title: Diets labelled with (13)C-starch and (15)N-protein reveal daily rhythms of nutrient use in gilthead sea bream (Sparus aurata).
abstract: All functions in animals rely on daily rhythms, and mealtime can act as a rhythm-marker of nutrients assimilation and use. The effects of meal timing and food composition on carbohydrate use and protein retention of gilthead sea bream were studied. Three groups were fed twice a day (10am and at 5pm) for two months with two alternating diets: a commercial diet (Cd) and a high-carbohydrate, low-protein diet (Ed). The Ed/Cd group received the Ed diet in the morning and the Cd diet in the afternoon, and the Cd/Ed group received these diets in the reverse order. The Cd/Cd group only received the commercial diet (control group). After 56days, two force-feeding experiments (PF1 and PF2) measured for all three groups the fate of a single meal labelled with (15)N-protein and (13)C-starch through the retention of both isotopes in the main organs and tissue reserves. In PF1 fish were fed at 10am (morning mealtime), and in PF2 at 5pm (afternoon mealtime). Fish were sampled at the next two mealtimes (PF1: 7 and 24h post-feeding, PF2: 17 and 24h post-feeding). Nutrients recovery differed according to, first, the dietary regime, and second, the last meal received (Cd or Ed). Daily lower protein intake was compensated with higher protein retention combined with more use of carbohydrates for energy. Nevertheless, carbohydrates from the morning meal were used more efficiently. So, the use of carbohydrate for energy production and protein for growth can be improved by adjusting diet composition and mealtime.
authors.affiliation: Xarxa de Referencia de Recerca i Desenvolupament en Aqüicultura de la Generalitat de Catalunya, Departament de Fisiologia i Immunologia Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain. Electronic address: olga.felip@ub.edu.
authors.forename: Olga
authors.initials: O
authors.lastname: Felip
authors.affiliation: Xarxa de Referencia de Recerca i Desenvolupament en Aqüicultura de la Generalitat de Catalunya, Departament de Fisiologia i Immunologia Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Josefina
authors.initials: J
authors.lastname: Blasco
authors.affiliation: Xarxa de Referencia de Recerca i Desenvolupament en Aqüicultura de la Generalitat de Catalunya, Departament de Fisiologia i Immunologia Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Antoni
authors.initials: A
authors.lastname: Ibarz
authors.affiliation: Xarxa de Referencia de Recerca i Desenvolupament en Aqüicultura de la Generalitat de Catalunya, Departament de Fisiologia i Immunologia Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain; Department of Genome Sciences, University of Washington, Seattle, USA.
authors.forename: Miguel
authors.initials: M
authors.lastname: Martín-Pérez
authors.affiliation: Xarxa de Referencia de Recerca i Desenvolupament en Aqüicultura de la Generalitat de Catalunya, Departament de Fisiologia i Immunologia Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Jaume
authors.initials: J
authors.lastname: Fernández-Borràs
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002244:Carbon / Q000378:metabolism; D002247:Carbon Isotopes; D002940:Circadian Rhythm; D004032:Diet; D004040:Dietary Carbohydrates / Q000378:metabolism*; D004044:Dietary Proteins / Q000378:metabolism*; D002149:Energy Intake; D005247:Feeding Behavior; D007553:Isotope Labeling; D008099:Liver / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D009587:Nitrogen Isotopes; D019518:Postprandial Period; D021541:Sea Bream / Q000097:blood / Q000378:metabolism*; D013213:Starch / Q000378:metabolism*; D014280:Triglycerides / Q000097:blood
chemical_list: D001786:Blood Glucose; D002247:Carbon Isotopes; D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D009587:Nitrogen Isotopes; D014280:Triglycerides; D002244:Carbon; D013213:Starch; D009584:Nitrogen
keywords: Delta (δ) (13)C; Feeding rhythm; Nutrient fate; Protein sparing; δ(15)N