Figure 1 Testosterone concentration in male rat plasma pre-ketamine/xylazine anaesthesia, one hour (n = 9) and 24 h (n = 9) later and after euthanasia by CO₂ (n = 4). Values are presented as the means of the treatment groups ± standard error of mean. Control is the pooled concentration of the preanaesthetic blood samples; one hour and 24 h are the concentrations of testosterone one and 24 h after anaesthesia, respectively, CO₂ is the concentration of testosterone after CO₂ euthanasia only