Elimination of adverse effects of ethoxyquin (EQ) by methionine hydroxy analog (MHA). Protective effects of EQ and MHA for bitterweed poisoning in sheep.

Dietary ethoxyquin (EQ) and methionine hydroxy analog (MHA) protected 6-8-month-old wethers from toxic doses of bitterweed (Hymenoxys odorata DC.). The EQ-MHA group received sweet feed (corn, oats, dehydrated alfalfa pellets, cane molasses and minerals), 500 g/day/sheep, supplemented with EQ and MHA (0.5% and 1.0% of feed, respectively) for 9 days prior to the poisoning with bitterweed while the MHA group received the same feed without EQ and controls received the same amount of feed with no additives. Two of 6 MHA-treated and 3 of 7 controls died whereas all 7 EQ-MHA-treated sheep survived after receiving 5 doses of bitterweed (5 X 5.5 g/kg) in 6 days. Coadministration of MHA and EQ eliminated the adverse effect of EQ; dietary EQ lowered the serum albumin, calcium, and alkaline phosphatase content while protecting the animals from bitterweed poisoning. EQ is the most promising protective agent tested for bitterweed poisoning in sheep.

Protective effects of antioxidants on bitterweed (Hymenoxys odorata DC) toxicity in sheep.

Antidotal effects of the 2 antioxidants butylated hydroxyanisole (BHA) and ethoxyquin (EQ) were evaluated in bitterweed (Hymenoxys odorata DC) toxicosis in sheep. Bitteerweed contains a toxic sesquiterpene lactone, hymenoxon, the toxicity of which is reduced by cysteine. Both BHA and EQ are known to induce hepatic glutathione production in rodents. Treatment of sheep with EQ (2.5 g/sheep/day for 9 days before poisoning) gave significant protection from toxic doses of bitterweed, but the protective effect of BHA was insignificant. Of 6 sheep given EQ in the feed, 5 survived 7 doses of bitterweed (4 g/kg/day or higher for 7 days), whereas 5 of 7 controls and 4 of 7 sheep given feed with added BHA died. The added EQ in the feed decreased the serum alkaline phosphatase activity and total protein, albumin, and calcium concentrations. Seemingly, EQ is the first protective agent with field application potential for bitterweed toxicity.