Assessment of the withdrawal period for ractopamine hydrochloride in the goat and sheep

Ractopamine hydrochloride often used as a bronchodilator, but its β-adrenergic agonist effects on un-striated muscle and its withdrawal time have not been assessed for Etawah goats and sheep. The aim of this study was to determine the safe time to slaughter goats and sheep post-treatment with ractopamine. Five clinically healthy adult goats and sheep (20 kg body weight) were treated with a single dose of ractopamine (1 mg, intravenously). Whole blood was sampled from the jugular vein at 120 min, 180 min and 300 min post-treatment. Ractopamine as a veterinary drug was analysed using HPLC at wavelength 225 nm. The concentrations at 120 min, 180 min and 300 min were 817.156 ± 13.460 µg.mL-1, 554.468 ± 50.157 µg.mL-1, and 294.588 ± 52.845 µg.mL-1 in goats and 706.266 ± 89.856 µg.mL-1, 579.194 ± 45.664 µg.mL-1, and 209.36 ± 54.797 µg.mL-1 in sheep, respectively. The withdrawal times in goats and sheep were 1141.710 ± 255.85 h and 989.741 ± 167.633 h, respectively, no drug residues detected. The safe time to slaughter goats after administration of 1 mg of ractopamine was approximately 3 months and 5 days post-treatment at a safety factor of 2, which was later than the sheep at 2 months and 22 days by a safety factor of two.