title: Effects of timing and size of daylength change on brown egg laying domestic hens: plasma luteinising hormone concentration and sexual maturity.
abstract: 1. Brown egg laying pullets were transferred from an 8-h photoperiod to an 8-, 10-, 13- or 16-h photoperiod at 6, 9, 12, 15, 18 or 20.3 weeks of age. Plasma luteinising hormone (LH) concentrations were measured at transfer and 7 and 14 d afterwards. 2. Significant increases in plasma LH occurred following light stimulations at 6, 9 and 12 weeks of age. 3. Changes in LH concentration 7 d after a light increase from 8 h to 8, 10, 13, 16 h were highly correlated with photoperiod length at 9 and 12 weeks of age. 4. Changes in LH were generally poorly correlated with age at sexual maturity, although the reduced influence on age at first egg of a light increase given close to sexual maturity was reflected in minimal LH responses at 18 and 20.3 weeks.
authors.affiliation: Department of Animal Husbandry, School of Veterinary Science, University of Bristol, England.
authors.forename: P D
authors.initials: PD
authors.lastname: Lewis
authors.forename: G C
authors.initials: GC
authors.lastname: Perry
authors.forename: T R
authors.initials: TR
authors.lastname: Morris
authors.forename: B K
authors.initials: BK
authors.lastname: Follett
mesh_terms: D000375:Aging; D000818:Animals; D002645:Chickens / Q000502:physiology*; D005260:Female; D007986:Luteinizing Hormone / Q000097:blood*; D010058:Oviposition / Q000502:physiology*; D017440:Photoperiod; D012741:Sexual Maturation; D013997:Time Factors
chemical_list: D007986:Luteinizing Hormone