Norgestomet
Norgestomet is a potent synthetic progestin delivered by subcutaneous ear implant (Crestar/Syncro-Mate-B) to synchronise estrus in cattle, often combined with estradiol. It is a 19-nortestosterone-derived progestagen used for reproductive management and growth-linked programmes, with no anabolic PED value.
01 Overview
Norgestomet is a highly active progestin implanted subcutaneously to hold cattle in a progestational state; on implant removal, synchronised estrus and ovulation follow. It is often paired with an estradiol valerate injection in estrus-synchronisation protocols.
Like other 19-nor progestins, its receptor profile is dominated by progestational activity rather than anabolic androgenicity, so it is irrelevant as a muscle-building agent. It is included as a real veterinary hormone implant and a residue/detection subject.
02 Mechanism
Potent progesterone-receptor agonist that suppresses gonadotrophin release to synchronise the estrous cycle; withdrawal of the implant triggers coordinated ovulation.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Cattle estrus-sync implant | 3–6 mg | SubQ | Ear implant per animal for ~9 days; not a human recommendation |
Ester comparison
| Ester | Half-life | Injection freq. | Testosterone by mass |
|---|
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Estrus synchronisationSynchronises ovulation across a herd for timed breeding. | Clinical | ||
| Reproductive cycle controlHolds cattle in a progestational state until implant removal. | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Implant-site reactionLocal irritation or infection at the subcutaneous ear implant site in treated animals. | Mild | Occasional (cattle) | Observational | |
| Progestogenic endocrine effectsPotent progestin activity would suppress gonadal function in humans with no anabolic benefit. | Moderate | Predicted in humans | Preclinical |