#### § 558.355 Monensin.

(a) *Specifications.* Type A medicated articles containing 45, 60, 90.7, or 110 grams monensin, USP, per pound.

(b) *Sponsors.* See sponsors in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) as follows:

(1) No. 058198 for use as in [paragraph (f)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)) of this section.

(2) No. 016592 for use of a Type A medicated article containing 90.7 grams monensin, USP, per pound as in [paragraphs (f)(3)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(3)), [(f)(4)(v)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(4)(v)), and [(f)(6)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(6)) of this section.

(c) *Related tolerances.* See [§ 556.420 of this chapter](/on/2024-09-17/title-21/section-556.420).

(d) *Special considerations.*

(1) Type C chicken feed containing monensin as the mycelial cake shall bear an expiration date of 90 days after its date of manufacture.

(2)-(3) [Reserved]

(4) Liquid Type B feeds shall bear an expiration date of 8 weeks after its date of manufacture.

(5) All Type A medicated articles containing monensin shall bear the following warning statement: When mixing and handling monensin Type A medicated articles, use protective clothing, impervious gloves, and a dust mask. Operators should wash thoroughly with soap and water after handling. If accidental eye contact occurs, immediately rinse thoroughly with water.

(6) All formulations containing monensin shall bear the following caution statement: Do not allow horses or other equines access to feed containing monensin. Ingestion of monensin by horses has been fatal.

(7) Type A medicated articles containing monensin intended for use in cattle and goats shall bear, in addition to the caution statement in [paragraph (d)(6)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(6)) of this section, the following statements:

(i) Monensin medicated cattle and goat feeds are safe for use in cattle and goats only. Consumption by unapproved species may result in toxic reactions.

(ii) Feeding undiluted or mixing errors resulting in high concentrations of monensin has been fatal to cattle and could be fatal to goats.

(iii) Must be thoroughly mixed in feeds before use.

(iv) Do not feed undiluted.

(v) Do not exceed the levels of monensin recommended in the feeding directions, as reduced average daily gains may result.

(vi) Do not feed to lactating goats.

(vii) If feed refusals containing monensin are fed to other groups of cattle, the concentration of monensin in the refusals and amount of refusals fed should be taken into consideration to prevent monensin overdosing (see [paragraphs (d)(10)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(10)(i)) and [(d)(10)(ii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(10)(ii)) of this section).

(viii) A withdrawal period has not been established for this product in pre-ruminating calves. Do not use in calves to be processed for veal.

(ix) You may notice the following: Reduced voluntary feed intake in dairy cows fed monensin. This reduction increases with higher doses of monensin fed. Rule out monensin as the cause of reduced feed intake before attributing to other causes such as illness, feed management, or the environment. Reduced milk fat percentage in dairy cows fed monensin. This reduction increases with higher doses of monensin fed. Increased incidence of cystic ovaries and metritis in dairy cows fed monensin. Reduced conception rates, increased services per animal, and extended days open and corresponding calving intervals in dairy cows fed monensin. Have a comprehensive and ongoing nutritional, reproductive, and herd health program in place when feeding monensin to dairy cows.

(x) Inadequate mixing (recirculation or agitation) of monensin liquid Type B or Type C medicated feeds has resulted in increased monensin concentration which has been fatal to cattle and could be fatal to goats.

(8) Type A medicated articles containing monensin intended for use in chickens, turkeys, and quail shall bear the following statements:

(i) Do not allow horses, other equines, mature turkeys, or guinea fowl access to feed containing monensin. Ingestion of monensin by horses and guinea fowl has been fatal.

(ii) Must be thoroughly mixed in feeds before use.

(iii) Do not feed undiluted.

(iv) Do not feed to laying chickens.

(v) Do not feed to chickens over 16 weeks of age.

(vi) Not for broiler breeder replacement chickens.

(vii) Some strains of turkey coccidia may be monensin tolerant or resistant. Monensin may interfere with development of immunity to turkey coccidiosis.

