南极磷虾粉作为鲟鱼饲料蛋白源的营养和氟含量的分析

Nutritional quality and fluoride content of Antarctic krill meal for feed formulations in sturgeons

通过分析商品南极磷虾粉、自制冻干南极磷虾粉和南极磷虾肽粉的主要营养成分和氨基酸含量,以6种鲟鱼肌肉为参比蛋白,利用3种营养评价指标(必需氨基酸指数、氨基酸比值系数分和关联度分析法)评价了这3种磷虾粉作为鲟鱼蛋白质饲料的营养价值;同时对3种南极磷虾粉的氟含量进行了检测分析。结果显示,3种南极磷虾粉平均粗蛋白含量在61.73%～67.13%,粗脂肪含量在3.56%～4.56%,灰分含量在15.56%～17.15%,达到了一级品甚至是特级品的指标。总氨基酸含量达51.46%～58.75%,10种必需氨基酸含量为23.69%～28.51%,三者必需氨基酸总量与粗蛋白的百分比为45.09%～47.94%;呈味氨基酸总量为18.60%～21.19%,占总氨基酸的比例达到了36.07%～36.17%。从必需氨基酸指数方面看,3种南极磷虾粉都为优质的蛋白源。同时从氨基酸比值系数分和关联度分析法,3种南极磷虾粉对于鲟鱼的必需氨基酸平衡性较好,相关系数和鱼粉相差不大,且要高于豆粕。氟含量方面,自制的冷冻冻干南极磷虾粉氟含量最高(2 382.83±112.43 mg.kg-1),其次为商品南极磷虾粉(1 122.73±62.82 mg.kg-1),而经过酶解后南极磷虾肽粉的氟含量(65.19±5.08 mg.kg-1)则显著下降,低于欧盟标准(350 mg.kg-1)。综合来看,3种南极磷虾粉氨基酸平衡性较好,营养价值较高,氟含量可通过一定方法降低,南极磷虾是一种具有较大开发利用前景的优质资源。

The main nutritional components and amino acids contents of 3 kinds of krill meals （ commercial Antarctic krill meal, freeze-dried Antarctic krill meal and Antarctic krill hydrolysates） were analyzed and discussed and the nutritional value of krill meal protein from the three samples were specifically evaluated and compared with fishmeal and soybean meal as main protein ingredients in sturgeon feeds based on the amino acids composition of dorsal muscles from six selected sturgeons by using three different protein quality evaluation methods （essential amino acids index, score of ratio coefficient of amino acids and relativity of essential amino acids ）. In addition, fluoride contents of commercial Antarctic krill meal, freeze-dried Antarctic krill meals and Antarctic krill hydrolysates were analyzed and discussed in details as well. The results showed that the contents of crude protein of commercial Antarctic krill meal, freeze-dried Antarctic krill meal and Antarctic krill hydrolysates were between 61.73% and 67.13%, the crude lipid contents were analyzed to be 3.56% -4.56% and the contents of ash of these 3 kinds of krill meals were found to between 15.56% and 17.15%. The 3 kinds of krill meals （commercial Antarctic krill meal, freeze-dried Antarctic krill meal and Antarctic krill hydrolysates） achieved the first class products index or even superfine products index according to fishmeal quality standards. And the total contents of amino acids of the three samples ranged from 51.46% to 58.75%. Results also showed that the contents of 10 kinds of essential amino acids for shrimp and fish in commercial Antarctic krill meal, freeze-dried Antarctic krill meal and Antarctic krill hydrolysates varied from 23.69% to 28.51% , and the essential amino acids/total amino acids （EAA/CPv） ratio was between 45.09% and 47.94%. The three samples were all rich in delicious amino acids, ranging from 18.60% to 21. 19%, and the delicious amino acids/total amino acids （DAA/AA） ratio was between 36.07% and 36.17%. Based on the results calculated from essential amino acids index （EA_AI） evaluation, commercial Antarctic kr]ll meal, freeze-dried Antarctic krill meal and Antarctic krill hydrolysates were all considered to be good sources of high quality protein. Moreover, the index of amino acids balance in commercial Antarctic krill meal, freeze-dried Antarctic krill meal and Antarctic krill hydrolysates was similar to that in fishmeal aceording to score of ratio eoeffieient of amino acid （SRC） and relativity of essential amino acid （r）, and the three samples showed a much more balanced amino acids composition for feed formulations in six sturgeons when compared with soybean meal using the same method. The highest fluoride eontent was found in freeze-dried Antarctic krill meal （2382.83 ＋ 112.43 mg~ kg-1） , followed by commercial Antarctic krill meal （1122.73 _＋62.82 mg ~ kg-1）, while significantly lower fluoride content was achieved when the Antarctic krill was appropriately hydrolysed （65.19 _＋ 5.08 mg~ kg-1）, the fluoride content in Antarctic krill hydrolysates was in the range of EU standards （350 mg ~ kg-~ ）. In conclusion, Antarctic krill had a high nutritional value with a well balanced amino aeids composition, and the fluoride content found in Antarctic krill could be redueed in some way without compromising the nutritional quality. Antarctic krill has a great prospect for further development and application in sturgeon feeds.