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 本研究评估了将油桐（Aleurites fordii）粕添加至银鲶（Rhamdia quelen）饲料中作为动物蛋白源替代物的可行性。试验选用银鲶幼鱼，设置三组日粮：粗制油桐粕日粮、经化学处理的油桐粕日粮，以及不含油桐粕的对照组日粮。该化学处理采用酸溶液与醇溶液依次浸提的工艺，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%。本试验周期为9周，通过生长性能、消化酶活性及生化响应指标，评估鱼体对该饲料原料的营养应答效果。饲养9周后，投喂粗制油桐粕日粮的鱼体生长受到显著抑制：体重较对照组降低57.9%、总长度降低21.09%、比生长速率降低99.74%；同时该日粮还降低了鱼体酸性蛋白酶与脂肪酶活性，减少血浆葡萄糖、胆固醇及甘油三酯浓度，并降低肝糖原与葡萄糖含量。与之相对，投喂经化学处理油桐粕日粮的鱼体在9周后表现出与对照组相当的生长性能（体重、总长度及比生长速率均无显著差异），代谢紊乱程度更低，这一效果可能源于抗营养因子与有毒物质的去除。当日粮中经化学处理的油桐粕添加比例为32%时，其可作为银鲶的替代蛋白源。