Animal Effectiveness
The salinomycin NADA (128-686)
established that salinomycin 40 to 60 g/ton (0.0044 - 0.0066% is a safe
and effective aid "for the prevention of coccidiosis in broiler chickens
caused by Eimeria tenella, E. necatrix, E. acervulina, E.maxima, E.
brunetti , and E. mivati" .
It has been established in
approved NADA's that bacitracin zinc and roxarsone are both safe and effective
for use in finished feeds for growing chickens and indicated for use to
increase rate of gain and improve feed efficiency. This application contains
data establishing that the action of each agent acts independently of
the other (additive) to increase weight gain and improve feed efficiency
while in the presence of salinomycin. These data demonstrate the safety
and effectiveness of the combined use of bacitracin zinc-salinomycin-roxarsone
when used in finished feeds containing bacitracin zinc 0.0011 to 0.0055%
(10 to 50 g/ton) and salinomycin 0.0044 to 0.0066% (40 to 60 g/ton) and
roxarsone 0.00375% (34.1 g/ton) for the prevention of coccidiosis in growing
chickens caused by Eimeria tenella, E. necatrix, E. acervulina, E.
maxima, E. brunetti , and E. mivati and for increasing rate
of gain and to improve feed efficiency. These data likewise demonstrate
that bacitracin zinc does not interfere with the anticoccidial activity
of salinomycin.
The approved salinomycin
plus roxarsone NADA 132-447, established that the addition of roxarsone
(3-nitro-4-hydroxyphenylarsonic acid) at a concentration of 0.005% to
finished feeds containing salinomycin sodium between the range of 0.0044
to 0.0066% is safe and effective for the prevention of coccidiosis,in
broiler chickens caused by E. necatrix, E. acervulina, E. brunetti
, and E. mivati, including some field strains of E. tenella
that are more susceptible to roxarsone combined with salinomycin than
the salinomycin alone.
A. Summary of Drug Noninterference
Studies
Two-week old, Hubbard x Hubbard,
broiler chickens were used in adequate, well-controlled, 2-week, battery
studies in a uniform environment with continuous artificial illumination
to test for noninterference of bacitracin zinc with the effectiveness
of salinomycin and roxarsone. Recent field strain isolates collected from
various broiler-producing regions of the United States were used. For
each study, combinations of E. mivati, E. brunetti, and, E.
necatrix , or E. acervulina, E. maxima, and E. tenella
were used. This facilitated identification of lesions.
These studies (Tables I and
II) were conducted by using the lowest approved level of salinomycin (40
g/ton) in the finished feed. The experimental treatment groups included
uninfected unmedicated controls, infected unmedicated controls, infected
groups receiving 40 g/ton of salinomycin with and without 100 g/ton bacitracin
zinc or roxarsone, 100 g/ton bacitracin zinc alone, 100 g/ton bacitracin
zinc plus 45 g/ton roxarsone, and 40 g/ton salinomycin and 45 g/ton roxarsone
plus 100 g/ton bacitracin zinc. The protocols were designed to show "noninterference",
of each component with the others for the bacitracin zinc-salinomycin
combination and the bacitracin zinc-salinomycin-roxarsone combination.
In each of these studies,
all pens were preselected, birds were randomized by weight and assigned
to cages with 10 birds/cage, and 4 replicates were used per treatment
group. Groups were medicated 2 days before infection was administered.
Evaluations were by lesion scores (analysis was performed on preselected
birds from each pen), dropping scores, weight gains, and feed conversions.
(Eds. note: The following
table consists of 13 columns.)
