title: Temperature Increase Negatively Affects the Fatty Acid Bioconversion Capacity of Rainbow Trout (Oncorhynchus mykiss) Fed a Linseed Oil-Based Diet.
abstract: Aquaculture is meant to provide fish rich in omega-3 long chain polyunsaturated fatty acids (n-3 LC-PUFA). This objective must be reached despite (1) the necessity to replace the finite and limited fish oil in feed production and (2) the increased temperature of the supply water induced by the global warming. The objective of the present paper was to determine to what extent increased water temperature influences the fatty acid bioconversion capacity of rainbow trout (Oncorhynchus mykiss) fed a plant-derived diet. Fish were fed two diets formulated with fish oil (FO) or linseed oil (LO) as only added lipid source at the optimal water temperature of 15°C or at the increased water temperature of 19°C for 60 days. We observed that a temperature increase close to the upper limit of the species temperature tolerance range negatively affected the feed efficiency of rainbow trout fed LO despite a higher feed intake. The negative impact of increased water temperature on fatty acid bioconversion capacity appeared also to be quite clear considering the reduced expression of fatty acid desaturase 2 in liver and intestine and the reduced Δ6 desaturase enzymatic activity in intestinal microsomes. The present results also highlighted a negative impact of increased temperature on the apparent in vivo enzymatic activity of Δ5 and Δ6 desaturases of fish fed LO. Interestingly, this last parameter appeared less affected than those mentioned above. This study highlights that the increased temperature that rainbow trout may face due to global warming could reduce their fatty acid bioconversion capacity. The unavoidable replacement of finite fish oil by more sustainable, readily available and economically viable alternative lipid sources in aquaculture feeds should take this undeniable environmental issue on aquaculture productivity into account.
authors.affiliation: Institut des Sciences de la Vie, Université catholique de Louvain, Louvain-la-Neuve, Belgium.
authors.forename: Julie
authors.initials: J
authors.lastname: Mellery
authors.affiliation: Unité de Recherche en Biologie Environnementale et Evolutive, Université de Namur, Namur, Belgium.
authors.forename: Florian
authors.initials: F
authors.lastname: Geay
authors.affiliation: Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, Scotland, United Kingdom.
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Tocher
authors.affiliation: Unité de Recherche en Biologie Environnementale et Evolutive, Université de Namur, Namur, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Kestemont
authors.affiliation: Institut des Sciences de la Vie, Université catholique de Louvain, Louvain-la-Neuve, Belgium.
authors.forename: Cathy
authors.initials: C
authors.lastname: Debier
authors.affiliation: Earth and Life Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium.
authors.forename: Xavier
authors.initials: X
authors.lastname: Rollin
authors.affiliation: Institut des Sciences de la Vie, Université catholique de Louvain, Louvain-la-Neuve, Belgium.
authors.forename: Yvan
authors.initials: Y
authors.lastname: Larondelle
mesh_terms: D000123:Acetyltransferases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D017756:Aquaculture; D004032:Diet; D044943:Fatty Acid Desaturases / Q000235:genetics / Q000378:metabolism; D000081031:Fatty Acid Elongases; D005227:Fatty Acids / Q000378:metabolism*; D007422:Intestines / Q000187:drug effects / Q000201:enzymology; D008043:Linseed Oil / Q000737:chemistry* / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D017686:Oncorhynchus mykiss / Q000254:growth & development / Q000378:metabolism*; D010938:Plant Oils / Q000737:chemistry* / Q000494:pharmacology; D013696:Temperature
chemical_list: D005227:Fatty Acids; D010938:Plant Oils; D008043:Linseed Oil; D044943:Fatty Acid Desaturases; D000123:Acetyltransferases; D000081031:Fatty Acid Elongases