NADA 140-445 Monteban® + Roxarsone - original approval

I. GENERAL INFORMATION:

II. INDICATIONS FOR USE

"For the prevention of coccidiosis in broiler chickens caused by Eimeria tenella, E. necatrix, E. acervulina, E. maxima, E. brunetti, and E. mivati including some field strains of E. tenella that are more susceptible to roxarsone combined with narasin than to narasin alone."

III. DOSAGE

IV. EFFECTIVENESS

Introduction

MONTEBAN® (narasin) Type A medicated article is approved (51FR 29097, August 14, 1986; 21 CFR §558.363) for the prevention of coccidiosis in broiler chickens caused by E. tenella, E. necatrix, E. acervulina, E. maxima, E. brunetti, and E. mivati. It is to be incorporated into broiler rations to provide from 54 to 72 g narasin/ton.

Roxarsone (3-nitro-4-hydroxyphenylarsonic acid) originally became effective March 23, 1951. It is currently approved (21 CFR 558.530) for use in feed of growing chickens for increased rate of weight gain, improved feed efficiency, and improved pigmentation at 22.7 and 45.4 g roxarsone/ton. Roxarsone is presently approved with other ionophorous anticoccidials.

In the present NADA it has been further established that the addition of roxarsone at a concentration of 45.4 g/ton to finished feeds containing narasin in the range of 54-72 g/ton is effective for use in broiler chickens for the prevention of coccidiosis caused by E. tenella, E. necatrix, E. acervulina, E. maxima, E. brunetti, and E. mivati including some field strains of E. tenella that are more susceptible to roxarsone combined with narasin than to narasin alone.

The effectiveness tests conducted are outlined as follows:

1. Battery Studies

   Series 1: A factorial arrangement of two levels of roxarsone (0 and 45.4 g/ton) and three levels of narasin (0, 54, and 72 g/ton) for a total of six treatments.

   Series 2: A factorial arrangement of three levels of roxarsone (0, 22.7 and 45.4 g/ton) and three levels of narasin (0, 54, and 72 g/ton) for a total of nine treatments.

2. Floor Pen Studies

   A series of four floor pen trials to substantiate the results of the battery trials under simulated field conditions.

3. Anticoccidial Compatibility of Narasin and Roxarsone

   A series of six battery experiments to evaluate the anticoccidial effectiveness compatibility of narasin and roxarsone fed in combination.

Effectiveness Study Summaries

1. Battery Studies

   Anticoccidial efficacy of the combination of narasin and roxarsone against E. tenella

   Two series of battery trials were conducted to evaluate the combination of narasin and roxarsone for anticoccidial efficacy against E. tenella. The first series was a factorial arrangement of two levels of roxarsone (0, 45 g/ton) and three levels of narasin (0, 54, 72 g/ton) for a total of six treatments. The second series was a factorial arrangement of three levels of roxarsone (0, 22, 45 g/ton) and three levels of narasin (0, 54, 72 g/ton) for a total of nine treatments. There were 15 trials in each series with each trial using a different field strain of E. tenella.

   Eight-day-old Hubbard X White Mountain broiler cockerels were used for these experiments. All chicks were received at one day of age and housed in an isolation room within an isolation facility dedicated to the early brooding of coccidia-free chicks. Chicks from one hatch were kept within the same isolation room unit and transferred to a second building for experimentation. The rooms for conducting the experiments were contained within an isolation wing of this second building. Temperature within the rooms was thermostatically controlled. The testing cages consisted of wire-floored suspended drawer-type units especially constructed to utilize disposable cardboard feeders. An individual feeder was used for one cage in one experiment only. Water was constant flowing with access at the rear of each cage.

   A typical broiler starter ration was used in the mash form for testing in battery units. Testing was also conducted with this ration in a crumble form following pelleting. The feeds were routinely assayed for narasin and roxarsone. The chicks were pen balanced by weight in groups of five birds/pen and medication was initiated 48 hours prior to oral inoculation with the oocyst suspensions. Five pen replicates were included in each treatment in the first series and six pen replicates were included in each treatment in the second series. The appropriate infected non-medicated and non-infected non-medicated controls were included in each experiment.

   The experiments were terminated on the 7th day post-inoculation, the time at which the maximum expression of clinical signs of infection would be expected to be present in the infected non-medicated birds. Mean weight gains were calculated as the mean weight gain per survivor. Fecal samples were collected to determine oocyst passage and the results are present as millions of oocysts per bird. The severity of lesions due to cecal coccidial infection was scored (0 -4) as follows:

   Cecal Lesion Scores
   (E. tenella)

   0 = negative, no macroscopic lesions
   1 = very few, discrete lesions
   2 = mucus, some hemorrhage, moderate cecal involvement
   3 = moderate hemorrhage, cecal walls thickened, cecal atrophy
   4 = massive hemorrhaging cores, cecal walls thin, cecal hypertrophy; or death due to coccidiosis

   Results

   When significant difference is stated in this summary, it refers to P< or = 0.05 unless otherwise stated.

   Results of Series 1

   The results of series 1 are presented in Tables 1, 2, 3 and 4 for average cecal lesion scores, average number of oocysts passed per bird, weight gain per bird, and mortality, respectively.

   Cecal Lesion Scores

   1. Each combination of narasin + roxarsone resulted in significant reduction in cecal lesion scores when compared to non-medicated control and either narasin or roxarsone alone.
   2. The high level of narasin in combination with roxarsone, 72 + 45 g/ton, resulted in a numerical improvement over the 54 + 45 g/ton combination.

   Oocyst Count

   1. Each combination of narasin + roxarsone resulted in significant reduction in numbers of oocyst passed when compared to non-medicated control and either narasin or roxarsone alone.
   2. The high level of narasin in combination with roxarsone, 72 + 45 g/ton, resulted in significant (P<.06) reduction in oocyst passed as compared to the 54 + 45 g/ton combination.

   Weight Gain

   1. Each combination of narasin + roxarsone and either narasin or roxarsone alone resulted in significant improvement in weight gain over the non-medicated control.
   2. There were no significant differences in weight gain among the treated groups.

   Mortality

   1. Each combination of narasin + roxarsone and either narasin or roxarsone alone resulted in reduced mortality when compared to the non-medicated control.
   2. The high level of narasin in combination with roxarsone resulted in reduced mortality when compared to roxarsone alone.
   3. The 72 + 45 g/ton combination of narasin + roxarsone resulted in reduced mortality when compared to the 54 + 45 g/ton combination.

   Results of Series 2

   The results of series 2 are presented in Tables 5, 6, 7 and 8 for average cecal lesion scores, average oocyst passed per bird, weight gain per bird and mortality.

