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224 Cards in this Set

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apparent digestibility
difference between how many nutrients were in the diet before consumption and how many measurable nutrients are found in the animal feces
growth
constructive or assimilatory synthesis of one substance at the expense of another (nutrient) that undergoes assimilation
What do growth and digestion trials help us learn?
percent of nutrients a particular GI tract can utilize from feed
Growth Trial Method
- measure absolute or relative weight of an animal on a diet compared to another animal on a "normal" diet with all other factors controlled
- use electronically controlled feeding devices and genetically cloned twins
Total Collection Method of Digestion Trial
- collect all feces and determine nutrients remaining in diet before consuming and then in feces
- difference= apparent digestibility
Apparent Digestibility (%) Formula
((Nutrient Intake-Nutrient in feces)/Nutrient Intake) x 100
What is true digestibility?
proportion of dietary intake absorbed from GI tract (excluding contributions made by body)
What is the associate effect?
mixtures that give unpredicted results compared to individual components
Feces marker method of Digestion Trials
- feces marked with material so researcher knows specifically what feces to analyze
- collected in a diaper-like thing
- examples of markers: lignin, silica, ash, rare earth markers (to estimate digestion kinetics, rate of passage, retention), water soluble material (to measure flow of fluids)
What are balance trials?
utilization of nutrients after absorption from GI tract (net retention of loss of nutrient?)

measure milk production, composition, sloughed body cells, hair loss
How are nutrient requirements for animals estimated?
by several factors:
1) level of harm to an animal in absence of nutrient
2) if animal lives or grows better once a nutrient is added, it is considered optimally required
What are the 4 rumen digestion techniques?
1) batch trials (rumen fluid obtained and tested)
2) continuous fermenters (more accurate, need less fluid)
3) nylon bag technique (bag inside of rumen)
What is the NRC and what do they publish standards for
- National Research Council
- feeding standards for livestock, lab animals, pets
Does water percentage decrease or increase with age?
Decrease
What kind of relationship does water have with body fat?
inverse
What is oxidation?
- means combining with oxygen
- substrates broken down by addition of oxygen and forms watr
2 definitions for respiration
1) series of metabolic steps involving consumption of O2 and liberation of CO2 and H20
2) placing air or dissolved gases in contact with circulating medium
What is specific heat?
heat in calorie required to raise temperature of one gram of a substance one degree Celsius
Functions of water?
1) lubricant (joints, saliva)
2) solvent (ex: urine)
3) hydrolysis reactions
4) temp regulation
How does water provide temperature regulation?
1) specific heat is high in order to neutralize heat in body (which is produced by numerous processes)
2) high heat of vaporization allowing animals to get rid of heat (sweating, panting, shade)
3) high thermal conductivity to bring heat away from sites of metabolism (ex: sweating)
What are the sources of water for an animal?
1) drinking water
2) water within feed
3) metabolic water (preformed water in catabolic processes and water liberated during metabolic processes)
What does oxidation of 1 mol glucose require and form?
- requires 6mol O2
- forms 6mol CO2 and 6mol H20
What kind of adaptations does the kangaroo rat have for its environment?
- converts dry seeds to water
- specialized kidneys to have output with little water loss
- spend days in burrow where air is moist and humid, comes out at night
Why do ruminants need more water than non-ruminants?
1) high-forage diet (low water content)
2) to suspend digesta in stomach
How do we lose water and what percent of water do we lose in these ways?
1) urine (~25%)
2) feces (~25%)
3) insensible (skin and lungs- about 50%
4) small losses in production and disease
How do high proteins diets effect water production in animals?
makes more urea, requiring more water to dilute it
What's so special about uric acid?
- semisolid, little water
- produces more metabolic water than urea
What factors can change water requirements of an animal?
1) environment (more needed in extreme temps)
2) physiological state (more needed if pregnant, lactating, or sick)
2) diet (more needed with low-moisture diets)
Why do dalmations need more water than other dog breeds and what happens if they get insufficient amounts of water?
