| dc.description.abstract | This study was undertaken to investigate the effects of lighting and stocking density on performance, carcass characteristics and some stress parameters (H-L ratio, serum glucose, cholesterol and triglyceride levels, tonic immobility test (TI), antibody production, relative asymmetry (RA) and external appearances). Four hundred and seventy day-old male broiler chicks (Ross 308) were obtained from a commercial hatchery. The chicks were randomly distributed into two light proof controlled rooms. In one room the lighting period remained at continuous lighting (24 L: OD) during the whole experiment, while in the other room the photoperiod was 16 h light and 8 h dark per day. Each lighting group was divided into two stocking density groups (11.9 b/m(2) (average 29.9 kg of BW/m(2)) and 17.5 b/m(2) (average 40.7 kg of BW/m(2))) with 5 replications per group. Lighting program did not influence slaughter weight, body weight gain, feed consumption, feed to gain ratio, carcass characteristics, percentage of abdominal fat, heart, gizzard, liver, spleen and bursa of Fabricius, RA of metatarsus length, RA of tarsometatarsus length and thickness, mean RA, claw length, foot health, serum glucose, cholesterol and triglyceride levels anti-SRBC and anti NDV titers. TI duration (p < 0.001), feather condition (p < 0.001) and H-L ratio (p < 0.05) of broilers were significantly different in lighting groups. TI duration was 255 and 431 s, feather condition was 16.3 and 14.5 and H-L ratio was 1.0 and 1.2 in broilers exposed to 16L:8D lighting program and 24L:OD lighting program, respectively. Stocking density influenced final body weight (p < 0.001), body weight gain (p < 0.001), feed consumption (p < 0.05) and feed to gain ratio (p < 0.05). Final body weight was 2515 and 2326 g, feed consumption was 3829 and 3662 g and feed to gain ratio was found 1.55 and 1.61 g/g in broilers reared at 11.9 b/m(2) and 17.5 b/m(2), respectively. Feather condition (p < 0.001) and foot health (p < 0.01) were significantly different in stocking density groups. Feather condition was 16.5 and 14.3 and foot health was 3.6 and 3.0 in broilers reared at 11.9 and 17.5 b/m(2), respectively. Percentage of heart (p < 0.05), TI duration (p < 0.001), H-L ratio (p < 0.001), serum glucose (p < 0.001) and serum cholesterol levels (p < 0.05) were statistically higher in broilers reared at 17.5 b/m(2) than in broilers reared at 11.9 b/m(2). In conclusion darkness period and stocking density play an important role in modern broiler rearing. | en_US |
