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MGA® TYPE A MEDICATED ARTICLE

(melengestrol acetate)

The only in-feed product for the suppression of estrus (heat) in heifers confined for slaughter or kept for breeding. In heifers confined for slaughter, this Type A medicated article mixed with non-medicated feed can increase rate of weight gain and improve feed efficiency.

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  • Uses:

    Type A medicated article for mixing with non-medicated feed for increased rate of weight gain, improved feed efficiency and suppression of estrus (heat).

    Key Facts:

    • Contains melengestrol acetate (MGA) for mixing with non-medicated feed.
    • MGA 500 is used in liquid feed. MGA 200 is used in dry feed.
    • Provides increased rate of weight gain, improved feed efficiency and suppression of estrus (heat) in heifers fed for slaughter and for suppression of estrus (heat) in heifers intended for breeding.
    • MGA is approved for the following combinations: 
      • MGA may be fed in combination with BOVATEC® (lasalocid) in a single dry supplement with or without Tylan® or Tylovet® (tylosin phosphate). 
      • MGA may be fed in combination with Rumensin® (monensin), with or without Tylan 
      • MGA may be fed in combination with ACTOGAIN® (ractopamine hydrochloride), Rumensin and Tylan.
      • Additionally, MGA may be fed in combination with Rumensin, with or without Zilmax® (zilpaterol hydrochloride).
      • MGA is also approved for use in combination with oxytetracycline. 
    • MGA has no pre-slaughter withdrawal.
  • MGA 500 Type A Medicated Article

    Heifers Fed in Confinement for Slaughter: MGA 500 (melengestrol acetate Type A liquid medicated article) should be thoroughly mixed in liquid Type C medicated feed which must be fed at 0.5 to 2.0 pounds per head daily to provide 0.25 to 0.5 mg of melengestrol acetate per head per day. Average daily intakes approximating the middle of this range provide the most optimal and economical improvements in rate of gain and feed utilization. Constant daily intakes of 0.35 to 0.50 mg per head per day give a high degree of estrus suppression. Levels of 0.25 to 0.35 mg provide a lower but still effective degree of estrus suppression.

    Heifers Intended for Breeding: MGA 500 should be thoroughly mixed in the supplement to provide 0.5 mg of melengestrol acetate per head per day.

    MGA 500 MIXING DIRECTIONS:

    Liquid Type B and C medicated feeds containing melengestrol acetate must have a pH of 4.0 to 8.0 and their labels must bear appropriate mixing directions. Mixing directions for liquid Type B or C feeds stored in recirculation tank systems are: “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 directed in this paragraph even when the Type B (or C) feed is not used.” Mixing directions for liquid Type B and C feeds stored in mechanical, air or other agitation-type tank systems are: “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 directed in this paragraph, even when the Type B (or C) feed is not used.” Intermediate medicated feeds should not be made from MGA 500 except as a part of a continuous mixing operation to make a complete liquid Type B or Type C medicated feed.
    Thoroughly mix 0.5 to 4 pounds of MGA 500 per ton of a non-medicated feed to prepare a Type C medicated feed containing 0.25 to 2.0 grams of melengestrol acetate per ton. The following Table may be used as a guide in determining the amount of MGA 500 to be added to prepare a ton of Type C medicated feed. 

    MGA-500-Bag-Label_Chart

    Type B medicated feed containing 4 to 10 grams melengestrol acetate per ton may be manufactured by thoroughly mixing 8 to 20 lbs of MGA 500 (melengestrol acetate Type A liquid medicated article) with 1992 to 1980 lbs of non-medicated feed. Labeling for such Type B feed shall contain directions for manufacturing Type C medicated feeds containing 0.25 to 2.0 grams melengestrol acetate per ton (0.125 to 1.0 mg/lb). The Type C medicated feed, containing melengestrol acetate, must be top dressed on grain or roughage or mixed with a complete ration at the rate of 0.5 to 2.0 pounds per head per day. Good manufacturing practice regulations must be adhered to in manufacturing feeds containing MGA 500. 

  • MGA 200 Type A Medicated Article

    Heifers Fed in Confinement for Slaughter: MGA 200 (melengestrol acetate Type A medicated article) should be thoroughly mixed in the supplement to provide 0.25 to 0.50 mg of melengestrol acetate per head per day. Average daily intakes approximating the middle of this range provide the most optimal and economical improvements in rate of gain and feed utilization. Constant daily intakes of 0.35 to 0.50 mg per head per day give a high degree of estrus suppression. Levels of 0.25 to 0.35 mg provide a lower but still effective degree of estrus suppression.

    Heifers Intended for Breeding: MGA 200 should be thoroughly mixed in the supplement to provide 0.5 mg of melengestrol acetate per head per day.

    MGA 200 MIXING DIRECTIONS:

    Thoroughly mix 1.25 to 10 pounds of MGA 200 per ton of non-medicated feed to prepare a Type C medicated feed containing 0.25 to 2.0 grams of melengestrol acetate per ton. The following Table may be used as a guide in determining the amount of MGA 200 to be added to prepare a ton of Type C medicated feed. 

    MGA -200-Bag-Label_Chart

    Type B medicated feeds containing 4 to 10 grams melengestrol acetate per ton may be manufactured by thoroughly mixing 20 to 50 lbs of MGA 200 with 1980 to 1950 lbs of non-medicated feed. Labeling for such Type B feeds shall contain directions for manufacturing Type C medicated feeds containing 0.25 to 2.0 grams melengestrol acetate per ton (0.125–1.0 mg/lb). The Type C medicated feed, containing melengestrol acetate, must be top dressed on grain or roughage or mixed with a complete ration at the rate of 0.5 to 2.0 pounds per head per day. 

WARNING: Not for human use.

PRECAUTIONS: Not effective in steers and spayed heifers. Heifers Fed in Confinement for Slaughter: Withdrawal periods of three to five days or more should be avoided to prevent the possibility that the heifers may come into estrus (heat) at loading time. Heifers Intended for Breeding: Do not exceed 24 days of feeding of melengestrol acetate to heifers intended for breeding. A reduced conception rate can be expected if heifers are bred at estruses observed within 1 to 12 days after withdrawal of melengestrol acetate, whereas heifers bred at subsequent observed estruses are expected to have normal conception rates.

Rumensin and Tylan are registered trademarks of Eli Lilly and Company, its subsidiaries or affiliates. Zilmax is a registered trademark of Intervet Inc. or an affiliate. Tylovet is a registered trademark of Huvepharma. 

MGA-00002