大黄鱼幼鱼对饲料中锌需要量

Dietary zinc requirement of juvenile large yellow croaker,Pseudosciaena crocea R.

  • 摘要: 以初始体重为1.78±0.02g的大黄鱼 (Pseudosciaena crocea R.)为实验对象,在室内流水系统(养殖桶规格:200L)中进行为期8周的摄食生长实验,研究大黄鱼对饲料中锌的需要量。通过在基础饲料中添加ZnSO4•H2O使饲料中锌含量分别达到9.68、30.63、48.94、91.28、167.49和326.81mg•kg -1。每种饲料设3个重复,每个重复放养40尾大黄鱼。实验采取饱食投喂方式,每天投喂2次(05:30和17:30),实验期间水温为26.5~29.5°C,盐度为25~28,溶解氧含量在7mg•L-1左右。实验结果表明各饲料处理组成活率(84.2~96.7 %)无显著差异。随着饲料中锌含量的增加,大黄鱼的特定生长率(SGR)显著升高(2.47~2.77%•d-1)(P<0.05),且在91.28mg•kg-1 锌饲料组达最大值(2.77%•d-1),然而,随着饲料中锌含量的进一步增加,SGR维持在一相对稳定水平。饲料锌含量显著影响大黄鱼脊椎骨、全鱼和血清中锌的含量,而对肝脏锌含量无显著影响。以SGR与骨骼锌含量为评价指标,根据折线模型得出大黄鱼对饲料中锌的需要量分别为59.6mg•kg-1和84.6mg•kg-1。

     

    Abstract: A growth experiment was conducted to determine the dietary zinc requirement for juvenile large yellow croaker (initial average weight 1.78 ± 0.02 g). Six semi-purified diets were formulated to contain 9.68, 30.63, 48.94, 91.28, 167.49 and 326.81 mg zinc ∕ kg diet, supplied as ZnSO4•H2O. Each diet was randomly assigned to triplicate groups of fish in flow-through system, and each tank was stocked with 40 juvenile fish. Fish were fed twice daily (05:30 and 17:30) to apparent satiation for 8 weeks. The water temperature fluctuated from 26.5 to 29.5°C, salinity from 25‰ to 28‰ and dissolved oxygen was approximately 7 mg l-1 during the experimental period. No significant differences in survival were found among dietary treatments. Specific growth rate (SGR) significantly increased with increasing dietary zinc from 9.7 to 48.9 mg ∕ kg of diet (P<0.05), and then leveled off. Zinc content in the vertebrae, whole body and serum were significantly affected by dietary zinc level (P<0.05). Broken-line analysis showed that the optimum dietary zinc requirement for large yellow croaker juveniles, using SGR and vertebrae zinc saturation as response criteria, was 59.6 and 84.6 mg zinc ∕ kg diet, respectively.

     

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