(viii) In the absence of coccidiosis in broiler chickens the use of monensin with no withdrawal period may limit feed intake resulting in reduced weight gain.

(9) Type B feeds containing monensin shall bear the statements specified in the following paragraphs of this section when intended for use in:

(i) *Cattle (as described in [paragraphs (f)(3)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(3)(i)) through [(iii)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(3)(iii)), [(vi)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(3)(vi)), and [(vii)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(3)(vii)) and [(f)(4)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(4)(i)) through [(vi)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(4)(vi)) of this section).* See [paragraphs (d)(6)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(6)) and [(d)(7)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(i)) through [(v)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(v)), [(vii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(vii)), and [(viii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(viii)) of this section.

(ii) *Dairy cows (as described in [paragraphs (f)(3)(iv)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(3)(iv)) and [(v)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(3)(v)) of this section).* See [paragraphs (d)(6)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(6)) and [(d)(7)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(i)) through [(iv)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(iv)), [(vii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(vii)), [(viii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(viii)), and [(ix)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(ix)) of this section.

(iii) *Goats* : See [paragraphs (d)(6)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(6)) and [(d)(7)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(i)) through [(d)(7)(vi)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(vi)) of this section.

(iv) *Chickens* : See [paragraphs (d)(8)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(i)) through [(d)(8)(vi)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(vi)), and [(d)(8)(viii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(viii)) of this section.

(v) *Turkeys:* See [paragraphs (d)(8)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(i)), [(d)(8)(ii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(ii)), [(d)(8)(iii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(iii)), and [(d)(8)(vii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(vii)) of this section.

(vi) *Quail* : See [paragraphs (d)(8)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(i)), [(d)(8)(ii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(ii)), and [(d)(8)(iii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(iii)) of this section.

(10) Type C feeds containing monensin shall bear the statements specified in the following paragraphs of this section when intended for use in:

(i) *Cattle (as described in [paragraphs (f)(3)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(3)(i)) through [(iii)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(3)(iii)), [(vi)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(3)(vi)), and [(vii)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(3)(vii)) and [(f)(4)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(4)(i)) through [(vi)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(4)(vi)) of this section).* See [paragraphs (d)(6)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(6)) and [(d)(7)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(i)), [(v)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(v)), [(vii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(vii)), and [(viii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(viii)) of this section. [Paragraph (d)(7)(vii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(vii)) of this section does not apply to free-choice Type C medicated feeds as defined in [§ 510.455 of this chapter](/on/2024-09-17/title-21/section-510.455).

(ii) *Dairy cows (as described in [paragraphs (f)(3)(iv)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(3)(iv)) and [(v)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(3)(v)) of this section).* See [paragraphs (d)(6)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(6)) and [(d)(7)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(i)), [(vii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(vii)), [(viii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(viii)), and [(ix)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(ix)) of this section. [Paragraph (d)(7)(vii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(vii)) of this section does not apply to free-choice Type C medicated feeds as defined in [§ 510.455 of this chapter](/on/2024-09-17/title-21/section-510.455).

(iii) *Goats* : See [paragraphs (d)(6)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(6)), [(d)(7)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(i)), [(d)(7)(v)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(v)), and [(d)(7)(vi)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(vi)) of this section.

(iv) *Chickens* : See [paragraphs (d)(8)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(i)), [(d)(8)(iv)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(iv)), [(d)(8)(v)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(v)), [(d)(8)(vi)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(vi)), and [(d)(8)(viii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(viii)) of this section.

(v) *Turkeys* : See [paragraphs (d)(8)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(i)) and [(d)(8)(vii)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(vii)) of this section.

(vi) *Quail* : See [paragraph (d)(8)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(8)(i)) of this section.

(11) Type B and Type C liquid feeds requiring recirculation or agitation that contain monensin and are intended for use in cattle (including dairy cows) and goats shall bear the caution statement specified in [paragraph (d)(7)(x)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(7)(x)) of this section.

