The Effect of Co-Administration of Death Camas (Zigadenus spp.) and Low Larkspur (Delphinium spp.) in Cattle

Abstract

In many rangeland settings, there is more than one potential poisonous plant. Two poisonous plants that are often found growing simultaneously in the same location in North American rangelands are death camas (Zigadenus spp.) and low larkspur (Delphinium spp.). The objective of this study was to determine if co-administration of death camas would exacerbate the toxicity of low larkspur in cattle. Cattle dosed with 2.0 g of death camas/kg BW showed slight frothing and lethargy, whereas cattle dosed with both death camas and low larkspur showed increased clinical signs of poisoning. Although qualitative differences in clinical signs of intoxication in cattle co-treated with death camas and low larkspur were observed, there were not any significant quantitative differences in heart rate or exercise-induced muscle fatigue. Co-treatment with death camas and low larkspur did not affect the serum zygacine kinetics, however, there was a difference in the larkspur alkaloid kinetics in the co-exposure group. Overall, the results from this study suggest that co-exposure to death camas and low larkspur is not significantly more toxic to cattle than exposure to the plants individually. The results from this study increase our knowledge and understanding regarding the acute toxicity of death camas and low larkspur in cattle.

Keywords: Delphinium; Zigadenus; cattle; death camas; larkspur; methyllycaconitine; zygacine.

Figure 1

Chemical structure of zygacine, the main alkaloid in Zigadenus paniculatus, and methyllycaconitine (MLA), a major toxic alkaloid in the low larkspur Delphinium andersonii.

Figure 2

Comparison of the kinetic profile of zygacine in serum from Holstein steers fed death camas alone versus death camas and low larkspur. Data represent the serum concentration of zygacine from Holstein steers dosed orally with 2.0 g/kg death camas (DC), which corresponded to 14 mg/kg zygacine. The group that received death camas and low larkspur (DC + LL) was dosed simultaneously with 2.0 g/kg of death camas (14 mg/kg zygacine) and 4.4 g/kg of low larkspur (14 mg/kg MSAL alkaloids). Results represent the mean ± SD of the concentration of zygacine in serum for four steers at each time point. A statistical comparison of the serum alkaloid concentrations was performed using a two-way ANOVA with a Bonferroni post hoc analysis. There were no significant differences (p < 0.05) observed between the two groups.

Figure 3

Comparison of the kinetic profile of total MSAL alkaloids in serum from Holstein steers fed low larkspur alone versus death camas and low larkspur. Data represent the serum concentration of total MSAL alkaloids from Holstein steers dosed orally with 4.4 g/kg low larkspur (LL), which corresponded to 14 mg/kg MSAL alkaloids. The group that received death camas and low larkspur (DC + LL) was dosed simultaneously with 2.0 g/kg of death camas (14 mg/kg zygacine) and 4.4 g/kg of low larkspur (14 mg/kg MSAL alkaloids). Results represent the mean ± SD of the concentration of total MSAL alkaloids in serum for four steers at each time point. A statistical comparison of the serum alkaloid concentrations was performed using a two-way ANOVA with a Bonferroni post hoc analysis. * indicates significant differences (p < 0.05) between the two groups.

Figure 4

Comparison of the kinetic profile of zygacine in serum from beef steers fed death camas alone versus death camas and low larkspur. Data represent the serum concentration of zygacine from beef steers dosed orally with 1.7 g/kg death camas (DC), which corresponded to 12 mg/kg zygacine. The group that received death camas and low larkspur (DC + LL) was dosed simultaneously with 1.7 g/kg of death camas (12 mg/kg zygacine) and 3.7 g/kg of low larkspur (12 mg/kg MSAL alkaloids). Results represent the mean ± SD of the concentration of zygacine in serum for three steers at each time point for the DC group and two steers at each time point for the DC + LL group. A statistical comparison of the serum alkaloid concentrations was performed using a two-way ANOVA with a Bonferroni post hoc analysis. There were no significant differences (p < 0.05) observed between the two groups.

Figure 5

Comparison of the kinetic profile of total MSAL alkaloids in serum from beef steers fed low larkspur alone versus death camas and low larkspur. Data represent the serum concentration of total MSAL alkaloids from beef steers dosed orally with 3.7 g/kg low larkspur (LL), which corresponded to 12 mg/kg MSAL alkaloids. The group that received death camas and low larkspur (DC + LL) was dosed simultaneously with 1.7 g/kg of death camas (12 mg/kg zygacine) and 3.7 g/kg of low larkspur (12 mg/kg MSAL alkaloids). Results represent the mean ± SD of the concentration of total MSAL alkaloids in serum for three steers at each time point for the LL group and two steers at each time point for the DC + LL group. A statistical comparison of the serum alkaloid concentrations was performed using a two-way ANOVA with a Bonferroni post hoc analysis. * indicates significant differences (p < 0.05) between the two groups.