If you are a Cal Poly student enrolled in AVS 303, then these notescover
every subject that will be (possibly) be covered on the final examination.
Do not memorize (you won't be able to), try to understand overall concepts
and relationships as much as possible. Make sure you are familarwith the
calculations we have covered in class, particularly those covered most
recently. These notes are a little cryptic (since I wrote themto lecture
from, not publish), but you should be able to use them to fill in anygaps
in your own class notes (assuming you took any). :-)
If you are NOT enrolled in AVS 303, and are just cruising the websitefor
some obscure reason, you're welcome to do so as well. :-)
Good luck!
Nutrient: Any chemical substance that provides nourishment to the body
Six basic classifications of nutrients:
1) Water
2) Carbohydrates
3) Protein
4) Lipids
5) Minerals
6) Vitamins
Water
Comprises 71-73% of fat-free body weight
Not considered when formulating livestock rations
Most essential nutrient - animal can live for weeks or monthswithout other
nutrients, but will die within days w/o water
Function:
Solvent
Lubricant
Transport medium in metabolism and excretion
Thermoregulation
Water has high specific heat
Absorbs a lot of heat energy before temperaturebegins to rise
Easier for body to maintain body temp within narrowrange
High heat of vaporization
Water lost through evaporation removes a lot ofheat energy from body
Sources of water:
Drinking
Free water
Moisture content contained in feedstuff
Common forages and grains contain 9-13% water availableto animal
Silage 65-75% free water, fresh pasture ~ 75-80%
Relationship to dry matter - 25% DM = 75% free water
Example:
Cow consumes 40 pounds of fresh pasture whichis 25% DM
25% DM = 75% free water
40 lbs x .75 = 30 lbs of water
30 lbs water ÷ 8 lbs/gallon = 3.75gallons
Metabolic water
Water which is chemically bound and released during metabolicprocesses
Amount varies with type of nutrient
Carbohydrates release 0.6 grams H2O/gram ofnutrient
Protein 0.4
Fats 1.0
Some spp of desert animal able to derive entire waterrequirements from
free and metabolic water, do not drink at all throughout lifetime (anddon't
know what to do with water if offered)
Example: Horse consumes 14 kgs of a complete ration that is 90%DM, 15%
protein,
4% fat and provides 7 kgs of carbohydrates. How many kgsof water is the
horse deriving through free and metabolic water?
Free water: - 90% DM = 10% water –> 14 kgs x .10 = 1.4 kgs H2O
Metabolic water:
14 kgs x .15 protein = 2.1 kgs protein = 2100 grams
Protein produces 0.4 grams water/gram nutrient –> 2100 g x 0.4g H20/g
protein
= 840 g water = .840 kgs water
Carbohydrates: 7 kgs = 7000 grams x 0.6 grams H20/gram nutrient
= 4200 grams = 4.2 kg
Fats: 14 kg x .04 = .56 kgs fat = 560 grams
Fats produce 1.0 gram H20/gram nutrient = 560 grams water =.56 kg
Total: 1.4 + .84 + 4.2 + .56 = 7 kgs water
Water Losses
Urine, feces, evaporative losses (respiration, skin surface),milk
Water losses through urine increase:
when ration contains high protein, high mineral salts, highfiber or when
feed consumption increases
Water losses through feces varies with species
Cows lose more water than sheep (reabsorb more water in largeintestine,
produce dryer feces)
Increase with high moisture ration - cattle on fresh pasturewill lose
more water than while in feedlot consuming hay and grain ration
Water losses through evaporation occur through respiration orskin surfaces
The only breeds of cattle capable of producing significant sweatare the
Indus breeds
English breeds also sweat, but not as well
Primary route of heat loss in ruminants is through respiratorylosses
Losses in all species increase as heat load increases
At 40 degrees Fahrenheit, a 1000-lb cow will lose .42kgs water/hr
At 70 " "
.63 kgs water/hr
In sheep, water losses increase as fleece length increases
In horses, water losses increase as intensity of exercise increases
Water losses through lactation increase with amount of milk produced
A cow producing 100 lbs of milk is losing 87 lbs of water, mustreplace in
addition to metabolic requirements.
