An 8-week feeding trial was conducted to detect the optimal dietary protein and energy, as well as the ef fects of protein to energy ratio on growth, for the rare minnow( Gobiocypris rarus), which are critical to nutr...An 8-week feeding trial was conducted to detect the optimal dietary protein and energy, as well as the ef fects of protein to energy ratio on growth, for the rare minnow( Gobiocypris rarus), which are critical to nutrition standardization for model fi sh. Twenty-four diets were formulated to contain three gross energy(10, 12.5, 15 kJ/g), four protein(20%, 25%, 30%, 35%), and two lipid levels(3%, 6%). The results showed that optimal dietary E/P was 41.7–50 kJ/g for maximum growth in juvenile rare minnows at 6% dietary crude lipid. At 3% dietary lipid, specifi c growth rate(SGR) increased markedly when E/P decreased from 62.5 kJ/g to 35.7 kJ/g and gross energy was 12.5 kJ/g, and from 75 kJ/g to 42.9 kJ/g when gross energy was 15.0 kJ/g. The optimal gross energy was estimated at 12.5 kJ /g and excess energy decreased food intake and growth. Dietary lipid exhibited an apparent protein-sparing eff ect. Optimal protein decreased from 35% to 25%–30% with an increase in dietary lipid from 3% to 6% without adversely ef fecting growth. Dietary lipid level af fects the optimal dietary E/P ratio. In conclusion, recommended dietary protein and energy for rare minnow are 20%–35% and 10–12.5 k J/g, respectively.展开更多
文摘三氯生(triclosan,TCS)和三氯卡班(triclocarban,TCC)是2种高效广谱抗菌剂,均具有胚胎毒性、内分泌干扰性和生殖毒性,并可能引发癌症、DNA损伤和不良妊娠结局等,是目前一类广泛关注的新污染物。美国食品与药品监督管理局(US FDA)于2016年已禁止含有TCS和TCC等抑菌剂的非处方抗菌洗浴产品进入市场,而目前在我国其为化妆品准用防腐剂,允许限量使用,且皂类产品不在限制范围内。TCS和TCC作为新兴的外源性化学污染物能够随生活污水的排放进入自然环境,对我国本土水生生物、生态安全和人身健康构成了潜在威胁。为探究TCS和TCC对我国本土鱼种稀有鮈鲫(Gobiocypris rarus)长期暴露及4个不同发育阶段(胚胎期、卵黄囊吸收阶段、仔鱼及幼鱼阶段)的毒性效应,本研究将稀有鮈鲫的受精卵暴露于TCS和TCC中,直至孵化后60 d(60 days post hatch,60 dph),试验过程中监测胚胎期的孵化率,卵黄囊吸收阶段、仔鱼及幼鱼阶段的成活率,长期暴露过程中的生长情况、性分化及内分泌干扰效应等多个指标。研究结果显示,在胚胎期,6.25~100μg·L^(-1)的TCS和0.938~15μg·L^(-1)的TCC对稀有鮈鲫的胚胎孵化率没有显著的毒性效应。在仔鱼阶段,6.25~100μg·L^(-1)的TCS和0.938~15μg·L^(-1)的TCC暴露组30 dph成活率的最高无可观察效应浓度分别为100μg·L^(-1)和0.938μg·L^(-1),根据我国国家标准,TCC对水生环境的危害可判定为长期慢性类别1,而TCS由于试验中的最高浓度未达到1 mg·L^(-1),无法作出明确的判断,但能判断其对水生环境的危害为非长期慢性类别1。在幼鱼阶段,6.25~100μg·L^(-1)的TCS和0.938~15μg·L^(-1)的TCC均对雌性及雄性稀有鮈鲫体内卵黄蛋白原具有一定的诱导作用,但在性分化上没有显著影响。在胚后发育过程中,通过长期暴露,6.25~100μg·L^(-1)的TCS对稀有鮈鲫体质量有显著毒性效应,随TCS浓度的升高,稀有鮈鲫体质量逐渐降低,TCS对稀有鮈鲫体质量具有抑制作用;0.938~15μg·L^(-1)的TCC对稀有鮈鲫体质量及体长等生长均无显著影响。此外,研究发现稀有鮈鲫在不同发育阶段的毒性效应存在差异,稀有鮈鲫胚胎期的耐受力明显高于胚后发育阶段,卵黄囊吸收阶段及仔鱼阶段的耐受力低于幼鱼阶段。可见,当更多的生命阶段被包括在一个测试中,能够通过较少的试验动物,获得较多的毒性终点,且测试中不同生命阶段的毒性效应来自同一批试验动物,使不同生命阶段的试验结果更具可比性。
基金Supported by the National Key Technology R&D Program of China(No.2011BAI15B01-41)the National High Technology Research and Development Program of China(863 Program)(No.2012AA06A302)
文摘An 8-week feeding trial was conducted to detect the optimal dietary protein and energy, as well as the ef fects of protein to energy ratio on growth, for the rare minnow( Gobiocypris rarus), which are critical to nutrition standardization for model fi sh. Twenty-four diets were formulated to contain three gross energy(10, 12.5, 15 kJ/g), four protein(20%, 25%, 30%, 35%), and two lipid levels(3%, 6%). The results showed that optimal dietary E/P was 41.7–50 kJ/g for maximum growth in juvenile rare minnows at 6% dietary crude lipid. At 3% dietary lipid, specifi c growth rate(SGR) increased markedly when E/P decreased from 62.5 kJ/g to 35.7 kJ/g and gross energy was 12.5 kJ/g, and from 75 kJ/g to 42.9 kJ/g when gross energy was 15.0 kJ/g. The optimal gross energy was estimated at 12.5 kJ /g and excess energy decreased food intake and growth. Dietary lipid exhibited an apparent protein-sparing eff ect. Optimal protein decreased from 35% to 25%–30% with an increase in dietary lipid from 3% to 6% without adversely ef fecting growth. Dietary lipid level af fects the optimal dietary E/P ratio. In conclusion, recommended dietary protein and energy for rare minnow are 20%–35% and 10–12.5 k J/g, respectively.