   Cecal Lesion Scores

   1. Each combination of narasin + roxarsone resulted in significant reduction in cecal lesion scores when compared to non-medicated control and either narasin or roxarsone alone.
   2. The high level of roxarsone in combination with narasin at each level resulted in significant reduction in cecal lesion scores when compared to corresponding low level of roxarsone in combination with narasin (54 + 22 g/ton vs 54 + 45 g/ton and 72 + 22 g/ton vs 72 + 45 g/ton).
   3. The high level of narasin in combination with the low level of roxarsone significantly reduced lesion scores as compared to the low level of narasin plus the low level of roxarsone (54 + 22 g/ton vs 72 + 22 g/ton).
   4. The high level of narasin in combination with the high level of roxarsone resulted in a numerical decrease in lesion scores as compared to the low level of narasin plus the high level of roxarsone (54 + 45 g/ton vs 72 + 45 g/ton).

   Oocyst Count

   1. Each combination of narasin with 45 g/ton of roxarsone resulted in significant reduction in oocyst count when compared to non-medicated control and to either narasin or roxarsone alone.
   2. The high level of roxarsone in combination with narasin at each level resulted in significant reduction of oocyst count when compared to corresponding low level of roxarsone in combination narasin (54 + 22 g/ton vs 54 + 45 g/ton and 72 + 22 g/ton vs 72 + 45 g/ton).
   3. The high level of narasin in combination with the high level of roxarsone resulted in significant decrease in oocyst count as compared to the low level of narasin plus the high level of roxarsone (54 + 45 g/ton vs 72 + 45 g/ton).

   Weight Gain

   1. Each combination of narasin and roxarsone resulted in significant improvement in weight gain over the non-medicated control and over either narasin or roxarsone alone at their respective low levels.
   2. Among the four treatments which were combinations of narasin and roxarsone, there were no differences in weight gain.

   Mortality

   1. Each level of narasin in combination with roxarsone at 45 g/ton resulted in reduced mortality as compared to each of the other treatments.

   Conclusion from Battery Studies

   The data from the two battery studies show that some field strains of E. tenella are more susceptible to roxarsone at 22.5 or 45.4 g/ton combined with 54 or 72 g/ton of narasin than to either drug alone.

   The above battery studies were conducted by:

   T. K. Jeffers, Ph.D.
   Lilly Research Laboratories
   Greenfield, Indiana

   Ed. note: The following table has 7 columns.

   TABLE 1 COMBINATION OF NARASIN AND ROXARSONE IN BATTERY STUDIES

   E. tenella Challenge
   Series 1
   Cecal Lesion Scores

   	Roxarsone, 0  g/ton			Roxarsone, 45 g/ton
   Trial	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin,  54 g/ton	Narasin, 72 g/ton
   85	3.80	2.28	2.36	2.20	1.88	0.86
   86	3.72	1.08	0.44	0.44	0.0	0.0
   87	3.79	2.00	1.81	2.47	0.96	0.41
   88	3.92	1.80	1.36	2.20	0.68	0.64
   90	2.68	0.88	1.16	1.04	0.04	0.24
   91	3.72	2.92	2.56	2.32	0.84	0.72
   92	2.72	0.51	0.24	0.80	0.12	0.08
   93	3.00	0.52	0.60	1.77	0.44	0.12
   94	3.96	2.97	2.10	3.72	2.08	1.64
   95	3.76	2.20	1.06	2.86	1.15	0.80
   96	3.96	1.44	1.72	3.19	0.98	0.56
   97	2.60	0.52	0.0	0.04	0.0	0.0
   98	1.2O	0.16	0.0	0.32	0.0	0.0
   A4	3.84	3.64	2.12	3.40	2.56	1.78
   A5	3.96	3.62	2.16	3.52	2.04	1.56
   L.S.Means	3.41	1.68	1.27	1.73	1.04	0.90

   Selected treatment contrasts

   N+R	N+R	Difference	P
   0+0	54+45	2.37	<0.0001
   0+0	72+45	2.52	<0.0001
   72+0	54+45	0.23	<0.0500
   72+0	72+45	0.37	0.0134
   0+45	54+45	0.69	<0.0001
   0+45	72+45	0.83	<0.0001
   +45	72+45	0.14	0.1944

   Ed. note: The following table has 7 columns.

   TABLE 2 COMBINATION OF NARASIN AND ROXARSONE IN BATTERY STUDIES

   E. tenella Challenge
   Series 1
   Average Oocyst Count millions per bird

   	Roxarsone, 0 g/ton			Roxarsone, 45 g/ton
   Trial	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton
   85	8.32	3.89	2.15	7.40	3.46	0.28
   86	9.36	0.83	0.15	0.04	0.0	0.0
   87	17.16	5.39	0.78	8.00	0.21	0.05
   88	21.18	6.85	4.21	10.06	0.26	0.19
   90	1.54	0.08	0.11	0.28	0.0	0.03
   91	16.19	20.72	22.70	6.66	3.51	1.39
   92	6.48	0.05	0.01	0.18	0.0	0.0
   93	18.61	0.04	0.11	2.63	0.14	0.01
   94	13.71	17.44	6.09	21.81	7.47	2.64
   95	9.88	4.77	0.46	16.92	0.89	0.83
   96	15.00	0.92	4.75	10.08	0.16	0.09
   97	13.38	1.15	0.01	0.03	0.0	0.0
   98	0.48	0.01	0.0	0.02	0.0	0.0
   A4	7.58	13.09	6.25	12.05	5.61	3.07
   A5	9.16	14.97	8.83	14.22	5.81	3.50
   L.S.Means	2.79	1.46	0.54	1.42	0.25	0.12

   Selected treatment contrasts

   N+R	N+R	Difference	P
   0+0	54+45	2.54	<0.0001
   0+0	72+45	2.67	<0.0001
   54+0	54+45	1.21	<0.0001
   72+0	72+45	0.41	0.0010
   0+45	54+45	1.16	0.0002
   0+45	72+45	1.29	<0.0001
   54+45	72+45	0.13	0.0595

   Ed. note: The following table has 7 columns.

   TABLE 3 COMBINATION OF NARASIN AND ROXARSONE IN BATTERY STUDIES

   E. tenella Challenge
   Series 1
   Average Weight Gain (g)

   	Roxarsone, 0 g/ton			Roxarsone, 45 g/ton
   Trial	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton
   85	154	249	229	235	234	237
   86	200	250	248	256	255	248
   87	200	235	242	239	263	244
   88	181	257	265	263	267	261
   90	279	277	284	282	277	279
   91	203	257	250	254	269	265
   92	262	263	271	269	267	263
   93	260	268	276	271	270	262
   94	113	175	217	166	222	228
   95	142	224	243	220	228	238
   96	160	258	251	218	261	269
   97	237	244	251	257	245	255
   98	220	219	231	241	225	212
   A4	152	200	235	221	226	233
   A5	147	204	217	201	239	229
   L.S.Means	206	238	245	241	245	243

   Selected treatment contrasts

   N+R	N+R	Difference	P
   0+0	54+45	39	<0.0001
   0+0	72+45	37	<0.0001
   54+0	54+45	7	0.2571
   72+0	72+45	-2	0.7657
   0+45	54+45	4	0.5329
   0+45	72+45	2	0.7115
   54+45	72+45	-2	0.7992

   Ed. note: The following table has 7 columns.