TABLE I
Anticocicdial Activity of Salinomycin and Salinomycin in Combinationion withZinc Bacitration
Against a mixed Eimeria Infection in 2-Week-Old Chicks Experiment 84-034
Average
Coccidiosis- Dropping -----------Weight Gain (g)---------- Average Live- Feed Conversion
Treatment Medication Induced Score* Bird Weight Total Lesion
Group Infection g/ton Mortality D4-D8 Day 5 Day 6 Day 7 Day 14 on Day 14 Day 7 Day 14 Scores**
I None 0 0/40 0.O 1803a 2227ab 2525a 6131a 944a 1.44b 1.45d 0.0c
Uninfected
II None 0 8/40 2.4 879d 559d 533c 3750c 702c 2.77a 2.10a 5.7a
Mixed
III Salincomycin 40 0/40 0.5 1880a 2214ab 2637a 6309a 958a 1.52b 1.52cd 1.3b
Mixed
IV Zinc Bacitracin 100 5/40 2.0 1083c 769d 746c 3950c 733c 2.57a 1.93b 5.2a
Mixed
V Saliomycin + 40 0/40 0.6 1918a 2390a 2625a 6320a 957a 1.5lb 1.50cd 0.9b
Zinc Bacitracin 100
Mixed
VI Zinc Bacitracin + 100 0/40 1.2 1498b 1720c 1963b 5497b 880b 1.65b 1.62 4.5a
Roxarsone 45
Mixed
VII Saliomycin + 40 0/40 0.4 1749a 2095b 2422a 6075a 937a 1.53b 1.53cd 1.0b
Zinc Bacitracin + 100
Roxarsone 45
Mixed
VIII Saliomycin + 40 0/40 0.3 1822a 2245ab 2560a 6068a 933a 1.49b 1.52cd 0.9b
Roxarsone 45
Mixed
NOTE: Comparisons are based on Duncan's Multiple Range Test at the 0.05 level of
significance. For a given column, any means not followed by the same letter are
siginficantly different.
* Pen dropping scores assigned using a scale of 0 to 4 (Morehouse and Baron,
1970).
** Lesion scores assigned using a score of O to 4 (Johnson and Reid, 1917) for
each area of the small intestine and ceca
(Eds. note: The following
table consists of 11 columns.)
Table II
Anticoccidial Activity of Salinomycin and Salinomycin in Combination with
Zinc Bacitracin Against a Mixed Eimeria Infection in 2-Week-Old Chicks (Pooled
Studies 84-035 and 84-110)
Average Dropping
Score*
Coccidiosis- -----D4-D8------ Weight Gain (g) Feed Conversion
Treatment Medication Induced Total
Group Infection g/ton Mortality 84-035 84-110 Day 7 Day 14 Day 7 Day 14 (g) Lesion Scores**
I None O 0/80 O.O 0 2236 5138 1.50 1.55 O.OOd
Uninfected
II None 0 11/80 1.1 1.7 1698 4902 1.91 1.79 5.62a
Mixed
III Salinomycin 40 3/80 O.7 1.6 1876 4793 1.79 1.71 2.08bc
Mixed
IV Zinc Bacitracin 100 10/80 1.3 2.1 1700 4737 1.82 1.75 5.46a
Mixed
V Salinomycin + 40 3/80 0.9 1.5 1740 4891 1.84 1.71 2.21bc
Zinc Bacitracin
Mixed
VI Zinc Bacitracin + 100 0/80 0.5 0.4 2106 5029 1.60 1.65 3.62ab 1.62 4.5a
Roxarsone 45
Mixed
VII Saliomycin + 40 0/80 0.4 0.3 2147 5095 1.64 1.68 1.04c 1.53cd 1.0b
Zinc Bacitracin + 100
Roxarsone 45
Mixed
VIII Saliomycin + 40 0/80 0.3 0.40 2123 5206 1.64 1.65 1.46c 1.52cd 0.9b
Roxarsone 45
Mixed
Note: Comparisons are based on Duncan's Multiple Range Test at the O.O5 level
of significance. For a given column, any means not followed by the same
letter are significantly different.
* Pen dropping scores assigned using a scale of 0 to 4 (Morehouse and Baron,
1970).
** Lesion scores assigned using a score of 0 to 4 (Johnson and Reid, 1970) for
each area of the small intestine and ceca.
