Potential of Cottonseed Oil as Fish Oil Replacer in European Sea Bass Feed Formulation

Triplicate groups of 20 European sea bass (35 g) were fed five diets in which the added lipid was 100% fish oil (FO), 40% (CSO40), 60% (CSO60), 80% (CSO80) and 100% (CSO100) refined cottonseed oil (CSO), for a period of 120 days. Overall fish growth, feed conversion ratio and protein utilization were unaffected by dietary treatment, but hepatosomatic and visceral fat indexes increased with increasing dietary CSO. Fillet fatty acid composition of total lipids reflected the fatty acids in the test diets. The monounsaturated fatty acids were significantly higher in fillet of fish fed diet FO, CSO40 and CSO60 compared to other treatments while saturated and polyunsaturated fatty acids (PUFA) were not affected by the dietary treatment. Some fatty acids (18:0, 18:1n-9, 20:5n-3 and 22:6n-3) were present in higher concentration in fillet lipid than in the CSO100 dietary lipid indicating accumulation in fillet relative to test diets. Retention of n-3 LC-PUFA within the fillet was increasingly inefficient among fish fed increasing levels of FO. Thus, this study suggests that CSO can be considered as a relatively effective substitute for fish oil in European sea bass (35 g) in terms of growth performances and feed efficiency as far as fish meal is present in the diet.Original Abstract: Yirmi adet Avrupa deniz levregi bireyi (35 g) 120 guen boyunca %100 balik yagi (BY), %40 Pamuk Toplama Yagi (PTY40), %60 (PTY60), %80 (PTY80) ve %100 (PTY100) oranlarinda rafine edilmis pamuk tohumu yagi (PTY) ilave edilmis bes yemle beslenmistir. Balik bueyuemesi, yem cevirim orani ve protein degerlendirme yem uygulamasiyla degismezken, hepatosomatik ve visseral yag indeksi yemdeki PTY'nin seviyesiyle artmistir. Fileto toplam lipit yag asidi kompozisyonu test yemlerinin yag asidi kompozisyonuna yansimistir. BY, PTY40 ve PTY60 ile beslenen bireylerin fileto tekli doymamis yag asidi miktari diger gruplara goere daha yueksek iken doymus (DYA) ve coklu doymamis. yag asitleri (CDYA) miktari etkilenmemistir. Test yemleri goez oenuene alindiginda, PTY100 grubu bireylerinin fileto yaglarinda bazi yag asitleri (18:0, 18:1n-9, 20:5n-3 ve 22:6n-3) yueksek oranda birikmistir. Filetodaki uzun zincirli n-3 CDYA'lerin birikimi artan balik yagi orani ile beslenen baliklarda yetersizdir. Bu calisma, yemlerde balik unu kullamldigi suerece, bueyueme performansi ve yem degerlendirme acisindan Avrupa deniz levregi (35 g) icin PTY'nin balik yagini ikame edilebilecegini oenermektedir.