Little works of literature studied the anesthetic effect of ketamine in different ages of broiler chickens, hence this study intended to examine these alterations in chickens at different ages. The doses of ketamine that causes hypnosis in 50% of the chickens (hypnotic ED50) were 7.90, 7.90 and 6.80 mg/kg, intramuscular (IM) at 10, 20 and 40-day-old chickens, respectively, whereas the doses that resulted in analgesia in 50% of the chickens (analgesic ED50) were 12.92, 12.92 and 6.50 mg/kg, IM.

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... he onset, duration and recovery from ketamine hypnosis were in an age-dependent manner and significantly longer at 40day-old, although the depth and sensitivity of chickens to ketamine hypnosis rises as the age advancing forward. Ketamine analgesia is more effective at 40-day-old. There are neurobehavioral deficits, according to the age of chickens when injecting ketamine in a subtle dose of 1 mg/kg, IM. The concentrations related to alanine transaminase (ALT) and aspartate transaminase (AST), tested in the serum, reveal that the 40-day-old chicken group differs significantly from 10 and 20-day-old chicken's groups which all treated with single ketamine dose (25 mg/kg, IM). In conclusion, the present work discovered that ketamine's efficacy, including hypnosis, analgesia and neurobehavioral activity will be increased as the age is progressing, suggesting that the veterinarians need to take it into account when preparing the dose regimen of ketamine anesthesia for different ages of animals.