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    Effects of Ulva rigida and Cystoseira barbata meals as a feed additive on growth performance, feed utilization, and body composition of Nile tilapia, Oreochromis niloticus
    (Tubitak Scientific & Technological Research Council Turkey, 2007) Guroy, Betul Kut; Cirik, Sukran; Guroy, Derya; Sanver, Feyza; Tekinay, Ahmet Adem
    In a 12-week feeding trial, the effect of 2 algae meals (Ulva rigida or Cystoseira barbata) on feed intake, growth, and nutrient utilization of juvenile Nile tilapia, Oreochromis niloticus, was investigated. This was the first attempt to utilize Cystoseira barbata as a feed supplement for Nile tilapia. The fish were fed to apparent satiation with formulated diets supplemented with various levels of Ulva meal (5%, 10%, or 15%) or Cystoseira meal (5%, 10%, or 15%). A diet without algae meal served as a control diet. The highest values for weight gain were for fish fed the 5% Cystoseira diet, control diet, and 5% Ulva diet (156%, 151%, and 150%, respectively), but the values were not significantly different (P > 0.05) compared to other treatments, except for the fish fed on the 15% Ulva diet (P < 0.05), which exhibited the lowest weight gain. Fish fed the diet containing 15% Ulva meal showed the poorest feed conversion ratio (FCR). Protein and energy utilization tended to decrease in the groups fed the algae meals at the highest supplementation level of 15%. Carcass lipid levels decreased with increasing levels of Ulva meal, while an increase in carcass lipid level with increasing levels of Cystoseira meal was observed (P < 0.05). The results suggested that Ulva rigida or Cystoseira barbata meals could be used in small percentages in tilapia diets.
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    Öğe
    Influence of feeding frequency on feed intake, growth performance and nutrient utilization in European sea bass (Dicentrarchus labrax) fed pelleted or extruded diets
    (Tubitak Scientific & Technological Research Council Turkey, 2006) Guroy, Derya; Deveciler, Emrah; Guroy, Betul Kut; Tekinay, Ahmet Adem
    In an 83-day-nutrition trial, effects of feed production technique and feeding frequency on feed intake, growth and nutrient utilization were determined in European sea bass (Dicentrarchus labrax). Three thousand six hundred fish (170 +/- 2.6 g) were randomly allocated to experimental sea cages (approx. 5800 l) according to a 2 x 2 experimental plan [2 processing techniques: steam pelleted diet (P) vs. extruded diet (E); 2 feeding frequencies: twice (2) vs. 3 times ( 3)]. The P3 group consumed significantly (P < 0.05) more feed than the fish fed extruded diets, irrespective of feeding frequency. Growth rates of all groups did not display any significant difference (P > 0.05) in terms of final weight (FW) or specific growth rate ( SGR), although there was a decreasing trend in final weight (E3 > E2 > P3 > P2). Feed efficiencies (FE) of E2 and E3 fish were higher than P2 and P3 treatments (P < 0.05). No significant difference (P > 0.05) was evident for the hepatosomatic index (%), mesenteric fat index (%), viscerasomatic index (%), or dress-out (%) parameters in all treatments. The carcass and muscle components (protein, lipid, and ash) did not reveal any significant difference (P > 0.05). According to the results, feeding sea bass twice or 3 times daily with steam pelleted or extruded diet did not influence the growth; however, extruded diet improved the feed efficiency of sea bass irrespective of feeding frequency.