(12) Mixing directions for liquid feeds requiring recirculation or agitation:

(i) For liquid feeds stored in recirculating tank systems: Recirculate immediately prior to use for not less than 10 minutes, moving not less than 1 percent of the tank contents per minute from the bottom of the tank to the top. Recirculate daily as described even when not used.

(ii) For liquid feeds stored in mechanical, air, or other agitation-type tank systems: Agitate immediately prior to use for not less than 10 minutes, creating a turbulence at the bottom of the tank that is visible at the top. Agitate daily as described even when not used.

(e) [Reserved]

(f) *Conditions of use.* It is used as follows:

(1) *Chickens* —

| Monensin in grams/ton | Combination in grams/ton | Indications for use | Limitations | Sponsor |
| --- | --- | --- | --- | --- |
| (i) 90 to 110 | | Broiler chickens: As an aid in the prevention of coccidiosis caused by *E. necatrix, E. tenella, E. acervulina, E. brunetti, E. mivati,* and *E. maxima* | Feed continuously as the sole ration. In the absence of coccidiosis, the use of monensin with no withdrawal period may limit feed intake resulting in reduced weight gain. Do not feed to laying chickens | 058198 |
| (ii) 90 to 110 | | Layer replacement chickens: As an aid in the prevention of coccidiosis caused by *E. necatrix, E. tenella, E. acervulina, E. brunetti, E. mivati,* and *E. maxima* | Feed continuously as the sole ration. Do not feed to chickens over 16 weeks of age. Do not feed to laying chickens | 058198 |
| (iii) 90 to 110 | Bacitracin methylenedisalicylate, 4 to 50 | Broiler chickens: As an aid in the prevention of coccidiosis caused by *E. necatrix, E. tenella, E. acervulina, E. brunetti, E. mivati,* and *E. maxima,* and for improved feed efficiency | Feed continuously as sole ration. In the absence of coccidiosis, the use of monensin with no withdrawal period may limit feed intake resulting in reduced weight gain. Do not feed to laying chickens. Bacitracin methylenedisalicylate provided by No. 054771 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 054771 |
| (iv) 90 to 110 | Bacitracin methylenedisalicylate, 4 to 50 | Broiler chickens: As an aid in the prevention of coccidiosis caused by *Eimeria necatrix, E. tenella, E. acervulina, E. brunetti, E. mivati,* and *E. maxima,* and for increased rate of weight gain and improved feed efficiency | Feed as the sole ration throughout the feeding period. Do not feed to laying chickens. Do not feed to chickens over 16 weeks of age. Do not allow horses, other equines, mature turkeys, or guinea fowl access to feed containing monensin. Ingestion of monensin by horses and guinea fowl has been fatal. In the absence of coccidiosis in broiler chickens, the use of monensin with no withdrawal period may limit feed intake resulting in reduced weight gain. Not for broiler breeder replacement chickens. Monensin provided by No. 058198, bacitracin methylenedisalicylate provided by No. 069254 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 069254 |
| (v) 90 to 110 | Bacitracin methylenedisalicylate, 4 to 50 | Laying hen replacement chickens and layer breeder replacement chickens: As an aid in the prevention of coccidiosis caused by *Eimeria necatrix, E. tenella, E. acervulina, E. brunetti,* *E. mivati,* and *E. maxima,* and for increased rate of weight gain and improved feed efficiency | Feed as the sole ration throughout the feeding period. Do not feed to laying chickens. Do not feed to chickens over 16 weeks of age. Do not allow horses, other equines, mature turkeys, or guinea fowl access to feed containing monensin. Ingestion of monensin by horses and guinea fowl has been fatal. Not for broiler breeder replacement chickens. Monensin provided by No. 058198, bacitracin methylenedisalicylate provided by No. 069254 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 069254 |
| (vi) 90 to 110 | Bacitracin methylenedisalicylate, 4 to 50 | Layer replacement chickens: As an aid in the prevention of coccidiosis caused by *E. necatrix, E. tenella, E. acervulina, E. brunetti, E. mivati,* and *E. maxima,* and for increased rate of weight gain and improved feed efficiency | Feed continuously as sole ration. Do not feed to chickens over 16 weeks of age. Do not feed to laying chickens. Monensin sodium provided by No. 058198, bacitracin methylenedisalicylate provided by No. 054771 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 054771 |
| (vii) 90 to 110 | Bacitracin methylenedisalicylate, 5 to 25 | Broiler chickens: As an aid in the prevention of coccidiosis caused by *E. necatrix, E. tenella, E. acervulina, E. brunetti, E. mivati,* and *E. maxima,* and for increased rate of weight gain and improved feed efficiency | Feed continuously as sole ration. In the absence of coccidiosis, the use of monensin with no withdrawal period may limit feed intake resulting in reduced weight gain. Do not feed to laying chickens. Bacitracin methylenedisalicylate provided by No. 054771 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 058198 |
