title: Voluntary timing of food intake increases weight gain and reduces basal plasma cortisol levels in common carp (Cyprinus carpio L.).
abstract: We investigated the effect of timing of food intake on growth in common carp (Cyprinus carpio L.). Juvenile carp were demand-fed for 22 days using a computerized pendulum feeder that registered meal requests. Controls were pair-fed at 10:00 h, both groups were kept at 12L:12D (lights on at 06:30 h). Demand-fed fish displayed highest food intake at 22:00 h, and the lowest at 10:00. After 22 days, demand-fed fish had grown by 20% of their initial body weight, compared to 4% of the pair-fed control. Plasma cortisol levels in demand-fed fish were remarkably low and stable, whereas in the control group levels had increased 60-fold at 10:00 h compared to 22:00 h. Hepatic mRNA expression of leptin-a1 and leptin-a2 also differed markedly between groups and time points, with leptin-a2 expression being lowest in the demand-fed group at the time point of lowest food intake. We conclude that timing of food intake is an important determinant of endocrine status, growth and welfare.
authors.affiliation: Department of Organismal Animal Physiology, Institute for Water and Wetland Research, Radboud University Nijmegen, The Netherlands. Electronic address: p.klaren@science.ru.nl.
authors.forename: Peter H M
authors.initials: PH
authors.lastname: Klaren
authors.forename: Stephanie C M
authors.initials: SC
authors.lastname: van Dalen
authors.forename: Wim
authors.initials: W
authors.lastname: Atsma
authors.forename: F A Tom
authors.initials: FA
authors.lastname: Spanings
authors.forename: Jasper
authors.initials: J
authors.lastname: Hendriks
authors.forename: Gert
authors.initials: G
authors.lastname: Flik
mesh_terms: D000818:Animals; D002347:Carps / Q000502:physiology*; D004435:Eating / Q000502:physiology*; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D006854:Hydrocortisone / Q000097:blood*; D020738:Leptin / Q000235:genetics / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D015430:Weight Gain / Q000502:physiology*
chemical_list: D020738:Leptin; D006854:Hydrocortisone
keywords: Common carp; Cortisol; Cyprinus carpio; Daily rhythm; Food intake; Growth; Leptin; Thyroid hormones