements
cellulolyitc bacteria
bacteria that produce cellulase
un-masticated (un-chewed)
birds have developed a digestive system adapted to eating ________ food
anatomic differences in the gut betwen a ruminant (foregut fermenter) and a hindgut formenter?
both are alloenzymatic digesters
vitamin A deficiency
can result in blindness
roughage
coarse food high in fiber but low in nutrients
diet formulation
comparable activity to dietetics with domestic animals
- nutrient digestion - metabolism - requirements - differences between mammalian, avian, and aqautic animals - requirements of diverse species
comparative nutrition recognizes that there are considerable differences between species in....?
fiber - they have a small rumen and reticulum, so they cannot consume a large quantity of feed at one time
concentrate selectors have a stomach anatomy adapted to the use of low ____ storage
coprophagy
consumption of feces
animal nutrition
conventionally described the study of nutritional needs of domestic animals
vitamin B9 deficiency (water soluble)
deficiency of folic acid causes birth defects, anemia, and diarrhea
alloenzymatic digesters
digesters in which digestion is accomplished in part by enzymes produced by microbes inhabiting the gut
alloenzymatic digestion
digestion is accomplished in large part by enzymes produced by microbes inhabiting the gut (allo=other)
large
digestive and absorptive functions of the intestine in autoenzymatic digesters are facilitated by a ______ surface area
- share some similarities with domestic species (ex. elephants and horses) - ex. the koala resembles the rabbit in hindgut function
digestive process in hindugt digesters in wild animals....?
ruminant digestive system
digestive systems of beef cattle, dairy cattle, goats, sheep, and deer
avian digestive system
digestive systems of chickens and turkeys
hind gut fermentor digestive system
digestive systems of horses, rabbits, and ostrich
monogastric digestive system
digestive systems of pigs, dogs, cats, and humans
0.6 (60% water)
each gram of glucose can produce ____ grams of water
1.0 (100% water)
each gram of lipids can produce ____ grams of water
0.42 (42% water)
each gram of protein can produce ____ grams of water
true
few species besides primates and the guinea pig have a dietary requirement for vitaminc C (T/F)?
eructation
gas expelled from the stomach through the mouth (i.e. belching)
crypts of lieberkuhn
glands located at the base of the intestinal villus
- similarily to proteins, much of the ingested carbs of ruminants are unavailable directly to the animal - carbs are fermeneted by microbes in the rumen
how are carbohydrates digested in ruminants?
- monosaccharides are absorbed by simple diffusion and by active transport against their concentration gradient - a Na+ dependent glucose transport protein binds both glucose and Na+ at separate sites and transport them through the enterocyte plasma membrane, releasing them into the cytosol
how are monosaccharides digested in auto-enzymatics?
with techniques such as dry or steam rolling, extrusion, popping and grinding
how are most grains processed for ruminant feeding?
- proteins are fermented in the rumen by microbial enzymes and may be completely degraded to ammonia - microbes synthesize AAs, which require ammonia and simple carbon compounds - much of the dietary protein is unavailable directly to the host animal - the ruminant derives a high proportion of its AAs from digestion of microbes in the small intestine
how are proteins digested in ruminants?
- order: Artiodactyla - suborder: Ruminantia - they are even-toed, hooved animals
how are ruminants classified?
about 250 square meters (the size of a tennis court)
how big is the absorptive area of the small intestine in autoenzymatic digesters?
- methane production per unit of feed is reduced on high concentrate diets - ionophores lower methane production in the rumen by altering rumen fermentation - ionophores decrease the amount of feed required to produce a given amount of weight gain, further reducing methane production - both high concentrate diets and ionophores (and other feed additives and implants) increase growth rate, reducing the age at slaughter - thus with a shorter lifespan, the animal has a lower lifetime methane production
how can high concentrate diets and ionophore feed additives reduce the contribution of cattle to global warming?