| (viii) 90 to 110 | Bacitracin methylenedisalicylate, 50 | Broiler chickens: As an aid in the prevention of coccidiosis caused by *Eimeria necatrix, E. tenella, E. acervulina, E. brunetti, E. mivati,* and *E. maxima,* and for the prevention of mortality caused by necrotic enteritis associated with *Clostridium perfringens* | Feed as the sole ration for 28 to 35 days, starting from the time chicks are placed for brooding. Do not feed to laying chickens. Do not feed to chickens over 16 weeks of age. Do not allow horses, other equines, mature turkeys, or guinea fowl access to feed containing monensin. Ingestion of monensin by horses and guinea fowl has been fatal. In the absence of coccidiosis in broiler chickens, the use of monensin with no withdrawal period may limit feed intake resulting in reduced weight gain. Not for broiler breeder replacement chickens. Monensin provided by No. 058198, bacitracin methylenedisalicylate provided by No. 069254 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 069254 |
| (ix) 90 to 110 | Bacitracin methylenedisalicylate, 50 | Laying hen replacement chickens and layer breeder replacement chickens: As an aid in the prevention of coccidiosis caused by *Eimeria necatrix, E. tenella, E. acervulina, E. brunetti, E. mivati,* and *E. maxima,* and for the prevention of mortality caused by necrotic enteritis associated with *Clostridium perfringens* | Feed as the sole ration for 28 to 35 days, starting from the time chicks are placed for brooding. Do not feed to laying chickens. Do not feed to chickens over 16 weeks of age. Do not allow horses, other equines, mature turkeys, or guinea fowl access to feed containing monensin. Ingestion of monensin by horses and guinea fowl has been fatal. Not for broiler breeder replacement chickens. Monensin provided by No. 058198, bacitracin methylenedisalicylate provided by No. 069254 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 069254 |
| (x) 90 to 110 | Bacitracin methylenedisalicylate, 50 | Broiler and layer replacement chickens: As an aid in the prevention of coccidiosis caused by *E. necatrix, E. tenella, E. acervulina, E. brunetti, E. mivati,* and *E. maxima,* and for improved feed efficiency, and as an aid in the prevention of necrotic enteritis caused or complicated by *Clostridium* spp. or other organisms susceptible to bacitracin | Feed continuously as sole ration. Do not feed to chickens over 16 weeks of age. Do not feed to laying chickens. Monensin sodium provided by No. 058198, bacitracin methylenedisalicylate provided by No. 054771 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 054771 |
| (xi) 90 to 110 | Bacitracin zinc, 4 to 50 | Broiler chickens: As an aid in the prevention of coccidiosis caused by *E. necatrix, E. tenella, E. acervulina, E. brunetti, E. mivati,* and *E. maxima,* and for increased rate of weight gain and improved feed efficiency | Feed continuously as sole ration. In the absence of coccidiosis, the use of monensin with no withdrawal period may limit feed intake resulting in reduced weight gain. Do not feed to laying chickens. Bacitracin zinc provided by No. 054771 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 054771 |
| (xii) 90 to 110 | Bacitracin zinc, 10 | Broiler chickens: As an aid in the prevention of coccidiosis caused by *E. necatrix, E. tenella, E. acervulina, E. brunetti, E. mivati,* and *E. maxima,* and for increased rate of weight gain and improved feed efficiency | Feed continuously as sole ration. In the absence of coccidiosis, the use of monensin with no withdrawal period may limit feed intake resulting in reduced weight gain. Do not feed to laying chickens. Bacitracin zinc provided by No. 054771 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 058198 |
| (xiii) 90 to 110 | Bacitracin zinc, 10 to 30 | Broiler chickens: As an aid in the prevention of coccidiosis caused by *E. necatrix, E. tenella, E. acervulina, E. brunetti, E. mivati,* and *E. maxima,* and for improved feed efficiency | Feed continuously as sole ration. In the absence of coccidiosis, the use of monensin with no withdrawal period may limit feed intake resulting in reduced weight gain. Do not feed to laying chickens. Bacitracin zinc provided by No. 054771 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 058198 |
| (xiv) 90 to 110 | Bambermycins, 1 to 2 | Broiler chickens: As an aid in the prevention of coccidiosis caused by *E. necatrix, E. tenella, E. acervulina, E. brunetti, E. mivati,* and *E. maxima,* and for increased rate of weight gain and improved feed efficiency | Feed continuously as sole ration. Do not feed to laying chickens. Bambermycins provided by No. 016592 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 016592, 058198 |

