The effect of dietary supplements on chronic bitterweed (Hymenoxys odorata) poisoning in sheep.

Two experiments were designed to establish a chronic bitterweed dose in sheep and to study the prevention of chronic bitterweed poisoning with dietary supplements of high protein (20% crude protein) and sodium sulfate. The first experiment consisted of 5 lambs in each of 3 groups. The low dose received up to 5.0 g bitterweed/kg/day which was equivalent to 10 mg hymenoxon/kg bw. The high dose group received a maximum bitterweed dose of 1 g/kg/day or 20 mg hymenoxon/kg. The final average weights of the low (29 kg) and the high (30 kg) dose groups were significantly different from the control (40 kg) group. The prophylactic experiment consisted of 5 groups of 4 sheep each. Each group received a different combination of bitterweed, a basal ration, soybean meal, urea, or sodium sulfate. The soybean meal and urea were used to adjust the ration to 20% crude protein, and each animal received 1.2 g bitterweed/kg/day. The high protein-sodium sulfate diet did not prevent chronic bitterweed toxicity, but soybean meal-sodium sulfate combination had the greatest effect on the reduction of bitterweed toxicity. Urea potentiated the toxic effects of bitterweed.