摄食水平对中华鳖(Trionyx sinensis)幼鳖生长和能量收支的影响

EFFECT OF RATION LEVEL ON ENERGY BUDGET IN JUVENILE SOFT-SHELLED TURTLE,TRIONYX SINENSIS

于2001年10月—2002年3月在深圳职业技术学院海洋生物技术实验室进行摄食-生长实验(实验周期为56天)。实验在水温30℃的条件下进行,设饥饿、1%、2%和饱食4个摄食水平,研究了中华鳖(Trionyxsinensis)幼鳖(296.60—396.09g)的生长和能量收支。结果表明,中华鳖幼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=-0.3621+0.8809Rl-0.1352Rl2(r2=0.896,n=26,P<0.01);除湿重的转化效率外,干物质、蛋白质和能量的转化效率在2%组均达到最大,分别为27.47%、31.48%和25.01%;摄食水平对中华鳖氨氮排泄率和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<0.01),总氮排泄率、氨态氮排泄率和尿素氮排泄率均随摄食水平的增加而升高,从饥饿组到饱食组的变动范围分别是4.71%—38.70%、3.50%—24.64%和1.21%—6.48%,而氨氮占总氮比例的变化规律与上述指的标略有不同,饥饿组的比例略高于1%组,摄食组的比例随摄食水平的增加而增加,该比例的变动范围是71.92%—83.20%,回归分析表明,幼鳖的总氮排泄率[μmol/(g·d)](GN)、氨氮排泄率[μmol/(g·d)](NH3N)及尿素氮排泄率[μmol/(g·d)](UN)

In order to investigate the effect of ration on growth and energy budget in juvenile soft-shelled turtle (Trionyx sinensis), a growth trial was conducted at 30℃ for a period of 56d. Initial body weights of the juvenile were 296.60—396.09g. The turtles were fed with commercial diet, produced by Shenzhen Xinguang artificial diet company, at four rations ranging from starvation level to ad libitum twice daily. ANOVA showed that the specific growth rate (SGR) of wet weight (SGR_w), dry matter (SGR_~dr ), protein (SGR_p) and energy (SGR_e) were affected significantly (P< 0.01) by ration level. Regression analysis showed that the SGR increased quadratically with increasing rations. The relationship between specific growth rate and ration level (Rl) could be expressed as SGR_w=-0.1224+0.5183Rl-0.0564Rl2 (r2=0.885, n=26, P<0.01) SGR_~dr =-0.3621+0.8809Rl-0.1352Rl2 (r2=0.896, n=26, P<0.01) SGR_p =-0.3817+0.8777Rl-0.1379Rl2 (r2=0.899, n=26, P<0.01) SGR_e=-0.3197+0.3804Rl+0.001Rl2 (r2=0.586, n=26, P<0.01) Conversion efficiency for dry matter, protein and energy was highest at 2% ration group which were 27.47%, 31.48 % and 25.01% respectively. ANOVA shows that the effect of ration level on ammonia, urea nitrogenous excretion and the proportion of ammonia excretion rate to total nitrogen excretion was significant (P<0.01). Ammonia, urea and total nitrogenouse xcretion rate increased along with increasing ration, the ranges were 3.50%—24.64%, 1.21%—6.48% and 4.71%—38.70% from starvation to ad libitum respectively. The range for the proportion of ammonia excretion to total nitrogen excretion was 71.92%—83.20%. Regression analysis showed also the relationship between nitrogen excretion [μmol/(g·d)] and protein intake rate (PL) (% body weight per day) could be expressed as G-N=-0.2499+52.5132PL (n=20, r2=0.8660,P<0.01) NH_3-N=2.6770+5.0427PL (n=20, r2=0.8633,P<0.01) U-N=4.7831+19.5836PL (n=20, r2=0.5761,P<0.01) G-N, NH_3-N and U-N indicate general nitrogen, ammonia and urea excretion rate. The proportions of energy intake allocated to various components of the energy budget were significantly affected by rations (P<0.01). The proportion of food energy lost in fecal and nitrogenous excretion increased with increasing rations, the ranges were 15.43%—19.74% and 4.56%—4.65% respectively, from starvation to maximum ration. The proportion of metabolic energy to food energy was highest at a 1% ration level which was 96.53%, while growth was highest when the ration was 2% which was 25.01%. The energy budget equation for the maximum ration group could be expressed as 100C=19.74F+4.65U+54.15R+21.46G This research shows that the nitrogenous excretion rate had a linear increase with increasing ration, while conversion efficiency of energy was highest at the middle ration level (2%). Thus, for culture of the soft-shelled turtle, the ration should be adjusted to the middle level to retain high conversion efficiency and optimum water quality. The equation expressing the relationship between ration and nitrogenous excretion rate could be used in water quality control for the soft-shelled turtle culture.