Fastest way to stop lactation in any animal is to restrict waterintake.
Water quality
Good quality water is that containing 0.25% dissolved solids(2,500 mg/l)
Levels of 1.5% (15,000 mg/l) may be tolerated, but palatabilityis
affected, intake and production is going to probably be affected
Water may become toxic before palatability is affected if thedissolved
solids are particularly harmful:
nitrates, fluorine, heavy metals, pathogenic microorganisms,algaes or
protozoa, hydrocarbons, pesticides or industrial chemicals
Dissolved solids may also be a source of minerals in the rations
Most common minerals sodium, chloride, calcium, magnesium, sulfatesand
bicarb
> 1% NaCl generally not palatable - higher than 1% is more thanruminants
can tolerate in the diet before production is adversely affected. Swine and
poultry won't tolerate 1% NaCl.
Recent advances indicate that pH of water may be a factor in developmentof
enteroliths in horses
Enteroliths are round stones that form in the large intestinesof horses
Composed of ammonium, magnesium, phosphorus
Alkaline water source may contribute to higher pH in the gut,in turn
contributes to favorable conditions for formation of stones
CARBOHYDRATES
Carbohydrates are the primary component in livestock feeds ona dry matter
basis (once you've removed the water)
70% of dry matter in forages
80% of dry matter in grains
Considered renewable resource b/c animals convert to CO2 + H2O –> consumed
by plants through photosynthesis –> plants consumed by animals
Carbohydrates composed of C, H, O
Simplest form is monosaccaride
Monosaccharides with 5 carbons are called pentoses
Arabinose
Ribose
Xylose
Monosaccharides with 6 carbons are called hexoses
Fructose
Galactose
Mannose
Glucose - primary building block in plant material
When two monosaccharides are bonded together = disaccharide
Cellobiose - glucose/glucose - plant cell walls,highest in forages
Lactose - glucose/galactose, found only in milk
Maltose - glucose/glucose - intermediate breakdownproduct of starch
Sucrose - glucose/fructose, source of table sugar
Multiple sugars = polysaccharide
When multiple pentose sugars = pentosan
Araban - multiple arabinose molecules
` Xylan - multiple xylose molecules
When multiple hexose sugars = hexosan
Cellulose - multiple glucose
Glycogen - " "
Starch - " "
Different bonding
Mixed polysaccharides contains both pentose andhexose sugars
Gums
Hemicellulose
Pectins
Disaccharides and polysaccharides are in much higher concentrationin
plant materials than simple sugars
Polysaccharides in highest concentration are starch andcellulose
Starch found in grains and tubers, ie potatoes
Alpha glucose bonds can be broken by enzymesproduced directly by
animal
Cellulose is found in highest concentration in foragesas a component in
structural plant cell walls
Beta bonds cannot be broken directly by animal
Necessary enzymes only produced by microorganisms
Gums, pectins and hemicellulose are found in varyingamounts in plant
materials
Bonds are broken by microbes through fermentation
End product VFAs, not simple sugars
Before any carbohydrate can be absorbed, must be broken downto
monosaccharide
Lignin - not a carbohydrate, but associated with fibrous feed, affects
animal's ability to digest cellulose and hemicellulose.
Indigestible polymer formed in structural cell walls of plants, morein
stems than leaves.
Lignin content increases as maturity of the plant increases; as maturity
increases, digestibility decreases
PROTEIN
All cells in a living body produce proteins, thousands of types of proteins
Insoluble (wool, hooves, feathers, hair) to highly soluble (plasma
globulins)
Functions:
protecting the body (hair, skin)
digestion and metabolizing food (enzymes)
stimulating and regulating growth (hormones)
defense against infection (immunoglobulins)
Proteins are made up of chains of amino acids, with –NH2 at one end,–COOH
at other end.
Physical and chemical characteristics are derived from sequenceand
linkages of amino acid chain, which is controlled by DNA.