- either reduce the rate of initiation or interfere with chain propagation - those that reduce initiation include catalase and other peroxidases that react with hydroperoxides, and chelators of metal ions (e.g.EDTA) - principal chain-breaking antioxidants include superoxide dismutase, which traps superoxide free radicals, and vitamin E, which traps peroxide free
how do antioxidants work?
the larger concentrate selecotrs, such as deer and giraffes, consume the leaves and succulent foliage of taller trees
how do larger concentrate selector (browser) ruminant utlize an ecological niche unavailable to grazing ruminants?
- in general, proteins contain about 16% of nitrogen - the protein content of feeds is usually measured by determining the nitrogen content and multiplying it by the factor of 6.25 - the crude protein is defined as N x 6.25 (16 g of nitrogen (N) come from 100 g protein; therefore, 1g of nitrogen is associated with 100/16 = 6.25 of protein)
how do you measure protein in feeds?
attracts and holds on to fat while it is simultaneously attracted to and help on to by water
how does bile/bile salts act as an emulsifier in the digestion of lipids in auto-enzymatics?
because most birds can fly, their metabolic rates are high in order to efficiently process food and keep their body weight low
how does flight affect avian digestion?
- secreted as H+ (derived from carbonic acid) and Cl- ions (secreted separately) - these two components form HCl at the membrane surface of the secretory glands
how is HCl secreted in an autoenzymatic digester's stomach?
- measured by the Kjeldahl procedure, which is named after the Danish chemist who developed it - it is important to recognize that the crude protein procedure measures nitrogen - thus, it does not distinguish between high and low quality proteins, or protein and non-protein nitrogen
how is nitrogen measured in feeds?
small
in autoenzymatic digesters, the caecum is relatively _____
- in the cloaca, into which urine is also excreted - feces and urine are voided together in all avian species except the ostrich, which excretes feces and urine separately
in birds, where does the GI tract terminate?
acidic (pH between 1.5-2.5)
in monogastrics, in order to speed up the actions of enzymes in the stomach, the environment of the stomach is extremely _______
- the gastric juices, which include enzymes in the stomach, act on the food particles and continue the process of digestion - further breakdown of food takes place in the small intestine where enzymes produced by the liver, small intestine, and pancreas contintue the process of digestion
in monogastrics, what happens in the digestion process after food reaches the stomach?
in the rumen or small intestine
in ruminants, where are the products of rumen fermentation, including microbes, digested and/or absorbed?
- the small intestine, with the jejunum being the principal area of absorption - digesta passes from the ileum into the hindgut, consisting of the caecum and colon (large intestine)
in typicaly autoenzymatic digesters, where does the bulk of digestion and absorption take place?
yes
is water a nutrient?
consortia
larger community of nutrient exchangers
hypothermia
lowered body temperature
pancreatic amylase
major enzyme involved in starch digestion in auto-enzymatics
true
mammalian species of autoenzymatic digesters, such as humans and pigs, have a pouch-like, non-compartmentalized stomach (T/F)?
symbiotic
microbes and ruminants have a _____ relationship
intestine; cloaca
most of the chemical digestion and absorption in avians happens in the ______, and the waste is excreted through the ________
- biochemsitry - physiology - endocrinology - immunology - microbiology - pathology
nutrition is a broad discipline, what other disciplines does it include?
human nutrition
nutrition that specifically targets humans
nutrition; application
nutritional science deals with the principles of _______, while dietetics and diet formulation deal with their _______
greater
on molecular levels, the similarities in metabolic processes among animals are far________ than the differences, reflecting their common evolutionary history
vagus; gastrin
perception of food by visual or taste senses causes stimulation of the ______ nerve, which results in the release of the hormone ____ from specialized secretory cells in the cardiac region
- amino acids - sugars - starch - cellulose - lignin - lipids
plants use the compounds formed in photosynthesis to synthesize all of their other organic compounds. What are some examples of these other organic compounds?