(2) *Turkeys* —

| Monensin in grams/ton | Combination in grams/ton | Indications for use | Limitations | Sponsor |
| --- | --- | --- | --- | --- |
| (i) 54 to 90 | | Growing turkeys: For the prevention of coccidiosis caused by *E. adenoeides, E. meleagrimitis,* and *E. gallopavonis* | For growing turkeys only. Feed continuously as sole ration. Some strains of turkey coccidia may be monensin tolerant or resistant. Monensin may interfere with development of immunity to turkey coccidiosis. Do not allow horses, other equines, mature turkeys, or guinea fowl access to feed containing monensin. Ingestion of monensin by horses and guinea fowl has been fatal | 058198 |
| (ii) 54 to 90 | Bacitracin methylenedisalicylate, 4 to 50 | Growing turkeys: For the prevention of coccidiosis caused by *Eimeria adenoeides, E. meleagrimitis,* and *E. gallopavonis,* and for increased rate of weight gain and improved feed efficiency | Feed continuously as the sole ration. The optimum level depends upon the severity of coccidiosis exposure. Do not allow horses, other equines, mature turkeys, or guinea fowl access to feed containing monensin. Ingestion of monensin by horses and guinea fowl has been fatal. Some strains of turkey coccidia may be monensin tolerant or resistant. Monensin may interfere with development of immunity to turkey coccidiosis. Bacitracin methylenedisalicylate as provided by No. 054771 or 069254 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 058198 069254 |
| (iii) 54 to 90 | Bacitracin methylenedisalicylate, 200 | Growing turkeys: For the prevention of coccidiosis caused by *E. adenoeides, E. meleagrimitis,* and *E. gallopavonis,* and as an aid in the control of transmissible enteritis complicated by organisms susceptible to bacitracin methylenedisalicylate | For growing turkeys only. Feed continuously as sole ration. Some strains of turkey coccidia may be monensin tolerant or resistant. Monensin may interfere with development of immunity to turkey coccidiosis. Do not allow horses, other equines, mature turkeys, or guinea fowl access to feed containing monensin. Ingestion of monensin by horses and guinea fowl has been fatal. Bacitracin methylenedisalicylate as provided by No. 054771 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 058198 |
| (iv) 54 to 90 | Bambermycins, 1 to 2 | Growing turkeys: For the prevention of coccidiosis in turkeys caused by *E. adenoeides, E. meleagrimitis,* and *E. gallopavonis,* and for improved feed efficiency | For growing turkeys only. Feed continuously as sole ration. Some strains of turkey coccidia may be monensin tolerant or resistant. Monensin may interfere with development of immunity to turkey coccidiosis. Bambermycins as provided by No. 016592 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 058198 |
| (v) 54 to 90 | Bambermycins, 2 | Growing turkeys: For the prevention of coccidiosis caused by *E. adenoeides, E. meleagrimitis,* and *E. gallopavonis,* and for increased rate of weight gain and improved feed efficiency | For growing turkeys only. Feed continuously as sole ration. Some strains of turkey coccidia may be monensin tolerant or resistant. Monensin may interfere with development of immunity to turkey coccidiosis. Bambermycins as provided by No. 016592 in [§ 510.600(c) of this chapter](/on/2024-09-17/title-21/section-510.600#p-510.600(c)) | 058198 |

