21 CFR §558.342

1. (a)Specifications.
   1. (1)Dry Type A medicated articles containing 100 or 200 milligrams (mg) melengestrol acetate per pound.
   2. (2)Liquid Type A medicated article containing 500 mg melengestrol acetate per pound.
2. (b)Sponsor. See sponsors in § 510.600(c) of this chapter for use as in paragraph (e) of this section.
   1. (1)No. 054771 for use of products described in paragraph (a)(1) of this section:
   2. (2)Nos. 016592, 051311, 054771, and 058198 for use of product described in paragraph (a)(2) of this section.
3. (c)Related tolerances. See § 556.380 of this chapter.
4. (d)Special considerations.
   1. (1)Type B or C medicated feeds may be manufactured from melengestrol acetate liquid Type A articles or Type B or C medicated feeds which have a pH of 4.0 to 8.0 and bear appropriate mixing directions as follows:
      1. (i)For liquid feeds stored in recirculating tank systems: Recirculate immediately prior to use for no 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.
      2. (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.
   2. (2)A physically stable melengestrol acetate liquid Type B or C feed will not be subject to the requirements for mixing directions prescribed in paragraph (d)(1) of this section provided it has a pH of 4.0 to 8.0 and contains a suspending agent(s) sufficient to maintain a viscosity of not less than 300 centipoises per second for 3 months.
   3. (3)Liquid or dry combination Type B or C medicated feeds containing melengestrol acetate and lasalocid must be labeled in accordance with § 558.311(d).
   4. (4)Liquid or dry combination Type B or C medicated feeds containing melengestrol acetate and monensin must be labeled in accordance with § 558.355(d).
   5. (5)Liquid combination Type B or C medicated feeds containing melengestrol acetate and tylosin must be manufactured in accordance with § 558.625(d).
   6. (6)Liquid melengestrol acetate may not be mixed with oxytetracycline in a common liquid feed supplement.
5. (e)Conditions of use—(1) Cattle.
   1. (2)Melengestrol may also be used in combination with:
      1. (i)Oxytetracycline as in § 558.450.
      2. (ii)Ractopamine as in § 558.500.
      3. (iii)Tylosin as in § 558.625.
      4. (iv)Zilpaterol as in § 558.665.