These studies demonstrate that
there is "noninterference" of bacitracin zinc and/or roxarsone
on the effectiveness of salinomycin. The combinations were compatible.
The investigators were as
follows:
Shi E. Cheng, D.V.M., Ph.D.
A.H. Robins Co., Inc.
1405 Cummings Drive
P.O. Box 26609
Richmond, VA 23261-6609
Michael D. Sims B. S.
A. H. Robins Co., Inc.
1405 Cummings Drive
P.O. Box 26609
Richmond, VA 23261-6609
Patricia C. Gerber, A.A.S.
A. H. Robins Co., Inc.
1405 Cummings Drive
P.O. Box 26609
Richmond, VA 23261-6609
B. Floor-Pen Studies
Three, adequate and well-controlled,
floor-pen studies, using approximately 9600 broiler chickens (equal number
of male and female), were conducted under simulated actual use to determine
the growth promoting and feed efficiency effects of bacitracin zinc in
the presence of salinomycin plus roxarsone. All diets were balanced to
provide adequate levels of nutrients (protein, energy, minerals, etc.).
The same general experimental design was used in all studies. All chickens
were maintained from one day of age to market weight. The studies were
conducted in 3 geographical areas.
These studies were conducted
as a 2 x 4 experimental design. Bacitracin zinc (0 and 50 g/ton) and roxarsone
(0, 22.7, 34.1 and 45.4 g/ton) served as the two trial factors. Pens were
randomly assigned to treatment within blocks; 50 to 60 birds, equally
divided by sex, were selected at random and assigned to pens; 6 to 8 replicates
were used per treatment group. Salinomycin, 60 g/ton (.0066%) was fed
in the diet to all treatment groups. Studies were designed to simulate
varying conditions, such as geographical locations, differences in climate,
changes in weather, differences in management practices, and degree of
disease contamination of the premises.
Data were collected for the
evaluation of bacitracin zinc and roxarsone alone and in combination for
increasing rate of weight gain and improving feed efficiency in the presence
of the highest recommended level of the anticoccidial drug (salinomycin,
.0066%). Parameters of evaluation included mortality, body weights and
feed to body weight gain ratio.
Birds medicated with the
drug combinations were healthy throughout the study periods as evidenced
by a survival rate of over 97% for all studies. There were no adverse
drug toxicity effects observed.
A detailed examination of
the 3 trials (Table III) was conducted. Data from the 3 studies were combined
and an analysis of variance (weighted by 1ocation) conducted. Table IV
defines the treatment groups and Tables V and VI gives the means for body
weight and feed efficiency by location and averaged across locations by
treatment group. The overall dose-titration analysis for weight gain showed
a significant treatment difference in favor of bacitracin zinc (P=.0001),
while the overall analysis for feed efficiency showed a marginally significant
(P=.108) difference in favor of roxarsone. Linear plateau models were
fit to the feed efficiency data to determine the optimum dose. The best
fitting model showed no difference between levels 0 and 22.7, but a marked
drop to a plateau beginning at leve1 34.2.
(Eds. note: The following
table consists of 5 columns.)
Table III
Location and Design Study Information
Trial Study Study Pens/ Birds/
Location No. Investigator Trt. Pen
Colorado C878 Dr. C.L. Quarles 6 50
Oklahoma C880 Dr. R.G. Teeter 8 50-60
Georgia C905 Dr. R.B. Davis 8 58
(Eds. note: The following
table consists of 9 columns.)
Table IV
Medication g/ton
--------------------Treatment Group---------------------
Treatments 1 2 3 4 5 6 7 8
Roxarsone 0 22.7 34.1 45.4 0 22.7 34.1 45.4
Bacitracin Zn 0 0 0 0 50 50 50 50
Salinomycin 60 60 60 60 60 60 60 60
(Eds. note: The following
table consists of 9 columns.)
