Animal & Veterinary

NADA 095-735 Rumensin - supplemental approval (October 22, 1990)

I. GENERAL INFORMATION:

NADA

095-735

Sponsor:

Elanco Products Company
A Division of Eli Lilly and Company
Lilly Corporate Center
Indianapolis, IN 46285

Generic Name:

monensin (as monensin sodium)

Trade Name:

Rumensin

Marketing Status:

Over the Counter (OTC)

Effect of Supplement:

This supplement provides for an additional claim for the use of monensin in the prevention and control of coccidiosis in feedlot cattle.

II. INDICATIONS FOR USE

For the prevention and control of coccidiosis in feedlot cattle due to Eimeria bovis and Eimeria zuernii.

III. DOSAGE:

A.

DOSAGE FORM

The Type A Medicated Article is to be incorporated into complete feeds to provide levels of 10 to 30 g monensin per ton or may be included in Type B or Type C medicated feeds. Type B or Type C medicated feeds are to be mixed with grain and roughage to provide 10-30 g/ton in complete feed. Feed to provide 100 to 360 mg monensin per head daily.

B.

ROUTE OF ADMINISTRATION

See above

C.

RECOMMENDED DOSAGES:

See above

 

NOTES

 

IV. EFFECTIVENESS:

Clinical Effectiveness in Monensin Fed to Cattle Inoculated With Coccidia Oocysts in a Four-Trial Dose Titration Experiment

Investigators:

Study No. 1 (T1F278303)
Bert E. Stromberg, Ph.D.
University of Minnesota
St. Paul, MN 55108

Study No. 2 (T1F178304)
Dr. Paul Fitzgerald
University of Illinois
Urbana, IL 61801

Study No. 3 (T1F398306)
Dr. Gary Davis
Greenbrier Veterinary Services, Inc.
Delaware, Ohio 43015

Study No. 4 (T1F278401)
Bert E. Stromberg, Ph.D.
John E. Schlotthaues, D.V.M., Ph.D
University of Minnesota
St. Paul, MN 55108

One hundred and twenty-three ruminating cattle weighing approximately 150 to 188 pounds were used in 4 trials to confirm the effectiveness of monensin fed at 0, 10, 20 or 30 g/ton against coccidiosis. The cattle were orally challenged with sporulated Eimeria bovis and/or Eimeria zuernii oocysts on the third day after monensin feeding began. The experimental design used was a randomized block at several locations with the challenge type (coccidia species) as the blocking factor. Oocyst counts and fecal score data were collected over time on several days throughout the 33 to 38-day trials. These data were viewed as sub-sampling units and analyzed accordingly. Animal weights and feed intakes were measured weekly, but analyzed over the entire length of the trial. Mortality within each treatment group was recorded upon occurrence. The least squares treatment means for pair-wise comparisons to the control treatment (0 g/ton monensin) were as follows:

  Monensin Level (g/ton)
Variable 0 10 20 30
Ave. Daily Weight Gain
(lbs/h/d)
1.310 1.592 1.941 1.960
Ave. Daily Dry Matter Intake
(lbs/h/d)
5.488 5.578 6.033 6.168
E. bovis oocysts
(sq. root,1000 g/feces)
49.936 29.077 15.894 11.163
E. zuernii oocysts
(sq. root,1000 g/feces)
18.472 7.032 2.313 2.214
Other oocysts
(sq. root,1000 g/feces)
19.275 9.233 8.666 4.710
Feces scores
(sq. root, scale1-5)*
1.40 1.28 1.12 1.09
Mortality
(% of initial number)**
16 0 0 0

* 1 = normal, 2 = slight diarrhea, 3 = diarrhea, 4 = diarrhea/blood, 5 = diarrhea/mucus
** Calculated percent (No. died/No. initially) x 100); not analyzed statistically

For both E. bovis and E. zuernii oocyst counts, the 10-gram level showed significant reduction as compared to controls. A statistically significant decrease in both oocyst counts was seen through 20 grams per ton. Although the 30 gram per ton level gave directionally lower oocyst counts than the 20-gram per ton level, the difference was not significant. Medical judgment was utilized in deciding that the 30-gram per ton level was medically meaningful.

