عنوان مقاله [English]
نویسندگان [English]چکیده [English]
In this study, the effects of different dietary protein and lipid levels including three dietary protein levels (35, 40 and 45%) and two dietary lipid levels (7 and 14%) were investigated on growth indices and hepatosomatic and viscera somatic index of Sobaity seabream juvenile (Sparidentex hasta) in triplicates. Fish with the mean initial weight 36.55±0.28 g were randomly introduced in eighteen 300 l polyethylene tanks and fed dietary treatments three times daily to satiation for a 56- day period. According to the results, weight gain and specific growth rate were significantly affected by different levelsof dietary protein (P<0.05). But varying levels of dietary protein and lipid had not any significant effects on condition factor, intraperitoneal fat percentage and feed intake (P>0.05). At the 14% dietary lipid level, hepatosomatic and viscera somatic index, protein efficiency ratio and carcass lipid content increased significantly(P<0.05). However, the food conversion ratio significantly decreased. With increasing the dietary lipid level, protein retention decreased and energy retention increased significantly. The highest nitrogen retention efficiency was observed at 40% protein level. Dietary protein and lipid levels significantly affected carcass protein and lipid contents (P<0.05), but had not any significant effect on moisture and ash contents (P>0.05). It was concluded that Sobaity seabream juveniles are able to utilize protein in 14% dietary lipid. Therefore, with increasing dietary lipid level to 14%, dietary protein level can be reduced to 40% in Sobaity seabream juveniles (S. hasta).