title: Dietary fish oil replacement by linseed oil: Effect on growth, nutrient utilization, tissue fatty acid composition and desaturase gene expression in silver barb (Puntius gonionotus) fingerlings.
abstract: Silver barb (Puntius gonionotus) is considered a promising medium carp species for freshwater aquaculture in Asia. This study in silver barb was carried out to evaluate the effects of total or partial substitution of dietary fish oil (FO) with linseed oil (LO) on growth, nutrient utilization, whole-body composition, muscle and liver fatty acid composition. Fish (12.1±0.4g of initial body weight) were fed for 60days with five experimental iso-proteinous, iso-lipidic and iso-caloric diets in which FO (control diet) was replaced by 33.3%, 50%, 66.7% and 100% LO. Final weight, weight gain, percent weight gain, SGR decreased linearly (p<0.001) with increasing LO levels in the diets. Dietary LO substitution levels did not significantly (p>0.05) affect the feed conversion ratio (FCR), protein efficiency ratio (PER) and whole body proximate composition. Furthermore, enhanced level of LO increased α-linolenic acid (ALA; 18:3n3) and linoleic acid (LA; 18:2n6) and decreased eicosapentaenoic acid (EPA; 20:5n3) and docosahexaenoic acid (DHA; 22:6n3) in muscle and liver. To understand the molecular mechanism of long chain-polyunsaturated fatty acid (LC-PUFA) biosynthesis, we cloned and characterized the fatty acyl Δ6 desaturase (Δ6 fad) cDNA and investigated its expression in various organs/tissues following replacement of FO with LO in the diet. The full-length Δ6 fad cDNA was 2056bp encoding 444 amino acids and was widely expressed in various organs/tissues. Replacement of FO with LO increased the expression of Δ6 fad mRNA in liver, muscle and intestine but no significant difference was found in the brain.
authors.affiliation: Division of Fish Nutrition and Physiology, ICAR-Central Institute of Freshwater Aquaculture, Kausalyaganga, Bhubaneswar, Odisha, India.
authors.forename: Madhusmita
authors.initials: M
authors.lastname: Nayak
authors.affiliation: Division of Fish Nutrition and Physiology, ICAR-Central Institute of Freshwater Aquaculture, Kausalyaganga, Bhubaneswar, Odisha, India. Electronic address: ashis73in@yahoo.co.in.
authors.forename: Ashis
authors.initials: A
authors.lastname: Saha
authors.affiliation: Division of Fish Nutrition and Physiology, ICAR-Central Institute of Freshwater Aquaculture, Kausalyaganga, Bhubaneswar, Odisha, India.
authors.forename: Avinash
authors.initials: A
authors.lastname: Pradhan
authors.affiliation: Division of Fish Nutrition and Physiology, ICAR-Central Institute of Freshwater Aquaculture, Kausalyaganga, Bhubaneswar, Odisha, India.
authors.forename: Mrinal
authors.initials: M
authors.lastname: Samanta
authors.affiliation: Division of Fish Nutrition and Physiology, ICAR-Central Institute of Freshwater Aquaculture, Kausalyaganga, Bhubaneswar, Odisha, India.
authors.forename: Shiba Shankar
authors.initials: SS
authors.lastname: Giri
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D003530:Cyprinidae / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D004032:Diet; D044943:Fatty Acid Desaturases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005227:Fatty Acids / Q000737:chemistry* / Q000378:metabolism; D005395:Fish Oils / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D008043:Linseed Oil / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D009132:Muscles / Q000187:drug effects / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D005395:Fish Oils; D008043:Linseed Oil; D044943:Fatty Acid Desaturases
keywords: Fatty acid; Fish oil; Growth; Linseed oil; Silver barb; Δ6 fad