Yazar "Sahin, Izzet" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • [ X ]
    Öğe
    Effect of Dietary Protein Level on Growth Performance and Nitrogen Excretion of the Yellow Tail Cichlid, Pseudotropheus acei
    (Israeli Journal Of Aquaculture-Bamidgeh, 2012) Guroy, Derya; Sahin, Izzet; Guroy, Betul; Altin, Aytac; Merrifield, Daniel Lee
    A 12-week growth trial was conducted to determine the effects of dietary protein on the growth of the yellow tail cichlid, Pseudotropheus acei, and on water quality in closed recirculating systems. Six test diets were formulated to contain protein levels ranging 25-50% by substituting corn oil and alpha-starch for fishmeal. Diets were assigned to triplicate groups of 10 fish in a completely randomized design. The feed conversion ratios of fish fed the 35% and 50% crude protein diets were significantly (p<0.05) lower than that of fish fed the 30% protein diet. The protein efficiency ratio declined as the dietary protein level increased. Dietary protein levels significantly influenced total ammonia-nitrogen excretion (TAN); fish fed 50% protein excreted higher concentrations of ammonia-nitrogen than fish fed 25-35% dietary protein (p<0.05). Results suggest that inclusion of more than 35% protein in diets containing 10% crude lipid does not benefit juvenile yellow tail growth performance. Further, as TAN excretion and feed costs increased at protein levels beyond 35%, we recommend a diet containing 35% protein and 10% lipid for promoting good growth of juvenile yellow tail cichlids under the conditions used in the present trial.
  • [ X ]
    Öğe
    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).