Differences in response of chickens from two genetic lines to diisopropyl phosphorofluoridate

Neurotoxicity of diisopropyl phosphorofluoridate (DFP) was examined at 85 weeks of age in hens of two lines selected for high (HA) and low (LA) antibody response to sheep erythrocytes. DFP was administered by subcutaneous injection in doses of 0.25, 0.50 and 1.00 mg/kg and hens were observed for cholinergic signs at 30 min and for delayed neuropathy 8 to 14 days post-administration. Toxicity to DFP increased in severity with the dose and genetic differences were present because hens of line HA were more sensitive to DFP than were those of line LA. HA hens also had lower A-esterase activities and higher heterophil-to-lymphocyte ratios. No line x treatment interaction was evident, however, for activities of neurotoxic esterase or brain cholinesterase measured 24 hr after DFP administration.