Melengestrol Acetate - MIB #46

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Revised July 2017

Approved Brands

  1. MGA 100 Premix contains melengestrol acetate at 220 mg/kg (Zoetis Canada Inc.)

Approved for use

In meal or pellet feed for feedlot heifers.

Approved claims

For feedlot heifers - Claim 1

Claim 1: For growth stimulation improved feed utilization and suppression of estrus (heat) in heifers fed for slaughter.

Level of Drug:

0.40 mg per feedlot heifer per day in supplements or complete feeds.


Feed continuously throughout the time that heifers are being fed for slaughter at a rate so that each animal will receive 0.40 mg of melengestrol acetate per head per day.


  1. Discontinue the use of this medicated feed at least 24 hours before slaughter.
  2. Keep out of reach of children (Required on supplement and premix label only).


  1. Used only in heifers being fed for slaughter. Not effective in spayed heifers or steers.
  2. Do not feed this medicated feed to heifers treated with other hormone drugs.

Accepted Compatibilities

Melengestrol acetate is compatible in single combination with any of the following drugs. For details refer to the MIB as indicated.
MIB # Medicated ingredients For use in feeds for
57 Monensin sodium (Claim 3 option 1a and option 2; and Claim 4; and Claim 5) feedlot beef heifers
66 Lasalocid sodium (Claim 3) feedlot beef heifers
69 Salinomycin sodium (Claim 3) beef heifers fed in confinement for slaughter
Melengestrol acetate is compatible with multiple drugs in the following combination. For details, refer to the MIB as indicated.
MIB # Medicated ingredients For use in feeds for



Tylosin phosphate from Tylan and Tylosin premixes (Claim 4) and

Monensin sodium (Claim 3 option 1b)

feedlot beef heifers

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