Individual batches of feed must be isolated and their flow controlled. People must be
ready at
each sampling location to take samples as the individual batches pass.
All samples must be
carefully identified and detailed records of all aspects of the test should be made.
The basic flow of feed at a feedmill includes the following:
1. feed ingredients after being ground to mash with a hammermill (if necessary)
are gravity fed
into a mixer and mixed.
2. the mixed feed is then dumped into a surge bin.
3. the feed is then discharged from the surge bin using a screw conveyer.
4. the feed is then elevated in the feedmill using a bucket elevator system.
5. the feed is then gravity dumped into a holding bin over a pellet mill.
6. the feed is then pelleted and cooled.
7. the feed is then elevated again using a bucket elevator or pneumatic system.
8. the feed is then distributed to holding bins.
9. the feed is then loaded into trucks.
10. the feed is then carried to farms where it is discharged into bins.
11. the feed is then distributed from the on-farm bins to the animals, poultry or fish for
consumption.
Medications are usually added as a microingredient into the mixer, sometimes by hand
but often
utilizing computer controlled micro-bin systems. "Cross Contamination"
of the medication may
occur in the micro-bin system even before the medication reaches the mixer.
"Cross contamination" to prior batches may also occur, as when mixer discharge gates leak
and
an earlier batch remains in the surge bin.
As an initial investigation, one may take samples of the "non-target" following feed
only at truck
loadout taking care to be certain the feed takes the identical route
as the medicated feed with
Microtracer. If one finds very little or no tracer from
the loadout samples, this indicates there may
be very little "cross contamination"
occurring anywhere in the system. If one finds Microtracers in
the "non-target"
following feed, however, much more extensive testing is required to diagnose
and
then have a basis for correcting the problem.
Portions of the medication may be left as "contamination" to non-target batches
at all the above
referenced production points. To reliably diagnose the potential for
"cross contamination" of
medications to non-target batches of feed, it is critical to
take multiple "grab" samples at multiple
locations of both the target batch
(with medication) as well as one or more following batches. It
must be re-emphasized
that it is critical the following batches take the identical route through the
feedmill
as the initial medicated batch formulated with Microtracer.
Analysis of Samples: Please refer to Microtracer literature items "L" and "O".
Results from Actual Tests
Test # 1. Premix Plant manufacturing Powdered Sulafethazine premix. Microtracer
F-Red was used to
estimate contamination of powdered sulfamethazine to flushing materials
and to subsequent premix
batches. The premix plant had been "red flagged" by the
US-FDA because it found more than 5 ppm
sulfamethazine in premix supposed to contain none
The premix plant had instituted rigorous flushing
cleanout procedures
and wanted to confirm these were efficacious.
Premix Formulation- 1 % sulfamethazine (10,000 ppm) and Microtracer F-Red at 0.8% (8,000
ppm).
Batch size 2,500-lbs.
Batch #1-
Microtracer F-Red Counts
Sulfamethazine Assay
Sample #1- 0.41 grams =
66
#2- 0.40
"
73
#3- 0.47
"
64
#4- 0.38
"
56
Total 1.66 grams =
259
Composite Assay 8,800 ppm
Percentage of Specification
77%
88%
(25,000 X 1.66 grams X 0.8% = 332 expected count - 259/332 = 77%)
Flush #1. 300-lbs. of ground limestone.
Sample #1- 20.0 grams =
85
#2-
"
86
#3-
"
104
#4-
"
88
Total 80.0 grams =
363
Composite Assay 331 ppm
Percentage of Specification
2.3%
3.3%
(25,000 X 80 X 0.8% = 16,000 expected count - 363/16,000= 2.3%)
Flush #2. 300-lbs. of ground limestone.
Sample #1- 200 grams =
106
#2-
"
90
#3-
"
109
#4-
"
101
Total 800 grams =
406
Composite Assay 82 ppm
Percentage of Specification 0.25%
0.82%
Flush #3. 300-lbs. of ground limestone.
Microtracer F-Red Counts
Sulfamethazine Assay
Sample #1 200 grams = 16
#2-
''
30
#3-
"
14
#4-
"
27
Total
800 grams 87
Composite Assay 65 ppm
Percentage of Specification 0.054%
0.65%
Flush #4. 1,000-lbs. of ground corn.
Sample #1- 200 grams
28
#2-
"
22
#3-
"
22
#4-
"
23
Total
800 grams 95
Composite Assay 32 ppm
Percentage of Specification 0.059%
0.32%
Flush #5. 1,000-lbs. of ground corn.