vitamin K deficiency
problems with blood coagulation (clotting) due to the enzyme role of vitamin K
peristalsis
processof muscular contractions by which contents are moved along the intestine by a moving ring of contraction, pushing material ahead
nitrogen metabolism in the rumen
proteins and other nitrogenous compounds can be digested (degraded) in the rumen by rumen microorgansims (RMO) with the conversion of dietary protein to microbial protein
true - they constitute a major part of the body structure as components of muscle, connective tissue, and cell membranes
proteins are an integral part of animal structure and metabolism (T/F)?
incomplete proteins
proteins found in plant food sources
true - the first time food passes through the digestive system, it collects in the cecum, and then it passes as soft feces called cecotrophes - the rabbit re-ingests these cecotrophs to further digest them
rabbits digest their food twice (T/F)?
autoenzymatic digestion
refers to the digestive processes carried out by enzymes that the animal secretes into the digestive tract (auto=self)
dietetics
refers to the formulations and preparations of diets to meet the needs of humans
calcium absorption
requires vitamin D
consortia
rumen bateria tend to form ____ with a common feeding strategy so that the end products of one organism are often the substrate for another
rumen bacteria
rumen microbe that function as starch digesters (amylolytic) and cellulose digesters (cellulolytic)
true
rumen microbes are similar among different species of ruminants, and between wild and dometic animals (T/F)?
true
ruminant animals do not normally have a dietary requirement for B-complex vitamins and amino acids (T/F)?
cellulose
ruminants have evolved digestive systems that help them digest vast amounts of ______
false - ruminants do NOT have upper incisor teeth - they use their lower teeth, tongue, and lips to tear and chew their food
ruminants have upper incisor teeth (T/F)?
salivation
secretion of saliva
enterocytes
specialized absorptive cells in the villi of the small intestine
chylomicrons
the class of lipoproteins that transport lipids from the intestinal cells to the rest of the body
blood
the concentration of H+ ions in the autoenzymatic digester's stomach acid is about a million times greater than that of the ______
free radicals
the deleterious effects of lipid peroxidation are caused by _____ ____ produced during peroxide formation from polyunsaturated FAs
lipid peroxidation
the destruction of polyunsaturated lipids, leading to membrane damage and increased permeability
ATP
the energy required to secrete H+ ions across such a huge concentration gradient is derived from ______
gas
the fermentation process in ruminants produces large amounts of ________ in the stomach chamber, which must be elimanted
dinosaurs
the fossil record suggests tht all extinct giant mammals were hindgut fermenters
teeth
the gizzard performs the functions of mammalian ____ in grinding ingesta materials into small particles
anaerobic
the hindgut in autoenzymatic digesters is also an area of _______ microbial growth
pepsinogen
the inactive form of pepsin that is first secreted by specialized (chief) cells located in gastric pits of the stomach
propionic acid (C3)
the major end product of starch fermentation in allo-enzymatics
glucose
the most important CHO is ________, which can be broken down via glycolysis, enter the kreb's cycle, and OXPHOS to generate ATP
active transport
the movement of materials through a cell membrane using energy (ATP)
gastrointestinal
the nutritional requirements of animals are greatly influenced by the nature of their _______ tracts
- food selection - food-seeking strategy - digestive tract physiology - digestive strategies
the passage of nutrients from the environment to the molecular level of the animal cells involves great species differents due to differences in.....?
fatty acids
the properties of a particular fat or oil are determined by the _____ _____ they contain
HCl; pepsinogen
the proventriculus elaborates _____ and _____ in much of the same manner as the mammalian stomach
false - the secretion of HCl is LOWER is young animals (pH=3-5) - this allows the colonization of intestinal bacteria,which can be a problem
the secretion in young autoenzymatic animals of HCl is higher (T/F)?
nitrogen cycle
the transfer of nitrogen from the atmosphere to the soil, to living organisms, and back to the atmosphere
true
there are similarities among wild avain species to domestic poultry, as well as numerous differences (T/F)?
true
to fully digest food in the stomach (autoenzymatics), you need both pepsin AND HCl (T/F)?
water calculations
total body water is 60% of your body weight
disaccharidases
various ___ such as maltase complete the degredation of starch fragments to freeglucose, which is then absorbed into enterocytes (auto-enzymatics)
true
vertebrates have evolved more complex digestive systems to adapt to their dietary needs (T/F)?
carotenoids
vitamin A precursors
hydrophobic
water hating
most (50-80% of the animal body is water)
water is the element _____ present in animals
hydrophilic
water loving
- synthesis of AAs and water-soluble vitamins by rumen bacteria - as a result, ruminants are largely dependent on dietary sources of AAs and water-soluble vitamins
what are some benefits of rumen fermentation in foregut fermenters?
