The toxic effects of monensin and chloramphenicol on laying turkey breeder hens

A case report of choramphenicol and monensin poisoning in turkey breeder hens is presented in which anorexia and a fall in egg production were features. An experiment study was then conducted in turkey breeding hens given increasing levels of monensin and chloramphenicol singly or in combination. Monensin fed at levels of 42 or 85 ppm had no adverse effect on egg production but chloramphenicol in the drinking water at 500 mg/l for 4 days caused a 9.2% fall in egg production compared to control untreated birds. When 500 mg/l chloramphenicol and 42 ppm monensin were given together for 8 days there was lameness, 12% mortality, but no drop in egg production. When 70 ppm monensin and 500 mg/l chloramphenicol were given together for 4 days, 14 of 22 birds died and egg production in the remainder ceased. Withdrawal of monensin arrested mortality but egg production did not recover. Serum creatine phosphokinase levels in this group were 20 times greater than those of the controls and were similar to birds studied in the case report.