(3) *Cattle* —

| Monensin in grams/ton | Indications for use | Limitations | Sponsor |
| --- | --- | --- | --- |
| (i) 5 to 40 | Growing beef steers and heifers fed in confinement for slaughter: For improved feed efficiency | Feed continuously in complete feed at a rate of 50 to 480 milligrams of monensin per head per day. No additional improvement in feed efficiency has been shown from feeding monensin at levels greater than 30 grams per ton (360 milligrams per head per day). See special labeling considerations in [paragraph (d)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)) of this section | 016592 058198 |
| (ii) 10 to 40 | Growing beef steers and heifers fed in confinement for slaughter: For prevention and control of coccidiosis due to *Eimeria bovis* and *E. zuernii* | Feed at a rate of 0.14 to 0.42 milligram per pound of body weight per day, depending upon the severity of challenge, up to maximum of 480 milligrams per head per day. See special labeling considerations in [paragraph (d)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)) of this section | 016592 058198 |
| (iii) 10 to 200 | Calves excluding veal calves: For prevention and control of coccidiosis due to *Eimeria bovis* and *E. zuernii* | Feed at a rate of 0.14 to 1.0 milligram monensin per pound of body weight per day, depending upon the severity of challenge, up to maximum of 200 milligrams per head per day. See special labeling considerations in [paragraph (d)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)) of this section | 016592 058198 |
| (iv) 11 to 22 | Dairy cows: For increased milk production efficiency (production of marketable solids-corrected milk per unit of feed intake) | Feed continuously to dry and lactating dairy cows in a total mixed ration (“complete feed”). See special labeling considerations in [paragraph (d)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)) of this section | 016592 058198 |
| (v) 11 to 400 | Dairy cows: For increased milk production efficiency (production of marketable solids-corrected milk per unit of feed intake) | Feed continuously to dry and lactating dairy cows in a component feeding system (including top dress). The Type C medicated feed must be fed in a minimum of 1 lb of feed to provide 185 to 660 mg/head/day monensin to lactating cows or 115 to 410 mg/head/day monensin to dry cows. See special labeling considerations in [paragraph (d)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)) of this section | 016592 058198 |
| (vi) 15 to 400 | Growing beef steers and heifers on pasture (stocker, feeder, and slaughter) or in a dry lot and replacement beef and dairy heifers: For increased rate of weight gain, and for prevention and control of coccidiosis due to *Eimeria bovis* and *E. zuernii* | For increased rate of weight gain, feed at a rate of 50 to 200 milligrams monensin per head per day in not less than 1 pound of feed or, after the 5th day, feed at a rate of 400 milligrams per head per day every other day in not less than 2 pounds of feed. For prevention and control of coccidiosis, feed at a rate of 0.14 to 0.42 milligram per pound of body weight per day, depending on severity of challenge, up to 200 milligrams per head per day. During first 5 days of feeding, cattle should receive no more than 100 milligrams per day in not less than 1 pound of feed. See special labeling considerations in [paragraph (d)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)) of this section | 016592 058198 |
| (vii) 25 to 400 | Beef cows: For improved feed efficiency when receiving supplemental feed, and for the prevention and control of coccidiosis due to *Eimeria bovis* and *E. zuernii* | Feed as supplemental feed, either hand-fed in a minimum of 1 pound of feed or mixed in a total ration. For improved feed efficiency, feed continuously at a rate of 50 to 200 milligrams monensin per head per day. For prevention and control of coccidiosis, feed at a rate of 0.14 to 0.42 milligram per pound of body weight per day, depending upon severity of challenge, up to a maximum of 200 milligrams per head per day. During first 5 days of feeding, cattle should receive no more than 100 milligrams per head per day in not less than 1 pound of feed. See special labeling considerations in [paragraph (d)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)) of this section | 016592 058198 |