   TABLE 4 COMBINATION OF NARASIN AND ROXARSONE IN BATTERY STUDIES

   E. tenella Challenge
   Series 1
   Mortality Due to Cecal Coccidiosis number died/total birds

   	Roxarsone, 0 g/ton			Roxarsone, 45 g/ton
   Trial	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton
   85	6/25	0/25	0/25	0/25	0/25	0/25
   86	2/25	0/25	0/25	0/25	0/25	0/25
   87	6/25	1/25	0/25	0/25	1/25	0/25
   88	6/25	0/25	0/25	0/25	0/25	0/25
   90	0/25	0/25	1/25	0/25	0/25	0/25
   91	3/25	2/25	0/25	1/25	1/25	0/25
   92	0/25	0/25	0/25	0/25	0/25	0/25
   93	0/25	0/25	0/25	0/25	0/25	0/25
   94	5/25	3/25	1/25	2/25	1/25	0/25
   95	7/25	1/25	0/25	1/25	0/25	0/25
   96	3/25	0/25	0/25	2/25	1/25	0/25
   97	0/25	0/25	0/25	0/25	0/25	0/25
   98v0/25	0/25	0/25	0/25	0/25	0/25
   A4	14/25	5/25	1/25	4/25	3/25	1/25
   A5	6/25	6/25	2/25	2/25	2/25	1/25
   Total	58/375	14/375	5/375	12/375	9/375	2/375

   Ed. note: The following table has 10 columns.

   TABLE 5 COMBINATION OF NARASIN AND ROXARSONE IN BATTERY STUDIES

   E. tenella Challenge
   Series 2
   Cecal Lesion Scores
   Trial

   	Roxarsone, 0 g/ton			Roxarsone, 22 g/ton			Roxarsone, 45 g/ton
   Trial	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton
   58	2.67	1.50	1.10	2.77	1.33	0.93	0.73	0.30	0.20
   59	3.15	0.67	0.47	2.26	0.20	0.10	0.48	0.03	0.03
   60	2.84	3.27	2.97	3.00	3.00	2.93	2.33	1.92	1.30
   61	3.03	3.21	2.80	2.90	2.43	2.03	1.67	0.67	1.33
   62	3.33	2.60	2.30	3.10	2.10	1.73	2.00	1.27	1.21
   63	3.03	3.20	2.77	3.14	2.64	2.30	2.03	1.60	1.27
   70	3.11	2.67	2.93	2.97	2.87	2.60	2.75	1.66	1.97
   71	2.63	2.00	1.37	2.73	1.93	1.60	1.71	1.13	0.77
   72	2.87	2.63	2.06	2.83	2.68	2.18	2.36	1.10	1.15
   73	2.63	2.90	2.55	2.97	2.63	2.36	1.83	1.07	0.83
   77	3.17	1.77	1.03	1.80	0.77	0.10	0.30	0.13	0.0
   78	3.15	3.22	3.17	3.07	3.05	2.50	1.52	1.88	1.33
   79	3.55	2.53	2.40	3.20	2.70	2.30	2.23	1.17	1.27
   80	3.50	3.00	3.10	3.42	2.50	2.07	1.87	1.66	0.71
   81	3.40	3.23	3.40	3.30	2.93	2.87	2.57	2.10	2.30
   L.S.Means	3.14	2.54	2.26	2.94	2.19	1.89	1.74	1.19	1.07

   Selected treatment contrasts

   N+R	N+R	Difference	P
   0+0	54+22	-0.95	<0.0001
   0+0	72+22	-1.25	<0.0001
   54+0	54+22	-0.35	0.0111
   72+0	72+22	-0.37	0.0075
   0+22	54+22	-0.75	<0.0001
   0+22	72+22	-1.05	<0.0001
   54+22	72+22	-0.30	0.0260
   54+22	54+45	-1.00	<0.0001
   72+22	72+45	-0.82	<0.0001
   0+0	54+45	-1.95	<0.0001
   0+0	72+45	-2.07	<0.0001
   54+0	54+45	-1.35	<0.0001
   72+0	72+45	-1.19	<0.0001
   0+45	54+45	-0.55	<>0.0002
   0+45	72+45	-0.67	<0.0001
   54+45	72+45	-0.12	0.2185

   Ed. note: The following table has 10 columns.

   TABLE 6 COMBINATION OF NARASIN AND ROXARSONE IN BATTERY STUDIES

   E. tenella Challenge
   Series 2
   Average Oocyst Count millions per bird

   	Roxarsone, 0 g/ton			Roxarsone, 22 g/ton			Roxarsone, 45 g/ton
   Trial	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton
   58	11.32	8.69	6.50	8.68	4.01	1.23	5.65	1.03	0.21
   59	14.63	3.14	1.44	8.01	0.25	0.04	2.94	0.04	0.02
   60	11.46	16.59	15.69	12.29	11.15	5.50	10.69	8.42	2.72
   61	10.73	9.85	13.43	13.24	10.78	8.86	10.28	5.09	4.31
   62	9.09	4.23	4.65	8.48	3.84	1.71	9.50	1.83	0.72
   63	5.30	6.57	8.51	9.58	11.41	6.38	10.55	8.72	5.81
   70	6.63	12.45	12.15	16.62	12.36	10.15	11.45	8.10	6.91
   71	16.73	15.36	11.29	13.61	11.72	8.95	10.57	4.95	3.82
   72	9.54	10.30	10.13	12.76	11.89	15.40	9.21	3.17	3.69
   73	6.63	11.79	9.47	9.70	10.47	12.06	10.92	5.65	1.93
   77	6.92	1.20	0.26	1.55	0.01	0.03	0.18	0.10	0.0
   78	11.15	11.27	16.32	14.49	13.53	10.81	4.33	3.75	2.27
   79	11.10	22.00	17.65	22.53	19.26	9.14	19.52	7.68	2.88
   80	9.95	10.16	6.65	14.94	7.28	9.93	8.92	7.28	1.13
   81	12.48	14.16	13.42	12.89	12.61	13.20	12.02	7.71	8.56
   L.S.Means	6.18	7.21	6.77	8.06	6.23	4.90	6.03	3.22	1.91

   Selected treatment contrasts

   N+R	N+R	Difference	P
   0+0	54+22	0.05	0.5139
   0+0	72+22	-1.28	0.1147
   54+0	54+22	-0.98	0.2234
   72+0	72+22	-1.87	0.0476
   0+22	54+22	-1.83	0.0912
   0+22	72+22	-3.16	0.0055
   54+22	72+22	-1.33	0.1082
   54+22	54+45	-3.01	<0.0050
   72+22	72+45	-2.99	<0.0050
   0+0	54+45	-2.96	0.0005
   0+0	72+45	-4.27	<0.0001
   54+0	54+45	-3.99	<0.0001
   72+0	72+45	-4.86	<0.0001
   0+45	54+45	-2.81	0.0008
   0+45	72+45	-4.12	<0.0001
   +45	72+45	-1.31	0.0039

   Ed. note: The following table has 10 columns.