Table V
Mean Body Weight, Kg
--------------------Treatment Group---------------------
Trial 1 2 3 4 5 6 7 8
C878 1.816 1.823 1.833 1.824 1.862 1.876 1.880 1.897
C880 1.513 1.536 1.585 1.595 1.582 1.591 1.704 1.634
C905 1.942 1.869 1.934 1.885 1.960 1.952 1.963 1.918
Average 1.757 1.743 1.784 1.768 1.801 1.806 1.849 1.816
Percent
Improvement --- 0.0 1.5 0.6 2.5 2.8 5.2 3.4
(Eds. note: The following
table consists of 9 columns.)
Table VI
Feed Efficiency (F/G)*
--------------------Treatment Group---------------------
Trial 1 2 3 4 5 6 7 8
C878 2.002 1.995 1.982 1.985 1.983 1.975 1.955 1.982
C880 2.016 1.951 1.909 1.861 1.866 1.864 1.728 1.754
C905 2.025 2.031 2.011 1.992 1.968 1.956 1.952 1.968
Average 2.014 1.992 1.967 1.946 1.939 1.932 1.878 1.901
Percent
Improvement --- 1.1 2.3 3.4 3.7 4.1 6.7 5.6
*F/G: Feed consumed per body weight gain
The above data satisfy the requirements
for approval under the CVM Policy outlined in the guidelines for combination
drugs revised October, 1983. The policy provides for granting a range approval
for production drugs in combination when the maximum level tested for the
claim is demonstrated to make a significant benefit to the combination. The
range approval for bacitracin zinc for weight gain, according to the revised
policy, is from 50 g/ton to the minimum approved level for bacitracin zinc
in the parent application of 4 g/ton. However, a minimum use level of 10 g/ton
of bacitracin zinc was used in establishing the feed stability data for the
combination. Accordingly, 10 g/ton of bacitracin zinc is the minimum approvable
level. Linear-plateau models demonstrated that roxarsone for feed efficiency
makes an optimal contribution at 34.1 g/ton. Thus the recommended use levels
for this application are bacitracin zinc 10-50 g/ton plus 40-60 g/ton salinomycin,
plus 34.1 g/ton roxarsone in broiler chicken rations.
The investigators were as
follows:
Dr. Carey L. Quarles
Colorado Quality Research, Inc.
2629 Redwing Road
Creekside Two, Suite 315
Fort Collins, Colorado 80526
Dr. Robert G. Teeter
Department of Animal Science
Oklahoma State University
Stillwater, Oklahoma 74078
Dr. Richard B. Davis
4785 Lexington Road
Athens, Georgia 30605
The original approved NADA's
for salinomycin (NADA D-128-686), bacitracin zinc (NADA 46-920) and for
roxarsone (NADA 7-891, MF-l9-roxarsone) contained adequate data to establish
the safety of each drug for broiler chickens.
The safety of the combined
use of the 3 drugs was demonstrated in the drug residue elimination study,
the floor-pen studies and the compatibility battery studies described
in this document. Birds in the drug elimination studies were in good health
throughout the study and did not have any gross pathology at sacrifice.
The birds in both the battery and floor-pen studies receiving the drug
combinations showed no signs of drug toxicity as evidenced by both gross
necropsy examination, weight gain and/or feed efficiency data. Mortality
data for each study was within an acceptable range, and there was no evidence
of any toxicity which could be attributed to the combined use of the 3
drugs.
Based on the data in the
parent NADAs, the compatibility battery studies, the drug elimination
residue study, and the floor-pen studies, we conclude that the combination
be fed to broiler chickens as indicated by the label.
These data provide evidence
for the combination of bacitracin zinc 10-50 g/ton; salinomycin 40-60
g/ton; and roxarsone 34.1 g/ton in the feed of broiler chickens that is
consistent with and fulfills all the requirements for a fixed combination
drug for animals as follows:
A. Each drug component makes
a contribution to to the claimed effects.