Prior to initiation of the above studies, two preliminary studies were conducted as follows:

Study No. 665
L. R. McDougald and W. H. Henry
Lilly Research Laboratories
Greenfield, IN

Study No. 715
L. R. McDougald, W. H. Henry and L. L. Schenck
Lilly Research Laboratories
Greenfield, IN

The design and conduct of each pivotal or preliminary study are discussed under

A. Pivotal Studies

Study No. 1

  1. The Clinical Effectiveness of Monensin in Controlling Bovine Coccidiosis. (T1F278303)
  2. Investigator:

    Bert E. Stromberg, Ph.D.
    University of Minnesota
    St. Paul, MN 55108

  3. General Design:
    1. Objective: To determine the effect of monensin on coccidial oocysts production, weight gain, feed intake, clinical signs, and mortality of ruminating cattle challenged with E. bovis or E. zuernii oocysts.
    2. Test Animals: Thirty-six male Holstein-Friesian cattle approximately 8 weeks of age.
    3. Each animal constituted an experimental unit. The four non-challenged animals served as controls for baseline performance and were confined in separate tie stalls adjacent to the coccidial challenged animals. The challenged controls and treated animals were blocked by inoculum (E. zuernii or E. bovis) into treatment groups of four animals each. Treatments (0, 10, 20, or 30 g/ton monensin) were assigned at random to each group as follows:
      Monensin g/ton No. of Animals Coccidial Challenge
      0 4 None
      0 4 E. zuernii
      10 4 E. zuernii
      20 4 E. zuernii
      30 4 E. zuernii
      0 4 E. bovis
      10 4 E. bovis
      20 4 E. bovis
      30 4 E. bovis
    4. Treatment:

      1) Treatment feeds were offered three days prior to E. bovis or E. zuernii inoculation to establish acceptance and normal intake.

      2) The cattle challenged with E. zuernii received an essentially pure inoculum containing about 235,000 sporulated oocysts in an oral gavage.

      3) The cattle challenged with E. bovis received an essentially pure inoculum containing about 150,000 sporulated oocysts in an oral gavage.

    5. e. Dosage Form:

      Rumensin Premix, 60 g monensin/lb. incorporated into complete feeds at levels of 0, 10, 20 and 30 monensin/ton.

    6. Test Duration:

      35 days

    7. Parameters Measured:

      1) Body weights were recorded and average daily gain was calculated.
      2) Feed intake was recorded.
      3) Fecal character for each animal was recorded daily on the following scale: 1 = normal, 2 = slight diarrhea, 3 = diarrhea, 4 = diarrhea/blood, and 5 = diarrhea/mucus.
      4) Oocyst counts were made. Oocysts were identified and recorded by species.

  4. Results (eds. note, the following table includes 11 columns)
                Cumulative Oocysts
    Days 19-23 Post Challenge
    Cumulative Fecal Character
    Days 19-23
    Monensin Trt. (g/ton) Coccidia Challenge Number of Animals Mortality ADG* (lbs) ADF** (lbs) E.zuernii E.bovis Other Total Post Challenge
    0 None 4 0 1.91 5.93 50 70 10 130 1.25
    0 E.zuernii 4 0 1.63 5.75 110 100 10 220 1.25
    10 E.zuernii 4 0 1.62 5.51 0 0 0 0 1.10
    20 E.zuernii 4 0 1.69 5.70 0 10 0 10 1.10
    30 E.zuernii 4 0 1.47 5.18 10 0 0 10 1.10
    0 E.bovis 4 2 1.93 5.46 750 1260 40 2050 2.05
    10 E.bovis 4 0   5.74 710 1670 0 2380 1.85
    20 E.bovis 4 0   6.05 20 60 0 80 1.45
    30 E.bovis 4 0   5.65 0 90 0 90 1.00

    *ADG = Average daily gain.
    ** ADF = Average daily feed.

