Studies on the effect of extrusion processing on availavility of trace elements to rainbow trout

为研究豆粕挤压加工对虹鳟鱼部分替代鱼粉型饲料中微量元素利用率的影响，进行了一系列饲养试验。采用温度等不同条件挤压SBM，并用白鱼粉代替。试验饲料投喂虹鳟鱼幼鱼21周。145 C挤压SBM替代白鱼粉的饲料的生长明显高于100 C挤压SBM的饲料。鱼体内的矿物质状况也有同样的趋势。因此，用白色鱼粉代替高温（150 C）挤压SBM（0、30、60%）的分级水平，并在含30%挤压SBM的饲料中添加Zn的分级水平。将试验饲料投喂虹鳟幼鱼12周。添加20 mg Zn/kg的30%膨化SBM含饲料后，生长达到平稳期，添加40mg Zn/kg的鱼粉饲料中锌含量与鱼粉饲料相当。饲料中含有60%膨化SBM的鱼的生长低于其他各组，但对鱼体内矿物质含量没有影响。研究结果表明，150°C的高温蒸煮对鱼粉的质量影响很大，可以作为替代鱼粉中微量元素的理想原料。

A series of feeding experiments was conducted to determine the effect of extrusion processing of soybean meal (SBM) on trace element availability in partially replaced fish meal based diet to rainbow trout. SBM was extruded by different conditions such as temperature, and replaced with white fishmeal. The experimental diets were fed to the juvenile rainbow trout for 21 weeks.The growth of the fish fed the diet replaced white fish meal with SBM extruded at 145ﾟC is much higher than that of the fish on the diet included SBM extruded at 100ﾟC.The same trend was obtained in mineral status in fish body.Consequently, the graded levels of high temperature (150ﾟC) extruded SBM (0,30,60%) were replaced with white fishmeal and the graded levels of Zn were supplemented to the 30% extruded SBM included diet. The experimental diets were fed to the juvenile rainbow trout for 12 weeks.The growth reached a plateau by the supplementation with 20 mg Zn/kg among the 30% extruded SBM included diets and Zn content became to the equivalent amount in fish fed the fish meal diet by 40mg Zn/kg. The growth of fish receiving the 60% extruded SBM included diet was lower than the other groups, but the mineral status in fish body was not influenced by dietary treatment.The results of these studies demonstrated that high temperature such as 150ﾟC extrusion cooking influences the quality of SBM very efficiently, and that extruded SBM might be a very suitable material for substitution of fishmeal in terms of trace element.