- need more water because metabolize purines into uric acid instead of urine
- insufficient water= urinary stone formation
How much water will an animal typically consume?
2-5kg water per every 1kg dry feed consumed (in normal conditions)
How many solids can we be okay with in water?
less than 1000mg/ml
What's so special about Oryx compared to cattle?
- specialized kidneys preventing excess loss of water through urine and sweat
- less water use and converts water to milk and meat more easily than cows
- more suitable for dry climates than cows
What effects do you see when you've lost 2% of your body weight in water?
thirst
What effects do you see when you've lost 4-5% of your body weight in water?
anorexic and uncomfortable
What effects do you see when you've lost 6-10% of your body weight in water?
slurring vocalization, headache, aching
What effects do you see when you've lost 12-14%% of your body weight in water?
delirious
What effects do you see when you've lost 15-20% of your body weight in water?
death
How does the body respond to dehydration?
- increased renal excretion of N, Na+, K+
- increase pulse rate, rectal temp, and respiration rate
Examples of fermentation?
- carbohydrate to CO2
- alcohol to organic acid
What does hydrolyzing involve?
- splitting of a bond and addition of a hydrogen cation and hydroxide anion of water
What is photosynthesis?
- combining of CO2 and water with sunlight, producing O2 and glucose
How much of the body do glucose and glycogen make up?
less than 1%
Examples of monosaccharides?
glucose, fructose, ribose, deoxyribose
Examples of disaccharides?
lactose (glucose + galactose) and sucrose (glucose + fructose)
What are oligosaccharides?
3-10 molecules of sugar
What are polysaccharides and give examples
- have more than 10 molecules of sugar
- ex: starch and cellulose
What is glycerol and why is it interesting?
- intermediate btw carb and lipid
- structurally an alcohol and partially soluble in water
- component of fats and soluble in ether
Empirical formulas for simple and complex carbs?
Simple: CnH2nOn
Complex: CnH(2n-2)O(n-1)
Functions of carbs?
- primarily energy source
- source of heat
- building blocks for other nutrients
- sources of fat when needed
2 major energy sources for animals?
1) carbs
2) lipids
2 common sources of carbohydrates
1) crude fibers (cellulose, hemicellulose, lignin) which are poorly digested
2) nitrogen-free extracts (sugars and starches) which are easily digested
What is lignin and what does it do?
- derived from wood, part of plant cell walls
- low in vegetable in cereals, some in grasses, high in legumes
- more lignin= less % cellulose and hemicellulose
- lignification increases with plant age
What kind of carbs are absorbed in the GI tract?
only monosaccharides (except in some babies)
What are carbohydrases?
- enzyme that hydrolyzes carbs into monosaccharides unless it has a glucose-4-beta-glucoside link (ex: amylose and amylopectin)
What does salivary amylase break down and in whom?
starch->maltose
none in ruminants
What does lactase break down and where?
lactose->glucose and galactose (in small intestine)
mostly small mammals
What does pancreatic amylase break down and where?
starch->maltose and isomaltose
(in pancreas)
What does Maltase isomaltase break down and where?
maltose and isomaltose->glucose (in small intestine)
What does sucrase break down and where?
sucrose->glucose and fructose (in small intestine)
ruminants don't produce sucrase!
What does oligoglucosidase break down and where?
oligosaccharides->monosaccharides (in small intestine)
None in ruminants
How can carbs be used and in whom?
- ruminants and specialized monogastrics (rabbits, horses) can ferment carbs and produce VFA's for energy
- some monogastrics can make VFAs by fermentation in large intestines
What do the duodenum and jejunum absorb that most other organs can'ts?
monosaccharides
What are the most to least absorbable sugars?
galactose, glucose, fructose, mannose, xylose, arabinose
What causes ketosis and what are the symptoms?
