Effect Of Dietary Energy To Protein Ratios On Growth, Nitrogen Budget And Energy Budget Of Juvenile Tinfoil Barb Barbodes Schwanenfeldi

Effects of various dietary energy protein ratios (E/P) on growth, feed utilization efficiency, nitrogen budget and energy budget for juvenile tinfoil barb Barbodes schwanenfeldi weighted 56.63±4.51 g were studied. All diets, containing fish meal and casein as the protein sources, were maintained approximately isocaloric by adjusting the corn starch and cellulose contents and keeping the lipid fractions identical. Six different E/P diets-60.75 kJ-g-1(D1),51.83 kJ-g-1(D2), 47.36 kJ·g-1(D3),43.52 kJ·g-1(D4),39.67 kJ·g-1(D5) and 36.39 kJ-g-1(D6)-were formulated.The results base on 8 weeks'growth trial showed as follows:1. Effects of six different dietary energy protein ratios on growth, final weight (FW), weight gain rate (WGR) and specific growth rate (SGR) of juvenile tinfoil barb were not obvious (P>0.05), however, that on feed utilization efficiency was significant (P<0.05). Among six diets, D3 and D4 were the most effective diets with low feed ration level (RL), low feed coefficient (FCE), and high protein efficiency rate (PER).2. With the decreasing of E/P ratio, the changes of fish gross energy (GE), crude protein (CP), crude lipid (CL) and moisture contents were similar. Among six dietary groups, there was no significant difference in crude protein contents (P>0.05) but significant differences were in moisture, gross energy, and crude lipid contents (P<0.05).3. Six nitrogen budgets of tinfoil barb during 8 weeks'experiment were expressed as follows:D1:100.00CN=32.70GN+10.58FN+57.72END2:100.00CN=25.77GN+8.91FN+65.32END3:100.00CN=24.66GN+8.88FN+66.46END4:100.00CN=25.57GN+9.32FN+65.11END5:100.00CN=22.36GN+9.00FN+68.63END6:100.00CN=20.24GN+7.92FN+71.84ENAs a whole, the proportion of growth nitrogen decreased and the proportion of excretion nitrogen increased with decreasing the dietary E／P ratios.4.Six energy budgets of tinfoil barb during 8 weeks'experiment were expressed as follows:D1:100.00C=26.28G+12.06F+3.77U+57.89RD2:100.00C=25.64G+10.61F+5.02U+62.27RD3:100.00C=27.94G+11.92F+5.47U+58.63RD4:100.00C=26.88G+12.18F+5.94U+55.00RD5:100.00C=25.32G+13.20F+6.87U+54.60RD6:100.00C=27.47G+12.81F+7.84U+51.88RAs a whole,with dietary E／P ratios decreasing,the proportion of metabolic energy decreased and excretion energy increased.