Protein chain may also contain minerals (hemoglobin high in iron, casein
high in P)
or contain lipids (lipoproteins, ie cholesterol)
or carbohydrates (glycoproteins, ie antibodies, antigenic determinants
(portion of an antigen which antibodies recognize and bind to)(example,
specificity of carbohydrate residue is different in people with different
blood types–if blood transfusion of wrong type is given to person,
antibodies will recognize different carbo residue as being foreignand will
bind and destroy RBC. If carbo is same type, no immune response)
In order to synthesize protein, a plant or animal needs source of amino
acids. Plants and most microorganisms are able to synthesizeall the amino
acids they need for tissue growth from nitrogen-containing compounds.
Animals can synthesize some, but not all, therefore require a dietarysource
of amino acids.
Categories - non-essential (those animal can synthesize), and essential
(cannot synthesize, or synthesize in sufficient quantity). Third categoryof
semi-essential - amino acids which in some species or under certain
conditions (such as growth) may not be synthesized in sufficient quantity
for optimal performance.
Example, arginine - required for growth, not for maintenance
Essential: phenylalanine, valine, threonine, methionine, arginine*,
tryptophan, histidine*, isoleucine, leucine, lysine, taurine (onlyin cats)
Non essential (those generally produced in sufficient quantitiy by animal)
alanine, aspartic acid, citrulline, cysteine*, glutamic acid, glycine*,
hydroxyproline, proline*, serine, tyrosine*
In livestock rations, amino acids most likely to be deficient are lysine,
methionine, tryptophan
Rations high in grains such as corn and milo are deficient in theseaa's,
must be supplemented with protein source.
If essential amino acid is missing in protein synthesis, body cannot
substitiute another aa, or put protein synthesis on hold until requiredaa
is available. Protein synthesis stops, aa chain is broken upfor energy and
production of that protein is inhibited until sufficient supplies of
essential amino acid is available.
If a specific aa is required for protein synthesis is not available,and
cannot be synthesized by animal, than that aa is referred to as a limiting
amino acid. Almost always, lysine is going to be limiting aminoacid in
livestock rations—if lysine is in sufficient supply, then almost always,
other essential amino acids are going to be sufficient.
Ruminants do not have same aa requirements that non-ruminants speciesdo –
microorganisms in rumen utilize nitrogen sources, ie ammonia and urea,to
synthesize microbial proteins containing both essential and nonessentialaa;
in turn digested and utilized as source of aa's. Ruminants cansurvive only
being provided a source of nitrogen, such as urea; high-producing dairy
cattle cannot synthesize sufficient quantities fast enough to supply
demands, require source of high-quality protein to supply additionalaa's.
What is "high quality" protein? Quality of protein is judged byit's
biological value – how digestible are the proteins in a protein source;and
how well the amino acids supplied match the animal's requirements.=> when a
protein source is consumed, what proportion of amino acids are retainedby
the animal?
Most protein sources fed to animals contain 75-80% digestible protein.
Example: 10 kg SBM containing 45% crude protein, of which 80% digestible.
4.5 kgs of crude protein, 3.60 kgs of digestible protein. Whenformulating
livestock rations, you will calculate CP values, also lysine content.
BV highest in egg = 100
SBM - 94
milk 85
meat proteins 72 - 79
legumes 67 -70
most grains - 50 - 65
wheat 40
gelatin 12 - 16
Protein Efficiency Ratio (PER) measure of how well a particular protein
supports weight gain. How many grams of test protein arerequired for
animal to gain 1 gram of BW? Method used to judge quality ofprotein in
human foods, specifically infant formulas and baby foods.
Protein is most expensive nutrient to supply, so generally will mixa large
amount of lower quality protein with a smaller amount of high quality
protein to give ration that supplies the animal's requirements. By doing
this, you supply sufficient protein at a more economical cost thanby simply
feeding all high-quality proteins. This is associative effectbetween
feeds.
