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作为能量源替代玉米，在育肥期尼罗罗非鱼（Oreochromis niloticus）日粮中的应用效果。选取200尾初始体质量为(190±4.5) g的尼罗罗非鱼，采用完全随机设计分配至20个养殖桶中。试验各组日粮以粗甘油分别按0、60、120、180、240 g·kg⁻¹的比例替代玉米，以维持日粮可消化能水平恒定。本研究测定了试验鱼的生产性能及鱼肉的化学成分，同时对肝胰腺、肠道及内脏脂肪组织开展了组织学分析。结果表明，粗甘油对生产性能参数无显著影响，但可使内脏脂肪呈二次方降低趋势；鱼肉的水分含量升高，粗脂肪含量降低。在饲喂无甘油日粮的试验组中，鱼体血糖水平呈线性变化，血糖峰值出现在摄食后90 min。肠道绒毛高度及肝细胞面积无显著组间差异。综上，育肥期尼罗罗非鱼日粮中粗甘油可安全替代玉米，且不会对鱼类代谢、生产性能或存活率产生不利影响。