- avian - carnivores - omnivores - herbivores
what are some categories of monogastrics?
bacteriodes succinogenes, rumitiococcus albus, and ruminococcus flavefaciens
what are some common cellulolytic bacteria in ruminants?
cattle, buffalo, camels, and a variety of african antelope species
what are some examples of roughage feeders (grazers)?
- soluble nutrients, such as sugars, AAs, vitamins and minerals, are absorbed in the small intestine - thus, the compositive of material entering the hindgut is less favorable for maximal microbial growth than in rumen - in rumen, microbes have all the nutrients in the ingested feed as available substrate
what are some nutritional disadvatages to the hindgut as the fermentation site comapred to the rumen?
- calcium - phosphorus - magnesium - sodium - potassium - cholrine - sulfur
what are the 7 macrominerals?
duodenum, jejunum, and ileum
what are the components of the small intestine?
- monogastrics - polygastrics - pseudo-ruminants - hindgut fermenters
what are the different categories of digestive systems?
- the enzymes present in saliva begin to chemically break down food (amylase-starch) - the esophagus is a long tube that connects the mouth to the stomach - using peristalsis, the muscles of the esophagus push the food towards the stomach
what are the first steps of digestion in monogastrics?
rumen, reticulum, omasum, and absomasum
what are the four compartments of the foregut fermenter's (ruminant) stomach?
- rumen, reticulum, omasum, & abomasum - these chambers contain many microbes that break down cellulose and ferment ingested food
what are the four compartments of the ruminant stomach?
1. amino acid production: - rumen microbes provide the essential amino acids that a cow's body cannot make 2. protein production: - some proteins cannot be made from plant sources - microbes can utilize sources of proteins that cows cannot (such as urea created from protein digestion) 3. synthesis of B-vitamins: - without microbes, cattle would be deficient in all but 2 of the B vitamins 4. break-down of cellulose: - rumen microbes produce the cellulase enzyme needed to break down cellulose into digestible glucose
what are the four key services that rumen microbes provide to cattle?
- absorption of water and electrolytes - as a resultof this, faeces are normally quite dry in comparison to the intestinal contents
what are the main digestive functions of the hindgut (large intestine) in autoenzymatic digesters?
- manganese - zinc - iron - copper - molybdenum - selenium - iondine - cobalt - chromium
what are the microminerals?
- neutral AA - proline and hydroxyproline - acidic AA - basic AA (lys, arg) and cistine
what are the six different Na+ dependent carriers in the absorption of AA?
- free water - water from food - metabolic water
what are the sources of water to animals?
- concentrate selector - intermediate - bulk and roughage eates (grazers)
what are the three classifications of ruminants (foregut fermenters/alloenzymatics)?
- acetic acid (C2) - propionic acid (C3) - butyric acid (C4) - other types include lactic acid, valeric acid, and branched-chain VFAs such as iso-butyric and iso-valeric acids
what are the three major types of VFAs?
bacteria, protozoa, and fungi
what are the three types of rumen microorgansims (RMO)?
- ergocalciferol (D2, in plants tissue) - cholecalciferol (D3, in animal tissues)
what are the two forms of vitamin D?
- glycolysis - citric acid cycle (or "kreb's cycle")
what are the two major pathways of glucose catabolism?
1. the starches, sugars and other ready available carbs - these carbs are associated with the plant cell content 2. cellulosic compounds which are more resistant to digestion - these carbs are constiuents of the fibrous cell walls of plant tissue
what are the two major types of carbs?
