Merck Manual

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Synthetic Steroid Hormones for Consideration as Growth Promoters

Synthetic Steroid Hormones for Consideration as Growth Promoters

Hormonea

Dosage

Duration of Effect (days)

Growth Response

Potential Adverse Effects

TBA

200 mg (heifers, cull cows)

60–90

5%–12%

TBA + EB

200 mg TBA + 28 mg EB (steers, heifers)

90–120

10%–20%

Transient increase in sexual behavior

100 mg TBA + 14 mg EB (steers)

90–120

10%–20%

Transient increase in sexual behavior

TBA + E

200 mg TBA + 20 mg E (steers, heifers)

90–120

120 mg TBA + 24 mg E (steers)

90–120

140 mg TBA + 14 mg E (heifers)

90–120

80 mg TBA + 16 mg E (steers)

90–120

80 mg TBA + 8 mg E (heifers)

90–120

40 mg TBA + 8 mg E (steers and heifers grazing pasture)

90–120

TBA + E

200 mg TBA + 40 mg E (steers)

200

Zeranol

36 mg zeranol

90–120

10%–15%

12 mg zeranol

90–120

10%–15%

MGA

0.25–0.5 mg/day, PO

As long as it is given

3%–10%

Increased mammary development after longterm administration

a TBA = trenbolone acetate; EB = estradiol benzoate; E = estradiol 17β; MGA = melengestrol acetate

Note: All administered as pellet implants except MGA, which is administered in feed.