(4) *Free-choice cattle feeds* —

| Monensin amount | Indications for use | Limitations | Sponsor |
| --- | --- | --- | --- |
| (i) 150 milligrams per pound of protein-mineral block (0.033%) | Growing beef steers and heifers on pasture (stocker, feeder, and slaughter) and replacement beef heifers on pasture: For increased rate of weight gain, and for prevention and control of coccidiosis caused by *Eimeria bovis* and *E. zuernii* in pasture cattle which may require supplemental feed | Provide 50 to 200 milligrams of monensin (0.34 to 1.33 pounds of block) per head per day, at least 1 block per 10 to 12 head of cattle. Roughage must be available at all times. Do not allow animals access to other protein blocks, salt or mineral, while being fed this product. See [paragraph (d)(10)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(10)(i)) of this section | 012286 |
| (ii) 175 milligrams per pound of protein-mineral block (0.038%) | Growing beef steers and heifers on pasture (stocker, feeder, and slaughter): For increased rate of weight gain | Provide 40 to 200 milligrams of monensin (0.25 to 1.13 pounds or 4 to 18 ounces of block) per head per day, at least 1 block per 4 head of cattle. Do not allow cattle access to salt or mineral while being fed this product. Ingestion by cattle of monensin at levels of 600 milligrams per head per day and higher has been fatal. See [paragraph (d)(10)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(10)(i)) of this section | 017800 |
| (iii) 400 milligrams per pound of protein-mineral block (0.088%) | Pasture cattle (slaughter, stocker, feeder, and dairy and beef replacement heifers): For increased rate of weight gain | Provide 80 to 200 milligrams of monensin (0.2 to 0.5 pounds of block) per head per day, at least 1 block per 5 head of cattle. Feed blocks continuously. Do not feed salt or minerals containing salt. The effectiveness of this block in cull cows and bulls has not been established. See [paragraph (d)(10)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(10)(i)) of this section | 067949 |
| (iv) 400 mg per pound of block | Growing beef steers and heifers on pasture (stocker, feeder, and slaughter) and beef replacement heifers): for increased rate of weight gain | Provide 50 to 200 mg of monensin (2 to 8 ounces of block) per head per day, in at least one block per five head of cattle. Feed blocks continuously. Do not feed salt of mineral supplements in addition to this block. Discontinue feeding if block consumption falls below 2 ounces or rises above 8 ounces daily. See [paragraph (d)(10)(i)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(10)(i)) of this section. | 086113 |
| (v) 1,620 grams per ton of mineral granules as specified in [paragraph (f)(4)(v)(A)](/on/2024-09-17/title-21/section-558.355#p-558.355(f)(4)(v)(A)) of this section | Growing beef steers and heifers on pasture (stocker, feeder, and slaughter) or in a dry lot and replacement beef and dairy heifers: For increased rate of weight gain, and for prevention and control of coccidiosis due to *Eimeria bovis* and *E. zuernii* | Feed at a rate of 50 to 200 milligrams per head per day. During the first 5 days of feeding, cattle should receive no more than 100 milligrams per day. Do not feed additional salt or minerals. Do not mix with grain or other feeds. Monensin is toxic to cattle when consumed at higher than approved levels. Stressed and/or feed- and/or water-deprived cattle should be adapted to the pasture and to unmedicated mineral supplement before using the monensin mineral supplement | 016592 058198 |