B. The dosage level of each
drug component is such the combination is safe and effective for the purposes
claimed.
C. For a significant animal
patient population that is affected by a significant disease condition,
Eimeria tenella is a major and widespread etiological organism
for coccidiosis and the most pathogenic Eimeria species for chickens
and, as such, possess the potential of causing extensive economic losses
to broiler producers.
D. The label claims are not
antagonistic.
A. Data to Support Human
Safety
Safety for the approved products
-- bacitracin zinc (Baciferm), salinomycin (Bio-Cox), and roxarsone (3-Nitro)
-- has been established by data submitted in their respective original
NADA's, NADA 46-920, NADA 128-686, and NADA 7-891 and Salsbury Master
File 19.
Tolerances for residues of
bacitracin zinc in edible tissue of chickens is established at 0.5 ppm
(21 CFR Section 556.70). Safe concentrations of salinomycin in the edible
tissues of chickens are 0.6 ppm for muscle, 1.8 ppm for liver and 1.2
ppm for skin/fat. Tolerances for residues of arsenic in the edible tissue
of chickens are established at 0.5 ppm in muscle and 2 ppm in edible by-products
(21 CFR 556.60).
B. Residue Depletion/Noninterference
Studies
The residue data supporting
the approved individual use of bacitracin zinc, salinomycin, and roxarsone
and their established withdrawal times of zero, zero, and 5 days respectively,
have been submitted in their respective applications (see Part A, above).
The following study, submitted
by A.H. Robins under NADA's 137-536 and 135-746, establishes that the
residues of each drug in the presence of the others is neither influenced
nor exceed the established safe concentration or tolerance at their established
withdrawal times, and that they do not interfere in each other's tissue
residue assays.
One hundred broilers, one
day old, were treated for 46 days with the three-way combination of salinomycin
(80 g/ton), bacitracin zinc (100 g/ton), and roxarsone (45 g/ton). Tissues
were collected and analyzed as shown in Table VII. From the residue data
in Table VII both bacitracin zinc and roxarsone (as arsenic) are below
their established tolerances of 0.5 ppm and 2 ppm at their established
withdrawal times of zero and five days respectively. Under NADA 128-686,
Robins Company established a research Rm, or tolerance, of 0.68 ppm for
parent salinomycin in skin/fat. The residue data in Table VII for salinomycin
confirms that, at zero withdrawal, the concentration of salinomycin is
below the research Rm of 0.68 ppm and is similar to the value for salinomycin
residues in skin/fat when salinomycin was used alone.
(Eds. note: The following
table consists of 3 columns.)
TABLE VII
RESIDUE LEVELS OF SALINOMYCIN, BACTRACIN ZINC, AND ROXARSONE IN BROILERS
Drug - Tissue Withdrawal (Days) Concentration
Salinomycin - Skin/fat 0 29.4 ppb (SD=10.1, N=6)
Bacitracin - Muscle 0 (less than 0.3 ppm,N=6)
Arsenic - Liver 0 1.60 ppm (SD=0.54, N=6)
5 0.74 ppm (SD=0.22, N=6)
A non-interference study for
bacitracin zinc was conducted by spiking control muscle tissue with 0.5
ppm bacitracin zinc and 80 ppb of salinomycin. There was no detectable assay
interferences caused by salinomycin when assaying for bacitracin zinc in
chicken muscle. Reference is made to Internationa1 Minerals & Chemical
NADA P-136-484, that demonstrates that arsenic in the presence of bacitracin
zinc in turkey muscle does not interfere with the bacitracin zinc assay.
These data support a 5-day
withdrawal time for the bacitracin zinc-salinomycin-roxarsone combination.
A regulatory analytical method
for salinomycin is not required. A practical analytical method for determination
of tissue residue of bacitracin zinc and roxarsone is available in the
Food Additives Analytical Manual on display in FDA's Freedom of Information
Room (Room 12A-30), 5600 Fishers Lane, Rockville, MD 20857.
