Effect of dietary crude glycerin on the productive performance of Nile tilapia fingerlings

Abstract The aim of this study was to evaluate the effect of different crude glycerin levels in the diet of Nile tilapia fingerlings (mean initial weight 0.32 ± 0.06 g, n = 450) on growth performance parameters, whole-body composition, blood glucose and liver morphology. Crude glycerin was tested at six different levels (0, 4, 8, 12, 16, and 20%) in diets containing 30% digestible protein and 3,000 kcal kg-1 digestible energy. After 37 days of feeding, the inclusion of crude glycerin resulted in positive effects on final weight, visceral fat, weight gain, feed conversion, specific growth rate and feed intake. The different treatments did not influence fillet yield, glycemia, survival and hepatosomatic index, but intermediate levels of inclusion decreased the area of hepatocytes. Regarding fish body composition, significant differences were found in moisture and ash contents, with no changes in crude protein and total lipid. The inclusion of crude glycerin in the Nile tilapia diet improves growth performance without negatively affecting survival rate and glycemia of fingerlings.摘要 本研究旨在探究日粮中不同水平粗甘油对尼罗罗非鱼幼鱼（初始平均体重0.32±0.06 g，n=450）生长性能指标、全鱼体成分、血糖水平及肝脏形态的影响。试验日粮设置30%可消化蛋白与3000 kcal·kg⁻¹可消化能，共设置6个粗甘油添加梯度（0、4、8、12、16、20%）。经过37天的饲喂试验后，结果表明：日粮添加粗甘油可对终末体重、内脏脂肪蓄积、增重率、饲料转化率、特定生长率及摄食量产生正向调控作用。各处理组对鱼肉得率、血糖水平、存活率及肝体比无显著影响，但中等添加水平会显著降低肝细胞面积。就鱼体组成而言，水分与灰分含量存在显著组间差异，而粗蛋白与总脂质含量无明显变化。综上，在尼罗罗非鱼日粮中添加粗甘油可有效改善其生长性能，且不会对幼鱼存活率与血糖水平产生负面影响。