Most forage testing laboratories do reasonably well at analyzing the "received" sample. The major problem in balancing rations is whether or not the analyzed samples represents what is being fed. Most laboratories will do dry matter and other analysis on approximately a 100 to 150 g sample. Larger samples are subsampled and only the Subsample analyzed.
A. Upright silos
- Run out at least a feed cart full of material. Take 10 - 15 subsamples, composite and send this in.
B. Bunkers -
-Take 10 - 15 samples in a grid approach representing the area fed out daily. Composite and send the composite in. It
is best to use a corer to sample at least 8 to 10 inches into the face.
- Alternately, take subsamples from several places/loads in the loader bucket
-Comments of feed sales reps:
1) Sampling face of bunker is not good:
a) dry matter not right
b) face of silage could slide down and bury person sampling
2). Hand sample of silage may bias particle score because fingers act as screen. Must use a scoop to get sample
3). Frequently there is a large layer of dry or spoiled silage where the
harvest had to stop for a day or two because of weather.
This could affect sample.
All of the above (except D) sample what
is being fed today. This may be acceptable to balance a ration for next
week if the vertical silo was filled rapidly (in 1 or 2 days) or the bunker
silo was filled in wedges over a short time (2 to 4 days). Sampling today’s
feedout to predict next week’s feed will not be acceptable otherwise due
to variation in the silo (see graphs below).
Silo Depth refers to distance in feet from height above ground in a vertical silo
Sampling at harvest gives you advance knowledge of the quality of silage stored in the silo. One can inventory and plan for purchasing supplemental feedstuffs based on forage quality needs.
While some fractions can show significant change during the fermentation following ensiling, crude protein and fiber fractions (ADF and NDF) show little change where forage was ensiled properly and normal fermentation occurred (see table below). Analysis will change when:
Ensiling matter CP ADF NDF
Before 44.1 19.9 32.3 40.5
After 42.4 20.7 34.8 40.4
Before 34.4 9.7 29.2 49.5
After 34.1 11.1 29.0 48.8