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    Effect of autoclaved Ulva meal on growth performance, nutrient utilization and fatty acid profile of rainbow trout, Oncorhynchus mykiss
    (Springer, 2013) Guroy, Betul; Ergün, Sebahattin; Merrifield, Daniel L.; Guroy, Derya
    A feeding trial was conducted to investigate the effects of the dietary incorporation of autoclaved and raw (non-autoclaved) Ulva meal on juvenile rainbow trout (Oncorhynchus mykiss) growth, nutrient utilization, body composition, diet digestibility and fatty acid composition. An algae-free control diet and four experimental diets with either 5 or 10 % inclusion levels of raw Ulva meal (5 % = RU5; 10 % = RU10) or autoclaved Ulva meal (5 % = AU5; 10 % = AU10) were formulated. Fish were fed three times daily to apparent satiation for 12 weeks. The growth of fish fed RU10 (final weight = 76.7 +/- A 3.31 g; SGR = 2.8 +/- A 0.05 %) diet was significantly higher than that in fish fed the AU10 diet (67.5 +/- A 1.61 g; SGR = 2.6 +/- A 0.03 %). The feed conversion ratio (FCR) was significantly better in fish fed the RU10 diet (0.9 +/- A 0.06) compared with control diet (1.0 +/- A 0.06). Condition factor, viscerosomatic index and dress-out remained unaffected by dietary treatment. The hepatosomatic index (HSI) was significantly lower (P < 0.05) in fish fed the AU10 diet (1.2 +/- A 0.19) than fish fed the other diets (a parts per thousand yen1.6). The level of eicosapentaenoic acid (20:5n-3-EPA) in muscle from fish fed the RU10, AU5 and AU10 diets was significantly higher than in fish fed control diet (P < 0.05). Dietary inclusion of Ulva meals resulted in a significant increase in muscle docosapentaenoic acid (22:5n-3-DPA) levels at the end of the feeding period. The results indicate that the dietary inclusion of raw Ulva meal at levels of up to 10 % can be used without significant negative effects on the growth performance, nutrient utilization, dietary digestibility and muscle fatty acid composition. In fact, the inclusion of dietary raw and autoclaved Ulva meal elevated n-3 fatty acids levels of rainbow trout muscle.
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    Replacement of fishmeal with rice protein concentrate in practical diets for European sea bass Dicentrarchus labrax reared at winter temperatures
    (Wiley-Blackwell, 2013) Guroy, Derya; Sahin, Izzet; Guroy, Betul; Merrifield, Daniel L.; Bulut, Musa; Tekinay, Ahmet Adem
    As no information is available regarding the efficacy of using rice protein concentrate (RPC) to replace fishmeal (FM) in diets for European sea bass (Dicentrarchus labrax), a trial was conducted to determine the optimum inclusion for European sea bass juveniles. Diets were formulated to replace 25%, 50% and 75% of fishmeal with RPC. Additional high level inclusion diets (50% and 75%) were supplemented with lysine and methionine to determine if these were limiting factors. Fish (18.0 +/- 0.06g) were fed the experimental diets for 12weeks. The final mean weight and specific growth rate (SGR) were significantly higher in fish fed the control diet (diet FM) and low level RPC (diet RPC25) than in fish fed the other diets. The supplementation of the amino acids had a positive effect on growth, elevating the final weight of the high level RPC (RPC75+AA) group above that of the non-supplemented group (RPC75). However, this was still not comparable to fish fed FM and RPC25 diets. No significant differences in body composition were observed. A digestibility study demonstrated an inverse relationship between elevating inclusion levels of RPC and apparent digestibility coefficients (ADCs) for dry matter and lipid, with significantly lower values than the control being observed with RPC inclusions above 25%. The mesenteric fat index followed this trend. Circulating leucocyte levels, leucocyte ratios and serum lysozyme activity remained unaffected by dietary treatment. However, compared with the control group, fish fed RPC75, RPC50+AA RPC75+AA displayed significantly lower haematocrit values. The present study demonstrates that the inclusion of RPC at 140gkg1 (effectively replacing 25% of FM content) does not compromise European sea bass growth performance, body quality or basic haematological parameters. It is suggested that future studies including higher levels test the efficacy of additional amino acid supplementation (e.g. tryptophan).