Salinomycin poisoning occurred in a flock of 700 point-of-lay turkeys; 400 birds died over 7 days as a result of consuming feed contaminated with 50 ppm salinomycin. No gross lesions were detected. Histologic evidence of a myopathy was most readily detected in leg muscles of turkeys 5 to 7 d after ingesting salinomycin. Feeding trials were undertaken and individual susceptibility to the drug was found to vary greatly. In affected birds the plasma concentrations of creatine kinase (CK) and aspartate aminotransferase (AST) were found to be in the range of 500,000 to 2,500,000 IU/l and 9000 to 25,000 IU/l, respectively. The marked increase in the plasma activities of these enzymes preceded histological evidence of segmental muscle necrosis.

Partially purified homogenates prepared from the livers of birds affected with BLS were used to inoculate intravenously young adult broiler breeder hens and incubating chicken embryos. Following inoculation, the broiler breeders developed pathological and serological responses typical of BLS infection. The same antigen resulted in persistent antigenaemia in chickens which were inoculated during various stages of incubation. This technique was very sensitive and could be used for detection and titration of virus in tissue preparations. Methods for optimization of the technique were investigated. Chick embryos demonstrated the greatest susceptibility to agent replication when inoculated at 11 days of embryonation. After hatching, agent replication appears to increase with age. Inoculated chickens bled at 8 days of age showed increased incidence of antigenaemia by this procedure.