- one cleaves alpha-1,4 bonds in random fashion - one successively removes disaccharide units (maltose) from the polysaccharide chain
what are the two major types of pancreatic amylases?
proventriculus and gizzard
what are the two stomach chambers of avians?
Bacteroides amylophilus, Streptococcus bovis, Succinimonas amylolytica and Succinivibrio dextrinosolvens
what are the types of amylolytic bacteria?
- carnivores (cats) - omnivores (pigs, chickens) - herbivores (cattle, sheep, horses, rabbits) *these feeding strategies can influence nutrient metabolism and requirements*
what are the types of domestic animals?
- digestion of cellulose and hemicellulose - provision of high quality protein - production of VFA - provision of B vitamins - detoxification of toxic compounds
what are things that microbes provide to the ruminant in their symbiotic relationship?
- housing - garbage removal - nutrients - optimal environment for growth
what are things that ruminants provide to the microbes in their symbiotic relationship?
intensive cattle production using high concentrate diets and ionophore feed additives
what can reduce the contribution of cattle to global warming?
birds face special challenges when it comes to obtaining nutrition from food becacuse they do not have teeth, so their digestive system must be able to process un-masticated food
what challenges do avians face in digestion?
- share the property of preventing peroxidation of unsaturated fatty acids in cell membranes - virtually all of the disorders and deficiency signs associated with these two nutrients can be explained by their antioxidant properties (an exception is the role of selenium in the thyroid gland)
what do vitamin E and selenium have in common?
birds have evolved a variety of beak types that reflect the vast variety in their diet, ranging from seeds and insects to fruits and nuts
what effects do beaks have on avian digestion?
- warm - moist and anaerobic - continual influx of food - continual removal of their waste products - the ruminant benefits from these "parasites" by being able to digest them and utilize them as a source of protein
what environment do RMO like?
- fat-breaking enzymes work on the triacylglycerols and diglycerides to sever fatty acids from their glycerol foundations - as pancreatic lipase enters the small intestine, it breaks down the fats into free fatty acids and monoglycerides - bile salts envelop the fatty acids and monoglycerides to form micelles - micelles have a fatty acid core with a watersoluble exterior - this allows efficient transportation to the intestinal microvillus
what happens in the digestion of lipids in auto-enzymatics once the stomach contents have been emulsified?
- the presence of dietary factors which destroy or inactivate the vitamin - thiaminases are enzymes which split thiamin into its two consituent rings, inactivating it
what is a significant cause of thiamin deficiency?
auto-enzymatics
what is another term used to describe monogastrics?
ruminants and/or allo-enzymatics
what is another term(s) used to describe polygastrics?
- food selection and dietary strategies - the ability of the animal to obtain nutritional benefit from particular types of feedstuffs
what is digestive physiology closely linked to?
- young animals (i.e. piglets) do NOT secrete pepsinogen, but rather seceret chymosin (rennin), which clots milk - formation of milk clots is necessary to keep the immature small intestine from being overloaded
what is special about young autoenzymatic digesters?
water
what is the aqueous medium of the GI tract in auto-enzymatics?
presence of circular folds in the duodenum, increasing the surface area by a factor of about three
what is the first order fo surface area enhancement in larger mammals (autoenzymatic digesters)?
- the liver has a central role in lipid transport and metabolism, with the following major functions: 1. facilitates the digestion and absorption of lipids by secretion of bile 2. synthesizes and oxidizes fatty acids 3. converts fatty acids to ketone bodies 4. involved in the synthesis and catabolism of lipoproteins
what is the liver's role in fat and FA metabolism?
the small intestine
what is the major site of digestion and absorption in birds?
the fermentation process
what is the most fundamental aspect of alloenyzmatic digestion?
- volitile fatty acids (VFAs), which are waste products of bacterial digestion - therefore, metabolism in ruminants is intimately associated with microbial digestion
what is the primary absorbed energy source of ruminants?