- carb or lipid metabolism is off, reduction of grain, not enough glucose in liver, excess ketones (acetone) in tissues and blood
- loss of body weight, increased water consumption, decreased performance in milk production, abortion, acetone smell of breath
What is diabetes mellitus?
- insufficient insulin production by pancreas
- genetic or induced by obesity/overfeeding
- high blood glucose, elevated mobilization of adipose tissue lipids, increased ketone production
How much ATP does forming glycogen require?
2 ATP for every molecule of glucose
How many ATP is made for every molecule of glucose through the Krebs Cycle?
38 (including to pyruvate)
Where does anaerobic metabolism (glycolysis) happen in the body?
mostly the liver
What are 2 things that are glucogenic?
-amino acids, lipids
-ruminants rely on acetate (3-C VFA's) for digestion
Glucose to 2 pyruvate molecule= ?ATP
8 per mol of glucose
What are the 2 fates of pyruvate?
1) Citric Acid Cycle= 30 ATP
2) anaerobic metabolism->lactic acid to liver
What happens if an animal is hypoglycemic?
- glucagons is active hormone and stimulates glycogenolysis (glycogen->glucose) in liver, liver puts glucose into blood
How are ruminants different in glucose homeostasis?
- no glucose absorbed in small intestine
- starch fermented in rumen
- main VFA's acetate (C2) and propionate (C3)
- liver converts all C3 into glucose- ruminants have to make their own glucose
How does Type I Diabetes differ from the 2 other types and what is it like?
- insulin-dependent
- develops over short term in younger people
- destroys beta cells in pancreas so don't produce insulin (or not enough)
- 5-10% of diagnosed diabetics
- increased thirst, urination, hunger, weight loss, blurred vision, extreme fatigue
How does Type II Diabetes differ from the 2 other types and what is it like?
- non-insulin dependent
- 90-95% of diabetics in US, 80% obese
- pancrease producing insulin, but body can't use it effectively; insulin production decreases over time and goes to Type I
- gradual symptom development- fatigue, frequent urination, increased thirst and hunger, weight loss, blurred vision, slow healing of wounds or sores, some asymptomatic
What is gestational diabetes and how many people get it?
- 3-8% pregnant women in US
- caused by hormones of pregnancy of shortage in insulin
- may be asymptomatic
- prevent by maintaining good weight and exercising
What are the ways of testing for diabetes?
1) fasting blood glucose (126mg/dL after 8-hours)
2) glucose tolerance test- OGTT (200mg/dL or more 2 hours after drinking beverage
3) random glucose level at 200mg/dL
What are the 6 main classes of nutrients?
1)water
2)protein
3)lipids
4)carbs
5)minerals
6)vitamins
What is an essential nutrient?
nutrient the body can't synthesize in sufficient amounts to satisfy metabolic needs
Who is Antoine Lavoisier?
founder of science of nutrients
What is marasmus a deficiency of and what are the symptoms of it?
- protein-energy deficiency
- emaciated, body weight reduced to less than 80%, dry skin, loose skin folds, loss of adipose in buttocks and thighs, fretful, irritable, voraciously hungry, pigmented/depigmented hair (flag sign), flaky pain appearance of skin
- usually after age 1
What is kwshiorkor a deficiency of and what are the symptoms of it?
- insufficient protein and anti-oxidant intake and high starch/carb diet after being weaned from breast milk
- occurs after 18 months old
- swollen abdomen (due to ascites or enlarged liver), reddish discoloration of hair and depigmented skin, "bull-dog" face, fail to produce antibodies after vaccinations, inadequate growth, hair loss
What is vitamin A deficiency characterized by?
- common in developing countries
- first night blindness, then go blind because cornea dry which damages retina
What are goiters a deficiency of and what are the symptoms of it?
- iodine deficiency which causes excess TSH causing thyroid to increase in size
- only problem in developing countries
What is iron deficiency anemia characterized by?
