Mineral-salt supplement does not attenuate tall larkspur (Delphinium barbeyi) toxicosis in cattle

Abstract

Severe livestock losses caused by tall larkspur (Delphinium spp.) consumption have caused many producers to try various preventative measures, including the use of mineral-salt supplementation. The objective of tbis study was to determine if additions or deletions of a mineral-salt supplement (Binn's #1 Alleviator) would alter the response (i.e., rate of nose pressing) of cattle to tall larkspur exposure. The dose response of 5 Jersey steers was examined by systematically adding 0.25 mg of mineral-salt/kg body weight, and comparing responses in the same steers without salt supplements. Steers were then run under a variable ratio (VR) reinforcement schedule and periodically dosed with tall larkspur at a level causing a significant decrease in responding without provoking overt signs of intoxication. Response rate with and without mineral-salt supplement was the major dependent variable; 3 to 5 "on-off" cycles were conducted for each subject. Steers reduced (P < 0.05) their rate of grain intake by 34% during operant sessions when larkspur was dosed compared to the previous non-dosed 3-day baseline. Rate of nose pressing was reduced (P < 0.01) on tall larkspur dose days by 28% vs. the 3-day non-dosed baseline. This reduction was indicative of the effects of the effects of subclinical larkspur intoxication on steers. On days when larkspur was dosed and animals were intoxicated, the addition of mineral did not alter (P > 0.1) grain intake (1.64 +/- 0.17 kg/session) compared to days when no mineral was given (1.76 +/- 0.13 kg/session). On larkspur dose days (i.e. when animals were intoxicated), the average response rates were 82.9 +/- 3.7 and 85.8 +/- 4.0 responses/min (P > 0.1) when off and on mineral, respectively. We concluded that mineral/salt supplementation had no effect on the response of steers to doses of tall larkspur that produced subclinical intoxication.