title: Protein level affects the relative lysine requirement of growing rainbow trout (Oncorhynchus mykiss) fry.
abstract: The effect of two digestible protein levels (310 and 469 g/kg DM) on the relative lysine (Lys; g Lys/kg DM or g Lys/100 g protein) and the absolute Lys (g Lys intake/kg 0.75 per d) requirements was studied in rainbow trout fry using a dose-response trial. At each protein level, sixteen isoenergetic (22-23 MJ digestible energy/kg DM) diets were tested, involving a full range (2-70 g/kg DM) of sixteen Lys levels. Each diet was given to one group of sixty rainbow trout fry (mean initial body weight 0.78 g) reared at 15 degrees C for 31 feeding d. The Lys requirements were estimated based on the relationships between weight, protein, and Lys gains (g/kg 0.75 per d) and Lys concentration (g/kg DM or g/100 g protein) or Lys intake (g/kg 0.75 per d), using the broken-line model (BLM) and the non-linear four-parameter saturation kinetics model (SKM-4). Both the model and the response criterion chosen markedly impacted the relative Lys requirement. The relative Lys requirement for Lys gain of rainbow trout estimated with the BLM (and SKM-4 at 90 % of the maximum response) increased from 16.8 (19.6) g/kg DM at a low protein level to 23.4 (24.5) g/kg DM at a high protein level. However, the dietary protein content affected neither the absolute Lys requirement nor the relative Lys requirement expressed as g Lys/100 g protein nor the Lys requirement for maintenance (21 mg Lys/kg 0.75 per d).
authors.affiliation: Laboratoire de Pisciculture M. Huet, Unité de Biochimie de la Nutrition, Université catholique de Louvain, Route de Blocry 2, B-1348 Louvain-la-Neuve, Belgium.
authors.forename: Noelie
authors.initials: N
authors.lastname: Bodin
authors.forename: Bernadette
authors.initials: B
authors.lastname: Govaerts
authors.forename: Tarik
authors.initials: T
authors.lastname: Abboudi
authors.forename: Christel
authors.initials: C
authors.lastname: Detavernier
authors.forename: Sarah
authors.initials: S
authors.lastname: De Saeger
authors.forename: Yvan
authors.initials: Y
authors.lastname: Larondelle
authors.forename: Xavier
authors.initials: X
authors.lastname: Rollin
mesh_terms: D000818:Animals; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000378:metabolism; D004063:Digestion; D008239:Lysine / Q000008:administration & dosage* / Q000378:metabolism; D008954:Models, Biological; D009751:Nutritional Requirements; D017686:Oncorhynchus mykiss / Q000254:growth & development* / Q000378:metabolism*; D011897:Random Allocation
chemical_list: D004044:Dietary Proteins; D008239:Lysine