Section 522.840 - Estradiol(a)Specifications. Each silicone rubber implant contains 25.7 or 43.9 milligrams (mg) estradiol and is coated with not less than 0.5 mg oxytetracycline powder.(b)Sponsor. See No. 058198 in § 510.600(c) of this chapter.(c)Related tolerances. See § 556.240 of this chapter.(d)Conditions of use - (1)Beef steer calves 2 months of age and older - (i)Amount and indications for use.(A) An extended-release implant containing 25.7 mg estradiol for increased rate of weight gain for up to 200 days.(B) An extended-release implant containing 43.9 mg estradiol for increased rate of weight gain for up to 400 days.(ii)Limitations. For subcutaneous ear implantation only. Not approved for repeated implantation (reimplantation) with this or any other cattle ear implant in beef steer calves 2 months of age and older. Safety and effectiveness following reimplantation have not been evaluated. Do not use in beef calves less than 2 months of age, dairy calves, and veal calves. A withdrawal period has not been established for this product in pre-ruminating calves. Do not use in dairy cows or in animals intended for subsequent breeding. Use in these cattle may cause drug residues in milk and/or in calves born to these cows.(2)Growing beef steers and heifers on pasture (stocker, feeder, and slaughter) - (i)Amount and indications for use.(A) An extended-release implant containing 25.7 mg estradiol for increased rate of weight gain for up to 200 days.(B) An extended-release implant containing 43.9 mg estradiol for increased rate of weight gain for up to 400 days.(ii)Limitations. For subcutaneous ear implantation only. Not approved for repeated implantation (reimplantation) with this or any other cattle ear implant in growing beef steers and heifers on pasture (stocker, feeder, and slaughter). Safety and effectiveness following reimplantation have not been evaluated. Do not use in beef calves less than 2 months of age, dairy calves, and veal calves. A withdrawal period has not been established for this product in pre-ruminating calves. Do not use in dairy cows or in animals intended for subsequent breeding. Use in these cattle may cause drug residues in milk and/or in calves born to these cows.(3)Growing beef steers and heifers fed in confinement for slaughter - (i)Amount and indications for use.(A) An extended-release implant containing 25.7 mg estradiol for increased rate of weight gain and improved feed efficiency for up to 200 days.(B) An extended-release implant containing 43.9 mg estradiol for increased rate of weight gain and improved feed efficiency for up to 400 days.(ii)Limitations. For subcutaneous ear implantation only. Not approved for repeated implantation (reimplantation) with this or any other cattle ear implant in growing beef steers and heifers fed in confinement for slaughter. Safety and effectiveness following reimplantation have not been evaluated. Do not use in beef calves less than 2 months of age, dairy calves, and veal calves. A withdrawal period has not been established for this product in pre-ruminating calves. Do not use in dairy cows or in animals intended for subsequent breeding. Use in these cattle may cause drug residues in milk and/or in calves born to these cows. 69 FR 67818 , Nov. 22, 2004, as amended at 77 FR 31723 , May 30, 2012; 81 FR 48702 , July 26, 2016; 87 FR 10969 , Feb. 28, 2022; 88 FR 14898 , Mar. 10, 2023; 89 FR 42357 , May 15, 2024 81 FR 48702, 7/26/2016; 87 FR 10969, 2/28/2022; 88 FR 14898, 3/10/2023; 89 FR 42357, 5/15/2024