摄食水平对中华鳖稚鳖生长、氮排泄和能量收支的影响

EFFECT OF RATION LEVEL ON GROWTH,NITROGENOUS EXCRETION AND ENERGY BUDGET IN JUVENILE SOFT SHELLED TURTLE,PELODISCUS SINENSIS

在 30℃水温下进行摄食 -生长实验 (实验周期为 5 6d) ,设饥饿、1%、2 %、4 %和饱食 5个摄食水平 ,研究了中华鳖稚鳖 (39 5 4— 4 4 2 2g)的生长和能量收支。结果表明 ,中华鳖稚鳖的特定生长率随摄食水平的增加 ,其湿重、干物质、蛋白质和能量的特定生长率均呈二次曲线增加 ,其中干物质的特定生长率 (SGRdr)与摄食率 (Rl)的关系式为 :SGRdr=- 1 8799+1 0 795Rl- 0 0 832Rl2 (r=0 90 6 ,n =2 5 ,P <0 0 1) ;除干物质转化效率外 ,湿重、蛋白质和能量的转化效率在 2 %组均达到最大 ,分别为 36 31%、2 1 4 7%和 2 8 10 % ;除能量转化效率外 ,4 %组湿重、干物质和蛋白质的转化效率与最大值均无显著差异 ;摄食水平对中华鳖稚鳖总氮排泄率、氨氮排泄率、尿素氮排泄率以及氨氮占总氮排泄率的比例均有显著影响 (P <0 0 1) ,除氨氮占总氮比例外其他指标均随摄食水平的增加而增加 ,氨氮比例在饥饿组最高为 5 5 83% ,由饥饿到饱食其变化范围是 4 4 5 0 %— 5 5 83% ;总氮排泄率、氨态氮排泄率和尿素氮排泄率的变动范围分别是 19 81%— 6 5 87%、9 4 4 %— 36 31%和 8 2 4 %— 2 9 5 6 % ,回归分析表明 ,幼鳖的总氮排泄率 (μmol/g·d) (G N)、氨氮排泄率 (μmol/g·d) (NH3 N)及尿素氮排泄率 (μmol/g·

The 56 day growth trial was conducted at 30℃ to investigate the effect of ration level on growth,nitrogenous excretion and energy budget in juvenile soft shelled turtle(Pelodiscus sinensis).Juvenile turtles(28 66—53 37g)were fed commercial diet(Shenzhen Xinguang Feed company)at five different levels ranging from starvation to ad libitum twice daily.The results showed that specific growth rate(SGR)of wet weight(SGRw),dry matter(SGRdr),protein(SGRp)and energy(SGRe)was affected significantly(P<0 01)by ration level.Regression analysis showed that the SGR increased quadraticly with increasing ration.The relationship between specific growth rate and ration level(Rl)could be expressed as the equation bellow: SGRw=-1 0473+0 7134R-0 0512Rl 2 (r 2=0 8314,n=25,P<0 01) SGRdr=-1 8779+1 0795Rl-0 0832Rl 2 (r 2=0 9064,n=25,P<0 01) SGRp=-1 9134+1 1460Rl-0 0943Rl 2 (r 2=0 9122,n=25,P<0 01) SGRe=-2 5872+1 4014Rl+0 1105Rl 2 (r 2=0 8844,n=25,P<0 01) Feed efficiency in wet weight,protein and energy was highest at 2% ration,which were 36 31%,21 47% and 28 10% respectively.The effects of ration level on ammonia,urea nitrogenous excretion and the proportion of ammonia excretion to total nitrogen excretion were significant (P<0 01).The urea and total nitrogenous excretion rate increased with increasing ration,and ranged 8 24—29 56(μmol/g·d)and 18 81%—65 87%(μmol/g·d)from starvation to ad libitum,respectively.Ammonia excretion rate and the proportion of ammonia excretion to total nitrogen excretion at starvation were higher than that of 1% and ranged 9 44—36 31(μmol/g·d)and 44 50%—55 09%,respectively.Regression analysis showed that the relationship between nitrogen excretion(μmol/g·d)and protein intake rate(PL)(%body weight per day)could be expressed as: G N=3 6592+49 1775PL (n=20,r 2=0 8716) NH 3 N=-1 1239+29 5939PL (n=20,r 2=0 8964) U N=4 7831+19 5836PL (n=20,r 2=0 6574) where the G N,NH 3 N and U N indicate general nitrogen,ammonia and urea excretion rate respectively.The proportions of energy intake allocated to various components of the energy budget were significantly affected by ration(P<0 01).The proportion of metabolic energy to food energy was highest at 1% ration level which was 86 22% and lowest at 2% which was 63 54%.the proportion of growth changes was highest at 2% ration level which was 28 10%.The energy budget equation for the starvation group could be expressed as: 100C=6 84F+2 64U+72 12R+17 76G where C,F.U,R and G is…… The results showed that the nitrogenous excretion rate increased with increasing ration linearly,while conversion efficiency of energy was highest at lower ration level(2%).In conclusion,the best ration level for juvenile soft shelled turtle culture is 4% because the turtle has higher specific growth rate,conversion efficiency and relatively lower nitrogen excretion rate.