title: Lighting programs for broilers that reduce leg problems without loss of performance or yield.
abstract: This study tested the effects of light schedules on performance and yields of broiler chickens. In Experiment 1, light treatments during Days 1 to 49 of age were: 1) 23 h light (L):1 h dark (D); 2) 16L:8D;3) 16L: 3D:1L:4D; and 4) 16L:2D:1L:2D:1L:2D. In Experiment 2, Light Treatments 1 and 2 were the same as Treatments 1 and 4, respectively, in Experiment 1; 3) 23L:1D Days 1 to 7, 16L:8D Days 8 to 14, the light period was increased by 2 h/wk during Days 15 to 35, and 23L:1D Days 36 to 42; and 4) 23L:1D Days 1 to 7, 16L:8D Days 8 to 14, 16L:3D: 2L:3D Days 15 to 21, 16L:2D:4L:2D Days 22 to 28, 16L: 1D:6L:1D Days 29 to 35, and 23L:1D thereafter. In Experiment 1, BW was greater in Treatment 4 than Treatment 2 at 22 (708 vs 642 g) and 49 d (2,948 vs 2,797 g), percentage leg problems was lower in Treatments 2 to 4 (9, 10 and 6%, respectively) than in Treatment 1 (20%), and percentage Grade A was greater in Treatment 4 than Treatment 2 (60 vs 46%) at 49 d. In Experiment 2, BW was greater in Treatment 1 (692 g) than Treatments 3 (617 g) and 4 (620 g) at 21 d, and the incidence of tibial dyschondroplasia was lower in Treatment 2 (3.1%) than Treatment 3 (15.3%) at 42 d. There were no differences for mortality among treatments in either experiment.
authors.affiliation: Department of Poultry Science, Auburn University, Alabama 36849, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Renden
authors.forename: E T
authors.initials: ET
authors.lastname: Moran
authors.forename: S A
authors.initials: SA
authors.lastname: Kincaid
mesh_terms: D000818:Animals; D001835:Body Weight / Q000502:physiology; D002645:Chickens / Q000254:growth & development* / Q000502:physiology; D006799:Housing, Animal; D015994:Incidence; D008027:Light; D008029:Lighting; D008297:Male; D010009:Osteochondrodysplasias / Q000453:epidemiology / Q000503:physiopathology / Q000662:veterinary*; D011201:Poultry Diseases / Q000453:epidemiology* / Q000401:mortality / Q000503:physiopathology; D011897:Random Allocation; D013977:Tibia / Q000002:abnormalities* / Q000254:growth & development / Q000502:physiology; D013997:Time Factors