Maintain the influence of progesterone until the CL regresses.
These products do not regress the CL. Estrus commences shortly after the progestin removal if left in long enough for the CL to regress normally or when artifical CL regression has already been triggered by giving prostaglandin.
Delivery
Product (comments, manufacturer)
Injection
Progesterone - may cause local inflamation
Implant
Syncro-Mate-B® (no longer made, previously made by Rhone Merieux, Inc., Athens, GA), Implanon® or Nexplanon® are made for humans but often used in zoo animals (Merck & Co. Inc.)
Oral
MGA (melengestrol acetate, Pharmacia & Upjohn, Kalamazoo
MI, cheap and added to regular feed)
Regu-Mate® or Matrix® (altrenogest, Intervet, oral delivery via syringe in the mouth or on top of morning feed, must feed animals individually)
CIDR
Eazi-Breed, CIDR®(Zoetis)
CIDR-S, CIDR-G (InterAg, Hamilton, New Zealand)