This experiment was conducted to study the effects of feeding level and photoperiod on growth,nutrient digestibility and liver leptin receptor(Ob-R) gene expression of growing layers. A 2 × 2 two-factor experiment was used in this experiment,the one factor was photoperiod(8L∶16D and 12L∶12D),and the other factor was feeding level [ad libitum feeding and limited feeding(80% of ad libitum feeding)]. A total of 32010-week-old healthy Hy-Line Grey grow ing layers were selected and randomly allotted to 4 groups ...