Optimum phosphorus level in diets for red snapper (Lutjanus argentimaculatus, Forskal)
2006
Juadee Pongmaneerat(Department of Fisheries, Bangkok (Thailand)) | Pitchaya Chainark(Department of Fisheries, Bangkok (Thailand). Phangnga Coastal Fisheries Research and Development Center) | Kovit Koaean(Department of Fisheries, Bangkok (Thailand). Phangnga Coastal Fisheries Research and Development Center) | Sawitri Silakes(Department of Fisheries, Bangkok (Thailand). Fisheries Inland Research and Development Bureau) | Darawan Yuttayong(Department of Fisheries, Bangkok (Thailand). Fisheries Inland Research and Development Bureau) | Twee Chindamaikul(Department of Fisheries, Bangkok (Thailand). Kung Krabaen Bay Royal Development Study Center)
Feeding trial was conducted to determine the optimum level of dietary phosphorus levels for red snapper in aquarium tank of 180 l with over-flow seawater system. Fish meal was used as the dietay protein sources. Six practical diets were formulated by adding NaH2PO42H2O into the basal diet at the levels of 0, 1 percent, 2 percent and 3 percent without CaCo3 in diets 1-4, respectively. Basal diet was added with NaH2PO42H2O 1 percent plus CaCO3 0.5 percent in diet 5 and NaH2PO42H2O 2 percent plus CaCO3 1 percent in diets 6. Each diet was randomly assigned to triplicate groups of fish, and each group was stocked with 20 fish with an initial mean weight of 1.87+-0.14 g and mean length of 4.87+-0.10 cm. Fish were fed twice daily to apparent satiation for 18 weeks. Final body weight, feed conversion ratio and survival rate were not significantly different among the groups. Finsl body weight ranged from 15.74 g to 22.97 g, feed conversion ratio ranged from 2.81 to 3.22 and percent survival ranged from 73.3 percent to 98.3 percent. However, weight gain of fish fed diet 2 adding with NaH2PO42H2O 1 percent had significantly higher than other groups. The content of whole body protein, lipid and ash was not markedly affected by dietary phosphorus and calcium supplementation. The content of vertebrae calcium and phosphorus was also did not show any marked different among the group, but the ratio of calcium to phosphorus (Ca:P ratio) was similar to 2:1 for all the groups. Based on the growth and feed utilization, it was indicated that the optimum phosphorus level in diet for red snapper was about 1.89 percent which is 1.6 percent of this derived from fish meal. In addition, supplementation of calcium is not necessary when the dietary phosphorus of 1.6 percent derived from fish meal and that is sufficient for normal growth of red snapper under the condition of this study.
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