(A) *Specifications.* Use as free-choice Type C medicated feed formulated as mineral granules as follows:

| Ingredient | Percent | International feed No. |
| --- | --- | --- |
| Monocalcium phosphate (21% phosphorus, 15% calcium) | 29.49 | 6-01-082 |
| Sodium chloride (salt) | 24.37 | 6-04-152 |
| Dried cane molasses | 20.0 | 4-04-695 |
| Ground limestone (33% calcium) or calcium carbonate (38% calcium) | 13.75 | 6-02-632 |
| Cane molasses | 3.0 | 4-04-696 |
| Processed grain by-products (as approved by AAFCO) | 5.0 | |
| Vitamin/trace mineral premix1 | 2.5 | |
| Monensin Type A article, 90.7 grams per pound | 0.89 | |
| Antidusting oil | 1.0 | |
| | | |
| --- | --- | --- |
| 1 Content of vitamin and trace mineral premixes may be varied. However, they should be comparable to those used for other free-choice feeds. Formulation modifications require FDA approval prior to marketing. Selenium must comply with [21 CFR 573.920](/on/2024-09-17/title-21/section-573.920). Ethylenediamine dihydroiodide should comply with FDA Compliance Policy Guide Sec. 651.100 (CPG 7125.18). | | |

(B) [Reserved]

(5) *Bobwhite quail* —

| Monensin in grams/ton | Indications for use | Limitations | Sponsor |
| --- | --- | --- | --- |
| (i) 73 | Growing bobwhite quail: For the prevention of coccidiosis caused by *Eimeria dispersa* and *E. lettyae* | Feed continuously in complete feed at a rate of 50 to 480 milligrams of monensin per head per day. No additional improvement in feed efficiency has been shown from feeding monensin at levels greater than 30 grams per ton (360 milligrams per head per day) | 058198 |
| (ii) [Reserved] | | | |

(6) *Goats* —

| Monensin in grams/ton | Indications for use | Limitations | Sponsor |
| --- | --- | --- | --- |
| (i) 20 | Goats maintained in confinement: For the prevention of coccidiosis caused by *Eimeria crandallis, E. christenseni,* and *E. ninakohlyakimovae* | Feed continuously. Do not feed to lactating goats. See [paragraph (d)(11)](/on/2024-09-17/title-21/section-558.355#p-558.355(d)(11)) of this section for provisions for monensin liquid Type C goat feeds | 016592 058198 |
| (ii) [Reserved] | | | |

(7) Monensin may also be used in combination with:

(i) Avilamycin as in [§ 558.68](/on/2024-09-17/title-21/section-558.68).

(ii) Chlortetracycline as in [§ 558.128](/on/2024-09-17/title-21/section-558.128).

(iii) Decoquinate as in [§ 558.195](/on/2024-09-17/title-21/section-558.195).

(iv) Lubabegron as in [§ 558.330](/on/2024-09-17/title-21/section-558.330).

(v) Lincomycin as in [§ 558.325](/on/2024-09-17/title-21/section-558.325).

(vi) Melengestrol acetate as in [§ 558.342](/on/2024-09-17/title-21/section-558.342).

(vii) Oxytetracycline as in [§ 558.450](/on/2024-09-17/title-21/section-558.450).

(viii) Ractopamine as in [§ 558.500](/on/2024-09-17/title-21/section-558.500).

(ix) Tilmicosin as in [§ 558.618](/on/2024-09-17/title-21/section-558.618).

(x) Tylosin as in [§ 558.625](/on/2024-09-17/title-21/section-558.625).

(xi) Virginiamycin as in [§ 558.635](/on/2024-09-17/title-21/section-558.635).

(xii) Zilpaterol alone or in combination as in [§ 558.665](/on/2024-09-17/title-21/section-558.665).

[[40 FR 13959](https://www.federalregister.gov/citation/40-FR-13959), Mar. 27, 1975]

###### Editorial Note

#### Editorial Note:

For Federal Register citations affecting [§ 558.355](/on/2024-09-17/title-21/section-558.355), see the List of CFR Sections Affected, which appears in the Finding Aids section of the printed volume and at *[www.govinfo.gov](http://www.govinfo.gov).*