An April 30 South Dakota court filing alleges that over 200 calves have died at a Letcher, S.D., farm due to toxic levels of the ionophore monensin, according to Courthouse News Service. Monensin is marketed as Rumensin® by Elanco Animal Health.

Sokota Dairy filed the lawsuit April 30 alleging that 223 calves have died, of 333 calves aged four months and younger, when fed calf starter mixed by Stan’s Inc. The dairy claims an Iowa State Veterinary Diagnostic Laboratory test showed toxic levels of monensin. Sokota Dairy says they used the feed for “three to four days.”

The calf starter was not labeled with the ionophore, and the dairyman said he did not request the additive included in the mix.

The Elanco website recommends feeding 0.14 to 0.42 mg monensin per pound body weight per day for prevention of coccidiosis due to Eimeria bovis and Eimeria zuernii. According to Michigan State University, the LD50 (lethal dose in which 50% of exposed cattle die) of monensin is estimated to be between 10 to 40 mg/lb (20 to 80 mg/kg) of body weight.

South Dakota law requires feed containing drugs or additives to be labeled for the amount, purpose, directions, and withdrawal time, according to Courthouse News Service.

By: Lucas Sjostrom, Assistant Editor, Dairy Herd Management
Source: Dairy Herd Management