Sample # 1- 200 grams 2
#2- "
2
#3-
"
5
#4-
"
11
Total 800 grams
20
Composite Assay 10.6 ppm
Percentage of Specification 0.0125%
0.106%
Followup Batch #1. 2,500-lbs.
Sample #1- 200 grams 4
#2-
"
2
#3-
"
1
#4-
"
2
Total 800 grams
9
Composite Assay 1.7 ppm
Percentage of Specification 0.0056%
0.017%
Conclusion: The various "flushes" did serve a useful purpose in reducing the
amount of tracer (and sulfamethazine) reaching premixes supposed to contain
none
Contamination was not uniform but rather
erratic when present at very low levels.
It appeared possible to keep sulfamethazine contamination
of
following premixes below the objective of 5 ppm.
"Cross Contamination" of the Microtracer F-Red from the premix
formulated with the tracer to
subsequent flushes and premix batches
was less than for the powdered sulfamethazine. It should be
possible to make
a curvilinear regression to accurately estimate contamination of the drug
based upon
tracer results. The results also may support the advantage
of granulated sulfamethazine over the
powdered product
as relates to their potential for cross contamination.
Total recovery of the Microtracer F-Red was about 80% of specification
and total recovery of the
sulfamethazine was about 90%. Most probably,
the Microtracer was lower than its specified count.The test continued through
four more production batches of premix. Microtracer was found in all
batches
and sulfamethazine assays of the final batches was 2.4ppm
and 2.5ppm (0.024% and 0.025% of the
specified level).
Test #2. Using Microtracers F to Design a Feedmill Identifying Locations
Where the Greatest
Contamination Occurs. A major designer/supplier
of "turnkey" feedmills wanted to minimize batch to
batch contamination in their new mills.
Microtracer F-Blue was formulated in "Batch #1" at 50 grams per 2,000-lbs.
of feed into 3 ton batch (150 grams of tracer mixed in ground corn added to batch).
Microtracer F-Red was formulated following
the same procedures into Batch #2
Samples were then taken at the Surge Bin, Conveyer and Top of the
Bucket Elevator
for five following batches.
Microtracer F-Blue Contamination to Subsequent Batches.
Batch (2,000 grams) Surge Bin
Conveyer
Elevator
#2- sample 1
2
1
17
2
1
0
98
3
1
3
112
4
0
3
58
Total
4
7
285
Percentage of Tracer Spec. 0.035%
0.065%
2.59%
Batch
Surge Bin
Conveyer
Elevator
#3- sample 1
0
3
10
2
2
0
9
3
0
0
23
4
0
1
44
Total
2
4
86
Percentage of Tracer Spec. 0.018%
0.035%
0.78%
#4- sample 1
2
0
2
2
0
0
0
3
0
0
0
4
0
0
15
Total
2
0
17
Percentage of Tracer Spec. 0.018%
0%
0.155%
#5- sample 1
0
0
0
2
1
0
0
3
0
0
1
4
0
1
5
Total
1
1
6
Percentage of Tracer Spec. 0.009%
0.009%
0.055%
Surge
Bin
Conveyer
Elevator
#6- sample 1
0
0
1
2
0
0
1
3
0
0
1
4
0
2
6
Total
0
2
9
Percentage of Tracer Spec. 0%
0.018%
0.082%
#7- sample 1
1
1
0
2
1
0
0
3
0
0
129
4
0
0
0
Total
2
1
129
Percentage of Tracer Spec. 0.018%
0.009%
1.17%
Conclusion: Comparatively little contamination of the Microtracer occurred
at the Surge Bin and Conveyer locations. The amount of contamination was
much greater at the top of the bucket Elevator. One sample in Batch #7
contained a "slug" of tracer illustrating that contamination is
not uniform and thee best chance to find problems is to take and
analyze many large samples. The amount of contamination increases
as the feed flows through the mill.
In detailed studies at three poultry feed mills (ref. Item "MM"), the following results were obtained:
Recovery of Microtracer F-Red from samples taken from the mixers - 95.7% of specified count
Recovery of Microtracer from pelleted feed samples at truck loading- Feedmill # 1- formula one 82.8%,
formula two- 89.3%; Feedmill #2- 75.4%.
Percentage of tracer appearing in non-target feeds- Feedmill # 1- 3.0%, Feedmill #2- 0.26%.
The
medicated premix at Feedmill # 1 was formulated in 60% of the mills feeds whereas the
medication at
feedmill #2 was formulated in only 10% of its production.
Qualitatively, the Microtracer results reflected feed medicated assays well,
though quantitatively results did
not match as well.
This was because of variability inherent in the particle statistics used to interpret
Microtracer spot counts and problems with the medicated feed assays.
1 /01 dae