-most common, usually causes microcytic anemia (small red blood cells)
- most common cause is blood loss during period
- pallor, fatigue, weakness, dyspnea, pica, hair loss, lightheaded
What is megoblastic anemia a deficiency of and what are the symptoms of it?
- deficiency of vitamin B12 and folic acid
- large immature red blood cells with pernicious anemia
- loss of stamina, shortness of breath, rapid heart rate, pale, headache, angina, smooth and sore tongue
What is pernicious anemia a deficiency of and what are the symptoms of it?
- vitamin B12 deficiency
- loss of gastric parietal cells which secrete HCL in stomach
- shortness of breath, chest pain, loss of appetite, diarrhea, tingling and numbness (neuropathy- later manifestation)
What does feedstuffs depend on?
1) cost of ingredient
2) palatability
3) available nutrients- more than 40 essential
4) absence of toxins
5) handling/mixing properties
What are roughages?
- all types of forages (vegetative part of plant)
- high in fiber, less digestible than grains
- energy for ruminants, horses, rabbits
What are the 2 types of concentrate feedstuffs?
1) high energy feeds
2) high protein feeds
What are high energy feeds?
- lowe in fiber
- high in calories
- less than 20% crude protein
- contain starch (grains, tubers) or lipids (fats, oils)
What are high protein feeds?
- at least 20% crude protein
- low in fiber
- high in calories
- protein from animal sources higher quality
- may consist of NPN too
What can feed additives provide?
1) health value
2) palatability
3) coloring
- NO nutritional value
How does one perform moisture analysis?
- dry at 100 degrees C in over
- moisture evaporates and what remains is dry matter
- %DM= 100-%moisture
How does one perform ash (total mineral content) analysis?
- oven hotter than 500 degrees C
- feed samples in porcelain crucibles
- 100-%Ash=%organic matter (OM)
-OM= all nutrients except minerals
How does one perform crude protein analysis?
- measure N
- amino acids average 16% N
- %Nx6.25=%CP
How does one perform lipid analysis?
- reflux sample with ether which dissolves lipids from sample
- evaporate ether and lipid is what remains
How does one perform fiber analysis?
- crude fiber not consistent from feed to feed
- instead measure NDF (neutral detergent fiber), ADF (acid detergent fiber), and TDF (total detergent fiber)
How does one perform energy content analysis?
- burn feed in bomb calorimeter
- measure heat output by measuring increase in temp of water in bucket surrounding bomb= potential energy
- BUT corn and sawdust have same potential energy!
How does one perform digestible energy analysis?
- track feed intake, do feces analysis
- what is gone is DE
What is a general description of non-ruminant species and give examples?
- most carnivores, few herbivores
- do not usually have high fiber diet
- ex: cats, dogs, humans, pigs, horses, elephants, most poultry
What is a general description of ruminant species and give examples?
- any hooved animal that digests its food in 2 steps (ruminating)- eat raw material than regurgitate (cud) then eat again
- usually herbivores
- even-number of toes
- high-fiber diets
- 4 compartment stomachs
-ex: cows, sheep, goats, deer, giraffes
What's up with newborn ruminants and their stomachs?
- don't have functioning rumen or reticulum (until 6 weeks old) so most of work goes through abomasum
- milk goes through esophageal groove
- can't digest forage or grain so must have milk
What is the order of a non-ruminant GI tract?
- esophagus leads to cardiac region of stomach then fundic region
- pyloric sphincter separates stomach from small intestines
Give examples of hindgut fermenters and explain why they're unique.
- horses, rabbits, manatees, elephants
- no rumen, HUGE CECUM for high-fiber diet
- small stomachs compared to other animals
Why are chickens different than most non-ruminants?
- don't have mouth for beginning of food breakdown (only beaks and tongue)
- food goes into esophagus than crop then proventriculus then gizzard
What is the crop for?
