CRUDE PROTEIN LEVELS IN THE DIETS OF TAMBAQUI, COLOSSOMA MACROPOMUM (CUVIER, 1818), FINGERLINGS

ABSTRACT: Tambaqui is intensively farmed because of its production characteristics; however, there is a lack of information lacks about the nutritional requirements of this species. The present study aimed to evaluate the effects of various crude protein (CP) levels in the diets of tambaqui fingerlings. A total of 750 fingerlings with an initial weight of 0.35 ± 0.09 g were selected in a completely randomized design with six treatments (experimental feeds with 20%, 24%, 28%, 32%, 36%, and 40% CP), five replicates, and 25 fish per experimental unit. Performance, survival rate, carcass yield, body composition, protein deposition, body fat, and nitrogen retention efficiency were evaluated after 45 days. CP levels did not affect the following: feed conversion, survival rate, moisture content, and carcass yield. However, with increasing CP levels, protein efficiency ratio decreased. Weight gain, feed conversion, and specific growth rate improved until CP levels of 31.57%, 28.90%, and 31.12%, respectively, were achieved. Quadratic effects of elevated CP levels on body fat and body fat deposition were observed at minimum CP levels of 26.55% and 23.77%, respectively; and on body protein, body protein deposition, and nitrogen retention efficiency at maximum CP levels of 29.26%, 32.50%, and 27.21%, respectively. We conclude that a CP level of 31.57% is recommended for the diets of tambaqui fingerlings weighing between 0.35 and 15.11 g, which corresponds to a digestible energy:CP ratio of 9.50 kcal DE/g CP.摘要：坦巴奎鱼（Tambaqui）因其生产特性而被集约化养殖，但目前对该物种的营养需求研究仍存在不足。本研究旨在评估日粮中不同粗蛋白（crude protein, CP）水平对坦巴奎鱼稚鱼的影响。本实验共选取初始体质量为0.35±0.09 g的稚鱼750尾，采用完全随机设计，设置6个处理组（分别投喂粗蛋白含量为20%、24%、28%、32%、36%、40%的实验饲料），每组设置5个重复，每个实验单元放养25尾鱼。养殖45天后，对各组的生长性能、存活率、胴体率、体成分、蛋白质沉积量、体脂肪含量及氮保留效率进行了测定。研究发现，粗蛋白水平对饲料转化率、存活率、水分含量及胴体率无显著影响。但随着日粮粗蛋白水平升高，蛋白质效率比显著降低。当日粮粗蛋白水平分别达到31.57%、28.90%和31.12%时，增重率、饲料转化率及比生长率均达到最优水平。日粮粗蛋白水平的升高对体脂肪及体脂肪沉积量存在二次效应，其最低响应拐点分别出现在粗蛋白水平为26.55%和23.77%时；而对体蛋白质含量、体蛋白质沉积量及氮保留效率的二次效应拐点则分别出现在粗蛋白水平为29.26%、32.50%和27.21%时。本研究建议，初始体质量0.35~15.11 g的坦巴奎鱼稚鱼，其日粮粗蛋白水平以31.57%为宜，对应的消化能与粗蛋白比值为9.50 kcal DE/g CP。