   TABLE 7 COMBINATION OF NARASIN AND ROXARSONE IN BATTERY STUDIES

   E. tenella Challenge
   Series 2
   Average Weight Gain (g)

   	Roxarsone, 0 g/ton			Roxarsone, 22 g/ton			Roxarsone, 45 g/ton
   Trial	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton
   58	257	266	272	255	276	263	259	271	268
   59	227	287	284	274	283	283	264	284	273
   60	208	209	206	203	209	229	217	225	224
   61	222	230	252	224	276	277	280	277	278
   62	202	272	272	230	267	281	270	283	278
   63	212	234	259	248	265	283	283	294	285
   70	199	210	222	203	232	228	203	241	220
   71	231	251	260	233	254	249	236	244	245
   72	237	251	257	234	237	247	250	260	260
   73	239	261	269	248	269	278	278	280	271
   77	253	264	264	258	277	274	263	263	272
   78	258	256	260	276	266	277	289	287	285
   79	208	242	241	208	251	255	250	246	250
   80	190	243	233	193	279	268	272	260	272
   81	205	229	237	207	259	265	250	273	278
   L.S.Means	227	249	255	237	259	261	255	263	261

   Selected treatment contrasts

   N+R	N+R	Difference	P
   0+0	54+22	32	<0.0001
   0+0	72+22	34	<0.0001
   54+0	54+22	10	0.0368
   72+0	72+22	6	0.1480
   0+22	54+22	21	<0.0001
   0+22	72+22	24	<0.0001
   54+22	72+22	2	0.5827
   0+0	54+45	36	<0.0001
   0+0	72+45	34	<0.0001
   54+0	54+45	14	0.0017
   72+0	72+45	6	0.1679
   0+45	54+45	8	0.0579
   0+45	72+45	6	0.1967
   54+45	72+45	-2	0.5382

   Ed. note: The following table has 10 columns.

   TABLE 8 COMBINATION OF NARASIN AND ROXARSONE IN BATTERY STUDIES

   E. tenella Challenge
   Series 2
   Mortality Due to Cecal Coccidiosis Number died/Total Birds

   	Roxarsone, 0 g/ton			Roxarsone, 22 g/ton			Roxarsone, 45 g/ton
   Trial	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton
   58	0/30	0/30	0/30	0/30	1/30	0/30	0/30	0/30	0/30
   59	1/30	0/30	0/30	1/30	0/30	0/30	0/30	0/30	0/30
   60	1/30	4/30	2/30	2/30	2/30	1/30	0/30	0/30	0/30
   61	4/30	1/30	1/30	2/30	2/30	1/30	0/30	0/30	0/30
   62	5/30	1/30	0/30	5/30	2/30	0/30	0/30	0/30	0/30
   63	5/30	4/30	1/30	6/30	1/30	1/30	1/30	0/30	0/30
   70	2/30	1/30	1/30	0/30	3/30	3/30	1/30	0/30	1/30
   71	0/30	0/30	1/30	0/30	0/30	0/30	0/30	0/30	0/30
   72	2/30	1/30	0/30	1/30	0/30	0/30	0/30	0/30	0/30
   73	1/30	1/30	0/30	0/30	0/30	0/30	0/30	0/30	0/30
   77	3/30	0/30	0/30	0/30	0/30	0/30	0/30	0/30	0/30
   78	3/30	4/30	2/30	1/30	1/30	1/30	0/30	0/30	2/30
   79	9/30	0/30	0/30	3/30	0/30	2/30	0/30	0/30	0/30
   80	12/30	5/30	6/30	9/30	0/30	0/30	1/30	2/30	1/30
   81	11/30	2/30	6/30	8/30	3/30	3/30	4/30	1/30	0/30
   Total	59/450	24/450	20/450	38/450	15/450	12/450	7/450	3/450	4/450

2. Floor Pen Trials with High Challenge of E. tenella

   Four floor pen trials were conducted to substantiate the results of the battery trials under simulated field conditions. Two trials were conducted at Wheeler, Arkansas, and two were conducted at Greenfield, Indiana. Each trial had the experimental design of 3 x 3 factorial arrangements of 0, 54, 72 g/ton of narasin and 0, 22.7, 45.4 g/ton of roxarsone. The trial results and treatment contrasts are presented in Tables 1, 2, and 3 for cecal lesion scores, weight gain, and mortality, respectively.

   Cecal Lesion Scores

   1. All combinations of narasin + roxarsone resulted in significant reduction in lesion scores when compared to the non-medicated control.
   2. The combination of 45 g/ton of roxarsone with either 54 or 72 g/ton of narasin resulted in significant reduction in cecal lesion scores when compared to either product alone.

   Average Weight Gain

   1. All combinations of narasin + roxarsone resulted in significantly greater weight gains than the non-medicated control.
   2. None of the combinations resulted in decreased weight compared to either product alone.

   Mortality

   1. The non-medicated control treatment group resulted in having the least mortality of all the treatments.
   2. All the narasin + roxarsone combinations had similar mortality.

   Conclusion from Floor Pen Studies

   These floor pen studies conducted under simulated use conditions confirm the effect observed in the battery studies. Some field strains of E. tenella are more susceptible to roxarsone at 45.4 g/ton combined with 54 or 72 g/ton of narasin than to either drug alone.

   Investigators for these studies were:

   B. F. Schlegel, D.V.M.
   Lilly Research Laboratories
   Fayetteville, Arkansas K. W. Bafundo, Ph.D.
   Lilly Research Laboratories
   Greenfield, Indiana

   TABLE 1 Combination of Narasin and Roxarsone in Floor Pen Studies Cecal Lesion Score
   Means and Analysis Results

   Ed. note: The following portion of this table has 4 columns.

   Roxarsone, g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton
   0	2.79	2.12	1.78
   22	2.12	1.97	1.91
   45	2.12	1.38	0.81

   Standard Error is 0.29

   Ed. note: The following portion of this table has 5 columns.

   Question	Comparison	Decrease	p	Answer*
   A. is the combination better than control?	0+0 -54+22	0.82	0.0377	Yes
   	-72+22	0.88	0.0300	Yes
   	-54+45	1.41	0.0041	Yes
   	-72+45	1.98	0.0006	Yes
   B. Does narasin contribute to the combination?	0+22 -54+22	0.15	0.3529	No
   	-72+22	0.21	0.3028	No
   	0+45 -54+45	0.74	0.0533	Maybe
   	-72+45	1.31	0.0059	Yes
   C. Does roxarsone contribute to the combination?	54+0 -54+22	0.15	0.3529	No
   	-54+45	0.74	0.0517	Maybe
   	72+0 -72+22	-0.13	0.6248	No
   	-72+45	0.97	0.0218	Yes
   D. Does the larger narasin level increase efficacy?	54+22 -72+22	0.06	0.4437	No
   	54+45 -72+45	0.57	0.0513	Maybe
   E. Does the larger roxarsone level increase efficacy?	54+22 -54+45	0.59	0.0931	Maybe
   	72+22 -72+45	1.10	1.10	Yes

   * At the 0 .05 level of significance

   Table 2 Combination of Narasin and Roxarsone in Floor Pen Studies Weight Gain Means and Analysis Results

   Ed. note: The following portion of this table has 4 columns.

