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Digestibility Tip Sheet
Terminology
IVTD## – in vitro true digestibility followed by the
incubation period. For example, IVTD48 is the digestibility of the
sample after 48 hours of incubation.
NDFD## – neutral detergent fiber digestibility expressed
as a percentage of the NDF followed by the incubation period. For
example, NDFD48 is the percentage of NDF digested after 48 hours
of incubation.
RFQ – Relative Forage Quality. A score given to a hay
crop forage based on CP, ADF, NDF, NDFD48, fat and ash. Utilizes
the same scale as RFV. The higher the score, the better the quality.
A typical alfalfa hay (20% CP, 30% ADF, 40% NDF, 45% NDFD) will
have a RFQ of 150.
Milk lbs./ton – an estimate of the amount of milk potentially
produced per ton of forage dry matter.
General
Information
| 1. |
Determine
the incubation time period. Typically 30 or 48 hours. Consult
your nutritionist for the appropriate time.
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| 2. |
NIR
IVTD
| a. |
May
be added to any standard NIR package for hays, haylages
or corn silage (no small grains or TMRs). |
| b. |
May
be added to any standard wet chemistry package ONLY
if the sample is a NIR applicable hay, haylage or corn
silage. |
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| 3. |
Wet
chemistry IVTD – can be added to any standard NIR or
wet chemistry package regardless of sample type.
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| 4. |
Single
time periods – (NIR $4, wet $13) select only one time
period. Do not check off both NIR and wet boxes for the same
time period. Our system is designed to accept only one IVTD
per time period. If both boxes are checked, NIR will be given
where applicable, else the sample will be assigned wet chemistry.
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| 5. |
Multiple
time periods – for modeling, select the 24/48 combination
for NIR applicable forages. Other sample types must get wet
chemistry for both times at a cost of $38. The same holds true
for 6 and 30 hour combinations. Avoid using more than two time
points.
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| 6. |
NDFD
– accompanies an IVTD analysis when the sample is also
analyzed for NDF. An IVTD48 analysis must be performed in conjunction
with NDF in a standard package to yield a NDFD48 used for RFQ
and Milk lb/ton calculations.
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| 7. |
RFQ
– requires NDFD48 for calculation. Select the Hay Market
Profile or add IVTD48 to one of the standard packages.
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| 8. |
Milk
lbs/ton – requires NDFD48. Select the Hay or Corn Silage
Market Profile or add IVTD48 to a standard package.
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| 9. |
IVTD
options as they appear on the Sample
Information Sheet. |
10/2007
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