    Animals inoculated with E. bovis exhibited more marked signs of bovine coccidiosis than those inoculated with E. zuernii. A monensin dose related oocyst passage response was observed in cattle receiving each challenge.

    The daily fecal character indicated in reduction in diarrhea of monensin treated cattle when compared to non-treated challenged control animals.

    All species of coccidial oocyst isolations following challenge were considerably reduced in the monensin treated groups of cattle when compared ton non-treated challenged control animals

    There were no mortalities in this study.

  5. Statistical Analysis

    This trial was part of a four trial experiment. Statistical analysis was performed on the whole experiment run under a common protocol.

  6. Conclusions

    The cattle in the monensin treated groups demonstrated reduced coccidial oocyst shedding and diarrhea, over the non-treated challenged control animals.

  7. Adverse Reactions

    There were no adverse reactions attributable to the drug.

A. Pivotal Studies

Study No. 2

1. The Clinical Effectiveness of Monensin in Controlling Bovine Coccidiosis. (T1F178304)

2. Investigator:

Dr. Paul Fitzgerald
University of Illinois
Urbana, IL 61801

3. General Design

  1. Objective: To determine the effect of monensin on coccidial oocysts production, weight gain, feed intake, clinical signs, and mortality of ruminating cattle challenged with E. bovis or E. zuernii oocysts.
  2. Test Animals: Thirty-six male Holstein-Friesian cattle approximately 8 weeks of age.
  3. Each animal constituted an experimental unit. The four non-challenged animals served as controls for baseline performance and were confined in separate tie stalls adjacent to the coccidial challenged animals. the challenged controls and treated animals were blocked by inoculum (E. zuernii or E. bovis) into treatment groups of four animals each. Treatments (0, 10, 20, or 30 g/ton monensin) were assigned at random to each group as follows:
    Monensin g/ton No. of Animals Coccidial Challenge
    0 4 None
    0 4 E. zuernii
    10 4 E. zuernii
    20 4 E. zuernii
    30 4 E. zuernii
    0 4 E. bovis
    10 4 E. bovis
    20 4 E. bovis
    30 4 E. bovis
  4. Treatment

    1) Treatment feeds were offered three days prior to E. bovis or E. zuernii inoculation to establish acceptance and normal intake.

    2) The cattle challenged with E. zuernii received an inoculum containing about 228,000 sporulated oocysts in an oral gavage as follows: E. zuernii, 76%; E. bovis, 4%; E. auburnensis, 6%; and E. ellipsoidalis/cylindrica, 14%.

    3) The cattle challenged with E. bovis received an inoculum containing about 250,000 sporulated oocysts in an oral gavage as follows: E. bovis, 99%; less than 1% of E. zuernii, E. auburnensis, or E. ellipsoidalis/cylindrica.

  5. Dosage Form
    Rumensin Premix, 60 g monensin/lb. incorporated into complete feeds at levels of 0, 10, 20, and 30 g monensin/ton.
  6. Test Duration: 35 days
  7. Parameters Measured

    1) Body weights were recorded and average daily gain calculated.
    2) Feed intake was recorded.
    3) Fecal character for each animal was recorded daily on the following scale: 1 = normal, 2 = slight diarrhea, 3 = diarrhea, 4 = diarrhea/blood, and 5 = diarrhea/mucus.
    4) Oocyst counts were made. Oocysts were identified and recorded by species.

4. Results (eds. note, the following table includes 11 columns of results)

            Cumulative Oocysts
Days 19-23 Post Challenge
Cumulative Fecal Character
Days 19-23
Monensin Trt. (g/ton) Coccidia Challenge Number of Animals Mortality ADG* (lbs) ADF** (lbs) E.zuernii E.bovis Other Total
Post Challenge
0 None 4 0 2.12 5.84 30 1120 410 1560 1.00
0 E.zuernii 4 0 1.36 4.23 1580 3970 6410 11960 1.85
10 E.zuernii 4 0 2.28 5.84 110 870 3260 4240 1.15
20 E.zuernii 4 0 2.31 6.10 220 270 4030 4520 1.05
30 E.zuernii 4 0 2.11 5.24 60 200 3070 3330 1.00
0 E.bovis 4 3 0.02 3.71 8107 87493 2227 97827 4.20
10 E.bovis 4 0 0.70 3.70 1965 22710 840 25515 3.20
20 E.bovis 4 0 1.73 4.49 350 13030 180 13560 1.60
30 E.bovis 4 0 1.62 4.85 740 10680 30 11450 1.75

*ADG = Average daily gain.
** ADF = Average daily feed.