   Roxarsone, g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton
   0	4.302	4.470	4.570
   22	4.378	4.529	4.509
   45	4.417	4.544	4.478

   Standard Error is 0.051

   Ed. note: The following portion of this table has 5 columns.

   Question	Comparison	Decrease	p	Answer*
   A. Is the combination worse than control?
   	0+0 -54+22	-0.227	0.9933	No
   	-72+22	-0.207	0.9898	No
   	-54+45	-0.242	0.9951	No
   	-72+45	-0.176	0.9501	No
   B. Does the contribution of narasin produce a disease?	0+22 -54+22	-0.151	0.9658	No
   	-72+22	-0.131	0.9478	No
   	0+45 -54+45	-0.127	0.9433	No
   	-72+45	-0.061	0.7918	No
   C. Does the contribution of roxarsone produce a decrease?	54+0 -54+22	-0.059	0.7808	No
   	-54+45	-0.074	0.8340	No
   	72+0 -72+22	0.061	0.2103	No
   	-72+45	-0.092	0.1185	No
   D. Does the larger narasin level produce a decrease?	54+22 -72+22	0.020	0.3958	No
   	54+45 -72+45	0.066	0.1923	No
   E. Does the larger roxarsone level produce a decrease?	54+22 -54+45	-0.015	0.5833	No
   	72+22 -72+45	0.031	0.3395	No

   *At the 0.10 level of significance

   TABLE 3 Combination of Narasin and Roxarsone in Floor Pen Studies Percent Mortality Means and Analysis Results(1)
    
   Ed. note: The following portion of this table has 4 columns. 
   
   

   Roxarsone, g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton
   0	2.39	4.64	2.56
   22	4.44	3.03	4.91
   45	3.10	3.50	4.16

   
   Standard Error is 0.60
   
   

   Question	Comparison	Decrease	p	Answer*
   A. Is the combination worse than control?	54+22-0+0	0.64	0.2263	No
   	72+22-	2.52	0.0020	Yes
   	54+45-	1.11	0.0975	Yes
   	72+45-	1.77	0.0203	Yes
   B. Does the contribution of narasin produce an increase?	54+22-0+0	-1.41	0.9483	No
   	72+22-	0.47	0.2912	No
   	54+45-0+45	0.40	0.3193	No
   	72+45-	1.06	0.1083	Maybe
   C. Does the contribution of roxarsone produce an increase?	54+22-54+0	-1.61	0.9685	No
   	54+45-	-1.14	0.9071	No
   	72+22-72+0	2.35	0.0036	Yes
   	72+45-	1.60	0.0320	Yes
   D. Does the larger narasin level produce an increase?	72+22-54+22	1.80	0.0153	Yes
   	72+45-54+45	0.66	0.2208	No
   E. Does the larger roxarsone level produce an increase?	54+45-54+22	0.47	0.2920	No
   	72+45-72+22	-0.75	0.8080	No

   
   *At the 0.10 level of significance.
   
   (1) The mortality reflected in this table is not drug related or medically significant.
    

3. Anticoccidial Compatibility of Narasin and Roxarsone

   Six battery experiments were conducted to evaluate the anticoccidial compatibility of 54 g/ton narasin in combination with 45 g/ton roxarsone. In three of these experiments the inoculum consisted of a mixture of E. acervulina, E. maxima and E. tenella oocysts, while in the remaining three experiments the inoculum consisted of a mixture of E. brunetti, E. mivati, and E. necatrix oocysts. The anticoccidial effectiveness of each of the respective treatments was assessed by weight gain relative to controls, the efficiency of feed utilization (feed/gain ratios), and reduction in mortality and the severity of coccidial lesions. The results of these studies are presented in Tables 1 - 6.

   The addition of 45 g/ton roxarsone to 54 g/ton narasin did not interfere with the anticoccidial effectiveness of narasin. Furthermore, the addition of 45 g/ton roxarsone to 54 g/ton narasin enhanced anticoccidial effectiveness as measured by reduction in the severity of cecal lesions in birds infected with E. tenella.

   The investigator for these studies was:

   Mr. M. E. Callender
   Lilly Research Laboratories
   Box 708
   Greenfield, Indiana 46140

   Ed. note: The following table has 11 columns.

   TABLE 1 Percent Mortality, Weight Gain, Feed/Gain, Intestinal and Cecal Lesion Scores of Broiler Cockerels Inoculated with E. acervulina, E. maxima, and E. tenella

   Lesion Scores
   
   

   Treatment	g/ton	% Mort.(1) - #	% Mort.(1) - Mean	Wt. Gain(2) - #	Wt. Gain(2) - Mean	Feed/Gain(3) - #	Feed/Gain(3) - Mean	Intestinal - #	Intestinal - Mean	Cecal -#	Cecal - Mean
   Non-inoculated Controls	0	6	0.0	6	273.2	5	1.643
   Inoculated Controls	0	6	23.3	6	167.3	6	7.88	6	3.10
   Narasin	54	6	0.0	6	259.8	3	1.645	6	0.98	6	1.27
   Roxarsone	45	6	0.0	6	192.0	6	2.122	6	8.70	6	2.27
   Narasin+Roxarsone	54+45	6	0.0	6	263.1	5	1.718	6	0.73	6	0.45

   
   
    

   (1) Due to coccidiosis
   (2) Per survivor
   (3) Reps without mortality

   Ed. note: The following table has 9 columns.
   
   TABLE 2 Percent Mortality, Weight Gain, Feed/Gain, and Intestinal Lesion Scores of Broiler Cockerels Inoculated with E. mivati, E. necatrix, and E. brunetti

   Lesion Scores
   
   

   Treatment	g/ton	% Mort.(1) - #	% Mort.(1) - Mean	Wt. Gain(2) - #	Wt. Gain(2) - Mean	Feed/Gain(3) - #	Feed/Gain(3) - Mean	Intestinal - #	Intestinal - Mean
   Non-inoculated Controls	0	6	0.0	6	309.9	6	1.563
   Inoculated Controls	0	6	0.0	6	229.7	6	1.811	6	6.57
   Narasin	54	6	0.0	6	281.5	6	1.602	6	1.63
   Roxarsone	45	6	0.0	6	259.2	6	1.650	6	6.33
   Narasin+Roxarsone	54+45	6	0.0	6	290.6	5	1.553	6	1.22

   -----------------------------------------------------------------
   (1) Due to coccidiosis
   (2) Per survivor
   (3) Reps without mortality
    
   Ed. note: The following table has 11 columns.
   
