Effect of Short Photoperiod on Some Blood Parameters in Sprague Dawley Rats: I- Enzyme Levels

The effect of short photoperiod on body weight gain and some enzyme levels in outbred Sprague dawley rats was examined. The pups (n= 96) were assigned into two photoperiod groups: 12 h of light/dark (control) and short photoperiod (9 h light/15 h dark: experiment). The enzyme levels in the experimental group rats were compared to those of control group, at 15 weeks of age. No significant differences (P 0.05) were observed between control and experimental groups, with regard to body weight gain and measured enzymes, except for CK-MB (myocardial creatine kinase). It is concluded that, outbred Sprague dawley rats could be kept under short photoperiod conditions, without marked change in the levels of weight gain and some blood enzymes.