21 C.F.R. § 558.55
Amprolium.
Cite as 21 C.F.R. § 558.55 (2026)
(a)
Specifications.
Type A medicated article containing 25 percent amprolium.
(b)
Sponsor.
No. 016592 in § 510.600(c) of this chapter.
(c)
Related tolerances.
See § 556.50 of this chapter.
(d)
Special considerations.
Do not use in Type B or Type C medicated feeds containing bentonite.
(e)
Conditions of use
—(1)
Cattle.
It is used as follows:
Amprolium in grams per ton
Indications for use
Limitations
Sponsor
(i) 113.5 to 11, 350; to provide 5 milligrams per kilogram of body weight per day
Calves: As an aid in the prevention of coccidiosis caused by
Eimeria bovis
and
E. zuernii
Top-dress on or mix in the daily ration. Feed for 21 days when experience indicates that coccidiosis is likely to be a hazard, as the sole source of amprolium. Withdraw 24 hours before slaughter. A withdrawal period has not been established for this product in preruminating calves. Do not use in calves to be processed for veal
016592
(ii) 113.5 to 11, 350; to provide 10 milligrams per kilogram of body weight per day
Calves: As an aid in the treatment of coccidiosis caused by
Eimeria bovis
and
E. zuernii
Top-dress on or mix in the daily ration. Feed for 5 days as the sole source of amprolium. Withdraw 24 hours before slaughter. A withdrawal period has not been established for this product in preruminating calves. Do not use in calves to be processed for veal
016592
(2)
Chickens.
It is used as follows:
Amprolium in grams per ton
Combination in grams per ton
Indications for use
Limitations
Sponsor
(i) 36.3 to 113.5
Replacement chickens: For development of active immunity to coccidiosis
Feed continuously until onset of production as follows:
016592
Growing conditions
Up to 5 weeks of age
From 5 to 8 weeks of age
Over 8 weeks of age
Amprolium in grams per ton
Amprolium in grams per ton
Amprolium in grams per ton
Severe exposure to coccidiosis
113.5
72.6-113.5
36.3-113.5
(0.0125%)
(0.008%-0.0125%)
(0.004%-0.0125%)
Moderate exposure to coccidiosis
72.6-113.5
54.5-113.5
36.3-113.5
(0.008%-0.0125%)
(0.006%-0.0125%)
(0.004%-0.0125%)
Slight exposure to coccidiosis
36.3-113.5
36.3-113.5
36.3-113.5
(0.004%-0.0125%)
(0.004%-0.0125%)
(0.004%-0.0125%)
Amprolium in grams per ton
Combination in grams per ton
Indications for use
Limitations
Sponsor
(ii) 36.3 to 113.5
Bacitracin methylenedisalicylate 4 to 50
Replacement chickens: For development of active immunity to coccidiosis; and for increased rate of weight gain and improved feed efficiency
Feed according to subtable in item (i). Bacitracin methylenedisalicylate as provided by No. 054771 in § 510.600(c) of this chapter
054771
(iii) 72.6 to 113.5
Broiler chickens: For prevention of coccidiosis caused by
Eimeria tenella
only
Feed continuously as the sole ration; as sole source of amprolium
016592
(iv) 72.6 to 113.5
Bambermycins 1 to 2
Broiler chickens: For prevention of coccidiosis caused by
Eimeria tenella
only; and for increased rate of weight gain and improved feed efficiency
Feed continuously as the sole ration; as sole source of amprolium. Bambermycins as provided by No. 016592 in § 510.600(c) of this chapter
016592
(v) 113.5
1. Laying chickens: For prevention of coccidiosis
Feed continuously as the sole ration; as the sole source of amprolium
016592
2. Laying chickens: For treatment of coccidiosis in moderate outbreaks
Feed for 2 weeks
(vi) 113.5 to 227
1. Replacement chickens: For prevention of coccidiosis where immunity to coccidiosis is not desired
Feed continuously from day-old until onset of production; as the sole source of amprolium
016592
2. Broiler chickens: For prevention of coccidiosis where immunity to coccidiosis is not desired
Feed continuously as the sole ration; as sole source of amprolium
(vii) 113.5 to 227
Bambermycins 1 to 2
Broiler chickens: For prevention of coccidiosis where immunity to coccidiosis is not desired; and for increased rate of weight gain and improved feed efficiency
Feed continuously as the sole ration; as sole source of amprolium. Bambermycins as provided by No. 016592 in § 510.600(c) of this chapter
016592
(viii) 227
Laying chickens: For treatment of coccidiosis in severe outbreaks.
Feed for 2 weeks
016592
(3)
Turkeys.
It is used as follows:
Amprolium in grams per ton
Combination in grams per ton
Indications for use
Limitations
Sponsor
(i) 113.5
Bambermycins 1 to 4
Growing turkeys: For prevention of coccidiosis; and for increased rate of weight gain and improved feed efficiency
Feed continuously as the sole source of amprolium; bambermycins as provided by No. 016592 in § 510.600(c) of this chapter
016592
(ii) 113.5 to 227
Turkeys: For prevention of coccidiosis
Feed continuously as the sole ration; as sole source of amprolium
016592
(4)
Pheasants.
It is used as follows:
Amprolium in grams per ton
Combination in grams per ton
Indications for use
Limitations
Sponsor
(i) 159
Growing pheasants: For the prevention of coccidiosis caused by
Eimeria colchici, E. duodenalis,
and
E. phasiani
Feed continuously as sole ration. Use as sole source of amprolium
016592
(ii) [Reserved]
(5)
Permitted combinations.
Amprolium may also be used in combination with:
(i) Virginiamycin as in § 558.635.
(ii) [Reserved]
[41 FR 10985, Mar. 15, 1976]
Editorial Note:
For
Federal Register
citations affecting § 558.55, see the List of CFR Sections Affected, which appears in the Finding Aids section of the printed volume and at
www.govinfo.gov.
- Cross-references to the CFR
- 510.600556.50558.55558.635.