   TABLE 3 Percent Mortality, Weight Gain, Feed/Gain, Intestinal and Cecal Lesion Scores of Broiler Cockerels Inoculated with E. acervulina, E. maxima, and E. tenella

   Lesion Scores
   
   

   Treatment	g/ton	% Mort.(1) - #	% Mort.(1) - Mean	Wt. Gain(2) - #	Wt. Gain(2) - Mean	Feed/Gain(3) - #	Feed/Gain(3) - Mean	Intestinal - #	Intestinal - Mean	Cecal -#	Cecal - Mean
   Non-inoculated Controls	0	6	0.0	6	281.9	6	1.582
   Inoculated Controls	0	6	20.0	6	147.9	2	2.476	6	7.73	6	3.37
   Narasin	54	6	0.0	6	271.6	4	1.619	6	1.84	6	1.65
   Roxarsone	45	6	6.7	6	182.4	3	2.141	6	8.35	6	2.53
   Narasin+Roxarsone	54+45	6	0.0	6	264.5	6	1.636	6	1.07	6	0.57

   ----------------------------------------------------------------------------
   (1) Due to coccidiosis
   (2) Per survivor
   (3) Reps without mortality
   
   Ed. note: The following table has 9 columns.
   
   TABLE 4 Percent Mortality, Weight Gain, Feed/Gain, and Intestinal Lesion Scores of Broiler Cockerels Inoculated with E. mivati, E. necatrix, and E. brunetti

   Lesion Scores
   
   

   Treatment	g/ton	% Mort.(1) - #	% Mort.(1) - Mean	Wt. Gain(2) - #	Wt. Gain(2) - Mean	Feed/Gain(3) - #	Feed/Gain(3) - Mean	Intestinal - #	Intestinal - Mean
   Non-inoculated Controls	0	6	0.0	6	273.0	6	1.929
   Inoculated Controls	0	6	0.0	6	192.1	6	2.169	6	7.30
   Narasin	54	6	0.0	6	232.0	5	2.002	6	2.14
   Roxarsone	45	6	0.0	6	216.4	4	1.957	6	7.35
   Narasin+Roxarsone	54+45	6	0.0	6	239.2	5	1.943	6	2.25

   ------------------------------------------------------------------
   (1) Due to coccidiosis
   (2) Per survivor
   (3) Reps without mortality
   
   Ed. note: The following table has 11 columns.
   
   TABLE 5 Percent Mortality, Weight Gain, Feed/Gain, Intestinal and Cecal Lesion Scores of Broiler Cockerels Inoculated with E. acervulina, E. maxima, and E. tenella

   Lesion Scores
   
   

   Treatment	g/ton	% Mort.(1) - #	% Mort.(1) - Mean	Wt. Gain(2) - #	Wt. Gain(2) - Mean	Feed/Gain(3) - #	Feed/Gain(3) - Mean	Intestinal - #	Intestinal - Mean	Cecal -#	Cecal - Mean
   Non-inoculated Controls	0	6	0.0	6	260.3	5	1.583
   Inoculated Controls	0	6	10.0	6	170.9	3	2.081	6	7.87	6	3.03
   Narasin	54	6	0.0	6	242.1	5	1.611	6	1.56	6	1.22
   Roxarsone	45	6	0.0	6	183.5	5	2.010	6	7.81	6	2.63
   Narasin+Roxarsone	54+45	6	0.0	6	257.1	6	1.571	6	0.93	6	0.57

   ----------------------------------------------------------------------------
   (1) Due to coccidiosis
   (2) Per survivor
   (3) Reps without mortality
   
   Ed. note: The following table has 9 columns.
   
   TABLE 6 Percent Mortality, Weight Gain, Feed/Gain, and Intestinal Lesion Scores of Broiler Cockerels Inoculated with E. mivati, E. necatrix, and E. brunetti

   Lesion Scores
   
   

   Treatment	g/ton	% Mort.(1) - #	% Mort.(1) - Mean	Wt. Gain(2) - #	Wt. Gain(2) - Mean	Feed/Gain(3) - #	Feed/Gain(3) - Mean	Intestinal - #	Intestinal - Mean
   Non-inoculated Controls	0	6	0.0	6	248.1	6	1.838
   Inoculated Controls	0	6	0.0	6	188.2	6	2.224	6	8.33
   Narasin	54	6	0.0	6	256.8	5	1.787	6	4.62
   Roxarsone	45	6	0.0	6	237.1	5	1.961	6	7.42
   Narasin+Roxarsone	54+45	6	0.0	6	256.7	5	1.896	6	2.19

   -------------------------------------------------------------------
   (1) Due to coccidiosis
   (2) Per survivor
   (3) Reps without mortality

V. ANIMAL SAFETY

Narasin Type A medicated article is approved (21 CFR 558.363) for incorporation into the rations of broiler chickens to provide levels of 54 to 72 g narasin per ton of complete feed.

Roxarsone is approved (21 CFR 558.530) for incorporation into the rations of growing chickens at levels of 22.7 and 45.4 g/ton.

Three series of trials were conducted to confirm the safety of the feeding of a combination of narasin and roxarsone to broiler chickens.

1. Field Studies
   A series of five trials conducted in commercial broiler production facilities over a wide geographical area.
2. Floor Pen Trials (Series 1)
   A series of six trials conducted to evaluate the performance of broiler chickens fed various levels of narasin and roxarsone.
3. Floor Pen Trials (Series 2)
   A series of five trials to evaluate the difference between feeding narasin alone at 72 g/ton and narasin at 72 g/ton combined with roxarsone at 45 g/ton.

Safety Study Summaries

1. Field Studies
   The feeding of narasin alone and in combination with roxarsone to broilers was evaluated in a series of five trials conducted in commercial broiler production facilities. The trials were located in four geographical locations (Arkansas, Pennsylvania, Alabama, and North Carolina), and involved 259,883 birds from three broiler strains. At each of the trial sites the day-old straight run broiler chicks were placed in the test houses on a farm on the same day. Narasin at 72.5 g/ton was fed to the broilers in one house(s) and narasin at 72.5 g/ton plus roxarsone at 45.4 g/ton were fed until withdrawn five days prior to slaughter.

   The overall results are summarized as follows:

   Ed. note: The following table has 6 columns.

   Treatment	Number Broilers Started	Average Age (days)	Average Weight/gain	Average Feed	Total mortality %
   Narasin 72.5 g/t	129,932	46	3.681	1.988	4.59
   Narasin 72.5 g/t plus roxarsone 45.4 g/t	129,951	46	3.669	1.996	3.17

   Obvious roxarsone toxicity was observed in broilers fed 72.5 g narasin and 45.4 g roxarsone/ton of feed in one house of broilers in the trial conducted at the Doyce Smith Farm, Almond, Arkansas.

   In that trial 14,970 chicks were placed in House 1 (narasin 72.5 g/t) and 15,020 chicks were placed in House 2 (narasin 72.5 g/t, roxarsone 45.4 g/t). During the first ten days the chicks were watered with individual water jugs. Automatic 8 ft. long trough waterers were used thereafter.

   A mild diarrhea was observed to cause wet litter in House 2. Signs of ataxia and birds chirping loudly when forced to move were also observed. Upon termination of the trial the birds were observed to have dirty feathers and mildly wet litter. None of these effects was observed in House 1.

