LIVE PERFORMANCE AND CARCASS YIELD OF BROILER STRAIN CROSSES PROVIDED EITHER 16 OR 23 HOURS OF LIGHT PER DAY

The purpose of the present study was to compare a restricted (R) lighting program [16 h light (L):8 h dark (D)] with a standard extended (E) lighting schedule (23L:1D) for broilers. Experiment 1 was carried out during March and April (mean temperature of 23.3 C). Light treatments were 1) E; 2) R; 3) 16L:8D Days 1 to 21 and 23L:1D thereafter to 49 days (R3E); and 4) 16L:8D Days 1 to 14 and 23L:1D thereafter to 49 days (R2E)). Treatments were factorially arranged with two strain crosses [Indian River x Arbor Acres (IA) and Peterson x Arbor Acres (PA)]. Experiment 2 was carried out during the summer (mean temperature of 27.0 C). Light Treatments E and R were factorially arranged with two strain crosses [Cobb x Arbor Acres (C-A) and PA]. In Experiment 1, BW of Cross PA was greater than BW of Cross IA at 1, 14, 35, and 49 days of age. The percentage of birds with breast blisters was greater in Cross PA than IA. The incidence of broken clavicles was lower in Treatments R and R3E than in Treatments E or R2E. In Experiment 2, Treatment E had greater BW than R from 7 to 42 days of age, and BW of Cross CA was greater than that of PA from 1 to 48 days. Yield (percentage of lean carcass weight) of breast meat at 49 days of age was higher for Treatment E than R, and the percentage of birds with breast blisters was greater in Treatment R than E. In both experiments, Cross PA had lower breast meat yield (percentage of lean carcass weight) than the other strain crosses.