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：巨脂鲤（Tambaqui）因自身生产特性而被集约化养殖，但目前关于该物种的营养需求信息仍较为匮乏。本研究旨在评估日粮中不同粗蛋白质（Crude Protein, CP）水平对巨脂鲤幼鱼的影响。实验共选取初始体重为0.35±0.09 g的幼鱼750尾，采用完全随机设计，设置6个处理组（实验饲料的CP水平分别为20%、24%、28%、32%、36%及40%），每组设5个重复，每个实验单元放养25尾幼鱼。养殖45天后，测定其生长性能、存活率、胴体率、体成分、蛋白质沉积率、体脂肪含量及氮保留效率。结果显示，CP水平对饲料转化率、存活率、体水分含量及胴体率无显著影响，但随着CP水平升高，蛋白质效率比（Protein Efficiency Ratio, PER）显著下降。当CP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速率达到最优水平。粗蛋白质水平升高对体脂肪及体脂肪沉积率存在二次效应，其最低拐点分别对应26.55%和23.77%的CP水平；对体蛋白质含量、体蛋白质沉积率及氮保留效率也存在二次效应，其最高拐点分别对应29.26%、32.50%和27.21%的CP水平。本研究结论认为，针对初始体重0.35~15.11 g的巨脂鲤幼鱼，推荐日粮CP水平为31.57%，对应消化能（Digestible Energy, DE）与CP的比值为9.50 kcal DE/g CP。