Effect of feeding crude or treated tung meal (Aleurites fordii) in the diet of Rhamdia quelen on growth, digestive enzymes and biochemical parameters

Abstract This study evaluated the addition of tung (Aleurites fordii) meal to the feed of Rhamdia quelen, as an alternative to animal protein sources. Silver catfish juveniles were fed different diets which included crude tung meal, chemically treated tung meal and a control without tung meal. The chemical treatment was based on the sequential application of acid and alcohol solutions and reduced the phytic acid from 1.63 to 0.61% and condensed tannin content from 0.025 to 0.018%. The nutritional response of fish to these ingredients was evaluated over nine weeks, based on growth performance, digestive enzyme activity and biochemical responses. After nine weeks, the diet containing crude tung meal caused reduced growth (weight: -57.9%; total length: -21.09%; specific growth rate: -99.74%). This diet also reduced acid protease and lipase activities, decreased concentrations of glucose, cholesterol and triglycerides in plasma and decreased liver glycogen and glucose concentrations. However, after nine weeks, fish fed with treated tung meal showed higher growth (weight, total length and specific growth rate similar to control) and reduced metabolic changes, possibly due to the removal of antinutrients and toxic substances. At the 32% level of inclusion, the chemically treated tung meal can be considered an alternative protein source for silver catfish.

摘要 本研究评估了以油桐（Aleurites fordii）粕作为动物蛋白源替代品，添加至银鲶（Rhamdia quelen）饲料中的应用效果。实验将银鲶幼鱼分为三组，分别饲喂添加未处理油桐粕、化学处理油桐粕的饲料，以及不含油桐粕的对照组饲料。该化学处理方法采用酸溶液与醇溶液依次浸提，可将植酸含量从1.63%降至0.61%，缩合单宁含量从0.025%降至0.018%。本实验为期9周，通过生长性能、消化酶活性及生化指标响应，评估银鲶对上述饲料组分的营养生理响应。饲养9周后，饲喂未处理油桐粕饲料的银鲶生长性能显著下降：体重降低57.9%、全长降低21.09%、特定生长率降低99.74%。该饲料同时抑制了酸性蛋白酶与脂肪酶活性，降低了血浆中葡萄糖、胆固醇及甘油三酯浓度，并下调了肝脏糖原与葡萄糖含量。与之相反，饲喂化学处理油桐粕饲料的银鲶在9周后展现出更优的生长性能（体重、全长及特定生长率与对照组无显著差异），且代谢紊乱程度更低，这可能得益于抗营养因子与有毒物质的去除。当日粮中添加比例为32%时，化学处理后的油桐粕可作为银鲶的优质替代蛋白源。