title: Effects of strain and light intensity on growth performance and carcass characteristics of broilers grown to heavy weights.
abstract: Effects of genetic strain and light intensity on growth performance and carcass characteristics of broilers grown to heavy weights were investigated. The experimental design was a randomized complete block design. Treatment structure was a 2 × 5 factorial arrangement with the main factors being strain (Ross × Ross 308, Ross × Ross 708) and light intensity (25, 10, 5, 2.5, and 0.2 lx) with trial as replicates. In each of the 5 trials, chicks of 2 different strains of the same commercial hatchery were equally and randomly distributed into 10 environmentally controlled rooms (5 rooms/strain) at 1 d of age at 50% RH. Each room was randomly assigned 1 of 5 light intensities from 22 to 56 d of age. Feed and water were provided ad libitum. Birds and feed were weighed on 0, 14, 28, 42, and 56 d of age for growth performance. Humoral immune response was determined on d 28, whereas ocular and blood samples were performed on d 42 and 55, respectively. On d 56, 20 (10 males and 10 females) birds/strain from each room were processed to determine weights and yields. Genetic strain was significant (P ≤ 0.05) for most of the examined variables, where Ross × Ross 308 had better growth performance and meat yield in comparison with Ross × Ross 708. Although, there was no main effect of light intensity on growth performance and meat yield, results indicated that birds under 10 and 5 lx intensities showed slightly better growth performance and meat yield compared with birds under 25, 2.5, and 0.2 lx in both strains. There was no effect of strain and light intensity on ocular indices, immune response, plasma corticosterone levels, and mortality. This study shows the positive influence on profits to commercial poultry facilities that are using a low lighting environment to reduce energy cost, optimize feed conversion, and maximize production without compromising the welfare of the broilers.
authors.affiliation: USDA, Agricultural Research Service, Poultry Research Unit, PO Box 5367, Mississippi State, MS 39762-5367 Hammed.Olanrewaju@ars.usda.gov.
authors.forename: H A
authors.initials: HA
authors.lastname: Olanrewaju
authors.affiliation: Advanced Animal Eye Care, 1067 Old West Point Road, Starkville, MS 39759.
authors.forename: W W
authors.initials: WW
authors.lastname: Miller
authors.affiliation: College of Veterinary Medicine, Wise Center, Mississippi State University, Mississippi State 39762.
authors.forename: W R
authors.initials: WR
authors.lastname: Maslin
authors.affiliation: USDA, Agricultural Research Service, Poultry Research Unit, PO Box 5367, Mississippi State, MS 39762-5367.
authors.forename: S D
authors.initials: SD
authors.lastname: Collier
authors.affiliation: USDA, Agricultural Research Service, Poultry Research Unit, PO Box 5367, Mississippi State, MS 39762-5367.
authors.forename: J L
authors.initials: JL
authors.lastname: Purswell
authors.affiliation: USDA, Agricultural Research Service, Poultry Research Unit, PO Box 5367, Mississippi State, MS 39762-5367.
authors.forename: S L
authors.initials: SL
authors.lastname: Branton
mesh_terms: D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D001774:Blood Chemical Analysis / Q000662:veterinary; D002645:Chickens / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000276:immunology / Q000502:physiology*; D005123:Eye / Q000254:growth & development / Q000528:radiation effects; D005260:Female; D056724:Immunity, Humoral / Q000528:radiation effects; D008029:Lighting; D008297:Male; D008460:Meat / Q000032:analysis* / Q000528:radiation effects; D009799:Ocular Physiological Phenomena / Q000528:radiation effects; D011897:Random Allocation
keywords: broiler; genetic strain; growth; light intensity; meat yield