Animals inoculated with E. bovis exhibited more marked signs of bovine coccidiosis than those inoculated with E. zuernii. A monensin dose related response was observed in cattle receiving each challenge.

Monensin treated groups of cattle gained more weight than the non-treated, challenge control animals.

The daily fecal character indicated reduction in diarrhea of monensin treated cattle when compared to non-treated, challenged control animals.

All species of coccidial oocyst isolations following challenge were considerably reduced in the monensin treated groups of cattle when compared to non-treated, challenged control animals.

5. Statistical Analysis

This trial was part of a four trial experiment. Statistical analysis was performed on the whole experiment run under a common protocol.

6. Conclusions

The cattle in the monensin treated groups demonstrated improved performance and reduced coccidial oocyst shedding, diarrhea, and mortality over the non-treated, challenged control animals.

7. Adverse reactions

There were no adverse reactions attributable to the drug.

A. Pivotal Effectiveness Studies

Study No. 3

1. The Clinical Effectiveness of Monensin in Controlling Bovine Coccidiosis. (T1F398306)

2. Investigator:

Dr. Gary Davis
Greenbrier Veterinary Services, Inc.
Delaware, OH 43015

3. General Design

  1. Objective: To determine the effect of monensin on coccidial oocysts production, weight gain, feed intake, clinical signs, and mortality or ruminating cattle challenged with E. bovis or E. zuernii oocysts.
  2. Test Animals: Thirty-six male Holstein-Friesian cattle approximately 8 weeks of age.
  3. Each animal constituted an experimental unit. The four non-challenged animals served as controls for baseline performance and were confined in separate tie stalls adjacent to the coccidial challenged animals. The challenged animals were blocked both by inoculum (E. zuernii or E. bovis) and location (four animals/block). All four treatments (0, 10, 20, or 30 g/ton monensin) were assigned to each block.
    Monensin g/ton No. of Animals Coccidial Challenge
    0 4 None
    0 4 E. zuernii
    10 4 E. zuernii
    20 4 E. zuernii
    30 4 E. zuernii
    0 4 E. bovis
    10 4 E. bovis
    20 4 E. bovis
    30 4 E. bovis
  4. Treatment

    1) Treatment feeds were offered three days prior to E. bovis or E. zuernii inoculation to establish acceptance and normal intake.

    2) The cattle challenged with E. zuernii received an inoculum containing about 475,000 sporulated oocysts in an oral dose.

    3) The cattle challenged with E. bovis received an inoculum containing about 300,000 sporulated oocysts in an oral dose.

  5. Dosage Form

    Rumensin Premix, 60 g monensin/lb. incorporated into complete feeds at levels of 0, 10, 20, and 30 g monensin/ton.

  6. Test Duration: 35 days
  7. Parameters Measured

    1) Body weights were recorded and average daily gain calculated.

    2) Feed intake was recorded.

    3) Fecal character for each animal was recorded daily on the following scale: 1 = normal, 2 = slight diarrhea, 3 = diarrhea, 4 = diarrhea/blood, and 5 = diarrhea/mucus.

    4) Oocyst counts were made. Oocysts were identified and recorded by species.

