#### § 558.363 Narasin.

(a) *Specifications.* Type A medicated articles containing 36, 45, 54, 72, or 90 grams narasin per pound.

(b) *Sponsor.* See No. 058198 in [§ 510.600(c) of this chapter](/on/2024-09-23/title-21/section-510.600#p-510.600(c)).

(c) *Tolerances.* See [§ 556.428 of this chapter](/on/2024-09-23/title-21/section-556.428).

(d) *Special considerations.* An expiration date of 2 months (8 weeks) is required for narasin Type C medicated swine feeds.

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

(1) *Chickens* —

| Narasin grams/ton | Combination in grams/ton | Indications for use | Limitations | Sponsor |
| --- | --- | --- | --- | --- |
| (i) 54 to 90 | | Broiler chickens: For prevention of coccidiosis caused by *Eimeria necatrix, E. tenella, E. acervulina, E. brunetti, E. mivati,* and *E. maxima* | For broiler chickens only. Feed continuously as sole ration. Do not allow adult turkeys, horses, or other equines access to narasin formulations. Ingestion of narasin by these species has been fatal | 058198 |
| (ii) 54 to 72 | Bacitracin methylenedisalicylate, 10 to 50 | Broiler chickens: For 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 | For broiler chickens only. Feed continuously as sole ration. Do not feed to laying hens. Do not allow adult turkeys, horses, or other equines access to narasin formulations. Ingestion of narasin by these species has been fatal. Bacitracin methylenedisalicylate as provided by No. 054771 in [§ 510.600(c) of this chapter](/on/2024-09-23/title-21/section-510.600#p-510.600(c)) | 054771 |
| (iii) 54 to 72 | Bacitracin zinc, 4 to 50 | Broiler chickens: For 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 | For broiler chickens only. Feed continuously as sole ration. Do not allow adult turkeys, horses, or other equines access to narasin formulations. Ingestion of narasin by these species has been fatal. Bacitracin zinc as provided by No. 054771 in [§ 510.600(c) of this chapter](/on/2024-09-23/title-21/section-510.600#p-510.600(c)) | 054771 |
| (iv) 54 to 72 | Bambermycins, 1 to 2 | Broiler chickens: For 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 | For broiler chickens only. Feed continuously as sole ration. Do not allow adult turkeys, horses, or other equines access to narasin formulations. Ingestion of narasin by these species has been fatal. Bambermycins as provided by No. 016592 in [§ 510.600(c) of this chapter](/on/2024-09-23/title-21/section-510.600#p-510.600(c)) | 016592 |

(2) *Swine* —

| Narasin grams/ton | Combination in grams/ton | Indications for use | Limitations | Sponsor |
| --- | --- | --- | --- | --- |
| (i) 13.6 to 27.2 | | Growing-finishing swine: For increased rate of weight gain when fed for at least 4 weeks | Feed continuously for at least 4 weeks to swine during the growing-finishing period as the sole ration. No increased benefit in rate of weight gain has been shown when narasin concentrations in the diet are greater than 13.6 g/ton. Effectiveness has not been demonstrated when fed for durations less than 4 weeks. Do not allow adult turkeys, horses, or other equines access to narasin formulations. Ingestion of narasin by these species has been fatal. Not approved for use in breeding animals because safety and effectiveness have not been evaluated in these animals. Swine being fed with narasin should not have access to feeds containing pleuromutilins (*e.g.*, tiamulin) as adverse reactions may occur. If signs of toxicity occur, discontinue use | 058198 |
| (ii) 18.1 to 27.2 | | Growing-finishing swine: For increased rate of weight gain and improved feed efficiency when fed for at least 4 weeks | Feed continuously for at least 4 weeks to swine during the growing-finishing period as the sole ration. No increased benefit in rate of weight gain has been shown when narasin concentrations in the diet are greater than 13.6 g/ton. Effectiveness has not been demonstrated when fed for durations less than 4 weeks. Do not allow adult turkeys, horses, or other equines access to narasin formulations. Ingestion of narasin by these species has been fatal. Not approved for use in breeding animals because safety and effectiveness have not been evaluated in these animals. Swine being fed with narasin should not have access to feeds containing pleuromutilins (*e.g.*, tiamulin) as adverse reactions may occur. If signs of toxicity occur, discontinue use | 058198 |

(3) Narasin single-ingredient Type A medicated articles may also be used in combination with:

(i) Avilamycin as in [§ 558.68](/on/2024-09-23/title-21/section-558.68).

(ii) [Reserved]

[[83 FR 64741](https://www.federalregister.gov/citation/83-FR-64741), Dec. 18, 2018, as amended at [86 FR 14825](https://www.federalregister.gov/citation/86-FR-14825), Mar. 19, 2021]