| The sea cucumber Apostichopus japonicus belongs to Echinodermata, Holothuroidea and is one of the most valuable animals of aquaculture in north China such as Shandong and Liaoning. With the rapid growth in the culture of Apostichopus japonicus, the natural food has not been able to meet the need for mariculture and it is nessary to feed artificial feed. However, the existing feed-processing technology is still immature and less developed, which not only causes the disproportion in nutrients uptake by Apostichopus japonicus and excessive feed wastage but also influences water enviroment severely, usually results in bad water quality and the large-sale disease outbreaks. Therefore, it is important to prepare a artifical feed suitable for use in water environment, which is significant for the sustainable development in the culture of Apostichopus japonicus. This study involved the use of a micro-particle feed designed to optimize the delivery of nutrients in the feed for sea cucumber and make sure that the micro-particle which contained fully nutritional components, was easy to take in and had the least water pollution.Using trial and error method to make diets which contained aout 25%crude protein (CP), 4%crude fat (CF). Raw materials were processed by Pressure-shear Induced Chemical Transitions (PICT) to formed micro-powder feeds which could be divided into four diets as following:D1 (wheat flour), D2 (α-cassava starch), D3 (α-cassava starch and sodium alginate) and D4 (bentonite), according to the adding binders. Then, add water into the micro-powder, mix completely, compress repeatedly, dry in room temperature, crash and sieve to get micro-mixed bolus feeds. Mechanical analysis showed the micro-powder got by PICT was d90<30μm, the average diameter was about 13μm while the micelle feeds were d98=150-180μm, which ensured that the micro-mixed bolus feeds had complete nutrient components within every particle. Morphologic observation showed that micro-mixed bolus feeds were compacted and regular micro-particles.Stability tests indicated that all four diets of micro-mixed bolus feeds were significantly more stable than commercial feed with less mass losing rate and nutrition losses (P<0.05). Within micro-mixed bolus feeds, the mass losing rate of D1 and D4 was marginally less than D2 and D3 with significant difference (P<0.05). Powder feed was more unstable than micro-mixed bolus feed and the latter was not as stable as particle which means the way of processing and form of feed were important to the stability. Nutrition losing evaluation of micro-mixed bolus feeds and commercial powder feed proved that the losing of CP, CL and Vc in micro-mixed bolus feed was significantly lower than commercial powder feed (P<0.05). Comparing within the four micro-mixed bolus feeds, the losing of nutrition in D1 was more than the other three, and D2, D3& D4 were superior respectively in CP, CF and Vc. Considering the cost in practice, the D2 and D4 micro-mixed bolus feeds were chosen as the experimental feeds in the following culture test.During the culture test lasting 60 days, mass, the specific growth rate (SGR), rate of gut and wall and survival rate of D2 and D4 micro-mixed bolus feeds were detected with commercial feeds and D2 powder& particle feeds as controls. The two micro-mixed bolus feeds both had advantage over the others in the growth speed and final weight by significant difference (P<0.05). The rate of gut and wall in micro-mixed bolus group were lowder than commercial powder feed and survival rate of micro-mixed bolus feeds were higher than commercial feed,but differences were not significant(P>0.05).Then, the influence of different feeds on water environment was evaluated through detecting the turbidity, chemical oxygen demand (COD) and the concentration of NH3-N. The results indicated that both micro-mixed bolus feeds were superior in maintaining water quality than commercial powder feed and were equal to particle feed or excel them. And D4 displayed significant advantage over D2 in some indexes such as the value of COD.In conclusion, the micro-mixed bolus feeds containingα-cassava starch or bentonite have a definited advandage in the growth performance of Apostichopus japonicus with less influence on water quality, so it is of potential value in pratice.
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