- storing food in a chicken
- regulates food passing into stomach
What is the proventriculus for?
- releases HCL and enzymes for breakdown of food
What is the gizzard for?
- muscular for grinding course foods like seeds in rocks in food
How is the large intestine different in chickens?
- short and straight
- runs from colic ceaca to cloaca for water absorption and waste storage
What is the cloaca for?
- chamber for waste from digestive tract and urinary tract as well as products of reproductive system
How is the small intestine different in chickens?
- VERY long
- digestion and absorption of proteins, carbs, fats
How does the liver contribute to the GI tract?
- secretes bile for fat digestion and emulsification in the small intestine
How does the pancreas contribute to the GI tract?
- secretes buffers and enzymes into small intestine for digestion and protection of animal's internal organs
What are lymph fluids for and where does it go?
- transporting fat-soluble nutrients
- empties into bloodstream near heart (bypass liver)
Where do water-soluble nutrients go?
- portal vein which goes directly to liver then to rest of GI tract
What is prehension?
act of bringing food to mouth
What are the functions of saliva?
- moistens and lubricates feed
- provides nutrients for microbes (urea)
- buffering (bicarbonate)
What kind of enzyme does non-ruminant saliva consist of and what does it do?
- alpha-amylase
- breaks alpha bonds in starch
What is de-glutition?
- act of swallowing a bolus
What kind of skull structure do ruminants have?
- no upper incisors
- long longues to bring food in
- taste buds on tongue
What does the stomach secrete?
- pepsin to break down proteins
- HCl
- water passes quickly, dietary fibers pass slowly
What is the stuff that flows from stomachs called?
chyme
What is the rumen like and what are its main functions?
- warm, moist, anaerobic microbes live here
- cellulose broken down by microbes
-lined with papillae to increase SA for absorption of VFA's
What are the 3 types of microbes in rumen and how are they useful?
1) bacteria
2) protozoa
3) fungi
- help in digestion of dietary fibers
- waste products of these are main source of energy for ruminants (VFA's)
- make all B vitamins for ruminants and essential aa's
What are VFA's, what are their properties, and where do they go?
- volatile fatty acids/short fatty acid chains
- soluble in water
- get absorbed through rumen wall and enter portal vein
- cause papillae to grow in rumen
What is the omasum and what does it do?
- plies
- reswallowed food goes here after rumen
- only water absorption here
-NOT necessary for digestion
What is abomasum?
- almost exactly like stomach in non-ruminants
- HCl and pepsin secreted
What is the small intestine like and what are its main functions?
- lined with villi and microvilli to increase SA for absorption
- peristalsis here (if too fast- diarrhea)
- nutrients absorbed by blood in non-ruminants and most of protein digestion occurs here
What are the 3 parts of the small intestine and describe them?
1) duodenum- pancreas secretes buffers and enzymes (proteases) to raise pH
2) jejunum
3) ileum
What animals don't have a gallbladder?
horses, deer, elk
What is the ileocecal valve?
- distal end of small intestine
- prevents backflow from cecum to ileum
What is the cecum and what is its main function?
- microbes here digest fiber in small intestine (anaerobic)
- usually herbivores, some omnivores
- VFA's absorbed through wall of cecum and enter portal vein
What does the large intestine consist of and what are its main functions?
- consists of cecum, colon, rectum, anal canal
- fermentation towards beginning
- absorb water and ferment feed
- VFA's, electrolytes, vitamins absorbed near beginning
- rectum is storage area for digested food
What is coprophagy?
consuming of feces to utilize nutrients excreted by body
- foals, rabbits, manatees
What is reticulitis/hardwire disease caused by?
- environmental debris in feeder consumed which falls to bottom of reticulum and punctures wall with muscular action
What is acidosis and what is it caused by?
- common in feedlot ruminents
- high grain diet causes pH level in rumen to drop into 5's
What is bloat?