4. Results (eds. note, the following table includes 11 columns)

            Cumulative Oocysts
Days 19-23 Post Challenge
Cumulative Fecal Character
Days 19-23
Monensin Trt. (g/ton) Coccidia Challenge Number of Animals Mortality ADG* (lbs) ADF** (lbs) E.zuernii E.bovis Other Total Post Challenge
0 None 4 0 2.04 6.68 0 0 0 0 1.08
0 E.zuernii 4 0 2.12 6.44 25 0 5 70 1.53
10 E.zuernii 4 0 2.04 5.88 0 0 0 0 1.08
20 E.zuernii 4 0 1.96 6.01 0 5 0 5 1.58
30 E.zuernii 4 0 2.46 6.43 15 0 0 15 1.10
0 E.bovis 4 2 -0.25 4.11 1067 22008 4831 25420 3.88
10 E.bovis 4 0 0.21 4.65 265 2198 1337 10750 3.20
20 E.bovis 4 0 2.04 6.18 23 12175 1688 14065 2.23
30 E.bovis 4 0 2.25 6.12 0 630 125 2610 1.73

*ADG = Average daily gain.
** ADF = Average daily feed.

Animals inoculated with E. bovis exhibited more marked signs of bovine coccidiosis than those inoculated with E. zuernii. A monensin dose related response was observed in cattle receiving each challenge.

Monensin E. bovis treated groups of cattle gained more weight than the non-treated, challenged control animals.

The daily fecal character indicated reduction in diarrhea of monensin treated cattle when compared to non-treated, challenged control animals.

All species of coccidial oocyst isolations following challenge were considerably reduced in the monensin treated groups of cattle when compared to non-treated, challenged control animals.

5. Statistical Analysis

This trial was part of a four-trial experiment. Statistical analysis was performed on the whole experiment run under a common protocol.

6. Conclusions

The cattle in the monensin treated groups demonstrated reduced coccidial oocyst, shedding, diarrhea, and mortality from E. bovis over the non-treated, challenged control animals.

7. Adverse Reactions

There were no adverse reactions attributable to the drug.

Study No. 4

1. The Clinical Effectiveness of Monensin in Controlling Bovine Coccidiosis. (T1F278401)

2. Investigator:

  • Bert E. Stromberg, Ph.D.
  • John C. Schlotthaues, D.V.M., Ph.D.
  • William J. Bemrick, Ph.D.
  • University of Minnesota
  • St. Paul, MN 55108

3. General Design

  1. Objective: To determine the effect of monensin on coccidial oocysts production, weight gain, feed intake, clinical signs, and mortality of ruminating cattle challenged with E. bovis or E. zuernii oocysts.
  2. Test Animals: Thirty-six male Holstein-Friesian cattle approximately 8 weeks of age.
  3.  Each animal constituted an experimental unit. The four non-challenged animals served as controls for baseline performance and were confined in separate tie stalls adjacent to the coccidial challenged animals. The challenged controls and treated animals were blocked by inoculum (E. zuernii or E. bovis) into treatment groups of four animals each. Treatments (0, 10, 20, or 30 g/ton monensin) were assigned at random to each group as follows:
    Monensin g/ton No. of Animals Coccidial Challenge
    0 4 None
    0 7 Mixed*
    10 7 Mixed*
    20 7 Mixed*
    30 7 Mixed*
    *Challenged with both E. bovis and E. zuernii.
  4. Treatment

    1) Treatment feeds were offered three days prior to E. bovis or E. zuernii inoculation to establish acceptance and normal intake.

    2) The cattle were challenged with predominantly (99+%) E. zuernii inoculum containing 500,000 sporulated oocysts and a predominantly (99+%) E. bovis inoculum containing 300,000 sporulated oocysts. Each animal received these inocula oral gavages.

  5. Dosage Form

    Rumensin Premix, 60 g monensin/lb incorporated into complete feeds at levels of 0, 10, 20 and 30 g monensin/ton.

  6. Test Duration: 31 days
  7. Parameters Measured

    1) Body weights were recorded and average daily gain was calculated.

    2) Feed intake was recorded.

    3) Fecal character for each animal was recorded daily on the following scale: 1 = normal, 2 = slight diarrhea, 3 = diarrhea, 4 = diarrhea/blood, and 5 = diarrhea/mucus.

    4) Oocysts counts were made. Oocysts were identified and recorded by species.