- a salt sodium selenite - has a high bioavailability - selenium in plants is largely in the form of seleno-amino acids and has a high bioavailability - bioavailability of selenium to ruminants is greater with high concentrate diets than with high roughage diets
what is the useful form of selenium addition to feeds?
- from the small intestine, waste material traavels on to the large intestine, where WATER is absorbed and the drier waste material is compacted into feces - feces is stored until it is excreted through the rectum
what major role does the large intestine play in monogastric digestion?
nutrient absorption by the epithelial cells lining the walls of the small intestines (microvilli)
what major role does the small intestine play in monogastric digestion?
- the high acidity sterilizes the stomach contents, killing virtually all bacteria consumed together with the food (diet) - the low pH causes hydrolysis of proteins and polysaccharides and denaturation of proteins, exposing the bonds of the amino acid polymer to further enzymatic digestion in the stomach and small intestine - also activates the pro-enzyme pepsinogen
what role does the high acidity in the stomach (autoenzymatic digesters) play?
fat soluble and water soluble vitamins
what two groups classify vitamins?
- B1 (Thiamin) - B2 (Riboflavin) - B6 ( Pyridoxine) - B12 (Cyanocobalamin) - Niacin (Nicotinic acid, B3) - Folacin (Folic acid, B9) - Biotin (B7) - Choline - Pantothenic acid (B5)
what vitamins are included in the vitamin B-complex?
with high fiber diets, and is more important in roughage eaters than in concentrate selectors
when is rumination greatest?
- across the surface of the villi, with nutrients entering the circulatoring system or lymph in the case of lipids - besides the enterocytes, the villi have goblet cells
where does absorption of nutrients take place in the small intestine (autoenzymatic digesters)?
- begins in the intestinal lumen with the action of pancreatic enzymes, which break large molecules (proteins, polysaccharides, etc.) into smaller molecules (polypeptides, oligosaccharides, etc.) - these smaller moelcules become trapped in the glycocalyx, which contains the enzymes that complete the digestive process
where does digestion begin in autoenzymatic digesters?
gizzard - there is some refluxing of ingesta from the gizzard back to the proventriculus
where does grinding of the ingesta occur in avians (autoenzymatics)?
- foregut (ruminants) - hindgut (horses and other nonruminant herbivores)
where is the site of microbial activity in alloenzymatic digesters?
ruminants, horses, dogs, cats, and birds
which animals do NOT have the alpha amylase enyzme from saliva?
- because caecal fermentation is an adaptation for utilizing fibrous diets without the encumbrance of an overly large gut - small animals have a much greater relative metabolic rate and energy requirements than do large animals
why are most caecal fermenters small animals?
because of direct digestion without fermentation combined with coprophagy
why are small, non-ruminant herbivores better able to utilize high quality forage than small ruminants?
- because they have double bonds which react with oxygen - the more double bonds (i.e. the more unsaturated), the greater the susceptibility to auto-oxidation
why are unsaturated FAs susceptible to peroxidation?
- because plant cell walls contain the polymeric sugar molecule cellulose and the digestive enzymes of these animals cannot break down cellulose (however, microorgansims present in their digestive system can)
why is digesting plant material difficult for pseudo-ruminants?
- these terms are unsatisfactory in some respects - all animals are monogastric (i.e. have one gastric stomach) - many animals such as the ruminants have a complex, compartmentalized stomach, but technically speaking, they are monogastric
why is referring to autoenzymatic digesters as monogastrics or non-ruminants controversial?
it provides a larger space and the microbial support necessary to digest plant material
why is the four-compartment gastric chamber in ruminants important?
- water for domestic animals doesn't totally fit the definition of a nutrient bc it is not generally required in the diet (food), but is usualyl consumed separately (drinking) - some desert animals (i.e. pack rats) never drink but survive on metabolic water - marine mammals (i.e. seals & sea lions) never drink, but obtain their water from their diets (fish tissue) - frugivores obtain a major portion of thier water from the diet (fruits)
why is water considered a nutrient?