- more common in horses and dogs
- in feedlot conditions or bloat in pastures
What is scratch factor?
- young ruminants need solid food to help develop muscles for contractions
In adult ruminants, what goes on top and what goes to the bottom of the rumen?
- forages stay on top and grains sink to bottom
- liquid portion of rumen contents at bottom
What is "raft"?
- floating material on top of rumen
- traps feed particles making them stay in rumen much longer
What are feed-associated or adherent bacteria?
- fiber digesting bacteria
- sensitive to drop in pH below 6.0
- 3/4 of ruminal bacteria
- colonize feed particle and digest it
What are free-floating or liquid pool bacteria?
live on substrates like starch
What are facultative bacteria?
- live along edge of rumen wall
- urease activity
What is the result of fermentation and why is it needed?
- CO2 and CH4 belched- gets rid of excess H which causes harmful gases like CH4 to be removed, prevents pH levels from dropping too
- end product of this is VFA's--ruminant animal's main source of energy
What are the most common VFA's seen in rumen?
1) acetate- main energy source for muscles, can't be made into glucose, 2-C
2) propionate- 3-C, glucogenic
3) butyrate- 4-C, made from 2 acetates, not glucogenic
How is VFA prodction impacted by high forage and high concentrate (grain) diets?
high forage diet= 70% acetate, 20% propionate 7% butyrate

high concentrate diet= 55% acetate, 35% propionate, 7% butyrate
Is more or less gas production more efficient for animals?
- less because get to use more C's
What does starch lead to?
- more propionate production meaning less gas produced and more weight gain
What is acidosis caused by?
- more starch= lower pH level
- favors bacteria producing lactic acid
- ruminal buffering can't keep up and lactobacilli survive
What do ionophores do?
change bacterial population
What is unique about a cat skull?
- 30 teeth on average, less than most mammal species
What is the main function of incisors? (carnassial teeth)
catching and killing prey
What is the main function of molars?
- cutting meat and grinding plant material
What is unique about equine skulls?
- large premolars and molars for grinding plant material
- upper jaw 30% wider than lower jaw so wear unevenly
- quality of teeth shows animal's age
What is unique about a lagamorph (rabbit) skull compared to a rodent skull?
-rabbits have large incisors with 6 behind the while rats have only 4 behind them
- both have teeth that grow continuously, may cause malocclusion
What about sheep and goat skulls?
- neither have upper incisors, instead have incisor pad/dental pad to grip food
- goats are browsing animals- eat leaves, trees, shrubs
- sheep grazing animals- have split upper lip, eat grass
Which vitamins are fat-soluble?
A,D,E,K
What are chylomicrons?
spheres soluble in water
used to transport TAG, fat-soluble vitamins and other lipids from enterocytes after absorption to target location for storage or energy use
What are fatty acids?
long carbon chains, usually 16-18 C's long
R-COOH
What is an FFA
free fatty acid, not attached to anything
What is glycerol?
- 3-C molecule
- fatty acod attached to form MAG, DAG, TAG
What is lipase?
enzyme that breaks down fat
What is MAG?
monoacylglycerol
- glycerol with single fatty-acid chain
- fatty acid attached to middle C and called 2-monoacylglycerol
What are micelles?
-spheres formed in intestinal lumen from MAG, FFA, and bile
-soluble in water
-transport to enterocytes
What are triglycerides?
- also called TAGs
- 3 fatty acids attached to glycerol
What form are unsaturated fatty acids in at room temp? Saturated?
Unsaturated- liquid at room temp

saturated- solid at room temp
What elements do lipids consist of?
C, H, O
Why are lipids almost always consisting of an even # carbons?
because starts with acetic acid and 2-C units added to form longer chain
What lipids have odd numbers of Carbons?
- made by microorganisms
- sometimes found in ruminants
What synthesizes fatty acids and triglycerides?