4. Results (eds. note, the following table includes 11 columns)

            Cumulative Oocysts
Days 19-23 Post Challenge
Cumulative Fecal Character
Days 19-23
Monensin Trt. (g/ton) Coccidia Challenge Number of Animals Mortality ADG* (lbs) ADF** (lbs) E.zuernii E.bovis Other Total Post Challenge
0 None 4 0 1.83 8.56 0 5 145 150 1.05
0 Mixed*** 7 0 2.21 8.19 651 8783 123 9614 1.94
10 Mixed*** 7 0 2.41 7.90 72 2623 54 4549 2.09
20 Mixed*** 7 0 2.39 8.37 0 103 3 106 1.06
30 Mixed*** 6**** 0 2.49 9.37 3 346 0 349 1.34

*ADG = Average daily gain.
** ADF = Average daily feed.
*** Challenged with both E. zuernii and E. bovis.
**** One animal was removed due to inability to measure feed consumption.

The signs of bovine coccidiosis exhibited by these animals inoculated with a mixture of E. zuernii and E. bovis were more severe than previous trials using pure E. zuernii inoculation. A monensin dose-related response was observed in the animals.

Monensin-treated groups of cattle gained more weight than the unmedicated, challenged control animals.

The daily fecal character indicated, in most cases, reduction in diarrhea of monensin treated cattle when compared to the unmedicated, challenged control animals.

There were no mortalities in this study.

5. Statistical Analysis

This trial was part of a four-trial experiment. Statistical analysis was performed on the whole experiment run under a common protocol.

6. Conclusions

The cattle in the monensin treated groups demonstrated improved performance and reduced coccidial oocyst shedding, and in most cases, diarrhea over the non-treated challenged control animals.

7. Adverse Reactions

There were no adverse reactions attributable to the drug.

4. A. Preliminary Effectiveness Studies

Study No. 665

1. Monensin Coccidiosis Experiment No. 665

2. Investigator:

L. R. McDougald and W. H. Henry
Lilly Research Laboratories
Greenfield, IN

3. General Design

  1. The study was designed as a pilot experiment to evaluate the efficacy of monensin against Eimeria bovis and E. zuernii in calves.
  2. Eight newborn male Holstein calves were acquired from Florida. They were fed milk replacer until weaning onto the calf starter ration and housed in isolation pens.
  3. Treatment

    Pen 19 Monensin - 30 g/ton
    Pen 20 Infected controls

  4. Coccidia Challenge

    Each calf was orally administered sporulated oocysts of the following species:

    E. bovis (LB7) 100,000 oocysts (passed 6-1-76)
    E. zuernii (LB6) 100,000 oocysts (passed 6-1-76)

  5. Rations and Administration

    A calf starter ration containing monensin levels of 0 to 30 g/ton was fed during the 35-day experiment.

  6. Experimental Design

    Eight calves were divided into 2 groups of 4 calves/group on an equal weight pen basis. Treated calves were on medicated feed (8-3-76, day 1) prior to inoculation (8-10-76, day 7). The following data were collected: weight gains per pen, feed/gain by pen and mortality. All calves and feed were weighed as shown in the following tables.

4. Results

Mean Weight Gain Per Pen (lbs)

Monensin (g/t) Day 7 Day 14 Day 21 Day 28 Day 35
30 27 69 109 157 168
0 38 76 98 132 170

Mean Feed/Gain Per Pen

Monensin (g/t) Day 7 Day 14 Day 21 Day 28 Day 35
30 2.87 2.39 2.46 2.07 2.68
0 2.38 2.38 2.72 2.38 2.55

Oocysts Passage Per Pen*

Days P.I. Monensin Infected Controls
15 0 0
16 0 Trace
17 0 Trace
18 0 Trace
19 0 4,442,000
20 0 603,000
21 0 670,000
22 0 Trace
23 0 Trace
24 0 Trace

* Count based on 1 liter of fecal material.

Percent Mortality Due to Coccidiosis

Monensin (g/t) Percent Mortality
30 0
0 0

5. Statistical Analysis

This was a preliminary pilot study. Statistical analysis is not applicable.

6. Conclusions

Monensin was effective in prevention of bovine coccidiosis caused by Eimeria bovis when fed to calves at 30 g/ton in finished feed.

