Merck Manual

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Synthetic Steroidal and Nonsteroidal Estrogen Hormone Growth Promotants in Cattle

Synthetic Steroidal and Nonsteroidal Estrogen Hormone Growth Promotants in Cattle

Hormone

Dose

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, heifers)

90–120

10%–20%

Transient increase in sexual behavior

150 mg TBA + 21 mg EB (coated implant, steers and heifers grazing pasture)

200

200 mg TBA + 28 mg EB (coated implant, steers and heifers)

200

TBA + E

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

90–120

200 mg TBA + 20 mg E (coated implant, heifers)

Initial and delayed release implant that provides hormonal payout for up to 200 days after implantation

200 mg TBA + 20 mg E (coated implant, steers)

Delayed release implant that does not begin hormonal payout until ~70 days after implantation

200 mg TBA + 40 mg E (coated implant, steers)

Initial and delayed release implant that provides hormonal payout for up to 200 days after implantation

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

Zeranol

36 mg zeranol

90–120

10%–15%

12 mg zeranol

90–120

10%–15%

Melengestrol acetate

0.25–0.50 mg/day

As long as it is fed

3%–10%

Increased mammary development after long-term administration

E = Estradiol 17-beta. EB = Estradiol benzoate. TBA = Trenbolone acetate.

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