1) liver
2) mammary gland
3) adipose tissue
How do double bonds effect melting point of lipids? Chain length?
- double bonds decrease melting point
- increased chain length increases melting point
What are compound lipids and give examples?
- fatty acids with nonlipid substances in addition to alcohol and fatty acid
- ex: phosopholipids (phosphoric acid and N), glycolipids (carbs and N), lipoproteins (lipids bound to proteins in blood and other tissues)
What are derives lipids and give examples?
- derived from simple or compound lipids by hydrolysis
-ex: fatty acids, glycerol, alcohols
What are sterols and give examples?
- lipids with complex phenanthrene-type ring structures
- ex: cholesterol, sex hormones
What are terpenes?
compounds with isoprene-type structure
What are some advantages of fats?
1) high in energy
2) little heat produced when digesting
3) reduces dustiness of food
4) slows stomach emptying
What are some disadvantages of fats?
1) decreases flow in automatic feeders (if more than 6%)
2) lots of unsaturated fats lead to soft fat in pork carcasses
3) fat gets rancid
4) hydrophobic, non-polar
What organs are involved in digestion of fat?
1) stomach
2) small intestine (and liver, pancreas help...and lymph system to disperse it)
What is the stomach's involvement in digesting fats?
mixes and emulsifies lipids with gastric lipase
What is the small intestine's involvement in digesting fats?
- most of fat digestion happens here by lipase and all of fat absorption
- gets bile from liver in duodenum
- gets pancreatic lipase in duodenum to break down fat by cleaving at 1 and 3 position making 2 FFA's and 2-MAG
What are micelles' involvement in digesting fats?
- MAG and FFA from small intestine combines with bile to form micelles which transport to enterocytes of small intestine
What happens in the enterocyte after the micelle brings FFA and MAG?
-TAG and 2 FFA's reform with glycerol and get packaged into chylomicrons which enter the lymph system (not through portal vein, except in chickens)
What do chylomicrons do with FFA's and TAG after leaving the enterocyte?
- deliver fat to cells of body
- lipase on surface of cells graps chylomicrons and takes TAG from inside
- muscles oxidize fat for energy (req energy)
- adipocytes store fat, but FFA re-esterified to TAG for this
What are 3 essential fatty acids?
1) linoleic acid= 18 carbons, 2 double bonds (in omega-6 and omega-3 fatty acids)
2) linolenic acid= 18 carbons, 3 double bonds
3) arachidonic acid= 20 carbons, 4 double bonds
- body doesn't make these by itself
How is the digestion of dietary fat different in ruminants?
1) no oxygen in rumen, so rumen microbes can't burn fat for energy
2) rumen microbes cleave FFA from glycerol instantaneously
3) microbes saturate FFA
What is the implication of the way the microbes change the fat in a ruminant?
- all fats absorbed will be absorbed as saturated fatty acids
- ruminant carcass fat always firm
What are the problems with FFA in the diet?
- FFA in rumen can interfere with digestion of dietary fat if over 6% ruminant diet
How is is possible to fix the problem with FFA in ruminants?
- using calcium-fatty acid complexes, which are insoluble
- FFA can't come off Ca once they combine in rumen
- dissociate in abomasum then associate again after duodenum and can't be absorbed so get passed in feces
What problems do too much dietary fat cause?
- interfere with digestion of fiber in rumen
- results in reduction of Ca absorption
In the small intestine of ruminants, what is and isn't necessary for digesting fat?
- need bile to make micelles
- don't need lipase
What do all proteins contain?
Nitrogen!
With age, does our need for protein increase, decrease, or stay the same?
decrease
What are amino acids made of?
NH2, COOH, R group
connected by peptide bonds
What are limiting amino acids and give common examples.
- limit use of other aa's/proteins if not available in sufficient quantities (EAA present in lowest amount relative to animal's requirement)
- usually lysine or methionine, sometimes tryptophan (in monogastrics)
What is unique about ruminants and amino acids?
