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The
measurement of nitrogen in the ruminant manure has been a research
tool for many years. This can be used to simplify measuring nutritional
performance. The lower the percentage of nitrogen in the feces,
the poorer the performance. All agricultural labs that can run a
protein analysis can perform this test. Kjeldahl is
the name of the procedure, and is the same method used for finding
the protein content of alfalfa hay. For our use, only forage diets
qualify for accurate and significant analysis of nutritional status
by this method.
Both
the rate of bacterial growth and the amount of bacterial growth
in the rumen predict the amount of volatile fatty acids produced--
the main source of energy supplied to the animal from forage
digestion. As these microorganisms pass out of the rumen into the
lower tract, they are digested and are the main source of protein
from forage digestion.
Rumen
organisms contain significant quantities of lipids, carbohydrates
and minerals that are entirely available to the animal. This represents
an important transfer of food energy from the rumen.
The
bacterial dry matter contains 55% protein; of this 85% is digestible.
This leaves 15% of the crude protein from this source as a variable
passed out with the feces. This fraction reflects rate of fermentation
that took place in the rumen and accurately predicts quantities
of energy and protein made available to the animal. Fecal Nitrogen
reflects performance on a forage ration only. Concentrate feeding
can cause lower tract fermentation that will make this analysis
inaccurate for measuring the animals performance.
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following percentages of fecal nitrogen can be looked at as objectives
on cows: |
| 1)
Maintenance level |
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1.50% |
| 2)
Calving for Cow |
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1.90
- 2.00% |
| 3)
Optimum |
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2.80
- 3.50% |
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| Fecal
Nitrogen on Yearlings |
| Percentage
of the total nutrients digested, as measured by fecal nitrogen,
required for maintenance of the animal unit: |
|
Pounds
of
Gain
|
Fecal
"N"
|
Maintenance
|
Maintenance
As A % of
Digestible Energy
|
| 0.0 |
1.50 |
1.5 |
100%
= parity or par |
| 1.0 |
1.75 |
> |
86%
only 14% productive |
| 1.5 |
2.05 |
> |
73%
(=27%) |
| 2.0 |
2.80 |
> |
54%
(=46%) |
| 3.0 |
3.25 |
> |
46%
(=54%) |
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Walt
Hunsaker conducted a field trial near Ducor, CA. The cows were on
a 3% crude protein (dry feed) with a 53% acid detergent fiber (low
digestibility). Three pounds of wheat midds were hand-fed daily,
along with the molasses supplement, due to very low crude protein.
Mr. Hunsaker said he could do without the wheat midds on his older
cows but may be necessary on heifers.
|
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| Type
of Supplement |
Intake/Day |
Fecal
Nitrogen |
| Cow/Calf
28% |
1.2
lbs/day |
1.60% |
| ALL-IN-ONE
30% |
0.6
lbs/day |
1.65% |
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Ferris
Brough conducted a field trial near Wells, NV. The cows were placed
on stubble fields and hay, were sorted to flesh prior to the start.
Cows with good flesh received no supplement and the medium flesh
cows received our new ALL-IN-ONE supplement. Mr. Brough said the
control cows lost weight and body condition and had to be supplemented
later in the season, but the thinnest cows visually improved in
flesh and condition.
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| Type
of Supplement |
Intake/Day |
Fecal
Nitrogen |
| Controls
- none |
n/a |
1.30% |
| ALL-IN-ONE
30% |
0.35
lbs/day |
1.67% |
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