单胞藻饵料强化对太平洋纺锤水蚤营养成分的影响

Effect of enrichment of unicellular algae food on the nutritional quality of Acartia pacifica

采用生化手段对舟山附近海域中浮游桡足类夏季优势种—太平洋纺锤水蚤(Acartia pacifica)进行营养成分测定,比较分析两种单胞藻饵料小球藻(Chlorella sp.)和三角褐指藻(Phaeodactylum tricornutum)对其营养价值的影响。结果表明,太平洋纺锤水蚤在投喂三角褐指藻和投喂小球藻后,其体内粗蛋白湿重含量分别为(6.51±0.46)%和(5.21±0.98)%,比对照组(2.44±0.63)%显著上升(P<0.05);投喂三角褐指藻后太平洋纺锤水蚤粗脂肪湿重含量(0.25±0.03)%显著上升(P<0.05),投喂小球藻后粗脂肪湿重含量(0.15±0.03)%显著下降(P<0.05);但总糖和灰分湿重含量变化不明显(P>0.05)。本研究检测出太平洋纺锤水蚤体内共含17种氨基酸,其中鱼类必需氨基酸(EAA)9种,非必需氨基酸(NEAA)8种,对照组与投喂两种饵料后太平洋纺锤水蚤中EAA含量均较高,干重含量为(47.56±0.04)%^(49.84±0.07)%;检测出太平洋纺锤水蚤共含21种脂肪酸,投喂三角褐指藻后太平洋纺锤水蚤的DHA和EPA干重含量之和最高(28.00%),其次为投喂小球藻(21.51%),均高于对照组(9.77%),而对照组干重(9.77%)也仍高于强化后轮虫DHA和EPA干重含量(0.8%)和强化后卤虫DHA和EPA干重含量(8.40%)。通过本实验发现,自然状态下的太平洋纺锤水蚤DHA和EPA含量较高,营养价值高,而投喂后三角褐指藻后太平洋纺锤水蚤营养价值明显增加,表明人工培养条件下太平洋纺锤水蚤具有作为水产经济动物活体开口饵料的潜在开发价值。

Acartia pacifica is the summer dominant species of planktonic copepod in Zhoushan waters.We evaluated the effects of two kinds of unicellular algae food-Chlorella sp.and Phaeodactylum tricornutum-on the nutritional value of A.pacifica using biochemical methods.The aim of this paper was to provide theoretical information to evaluate the nutritional value and large-scale cultivation of A.pacifica.The results indicated that the crude protein content(wet weight)of A.pacifica after feeding on P.tricornutum(6.51±0.46)%and Chlorella sp.(5.21±0.98)%was significantly higher than that of the control group(2.44±0.63)%(P<0.05).The lower crude protein content of the control group may have been due to the poorer growth conditions,less food availability,and higher energy consumption under natural conditions.After feeding on P.tricornutum,the crude fat content(0.25±0.03)%(wet weight)increased significantly(P<0.05),but decreased significantly after feeding on Chlorella sp.(0.15±0.03)%,most likely as the fatty acid content of P.tricornutum is higher than that of Chlorella sp..The content of crude protein and crude fat in A.pacifica was lower after feeding on Chlorella sp.;therefore,it was possible that A.pacifica consumed protein to supplement the energy required for growth due to the inadequate fat content in this food.The changes in content(wet weight)of total sugar and ash were not significant.Nine essential amino acids(EAA)and8non-essential amino acids(NEAA)of A.pacifica were detected in this study.The content(dry weight)of EAA in A.pacifica was(47.56±0.04)%to(49.84±0.07)%,EAA:NEAA was approximately5:5,higher than that of Centropages mcmurrichi,which may be beneficial for the growth of this fish.Twenty-one kinds of fatty acids in A.pacifica were determined.The content(dry weight)of DHA and EPA in the control group(9.77%)was lower than the group that fed on P.tricornutum(28.00%)and Chlorella sp.(21.51%),but higher than the group that fed on Rotifers(0.8%)and Artemia(8.40%).Therefore,the proportion of DHA and EPA in P.tricornutum was much higher than in Rotifers or Artemia,and could better meet the needs of juvenile fish growth.Overall,the results indicated that the nutritional value of A.pacifica was higher under artificial cultivation conditions and had potential value for the live food economy.