- they can make all 20 in the rumen with microbes!
What is bypass protein?
- dairy cows can't survive off of the proteins its rumen makes
- needs protein source protected from microbial digestion that goes straight to small intestine to be absorbed
What kind of animals use protein for energy, and how do they get energy?
- carnivores!
- get energy by "deaminating" aa's
What do mammals do with NH3?
make into urea, excreted as lost nitrogen through urine
What do ruminants do with NH3?
-rumen microbes use urea to make microbial protein (can be fed urea)
- urea a protein supplement for ruminants (NPN)
What are protein supplements?
- contain at least 20% crude protein (string of aa's hundreds long of C and N)
- crude protein equivalent can be used too, comes from NPN like urea which is combined with starch for C's
Is bacteria protein?
50% high quality protein
How do we determine whether a natural source like silages have real protein or NPN?
- Kyeldahl procedure
- measure N not aa's
What is digestible protein?
-accounts for fecal losses of N
What is metabolizable protein?
-accounts for urinary losses of N, hard to measure
What is biological value?
- how much of digested protein used by animal?
- BV= ((Nintake-(fecal+urine))/(N intake-fecal intake))*100
What does heat damaged mean?
- for ruminants, sometimes feed protein can't be difested by rumen microbes
- either artifically heated or naturally heated by hay baled when grass wasn't dry
How does soybean meal compare as a protein supplement?
- can be eaten by all species
- no toxins (as long as roasted first because heat inactivates the trypsin inhibitor)
How does cottonseed meal compare as a protein supplement?
- fed to adult ruminants because contains gossypol
- toxic to mongastrics and calves because not deactivated by heat
What are the 2 types of protein digestion?
1) mechanical- chewing in mouth, churning through GI
2) chemical- starts in stomach with HCl
How is protein digested in the stomach?
- pepsin breaks down proteins (protease) by snipping peptide bonds making polypeptides
What is pepsin's inactive proenzyme?
pepsinogen, turns into pepsin with presence of HCl
What hormone is produced by cells lining the duodenum for protein digestion?
secretin- causes pancreas to release buffers into duodenum to bring pH up
What are the 3 proteases secreted by the pancrease into the duodenum for protein digestion?
1) trypsin
2) chymotrypsin
3) carboxypeptidase
What is the inactive form of trypsin and what activates it?
trypsinogen activated by enterokinase
What is the inactive form of chymotrypsin and what activates it?
chymotrypsinogen activated by trypsin
What is the inactive form of carboxypeptidase and what activates it?
proenzyme activated by trypsin--snips off one aa at a time from carboxyl end of peptide chain
What does the small intestine secrete into the duodenum for protein digestion and what do they do?
1) aminopeptidase- snips off one aa at a time from amino end of chain, proenzyme becomes active by trypsin
2) dipeptidase- cuts dipeptides into 2 aa's
How are amino acids absorbed through the small intestinal wall and what does it require?
- active transport
- req energy and vitamin B6
Where do amino acids go from the small intestine?
- enter portal blood system and go through liver
How is protein digestion in ruminants different?
- no animal enzymes secreted into rumen/reticulum
- only digestion in rumen done by microbes which break down dietary protein by deaminating dietary aa's to make new ones
- icrobial protein digested to aa's and absorbed through wall of small intestine
- abomasum, etc. same as in non-ruminants
What does the cecum do in protein digestion?
- microbial digestion occurs and more microbial protein made when bacteria reproduce
- no enzymes secreted by animal here or in large intestine
What other use do amino acids have?
can be used to make glucose to be utilized by cells that can't burn fat
What is nitrogen balance and what does it mean?
- positive number if anabolism greater than catabolism (net increase in amount of protein being deposited in animal's body) and vice versa
- if negative number, happen if aa's deaminated to make glucose to be used for energy, NH3 excreted in form of urea