Study on Growth,Serum Biochemical and Antioxidant Enzyme Indices of Juvenile Siganus guttatus Fed with Enteromorpha prolifra and Artificial Feed

In order to provide reference for using Sigartus guttatus to control overgrowth of Ertteromorpha prolifra, the growth, serum biochemical and antioxidant enzyme indices of juvenile S. guttatus respectively fed with E. prolifra and artificial feed were studied. One hundred and eighty individuals were cultivated for 90 days in six 2.5 m × 1.5 m × 1.5 m cages （30 ind. per cage） which mesh size were 0.5 mm. The experimental animals were divided into two dietary groups （ three cages for each group） that were fed with E. prolifra and artificial feed respectively. During the culture period, temperatures ranged from 23.0 to 26.5℃, pH was between 7.8 and 8.2, dissolved oxygen was more than 5.0 mg/L. The weight gain rate, specific growth rate, relative growth rate, hepato-somatic index of juvenile S. guttatus fed with E. prolifra were significantly lowe than that fed with artificial feed （P 〈 0.05）. The total protein （TP）, urea nitrogen （UN） and alkaline phosphatase （AKP） of juvenile S. guttatus fed with E. Prolifra were significantly higher than that fed with artificial feed （P 〈0.05）, while glutamic oxalacetie transaminase （AST/GOT） and glutamic-pyruvic transaminase （ALT/GPT） of juvenile S. guttatus fed with E. prolifra were significantly lower than that fed with artificial feed （P 〈 0.05 ）. SOD, GPX and anti-superoxide anion radical activity in liver, kidney, gill and muscle of juvenile S. guttatus fed with E. prolifra were higher than that fed with artificial feed, and these antioxidant enzyme activities in kidney of juvenile S. gtatatus fed with E. prolifra was significantly higher than that fed with artificial feed （P 〈 0.05）, while CAT and hydroxyl radical-inhibiting activity in liver of juvenile S. guttatus fed with arti- ficial feed were significantly higher than that fed with E. prolifra （P 〈 0.05 ）. Juvenile S. guttatus fed with E. prolifra showed poor growth performance but better antioxidant defense system. S. guttatus is easily raised and has stronger ability of digestion and absorption of E. Prolifra. The technique that uses S. gtatatus to control E. prolifra deserves deeply study.

Comparison of Nutritional Components in the Muscle of Juvenile Siganus guttatus Fed with Enteromorpha prolifera and Artificial Feed

[ Objective] This experiment was conducted to analyze and compare the nutritional components in the muscle of juvenile Siganus guttatus fed with Enteromorpha prolifera and artificial feed. [ Method] A total of 180 healthy S. guttatus juveniles with similar body size were assigned into two groups： one fed with E. prolifera, and the other fed with artificial feed, respectively. There were three replicates in each group, and 30 fish in each replicate. And the experiment lasted for 90 d. [ Result] The results showed that the weight gain rate, specific growth rate and relative growth rate of E. prolifera-fed group were significantly lower than those of artificial feed-fed group （P 〈0.05） ; the contents of crude protein and crude ash of E. prolifera-fed group were significantly higher than those of artificial feed-fed group （P 〈 0.05 ）. However, the content of crude fat of E. prolifera-fed group was significantly lower than that of artificial feed-fed group （P 〈 0.05 ）. The moisture content had no significant difference between the two groups （P 〉 0.05 ）. The amino acid composition was similar between the two groups. Seventeen amino acids were found in both groups, and the essential amino acid index （EAAI） was 76.71 in E. prolifera-fed group and 70.05 in artificial feed-fed group, both of which met the criteria set by the Food and Agriculture Organization of the United Nations （FAO）/World Health Organization （WHO）. The content of eicosapentaenoic acid （EPA） ＋ docosahexaenoic acid （DHA） and the content of to-3 polyunsaturated fatty acids （ to-3 PUFAs） of E. prolifera-fed group were significantly higher than those of artificial feed-fed group （ P 〈 0.05 ）. [ Conclusion ] In conclusion, the juvenile S. guttatus in both groups contains a variety of nutritional components. S. guttatus fed with E. prolifera has higher levels of essential amino acids, more balanced composition of polyunsaturated fatty acids, higher nutritive val- ue and better taste than that fed with artificial feed.

不同网箱混养模式对日本黄姑鱼生长性能的影响

研究了不同网箱混养模式对日本黄姑鱼(Nibea japonica)幼鱼生长、摄食以及网箱网衣附着情况的影响。平均体重(36.33±1.03)g的日本黄姑鱼在1 m×1 m×1 m网箱内单养27尾42 d后成活率100%,平均体重达到(85.92±2.87)g;而单养21尾日本黄姑鱼体重从(35.52±1.79)g上升到(100.10±1.90)g。本试验中梭鱼(Liza heamatocheilus)无法与日本黄姑鱼混养,三个实验组在42 d的养殖周期内梭鱼均全部死亡。日本黄姑鱼与点篮子鱼(Siganus guttatus)在网箱混养模式下有着较好的生长指标,混养27尾平均质量(36.83±0.65)g的日本黄姑鱼与18尾点篮子鱼,经过42 d日本黄姑鱼体重达到(98.32±2.90)g;而混养21尾平均质量(35.38±2.12)g的日本黄姑鱼与54尾点篮子鱼,经过42 d体重达到(120.13±2.63)g,增重率达到了(239.17±5.26)%。结果表明,在本试验条件下,与点篮子鱼混养模式下的日本黄姑鱼的存活率与单养情况下基本一致,生长及摄食情况都要优于单养模式,增重速度快,且摄食率低而饲料转化效率高。同时,优化日本黄姑鱼与点篮子鱼的混养比例可以进一步提高日本黄姑鱼的生长及摄食情况;另外,日本黄姑鱼与点篮子鱼混养情况下网箱网衣藻类附着程度也较低。