Anabolic steroidAndrogenTestosterone esterInjectableGrowth promotantVeterinary implant component

Testosterone Propionate (Cattle Implant Component)

Also known as Synovex-S (component) · Revalor-S (component) · Test prop · TP

Written by enwyReviewed 15 Jul 20261 sources0 comments

Testosterone propionate is the androgenic component of steer-specific cattle growth implants such as Synovex-S and Revalor-S, usually paired with estradiol benzoate. In the implant it drives weight gain in feedlot steers; the same short-ester testosterone is also the classic diverted androgen for human PED use.

01 Overview

In combination cattle implants, testosterone propionate supplies the androgenic half of an androgen-plus-estrogen blend that boosts weight gain and feed efficiency in steers. The propionate ester is short-acting, chosen to match the implant's release profile.

The identical molecule is the original injectable testosterone ester used in human medicine and, illicitly, in bodybuilding, where its short ester gives fast onset and quick clearance. This entry addresses the veterinary implant component and its role as a growth-promotant androgen; diverted human use carries the full testosterone side-effect profile plus veterinary-sourcing risks.

02 Mechanism

Testosterone is the prototypical androgen-receptor agonist; it aromatises to estradiol and is 5-alpha reduced to DHT. The propionate ester gives short-duration release from oil or implant matrix.

03 Dosing

Tier	Dose	Route	Notes
Diverted human use (anecdotal)	300–500 mg/wk	IM	Illicit human dosing of the ester; veterinary use is as a cattle implant

Ester comparison

Ester	Half-life	Injection freq.	Testosterone by mass

04 Effects

Effect	Magnitude	Evidence
Increased weight gain (steers)As an implant component it raises average daily gain and feed efficiency, synergising with estradiol.	+8-15% ADG	Clinical
Lean mass and strength (if diverted)The testosterone molecule produces robust lean-mass and strength gains in humans.		Clinical

05 Side effects

Effect	Severity	Frequency	Evidence	Countermeasures
Estrogenic effectsAromatisation can cause gynecomastia and water retention.	Moderate	Dose-dependent	Clinical
HPTA suppressionSuppresses endogenous testosterone production during exogenous administration.	Severe	Universal at PED doses	Clinical

06 Legal status

Banned hormonal growth promotant

Growth-promotant use in food animals prohibited under Directive 96/22/EC · as of Jan 2026

United States

Schedule III anabolic steroid

Cattle-implant component; human use is controlled-substance diversion · as of Jan 2026

07 References

Testosterone-estradiol implants in feedlot steersJournal of Animal Science

08 Discussion0 comments

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This page is reference information, not medical advice. Doses and protocols are documented as they appear in the clinical literature and in practice — describing them is not a recommendation to use them. Countermeasures listed here are not a substitute for a physician. Legal status varies by jurisdiction and changes.