7. Adverse reactions

There were no adverse reactions attributable to the drug.

Study No. 715

1. Monensin Coccidiosis Experiment No. 715

2. Investigators:

L. R. McDougald, W. H. Henry and L. L. Schenck
Lilly Research Laboratories,
Greenfield, IN

3. General Design

  1. The study was designed to test the prophylactic effectiveness of monensin against Eimeria bovis infections in calves.
  2. Thirty-two calves, 6 weeks old, male Holstein, obtained as 1-3 day old calves and fed milk replacer until weaning at 4 weeks of age.
  3. Treatments
    1. Noninfected, nonmedicated controls (2 x 4 calves)
    2. Infected, nonmedicated controls (2 x 4 calves)
    3. Infected, monensin 15 g/ton (2 x 4 calves)
    4. Infected, monensin 30 g/ton (2 x 4 calves)
  4. Coccidia Challenge

    72 hrs. after initiation of the feeding regiment, each calf was given 100,000 oocysts of E. bovis (isolate LB7, Lot 60176) by oral inoculation.

  5. Rations and Administration

    A pelleted cattle ration containing levels of 0, 15 and 30 g monensin per ton was fed during the 28-day experiment.

  6. Experimental Design

    Each treatment was fed to two groups of 4 calves each. Calves were distributed to pens on a weight basis, to achieve approximately equal pen weights.

    Each pen was supplied with the appropriate feed ad libitum and pine shavings used for bedding. At the onset of oocyst passage, bedding material was removed and the total fecal output was collected on a daily basis. Calves were weighed individually at the time of the infection and subsequently at 7-day intervals until termination at 28 days post-infection. The following data were collected: Clinical observations, daily oocyst passage per pen, weight gain, individual weight gain and feed consumption per pen.

4. Results

  1. Clinical Observations

    Diarrhea and anorexia were noted in both infected control groups from day 12 through day 21 post-infection. No untoward effects were seen in any other treatments.

  2. Oocyst Passage per Pen

    Substantial oocyst passage was noted on days 19-28 post-infection in both infected control groups.

Monensin (g/t) Infection Total Oocyst Passage
Calf (x 10 degrees)
0 + 58.7
0 - 0
15 + ---*
30 + 0

*Positive, but too few to count

Weight Gain/Calf

Monensin Conc. (g/t) Total Gain/Infection Calf (lbs) Average Daily Gain(lbs)
0 + 47.75 1.54
0 - 56.75 1.83
15 + 62.67 2.02
30 + 63.00 2.03

Feed Consumption and Feed/Gain

Monensin Conc.(g/t) Infection Feed Consumption (lbs/calf) Feed/Gain
0 + 142.8 3.00
0 - 157.3 2.77
15 + 155.0 2.48
30 + 154.3 2.45

5. Statistical Analysis

The data from this equipment were not statistically analyzed.

6. Conclusions

Monensin was effective in preventing bovine coccidiosis due to Eimeria bovis and E. zuernii when fed continuously at 15 and 30 g/ton in a complete feed. Control animals suffered depressed weight gain during the patent period but recovered by the end of the experiment.

7. Adverse Reactions

There were no adverse reactions attributable to the drug.

4. B. Corroborative Effectiveness Study

B. Corroborative Study

1. Comparison of Two Forms and Two Levels of Lasalocid with Monensin on Feedlot Cattle Performance. Journal of Animal Science, Vol. 53, No. 6, 1981, pages 1440-1445.

2. Investigators:

L. L. Berger, S. C. Ricke and G. C. Fahey, Jr.
University of Illinois
Urbana, IL 61801

3. General Design:

The purpose of these trials as regards anticoccidial activity was to determine the effects of lasalocid and monensin on the incidence and concentrations of coccidia oocysts.

4. Summary and Conclusions

Results:

Refer to Tables 3 and 5 below of the study. Monensin and lasalocid decreased the incidence and concentration of coccidial oocysts.