   According to L. H. Jones, et al, in Veterinary Pharmacology and Therapeutics, 1977, page 1281, "Poultry may be poisoned by roxarsone. If birds have diarrhea and are debilitated or dehydrated or if water supply is restricted, even the recommended concentrations of roxarsone can cause toxicosis. Poultry manifest incoordination and ataxia after poisoning with roxarsone.

   The cause of the diarrhea in this instance was undetermined, but it is likely that the condition contributed to the dehydration of the birds and manifestation of signs of roxarsone toxicity.

   No signs of such toxicity were observed in the other field trials involving approximately 117,000 birds which received 72 g/ton narasin plus 45 g/ton roxarsone. No signs of toxicity were observed in the floor pen safety studies or in the battery or floor pen efficacy studies described under "IV. EFFICACY".

   Investigators for these studies were:

   Dr. L. J. Camp 3109 Poplarwood Court, Suite 101 Raleigh, North Carolina 27625-1011 Dr. J. T. Hays 3035 Directors Row Ste 408 Memphis, Tennessee 38131

   Dr. B. F. Schlegel 314 Fairway Lane Fayetteville, Arkansas 72701 Dr. D. L. Snyder 800 Weadley Rd. Radnor, Pennsylvania 19087

2. Floor Pen Trials Series

   Six trials were conducted to evaluate the performance of broiler chickens fed various levels of narasin plus roxarsone. Two trials were conducted at Fayetteville, Arkansas, one at Raleigh, North Carolina, one at Puyallup, Washington, and two at Greenfield, Indiana. Each trial had the same basic experimental design of a 3 x 4 factorial arrangement of narasin at 0, 54 and 72 g/ton with roxarsone at 0, 11, 22 and 45 g/ton. These trials were not challenged with coccidia. The results of this series are in Tables 1, 2 and 3 for weight gain, feed/gain ratio, and mortality, respectively.

   Weight Gain

   There were no differences among the treatments in weight gain.

   Feed/Gain Ratio

   Combinations of each level of narasin plus 45 g/ton of roxarsone resulted in improvement in feed/gain ratio when compared to the non-medicated control.

   Combinations of each level of narasin plus 45 g/ton of roxarsone resulted in improvement in feed/gain ratio as compared to the levels of narasin alone.

   Combinations of each level of narasin plus either 22 or 45 g/ton of roxarsone resulted in improvement in feed/gain ratios as compared to roxarsone alone.

   Mortality

   There were no differences in mortality between the non-medicated control and any of the combinations of narasin + roxarsone.

   There was a tendency for the combination of narasin + roxarsone to have less mortality than either narasin or roxarsone alone.

   Investigators in these studies were:

   P. W. Waldroup, Ph.D. University of Arkansas Fayetteville, Arkansas C. R. Parkhurst, Ph.D.
   North Carolina State University
   Raleigh, North Carolina

   L. E. Ousterhout, Ph.D.
   Western Washington Research and Extension Center
   Puyallup, Washington

   M. E. Callender
   Lilly Research Laboratories
   Greenfield, Indiana

   Ed. note: The following table has 13 columns.

   TABLE 1 SIX TRIALS WITHOUT COCCIDIAL CHALLENGE IN FLOOR PENS

   Average Weight Gain in Grams

   	Roxarsone, 0 g/ton			Roxarsone, 11.3 g/ton			Roxarsone, 22.7 g/ton			Roxarsone, 45.4 g/ton
   Trial	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton
   1	1690	1783	1755	1726	1786	1762	1766	1780	1808	1805	1796	1825
   2	1741	1770	1756	1757	1818	1767	1788	1852	1825	1833	1842	1887
   3	1740	1797	1852	1829	1875	1824	1798	1861	1870	1783	1859	1853
   4	1811	1845	1796	1795	1834	1794	1810	1805	1772	1779	1794	1735
   5	2417	2413	2404	2372	2386	2381	2371	2390	2394	2389	2353	2339
   6	2274	2321	2218	2319	2325	2262	2325	2296	2256	2229	2225	2267
   L.S. Means	1845	1884	1851	1857	1890	1852	1869	1880	1886	1853	1859	1853

   Ed. note: The following table has 13 columns.

   TABLE 2 SIX TRIALS WITHOUT COCCIDIAL CHALLENGE IN FLOOR PENS

   Average Feed/Gain Ratio

   	Roxarsone, 0 g/ton			Roxarsone, 11.3 g/ton			Roxarsone, 22.7 g/ton			Roxarsone, 45.4 g/ton
   Trial	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton
   1	2.156	2.074	2.087	2.208	2.082	2.091	2.121	2.088	2.073	2.098	2.034	2.049
   2	2.113	2.088	2.088	2.176	2.082	2.124	2.138	2.062	2.053	2.070	2.013	2.019
   3	2.017	2.020	1.958	1.923	1.984	2.038	2.106	1.942	1.940	2.052	1.968	1.918
   4	1.903	1.853	1.846	1.868	1.847	1.856	1.887	1.867	1.821	1.878	1.845	1.859
   5	2.018	2.152	2.143	2.243	2.170	2.121	2.216	2.175	2.124	2.180	2.120	2.106
   6	2.108	2.005	2.020	2.141	2.035	2.033	2.112	2.094	2.076	2.093	2.029	2.015
   L.S. Means	2.055	2.018	2.017	2.097	2.021	2.028	2.068	2.027	2.000	2.039	1.9 84	1.989

   Ed. note: The following table has 13 columns.

   TABLE 3 SIX TRIALS WITHOUT COCCIDIAL CHALLENGE IN FLOOR PENS

   Average Percent Mortality

   	Roxarsone, 0 g/ton			Roxarsone, 11.3 g/ton			Roxarsone, 22.7 g/ton			Roxarsone, 45.4 g/ton
   Trial	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin, 72 g/ton	Narasin, 0 g/ton	Narasin, 54 g/ton	Narasin 72 g/ton
   1	0.75	3.81	7.57	3.75	1.83	3.18	2.91	2.36	4.79	2.21	3.34	2.21
   2	2.21	3.28	1.91	5.03	4.43	1.81	5.16	3.06	1.95	4.91	2.48	4.32
   3	5.90	5.71	7.55	5.14	4.69	5.01	5.28	3.71	2.74	7.14	4.16	4.57
   4	1.52	1.05	2.79	3.18	1.22	4.51	4.44	2.25	2.16	4.05	3.40	4.07
   5	3.33	6.02	3.55	6.67	9.43	4.90	6.56	7.20	6.02	3.75	4.90	2.20
   6	3.18	4.86	4.12	5.43	4.12	2.43	3.85	4.38	2.16	7.63	1.38	1.38
   L.S. Means	2.62	3.87	4.41	4.52	3.86	3.43	4.40	3.37	2.90	4.75	3.03	3.00

3. Floor Pen Studies Series 2

   Five trials were conducted to evaluate the difference between feeding narasin alone at 72 g/ton and narasin at 72 g/ton + roxarsone at 45 g/ton. Two trials were conducted at French Village, Wisconsin, one at Athens, Georgia, one at College Station, Texas, and one at Fayetteville, Arkansas. None of the chickens were challenged with coccidia. The results of these trials are presented in Tables 1 and 2 for weight gain and feed/gain ratio, respectively.

