Resistance to toxic plants: The right animal at the right time in the right pasture

Abstract Text:

Neurotoxic poisonous plants negatively impact livestock on many western rangelands, which results in annual economic losses of millions of dollars from animal deaths, increased management and treatment costs, and if animals are deferred from grazing, the underutilization of otherwise highly nutritious pastures and rangelands.

One potential solution to the problem of toxic plants is to identify and select animals that are “resistant” to neurotoxic plants. Research at the Poisonous Plant Research Laboratory (PPRL) has focused on the physiological effects of two plant species, larkspur (Delphinium spp.) and lupine (Lupinus spp.). There are significant differences in the susceptibility of cattle breeds to larkspur and lupine. For example, when Angus and Hereford cattle were orally dosed with 8 mg/kg d -(methylsuccinimido) anthranoyllycoctonine (MSAL)-type alkaloids in the form of dried ground larkspur, Angus were significantly more resistant to the larkspur-induced fatigue (P < 0.0001, Two-tailed t-test, 33 Angus verses 48 Line 1 Herefords). Breed differences have also been observed for lupine which causes birth defects in cattle by the inhibition of fetal movement. For example, when six pregnant Angus and five pregnant Holstein heifers were orally dosed with 1.1 g/kg dried ground Lupinus leucophyllus and fetal activity monitored via transrectal ultrasonography, there were significantly more fetal movements in Holstein heifers at eight and 12 hours after oral dosing than the Angus heifers (P = 0.0430 and 0.0001 for eight and twelve hours after oral dosing, respectively, linear mixed model analysis). These results provide the basis for phenotypes, which can then be used in the development of a genetic test to facilitate selection of resistant animals, which can then be used to manage the risk of toxic plants.

Keywords: Cattle, Larkspur, Lupine, d-(methylsuccinimido) anthranoyllycoctonine