Improving Livestock Tolerance of Toxicants in Kochia Toward Increased Use as a Water-Efficient Crop

Herbage of Kochia scoparia (L) Schrad (kochia) was collected at bud stage, dried and fed to rats, sheep and cattle to characterize the nature of early kochia toxicosis, to identify better the primary toxicant(s), and to evaluate certain treatments as ways to improve animal tolerance of toxicants, toward increased use of kochia as a water-efficient forage crop. In rats, severity of toxicosis was correlated with content of substances reactive to Dragendorff’s reagent (presumably alkaloids) in fresh herbage. Clinical signs of toxicosis in rats, sheep and steers were consistent with alkaloids as the primary toxicant rather than oxalate or saponins. In rats, supplemental vitamins A and E or supplemental choline, inositol and folic acid tended to improve tolerance of dietary kochia, as did injected acetylcysteine; but for sheep, neither vitamins A and E nor injected acetylcysteine plus trans-stilbene oxide were effective, whereas supplemental zinc was detrimental. Earliest signs of kochia toxicosis in sheep and cattle were altered blood levels of metabolic hormones (insulin, prolactin, somatotropin) and impaired nitrogen retention, along with impaired bilirubin conjugation and leakage of hepatic enzymes. Findings suggest better ways to manage animal usage of kochia forage and suggest other treatments that might improve tolerance of toxicants in kochia.