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

Thermal Tolerance of Turkish Crayfish (Astacus leptodactylus) Acclimated to Three Different Temperatures

Critical thermal maxima (CTMax) and minima (CTMin) were determined for Turkish crayfish (Astacus leptodactylus) acclimated to 15, 20 and 25°C. CTMin and CTMax were 1.3, 1.1 and 2.0°C, and 37.4, 37.5 and 38.7°C, respectively. Thermal tolerance tests showed that acclimation temperatures (15, 20 and 25C) had significant effects on CTMin values of A. leptodactylus (P≤0.05). The area of thermal tolerance assessed using the CTMin and CTMax boundaries were calculated as 364°C2. The overall ARR values were calculated as 0.07 for CTMin and 0.13 for CTMax values between 15 and 25 C acclimation tempera-tures. All the crayfish crumpled at 0.5°C and showed overall spasm at 32.0 – 33.0°C. Farming A. leptodactylus in the southeastern part of the Mediterranean region may be practiced in terms of temperature tolerance

Avrupa deniz levreği yem formulasyonunda pamuk tohumu yağının potansiyel olarak balık yağına ikamesi

Yirmi adet Avrupa deniz levreği bireyi (35 g) 120 gün boyunca %100 balık yağı (BY), %40 Pamuk Toplama Yağı(PTY40), %60 (PTY60), %80 (PTY80) ve %100 (PTY100) oranlarında rafine edilmiş pamuk tohumu yağı (PTY) ilave edilmiş beş yemle beslenmiştir. Balık büyümesi, yem çevirim oranı ve protein değerlendirme yem uygulamasıyla değişmezken, hepatosomatik ve visseral yağ indeksi yemdeki PTY’nin seviyesiyle artmıştır. Fileto toplam lipit yağ asidi kompozisyonu test yemlerinin yağ asidi kompozisyonuna yansımıştır. BY, PTY40 ve PTY60 ile beslenen bireylerin fileto tekli doymamış yağ asidi miktarı diğer gruplara göre daha yüksek iken doymuş (DYA) ve çoklu doymamış yağ asitleri (ÇDYA) miktarı etkilenmemiştir. Test yemleri göz önüne alındığında, PTY100 grubu bireylerinin fileto yağlarında bazı yağ asitleri (18:0, 18:1n-9, 20:5n-3 ve 22:6n-3) yüksek oranda birikmiştir. Filetodaki uzun zincirli n-3 ÇDYA’lerin birikimi artan balık yağı oranı ile beslenen balıklarda yetersizdir. Bu çalışma, yemlerde balık unu kullanıldığı sürece, büyüme performansı ve yem değerlendirme açısından Avrupa deniz levreği (35 g) için PTY’nin balık yağını ikame edilebileceğini önermektedir.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

Balık yağ yerine kısmı bitkisel yağlar ın Avrupa deniz levreği (dicentrarchus labrax) ‘nin beslenmesine büyüme performansı ve yağ asitleri profili üzerine etkileri

Bu çalışma alternatif yağ kaynaklarının; levrek bireylerinde büyüme, vücut kompozisyonu ve yem değerlendirmesi üzerine etkilerini belirlemek üzere yapılmıştır. Denemede kullanılan yağlar susam yağı, kanola yağı ve soya yağı. Denemede kullanılan tüm yağlar, %50’sini balık yağının oluşturduğu diyetlere %50 oranında dahil edilmiştir ve %100 balık yağından oluşan bir diyetle karşılaştırılmıştır. Diyetlerin Spesifik Büyüme o ranı üzerinde hiçbir etkisi olmamıştır. Kanola yağı ve soya yağı ile beslenen balıklarla karşılaştırılınca, en yüksek final ağırlığı susam yağı ve balık yağı diyetleriyle beslenen balıklarda görülmüştür (P0 ,05). n -6 yağ asitlerinde, diğer diyetlere oranla soya yağı diyetinin önemli miktarda linoleik asit (LA, 18:2n -6) içerdiği gözlenmiştir.Diyet grupları arasında Eicosapentaenoic acid (EPA, 20:5n -3) ve docosahexaenoic acid (DHA, 22:6n -3)’nın depolandığı belirlenmiştir. Sonuç olarak, Avrupa deniz levreği diyetlerinde balık yağına alternatif, 585 mg/g balık unu içeren susam yağı kullanılabilir.The study was conducted to determine the effects of alternative oil sources on growth, body composition and feed conversion of sea bass individuals. The tested oils used in the study were as follows: sesame oil (SO), canola oil (CO) and soybean oil (SBO). All tested oils were included at a 50% substitution level of fish oil and were compared with a control diet containing 100% fish oil (FO). There was no effect of diet on specific growth rate. The highest final weight was seen in fish fed SO and FO diets co mpared to that of fish fed CO diet and SBO diets (0.05). In the n -6 fatty acids, fish fed SBO diet contained significant amount of linoleic acids (LA, 18:2n -6) compared to that of fish other dietary treatments diets . Deposition of eicosapentaenoic acid (EPA, 20:5n -3) and docosahexaenoic acid (DHA, 22:6n -3) was identical among the dietary treatments. In conclusion, the result of the trial show that sesame oil could be used as an alternative to fish oil in European sea bass diet formulation while when fish meal content of the diet is kept relatively high as it was the case our present in this study (585 mg/g

Fatty acid metabolism in European sea bass (Dicentrarchus labrax) : effects of n-6 PUFA and MUFA in fish oil replaced diets

Monounsaturated fatty acids (MUFA)-rich and n-6 polyunsaturated fatty acid (n-6 PUFA)-rich vegetable oils are increasingly used as fish oil replacers for aquafeed formulation. The present study investigated the fatty acid metabolism in juvenile European sea bass (Dicentrarchus labrax, 38.4 g) fed diets containing fish oil (FO, as the control treatment) or two different vegetable oils (the MUFA-rich canola/rapeseed oil, CO, and the n-6 PUFA-rich cottonseed oil, CSO) tested individually or as a 50/50 blend (CO/CSO). The whole-body fatty acid balance method was used to deduce the apparent in vivo fatty acid metabolism. No effect on growth performance and feed utilization was recorded. However, it should be noted that the fish meal content of the experimental diets was relatively high, and thus the requirement for n-3 long-chain polyunsaturated fatty acid (n-3 LC-PUFA) may have likely been fulfilled even if dietary fish oil was fully replaced by vegetable oils. Overall, relatively little apparent in vivo fatty acid bioconversion was recorded, whilst the apparent in vivo ?-oxidation of dietary fatty acid was largely affected by the dietary lipid source, with higher rate of ?-oxidation for those fatty acids which were provided in dietary surplus. The deposition of 20:5n-3 and 22:6n-3, as % of the dietary intake, was greatest for the fish fed on the CSO diet. It has been shown that European sea bass seems to be able to efficiently use n-6 PUFA for energy substrate, and this may help in minimizing the ?-oxidation of the health benefiting n-3 LC-PUFA and thus increase their deposition into fish tissues