The same thing in humans are called complementary foods, big thing in
vegetarians because plant sources of protein are lower in quality thanin
protein from animal sources (meat, milk, eggs = complete proteins). Only
Food sources that do not supply high quality profile of aa's are called
incomplete proteins, must mix different protein sources to supply complete
requirements -
Grains, Legumes, Seeds and nuts, vegetables
Same practice applies in animal rations - grain is cheap, supplies lotsof
energy, but does not supply sufficient amino acids. Mix withsmaller amount
of SBM (a legume) to supply complete aa profile.
EXCESS PROTEIN
The body doesn't store excess aa, only proteins in the body are in theform
of organized tissue, ie skeletal muscle (compared to carbos storedas
glycogen, triglycerides stored as adipose tissue, some fat-solublevitamins
are stored in liver).
If required aa is not available during protein synthesis, that proteindoes
not get synthesized. Because body does not store aa, proteinmust be
supplied through dietary sources on a regular basis, you cannot counton
last week's protein being available to supply this week's requirements.
If excess protein is fed at any given time, and any of the componentaas are
not required for protein synthesis, then the excess protein will beutilized
for energy.
In monogastric and avian species - deamination - amino group is snippedoff
end, either transferred to another carbon skeleton to form a non-essential
aa, or degraded to ammonia, ammonia degraded to urea, flushed throughurine.
Remaining amino acids will be degraded for energy. Monogastricand avian
species do not utilize ammonia, for them ammonia is toxic substancewhich
must be removed from system.
In ruminant species, remember we talked about how microorganisms inrumen
can utilize ammonia to synthesize microbial proteins:
Protein => component amino acids
=> hydrolyzed to VFAs
Absorbed in rumen as energy source
=> ammonia
Utilized by microbes to synthesize req'd microbialprotein
=> CO2
Expired as gas
=> ammonia
Utilized by microbes to synthesize req'd microbial proteins
Excess protein in confinement production animals doesn't occur becausecost
of protein (most expensive nutrient). Horses are not consideredproduction
animal, excess protein very common because alfalfa commonly fed andbecause
horses are pets and owners oversupplement them. In monogastricspecies,
generally accepted that excess protein will not cause major problemsas long
as animal has sufficient water to drink to flush ammonia/urea frombody.
However, can cause problems—in older dogs and cats, excess protein cancause
nephritis
In horses - protein produces 3-6 times the amount of waste heat asdo carbos
or fats.
In hot climates, increases heat load on animal - during sustained
performance, decreased performance
Excess protein means more urea to be flushed from body
1) increased water intake, increased urine output
2) more bedding/labor in stalled animals, increased ammonia fumesto
irritate upper respiratory tract
In ruminants, some indication that excess protein decreases fertilityin
dairy cattle.
If urea or nonprotein nitrogen is utilized, toxicity can occur if adequate
carbohydrates are not supplied as well. When this happens, ureais quickly
degraded to ammonia . Excess ammonia will be absorbed fasterthan the liver
can detoxify => toxicity
pH is an important factor because ammonia is absorbed faster throughthe
rumen wall at pH of 7 or above. At pH of 6 and below, ammoniaabsorbtion is
almost nil. Feeding adequate carbohydrates, microbes produceVFAs => lower
rumen pH => little or no absorption of ammonia. Low quality foragedoes not
produce adequate VFAs, must be carbohydrates in the form of highly
digestible starches or sugars, such as grain.
Urea/ammonia toxicity can also occur if large amounts of NPN arefed all at
once to an animal not yet adapted to urea (introduced too quickly)or if
feed isn't mixed well, animal consumes large amount all at once. Symptoms
of urea/ammonia toxicity are incoordination, tetany, slobbering, labored
breathing and/or bloating.
PROTEIN DEFICIENCY
Can be due to:
1) deficiency in one or more limiting essential amino acid
2) total dietary protein level is inadequate
Symptoms of deficiency:
1) poor growth rate or weight gain
2) decreased feed consumption
3) decreased birth weights/litter size
4) increased infant mortality
5) infertility
6) decreased egg or milk production
7) decreased N retention - if limiting aa is unavailable, the otheraas will
be utilized for energy, not protein synthesis