Lighting pattern and photoperiod affect the range use and feather cover of native laying hens under free range condition.

The study aimed to investigate the effects of lighting pattern and photoperiod on range use, feather cover and gait score of native laying hens. Six hundred and thirty 19-wks-old Beijing You Chicken (BYC) pullets were randomly allocated to 6 groups with 105 birds each, 3 replicates per group, reared in individually lit indoor pens with separate covered shed and outdoor areas. A 2 × 3 factorial experiment (2 lighting patterns: continuous and intermittent lighting; 3 photoperiods: 16 h, 14 h, 12 h) was arranged indoors, including 16L:8D (6:00-22:00) for group 1; 12L:2D:4L:6D (6:00-18:00,20:00-24:00) for group 2; 14L:10D (6:00-20:00) for group 3; 10L:2D:4L:8D (6:00-16:00,18:00-22:00) for group 4; 12L:12D (6:00-18:00) for group 5, and 8L:4D:4L:8D (6:00-14:00,18:00-22:00) for group 6, respectively. The number of hens in indoor pen, covered shed and outdoor area were counted at 8:00, 9:00, 10:00, 11:00, 12:00, 13:00, 14:00 for consecutive 3 sunny days at 34 wks and 36 wks of age, feather cover and gait score of the laying hens were assessed at the end of 36 wks. The results showed that daily average hen percentage was the highest in continuous 12 h group (63.67%), and the lowest in intermittent 14 h group (58.36%) in indoor pen (P < 0.05); the daily average hen percentage was the lowest in continuous 12 h group (16.05%), and the highest in intermittent 14h group (21.22%) in outdoor area (P < 0.05). Lighting pattern significantly affected hen percentage in indoor pen and outdoor area, the hen percentage in indoor pen was higher in continuous lighting groups than in intermittent lighting groups (62.09% vs. 59.23%) (P < 0.05), the hen percentage in outdoor area was lower in continuous lighting groups than in intermittent lighting groups (16.60% vs. 19.95%) (P < 0.05). Photoperiod had no effect on the hen percentage (P > 0.05), but time of day affected the hen percentage in different areas (P < 0.05). The feather cover score was higher in intermittent lighting groups than in continuous lighting groups (17.43 vs. 15.04, P < 0.05). The average hen percentage in indoor pen is strongly negatively correlated with the feather cover score (r = -0.880, P = 0.050), and the hen percentage in outdoor area is strongly positively correlated with the feather cover score in intermittent lighting condition (r = 0.811, P < 0.05). The present study suggested that more range use is beneficial for the feather cover and physical health of laying hens under free range condition, and intermittent lighting is more conducive to range use and feather cover of native laying hens, which may be related to its affecting hens' rhythmic activities, increasing adaptation to outdoor environment, and reducing the incidence of feather pecking and parasites.