HomeMy WebLinkAboutFarming '89, 1989-03-22, Page 21FARMING ‘89, WEDNESDAY, MARCH 22, 1989. A21.
Feed analysis terminology: what it all means
BY ANNETTE MOORE
OMAF DAIRY SPECIALIST
Today’s fast pace often requires
us to use abbreviations and short
cryptic phrases. However, when
things speed up the rate at which
we understand often slows down.
Understanding feed analysis ter
minology is no exception and can
be quite confusing when choosing
the appropriate analysis. Listed
below are some definitions design
ed to alleviate some of the con
fusion.
Recommended tests for dairy
forages should include crude pro
tein, heat damaged protein if
warranted (for hay, haylage and
corn silage only), an energy esti
mate, a measurement of dietary
fibre, calcium, phosphorous, mag
nesium and potassium. Other tests
are available for problems specific
to your farm or area. For more
information, please feel free to
contact myself or your local OMAF
office staff.
AS FED - As fed refers to the
actual amount of a feed or nutrient
fed to livestock and includes the
moisture present in the feed.
DRY MATTER BASIS (DM) -
Feeds or nutrients listed on a dry
matter basis are dry feeds or
nutrients after the water is remov
ed. Used as a basis for comparing
feeds and estimating intakes.
DIGESTIBLE NUTRIENTS -
Digestible nutrients are the portion
of each feed nutrient that is
digested or absorbed by the ani
mal.
DIGESTIBILITY - Digestibility is
a measure of the extent to which a
feed is digested and absorbed by
the animal. Usually expressed as a
percent.
ENERGY - Energy is the ‘fuel’
that helps the body grow, maintain
itself and reproduce. Energy can
not be measured directly in the
laboratory like protein, fibre or
minerals. The units most common
ly used in North America to
measure energy are kilocalories
(Kcal). However, other units of
measure used are calories (cal),
mega calories (Meal) and Kilo
joules (KJ). Their relationship with
each other are as follows: 1 Kcal =
1000 cal, 1 Meal = 1000 Kcal, 1
Kcal = 4.18 KJ. Energy can also
be measured in terms of ration dry
matter (Mcal/kg) or as a percent
age of the total ration or feed.
NET ENERGY (N.E.) - N.E. is
the energy used for maintenance,
and for productive purposes, i.e.
growth, gestation and lactation.
Net energy is derived from animal
studies by measuring the gross
energy minus fecal energy, minus
energy lost in urine and minus
combustible gases and heat loss.
Net energy (lactation) however can
also be calculated on a dry matter
basis for hay, haylage and corn
silage using the forage Acid-Deter
gent Fiber (ADF) analysis.
TOTAL DIGESTIBLE NUTRI
ENTS (T.D.N.) - T.D.N. is derived
from animal studies by measuring
the percentage of digestible carbo
hydrates, digestible protein and
digestible fat (x 2.25). T.D.N.
values for hay, haylage and corn
silage however can also be calcu
lated on a dry matter basis using
the forage Acid-Detergent Fiber
(ADF) analysis.
PROTEIN - Protein is composed
of nitrogen, carbon, hydrogen and
oxygen and sometimes sulfur or
phosphorous. Proteins are made up
of complex combinations of various
amino acids and are necessary for
maintenance, growth, production
and reproduction.
AMINO ACIDS - Amino acids
are nitrogen containing compounds
that are the “building blocks” from
which proteins are formed. It is the
combination of the different amino
acids that dictate protein quality.
CRUDE PROTEIN (C.P.) - The
total amount of crude protein in the
feed is represented by the amount
of nitrogen present when analyzed
and then multiplied by the conver
sion factor of 6.25. This is based on
the assumption that true protein
contains 16 per cent nitrogen
(100/16 = 6.25). This test however
fails to differentiate between true
protein nitrogen and nitrogen that
is in the form of non protein
nitrogen (NPN), such as nitrates;
ammonia, urea and single amino
acids.
AVAILABLE PROTEIN - Avail
able protein is the portion of crude
protein that is digestible by the
ruminant. Usually used in describ
ing protein that is ‘available’ in
heat damaged hay, haylage or corn
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Acid-Detergent Fiber - Nitrogen
(ADF - N) test by measuring the
amount of bound protein.
UNAVAILABLE OR BOUND
PROTEIN - Unavailable or bound
protein is the portion of crude
protein that is non-usable by the
ruminant.
SOLUBLE PROTEIN - Soluble
protein is the portion of the
available protein that is completely
soluble in the rumen fluid and
rapidly attacked by bacteria. It
contains both non-protein and true
protein nitrogen. Feeds will vary in
their degree of solubility, for
example; forages have a high
percentage of soluble nitrogen in
the form of non-protein nitrogen,
while urea is 100 per cent soluble.
INSOLUBLE AVAILABLE PRO
TEIN - Insoluble available protein
is the portion of available protein
that is not soluble in rumen fluid,
but is still available to the rumi
nant. The rate of breakdown will
vary depending upon the feed and
its physical form. Insoluble avail
able protein which escapes degrad
ation in the rumen is almost
completely digested in the lower
tract and is then referred to as
rumen undegraded insoluble pro
tein or bypass protein.
RUMEN DEGRADABLE PRO
TEIN - The portion of protein that
is degraded by the rumen micro
organisms.
FIBER - Fiber is the portion of
the plant which provides the
plant’s structural strength and
form. Generally, the vegetative
parts, especially the stems, have
the highest fiber content. Seed
hulls and/or coats also often con
tain fiber. Fiber is composed of
several different types of com
pounds and is the major constituent
of plant cell walls. The components
of fiber that provide the ‘fiber’
value are hemicellulose, cellulose
and lignin. An adequate amount of
digestible fiber is required in the
diet of ruminants for efficient
production and health.
CRUDE FIBER (CF) - Crude
fiber analysis is an outdated me
thod to analyse fiber. It was once
thought to measure only the undi-
gestible portion of fiber, but in fact
is often partially digestible. It
measures only part of the cellulose
and lignin as well as some hemicel
lulose and is often not very
repeatable. It is still however
required on commercial feed tags.
ACID-DETERGENT FIBER
ADF) - ADF is the portion of fiber
that is composed of cellulose and
lignin. ADF is related to forage
digestibility (energy) and is used to
calculate forage, TDN or NE for
hay, haylage and cornr silage.
Forages lower in ADF are usually
higher in energy.
NEUTRAL DETERGENT FIBER
Continued on page A23