Sex‐dependent responses to norditerpenoid alkaloids from Delphinium in Angus cattle

Plants produce bioactive secondary chemical compounds which are not involved in metabolism, photosynthesis or reproduction. Norditerpenoid alkaloids produced by Delphinium spp. (larkspur) poison cattle grazing on rangelands of western North America. The objective of this study was to compare the physiological responses of yearling and two year old Angus heifers, steers, and bulls with a standardized dose of norditerpenoid alkaloids in the form of dried ground Delphinium barbeyi . Clinical signs of intoxication, including loss of muscle coordination and function were measured 24 h after oral dosing with larkspur by walking the cattle at a pace of 5–6 km/h for up to 40 min on an oval dirt track. The walk times of the yearling cattle were: 2.9 ± 1.2 minutes (30 heifers), 16.6 ± 1.9 minutes (60 steers), and 15.5 ± 2.4 minutes (33 bulls). Two‐year old heifers walked 6.7 ± 3.3 minutes (15 heifers). Serum alkaloid concentrations were measured immediately prior to walking, and deltaline concentrations averaged 266 ± 28, 131 ± 20, and 219 ± 28 ng/mL for all heifers, steers and bulls, respectively, and serum methyllycaconitine concentrations averaged 660 ± 46, 397 ± 32, and 612 ± 34 ng/mL for all heifers, steers and bulls, respectively. These results suggest that yearling and two year old Angus heifers are more susceptible to larkspur intoxication than bulls or steers. Support or Funding Information Supported by USDA This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .