title: Growth responses of broiler chickens to different periods of artificial light.
abstract: This study aimed to establish response curves between broiler chicken growth parameters and artificial light periods, as opposed to optimizing a lighting regimen for broiler production. Medium-growing broiler chickens were illuminated for periods of 12, 14, 16, 18, 20, 22, or 24 h each day. The BW of the broilers were significantly influenced by light periods ( < 0.05). Moreover, BW responded to light periods in a linear fashion, suggesting that long light periods result in greater BW. In addition, a linear relationship was found between feed intake and light periods. However, the relationship between shank length and light period was quadratic. When the light period was too short (12 h) or too long (24 h), the light stimulus did not enhance shank growth in the broiler chickens ( < 0.05). In addition, a quadratic relationship between the quantity of abdominal adipose tissue and light period suggested that the quantity of abdominal adipose decreases when the period of the light stimulus was too short or too long ( < 0.05). Moreover, a broken-stick analysis suggested that the triiodothyronine (T3) concentration in the blood was minimally affected beyond 18 h ( = 0.267), although a quadratic relationship was found between the period (from 18 to 24 h) and T3 concentrations in the blood. The response curves established in the present study will be valuable for designing future lighting regimes for medium-growing broiler strains.
authors.forename: Y F
authors.initials: YF
authors.lastname: Yang
authors.forename: S F
authors.initials: SF
authors.lastname: Jin
authors.forename: Z T
authors.initials: ZT
authors.lastname: Zhong
authors.forename: Y H
authors.initials: YH
authors.lastname: Yu
authors.forename: B
authors.initials: B
authors.lastname: Yang
authors.forename: H B
authors.initials: HB
authors.lastname: Yuan
authors.forename: J M
authors.initials: JM
authors.lastname: Pan
mesh_terms: D050154:Adiposity / Q000502:physiology; D000818:Animals; D001835:Body Weight / Q000502:physiology*; D002645:Chickens / Q000254:growth & development* / Q000502:physiology*; D004435:Eating / Q000502:physiology; D005260:Female; D006799:Housing, Animal; D008029:Lighting; D016014:Linear Models; D017440:Photoperiod; D011897:Random Allocation; D013997:Time Factors