title: Effect of timing and size of photoperiod change on plasma FSH concentration and the correlation between FSH and age at first egg in pullets.
abstract: 1. ISA Brown pullets were transferred at 6, 9, 12, 15, 18 or 20.3 weeks of age from an 8 h photoperiod to an 8, 10, 13 or 16 h photoperiod. Plasma follicle stimulating hormone (FSH) concentration was measured at transfer at 7 and 14 d afterwards, and age at first egg (AFE) was recorded. 2. Plasma FSH concentration in pullets reared on constant 8 h photoperiods generally increased with age but with a trough at 12 weeks. Plasma FSH increased during the first 14 d of photostimulation to a significantly higher concentration, compared with constant 8 h controls, when the photoperiod was increased to 13 or 16 h at 9, 12 or 15 weeks; but for the increase from 8 h to 10 h photoperiods FSH was only significantly higher than controls when the change was made at 12 weeks. 3. The change in plasma FSH concentration 14 d after photostimulation was significantly correlated with mean AFE (reported in Lewis et al., 1997) and appears to be a better predictor of gonadal development than concurrent changes in plasma LH concentration previously reported (Lewis et al., 1994).
authors.affiliation: Department of Clinical Veterinary Science, University of Bristol, Langford, UK.
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: J A
authors.initials: JA
authors.lastname: Douthwaite
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D002645:Chickens / Q000097:blood / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood*; D007986:Luteinizing Hormone / Q000097:blood; D010060:Ovulation / Q000502:physiology; D013997:Time Factors
chemical_list: D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone