21 C.F.R. § 558.254
Famphur.
Cite as 21 C.F.R. § 558.254 (2026)
(a)
Specifications.
Type A medicated articles containing 13.2 or 33.3 percent famphur.
(b)
Sponsor.
See No. 000061 in § 510.600(c) of this chapter.
(c)
Related tolerances.
See § 556.273 of this chapter.
(d)
Special considerations.
Famphur is a cholinesterase inhibitor. Do not use this product in animals simultaneously or within a few days before or after treatment with or exposure to cholinesterase-inhibiting drugs, pesticides, or chemicals.
(e)
Conditions of use.
It is used in cattle feed as follows:
Famphur amount
Indications for use
Limitations
Sponsor
(1) To provide 1.1 milligrams per pound (mg/lb) body weight per day
Beef cattle and nonlactating dairy cattle: For control of grubs and as an aid in control of sucking lice
Feed for 30 days. Withdraw from dry dairy cows and heifers 21 days prior to freshening. Withdraw 4 days prior to slaughter
000061
(2) To provide 2.3 mg/lb body weight per day
Beef cattle and nonlactating dairy cattle: For control of grubs
Feed for 10 days. Withdraw from dry dairy cows and heifers 21 days prior to freshening. Withdraw 4 days prior to slaughter
000061
[84 FR 39185, Aug. 9, 2019, as amended at 87 FR 17947, Mar. 29, 2022]
- Cross-references to the CFR
- 510.600556.273