   Weight gain

   1. The combination of narasin + roxarsone at 72 + 45 g/ton resulted in an improvement in weight gain.

   Feed/gain ratio

   1. The combination of narasin + roxarsone at 72 + 45 g/ton resulted in an improvement in feed/gain ratio.

   Investigators in these studies were:

   O. W. Charles Extension Poultry Science University of Georgia Athens, Georgia 30601 W. F. Krueger Department of Poultry Science Texas Agricultural Experiment Station College Station, Texas 77843

   Randall A. Primo Ponderosa Research Company French Village, Missouri 63036 P. W. Waldroup Department of Animal Science University of Arkansas Fayetteville, Arkansas 72701

   Ed. note: The following table has 3 columns.

   TABLE 1 COMBINATION OF NARASIN AND ROXARSONE IN FLOOR PEN STUDIES

   Five Trials without Challenge
   Weight Gain (g)

   Trial	Narasin, 72 g/ton	Roxarsone, 45 g/ton + Narasin, 72 g/ton
   AR84	1982	1993
   GA85	1793	1777
   MO83	1945	1947
   M085	1882	1893
   TX85	1716	1749
   L.S.Means	1861	1875

   Ed. note: The following table has 3 columns.

   TABLE 2 COMBINATION OF NARASIN AND ROXARSONE IN FLOOR PEN STUDIES

   Five Trials without Challenge
   Feed/Gain Ratio

   Trial	Narasin, 72 g/ton	Roxarsone, 45 g/ton + Narasin, 72 g/ton
   AR84	2.065	2.033
   GAS5	2.053	2.026
   M083	2.203	2.131
   M085	2.069	2.015
   TX85	1.981	1.965
   L.S.Means	2.076	2.034

4. VI. HUMAN SAFETY

   1. Data to Support Human Safety

      The toxicity, metabolism and total residue depletion studies that were used to establish human safety for narasin and roxarsone are described in the FOI Summaries for the individual products (51FR 29097, August 14, 1986; 21 CFR §558.363 and 52 FR 2686, January 26, 1987; 21 CFR §558.530).

   2. Residue Depletion/Non-Interference Studies

      The depletion of roxarsone in the presence of narasin was determined. The Agency accepted tissue residue depletion data using three-way combination studies in lieu of the two-way combination of narasin and roxarsone alone because it was not expected that inclusion of the other antibiotic would have an effect on the depletion of drug residues of either narasin or roxarsone.

      The tissue residue study in chickens fed narasin 90 g/ton, roxarsone 45 g/ton and another antibiotic was conducted at Cook College/Rutgers University (January 7, 1982 to March 6, 1982). The narasin assays were conducted by Lilly Research Laboratories, Greenfield, Indiana. The roxarsone assays were conducted by Salsbury Laboratories, Charles City, Iowa.

      Positive narasin responses were observed within each zero time tissue sample group: skin/fat, kidney, lean (muscle), and liver (Table 1). No narasin residues were detected in skin/fat or kidney tissue after one day's withdrawal from the treatment feed. Narasin residues were detected in liver through the two-day withdrawal period samples. No narasin residues were confirmed in muscle after the zero-day withdrawal. The presence of roxarsone does not affect the narasin tissue residue depletion profile in broiler tissues.

      The roxarsone assays show that the arsenic levels in muscle, liver, kidney, and skin/fat tissues were below the tolerance levels for roxarsone when these tissues were taken while the birds were on medicated feed.

      Ed. note: The following table has 7 columns.

      SUMMARY OF NARASIN TISSUE RESIDUES

      Sample Bird			Narasin Found (ppm)
      Day	No.	Sex	Fat/Skin	Kidney	Lean	Liver
      0	9	F	0.063	<0.010	<0.010	0.023
      0	10	M	0.042	<0.010	NDR*1	0.016
      0	11	F	0.052	<0.010	NDR	0.017
      0	12	M	0.057	<0.010	NDR	NDR
      0	13	F	0.16	0.012	<0.010	0.028
      0	14	M	0.028	<0.010	NDR	0.015
      1	9	F	NDR	NDR	NDR	<0.010
      1	10	M	NDR	NDR	NDR	<0.010
      1	11	F	NDR	NDR	NDR	0.011
      1	12	M	NDR	NDR	NDR	<0.010
      1	13	F	NDR	NDR	NDR	<0.010
      1	14	M	NDR	NDR	NDR	0.011
      2	9	F	NDR	NDR	NDR	<0.010
      2	10	M	NDR	NDR	<0.010	<0.010
      2	11	F	NDR	NDR	<0.010	<0.010
      2	12	M	NDR	NDR	NDR	<0.010
      2	13	F	NDR	NDR	NDR	<0.010
      2	14	M	NDR	NDR	NDR	<0.010

      NDR = no detectable narasin residue at the plate test sensitivity (usually 0.010 mcg narasin/g tissue).

      Ed. note: The following table has 5 columns.

      TOTAL ARSENIC ANALYSIS OF POULTRY TISSUE FROM BIRDS MEDICATED WITH BAMBERMYCINS, NARASIN AND ROXARSONE COMBINATION Tissue Residue Study - 0 Days Off Medication
      
      Arsenic Found
      

      As-N-No.	Kidney ppm	Liver ppm	Muscle ppm	Skin ppm
      381-384	0.78	1.13	0.09	0.15
      385-388	0.62	0.90	0.09	0.15
      389-392	0.69	0.93	0.09	0.14
      394-397	0.75	1.53	0.11	0.13
      398-401	0.59	0.98	0.12	0.15
      402-405	0.65	1.18	0.11	0.20

   VII. AGENCY CONCLUSIONS

   The data submitted in support of this NADA satisfy the requirements of Section 512 of the Act and demonstrate that narasin (from Monteban) at concentrations ranging from 54 to 72 g/ton and Roxarsone at a concentration of 45.4 g/ton in finished feed are safe and effective when fed to broiler chickens for the indications stated in the product labeling.

   The submitted data are adequate to satisfy the Agency's food safety requirements. The safe concentration for total narasin residues in noncooked edible chicken tissues are: 0.6 ppm in muscle; 1.8 ppm in liver; and 1.2 ppm in skin with adhering fat.

   Tolerances for total residues of combined arsenic in food are established as follows: 0.5 ppm in uncooked muscle, 2 ppm in uncooked edible by-products (21 CFR §556.60).

   Five day withdrawal time before slaughter is satisfactory.

   VIII. LABELING

   (Attached)

   Copies of applicable labels may be obtained by writing to the:

   Freedom of Information Office
   Center for Veterinary Medicine, FDA
   7500 Standish Place
   Rockville, MD 20855