Table 3 (eds. note, the following table includes 7 columns)

Coccidiostatic Effect of Two Forms of Lasalocid and Monensin in Trial 1

  % of Steers with Coccidia Oocysts Oocysts/g*
Treatment Day 1 Day 40 Day 120 Day 1 Day 40 Day 120
Control 70.8 41.5 58.3 495 275 715
Pure Lasalocid 79 4.2 21.0 883 50 200
Mycelia-Cake Lasalocid 58.3 4.2 8.5 833 50 100
Monensin 62.9 4.2 4.2 1,104 50 100
SE** 7.2 4.6 5.4 172 40.4 105.3

*Average concentration for those steers shedding oocysts.
** Standard error of the mean.

Table 5 (eds. note, the following table includes 7 columns)
Coccidiostatic Effect of Lasalocid at 30 and 45 g/ton and of Monensin at 30 g/ton

  % of Steers with Coccidia Oocysts Oocysts/g*
Treatment Day 1 Day 40 Day 120 Day 1 Day 40 Day 120
Control 66.9 10.2 6.3 742 19.7 12.5
Lasalocid, 30 g/ton 71.5 4.2 0 703 12.0 0
Lasalocid, 45 g/ton 63.1 5.1 0 794 10.3 0
Monensin, 30 g/ton 69.3 0 0 603 0 0
SE** 10.3 2.7 3 179.7 6.3 6.2

* Average concentration for those steers shedding oocysts.
** Standard error of the mean.

V. ANIMAL SAFETY:

Monensin premix is the subject of an approved NADA 095-735. The conditions of the existing approval are described in 21CFR 558.355. The feeding levels and rates proposed in this supplemental NADA providing for the control of bovine coccidiosis are essentially the same as for the existing approval. The differences involve changing the lower feeding level/rates of 5-30 g/ton and 50-360 mg/hd/day and providing 10-30 g/ton and 100-360 mg/hd/day when used for the control of coccidiosis. The duration of feeding will not exceed that already approved in the cited regulation. There is no reason to conclude that this additional approval at essentially the same levels will adversely affect the safety of animals receiving monensin.

VI. HUMAN FOOD SAFETY:

This information is addressed in the original FOI for monensin for cattle in confinement for slaughter (FR 58289-58290, Vol:40, No. 242, December 16, 1975).

VII. AGENCY CONCLUSIONS:

The data submitted in support of this supplemental NADA satisfy the requirements of section 512 of the Act and 21CFR 558 of the implementing regulations. It demonstrates that monensin (Type A medicated article) is safe and effective for the indications stated on the product labeling. The supplement provides for a new claim, the use of monensin in feedlot cattle for the prevention of coccidiosis caused by Eimeria bovis and E. zuernii.

Monensin sodium for use in food producing animals is an over the counter product. Accurate diagnosis can be made with reasonable degree of certainty by the layman, and the conditions for use prescribed on the labeling are likely to be followed in the practice. Therefore, the Center for Veterinary Medicine has concluded that this product remains under over-the-counter marketing status.

According to the Center's provisions of 21CFR 514.106 (2) (vii) this is a Category II change because the claim was expanded for the use of monensin in feedlot cattle to prevent coccidiosis caused by E. bovis and E. zuernii. It was concluded that the approval of this supplement neither poses an increased human risk from exposure to the drug nor alters the condition of the drug's safety in cattle.

The approved monensin sodium premix is codified in section 21CFR 558.355 as a Type A medicated article for use in broiler chickens, turkeys, replacement chickens intended for use as cage layers, bobwhite quail, and goats for the prevention of coccidiosis, and in cattle for the improvement of feed efficiency. The tolerance is codified in section 21CFR 556.420 (a) and is established at 0.05 part per million for negligible residues of monensin in the edible tissues of cattle and goats. Withdrawal time before slaughter is not required.

VIII. LABELING (Attached)

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

Food and Drug Administration
Freedom of Information Staff (HFI-35)
5600 Fishers Lane
Rockville, MD 20857

Or requests may be sent via fax to: (301) 443-1726. If there are problems sending a fax, call (301) 443-2414.

Page Last Updated: 06/16/2015
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