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!
 
 

Definition of feedstuff - any component of a ration which serves a useful
purpose:
a source of nutrients
modify characteristics of the ration:
 provide additional bulk
 enhance texture or taste or odor to improve palatability
 prevent spoilage
 affect digestive efficiency, such as buffers and probiotics

There are eight classifications of feedstuffs:

1) dry roughage
 feedstuffs containing more than 18% CF on DM basis
 hay, straw, CS hulls, shells and hulls, corn cobs, milling by-products
2) Pasture and range grasses
 green plants, greenchop/soilage, cannery and food crop residues  >18% CF,
DM basis
3) ensiled roughages
 silage, haylage
 Ensiling is process by which high moisture (25-50% DM) choppedforage is
packed into container.  Anaerobically ferments, produced volatilefatty
acids (primarily lactic acid), ph falls to below 4 and preserves thefeed.

4) Energy feeds - <18% CF, >70% TDN, <20% CP
 Cereal grains
 Milling by-product of cereal grains
 beet and citrus pulp
 molasses
 seed and mill screenings
 fats of all types
 roots and tubers, whether fresh or ensiled

5) Protein supplements - <18% CF, >20% CP
 Animal sources
 milk and milk by-products
 legume seeds
 dehydrated legume plants
 milling by-products of grains
 brewery/distillery by-products
 single-cell sources (algae, bacteria, yeasts)
 NPN (urea, ammonia)

6) Mineral supplements
7) Vitamin supplements
8) Non nutritive additives
 antimicrobials
 antioxidants
 probiotics (freeze-dried cultures to supplementing the microbialpopulation
in animals that maintain a microbial population)
 buffers
 colors and flavors
 emulsifying agents
 enzymes
 hormones
 medicines

Notice that "Milling by-product comes under roughage, energy and protein
source categories.  To differentiate what goes where, individualfeedstuffs
are given an International Feed Identification Number (IFN). The first
digit of an IFN indicates which category the feed belongs.

Example, sunflower seed meal w/o hulls => TDN 69%, CF 11.7%, CP 45.2%
IFN 5-04-739 => protein supplement

IFN system is used by NRC, used to formulate rations

Feed manufacturers may also use collective terms on feed tags and labels
according to American Feed Control Officials (AFCO)
Seven categories:
Animal Protein Products
Forage Products
Grain Products
Plant Protein Products
Processed Grain By-Products
Roughage Products
Molasses products

Difference is IFN categorizes based on nutrient provided, AFCO system
categorizes based on source of feed.  Used by feed processorsto satisfy
feed labeling regulations - ie, a manufacturer may use least-cost analysis
to manufacture a ration that contains x% protein, but exact ingredientsmay
differ from batch to batch, ie peanut skins, rice bran, corn flour.

He can put "processed grain by-products" on label and cover his bases

Nutrient compositions of feeds are analyzed through either chemicalanalysis
or digestion trials.

Chemical analysis - most widely used is Proximate Analysis.  Canaccurately
measure content of nutrients in feed sample, but cannot measure theamount
that will be utilized by an animal.

Measures moisture content, CP, CF, crude fat (ether extract), ash andNFE
(primarily sugars, starches and pectins).
Moisture - measure a sample of feed, dry in oven for several days,weigh it
again.  Direct measurement of free water.

CP - Indirect measurement, Kjeldahl procedure.  Nitrogen contentis
measured, plug into equation that relates nitrogen content to protein
levels, so protein is not measured directly, its estimated from nitrogen
level.  Does not measure quality of protein, ie heat damaged proteins,or aa
profile.  As CP increases, quality of feed increases.

CF - estimates structural carbohydrates (hemicellulose, cellulose and
lignin) As CF increases, quality of feed decreases.  CP and CFwill give
good estimation of total quality of feed, generally used to determineprice
of a feed.

CF (ether extract) - estimates all the fat-soluble lipids in a feed,does
not provide any information about digestibility of those fats. Ie, about
half the ee in beet pulp is a natural pigment that gives it the purple-black
color—measures as ee, but is not available as a source of energy toanimal.
Most feeds and forages will naturally contain about 2-4% ee, abouthalf of
which is available.

Ash - mineral content of a feed.  Measured by measuring out a feed,putting
it into a high temp furnace so that everything except minerals is drivenoff
as CO2 and water.  Measures total mineral content, but does notmeasure
mineral composition (though have to be done through other analysis)

NFE - done last because can't measure directly

%NFE = 100 - (%CP + %CF+ %EE+ % ash)

Problems with proximate analysis - estimations become more and more
inaccurate as hemicellulose content of a feed increases.  Thisis b/c
hemicellulose will show up as part of both CF and NFE.

Hemicellulose is 60-70% digestible, cellulose is 40-50% digestible,lignin
is 0% digestible and starches and sugars in NFE are about 95% digestible.

Two anlyses to determine hemicellose content, neutral detergent fiberand
acid detergent fiber.

NDF gives you a measurement of hemicellulose, cellulose and lignin
ADF gives you measurement of cellulose and lignin
NDF - ADF = hemicellulose content

Digestion trials - measures digestibility of a particular feed by measuring
the amount that goes in, subtracting the amount that comes out in feces

apparent digestibility = nutrient consumption - fecal excretion/nutrient
consumption x 100

"Apparent" because nutrients in feces may be due to other sources, is
protein content may be due to sloughing off of intestinal mucosal cells.
More bother, but more accurate measrement than chemical (proximate)
analysis.  Still tends to overestimate digestibility because doesn'tmeasure
losses through gas or urinary or heat.

When urinary, gas losses also measured => balance trial

Feeding trials - directly measures effect of a feed on performance or
growth.  Example, graded amounts of a feed of known quality (ieSBM) will be
replaced in a diet with same amounts of another test feed, CSM. Measure and
compare performance between two.

Problem with this is that performance may be affected by something other
than the test feed, very difficult to replicate so that all conditionare
exactly the same except for test sample, ie a coyote gets into thechickens
and kills a bunch and upsets the rest—are the results due to the feed
sample, or were they affected because of the stress of the coyote?