Crude glycerol in diets for Nile tilapia in the fattening stage

Abstract: The objective of this work was to evaluate the use of crude glycerol as an energy source to replace corn, in diets for Nile tilapia (Oreochromis niloticus) in the fattening stage. Two hundred Nile tilapia (190±4.5 g) were distributed in 20 tanks, in a completely randomized design. The treatments consisted of crude glycerol at 0, 60, 120, 180, and 240 g kg-1, to replace the dietary levels of corn, in order to maintain a constant digestible energy. Fish productive performance and the chemical composition of the fillet were evaluated. Histological analyses of the hepatopancreas, intestine, and visceral fat were also carried out. Crude glycerol had no effect on the performance parameters; however, it caused a quadratic reduction of visceral fat. There was an increase in the moisture and a decrease in the ether extract of the fillet. A linear effect on the blood glucose levels was verified in fish fed the diet without glycerol, and the peak occurred at 90 min. There were no differences for measurements of intestinal villi height and hepatocyte area. Crude glycerol can replace corn in diets for Nile tilapia in the fattening stage, without adversely affecting fish metabolism, productive performance, or survival.

摘要：本研究旨在评估粗甘油（crude glycerol）作为能量源替代玉米，用于育肥期尼罗罗非鱼（Oreochromis niloticus）日粮的应用效果。试验选取200尾初始体重为(190±4.5) g的尼罗罗非鱼，采用完全随机试验设计将其分配至20个养殖水箱中。设置5个粗甘油添加梯度：0、60、120、180、240 g·kg⁻¹，通过替代日粮中不同比例的玉米，维持日粮可消化能水平恒定。本研究评估了鱼类的生产性能与鱼肉的化学组成，同时对肝胰腺、肠道及内脏脂肪开展了组织学分析。结果表明：粗甘油对鱼类生产性能参数无显著影响，但可使内脏脂肪含量呈二次方下降趋势；鱼肉的水分含量升高，粗脂肪含量降低。投喂无甘油日粮的鱼只血糖水平呈线性变化，且在90分钟时达到峰值。肠道绒毛高度与肝细胞面积未出现显著差异。育肥期尼罗罗非鱼日粮中，粗甘油可安全替代玉米，不会对鱼类代谢、生产性能或存活率产生不利影响。