Effect of short photoperiod on some growth traits in Sprague Dawley rats [Sprague Dawley ratlarda ki{dotless}salti{dotless}lmi{dotless}ş işi{dotless}k süresinin bazi{dotless} büyüme özelliklerine etkisi]

The effect of short photoperiod on some growth traits in outbred sprague dawley rats was examined. the pups were assigned to two photoperiod groups: long/routin (12 h light/dark: control) and short (9 h light/15 h dark: experiment) lighting,since,in nature,photoperiod may decrease to 9 hours in winters,in subtropical regions. at 15 weeks of ages,body weight,weight of heart,liver,spleen,lungs,kidneys,gastear,adrenal glands,testis and ovaries of the rats from experimental group were compared to those in control group. body growth,weight of heart,liver and spleen and large intestine length in control and experimental rats were not significantly different (p>0.05). no differences were observed in testis and ovary weights between control and experiment groups,statistically. rats exposed to short photoperiod had lower lung,kidney,gastear,adrenal gland and intestine weight than those of control rats (p<0.01 and p<0.05). in outbred sprague dawley rats,short photoperiod had no effect on body growth and reproduction organs and it is concluded that,there may be a chance for some strains of outbred sprague dawley rats to be kept under short photoperiod conditions,without reducing body weight and reproductive organ growth.