选用初始体质量为(220.00±8.34) g的吉富罗非鱼(Oreochromis niloticus)360尾, 随机分成6组,每组3重复(每重复20尾), 于1 m×1 m×1.5 m池塘网箱中饲养。分别饲喂胆碱含量为97.80(对照组)、375.04、565.74、974.27、      1 409.81、1 824.35 mg/kg的半纯化饲料10周, 研究胆碱对吉富罗非鱼成鱼生长、饲料利用、鱼体营养组成、胆碱蓄积量及部分血液生化指标的影响。结果显示, 经过10周的饲喂, 饲料中添加胆碱可显著提高鱼体增重率、特定生长率和饲料效率(P<0.05); 降低肝脂肪含量(P<0.05), 提高肌肉脂肪含量(P<0.05); 显著升高肝胆碱蓄积量(P<0.05); 胆碱添加组血清甘油三酯(TG)和总胆固醇(T-CHO)显著高于对照组(P<0.05), 并随饲料胆碱含量增加呈现升高的趋势; 肝甘油三酯(TG)和总胆固醇(T-CHO)随着胆碱含量的增加而显著降低(P<0.05); 血清谷草转氨酶(ALT)、谷丙转氨酶(AST)和碱性磷酸酶(ALP)均随着饲料胆碱含量的增大而显著降低(P<0.05)。结果表明, 饲料中添加适量的胆碱可以改善吉富罗非鱼成鱼的生长性能, 提高饲料利用效率, 降低肝脂肪含量, 促进肝脂肪转运; 对特定生长率进行回归分析, 得出吉富罗非鱼成鱼对饲料中胆碱的最低需要量为506.43 mg/kg, 而对肝胆碱蓄积量回归分析得出的需要量为981.38 mg/kg。

A10-week feeding trial was conducted to study the effect of dietary choline chloride supplementation on the growth performance, lipid metabolism, feed utilization, body composition, serum biochemical indices, liver lipid content, and muscle and liver choline content of adult GIFT tilapia(Oreochromis niloticus). The basal diet contained 27.60% crude protein and 6.45% crude lipid. The basal diet was supplemented with choline chloride (0, 300, 600, 1200, 1 800, and 2 400 mg choline per kg food) to formulate six semi-purified diets containing choline of 97.80(control group), 375.04, 565.74, 974.27, 1409.81, and 1 824.35 mg choline per kg food. Each diet was randomly fed to three replicates of GIFT tilapia with an initial average weight of (220.00±8.34) g in 18 pond cages (1.0 m×1.0 m×1.5 m). Compared with the control group, the addition of choline to the diet significantly improved weight gain rate, specific growth rate, and feed utilization(P<0.05). The liver fat content decreased significantly (P<0.05) in all groups compared with the control. In addition, the liver choline and muscle fat content of all groups increased significantly(P<0.05). With increasing dietary choline levels, serum triglyceride and cholesterol content increased in the groups with significantly higher choline chloride than that of the control group(P<0.05), the liver triglyceride and cholesterol content decreased significantly(P<0.05). Serum aspartate aminotransferase(ALT), alanine aminotransferase (AST), and alkaline phosphatase (ALP) also decreased significantly (P<0.05) with increasing dietary choline content. The choline requirement of adult GIFT tilapia was 506.43 mg choline per kg food based on the specific growth rate; however, it was 981.38 mg choline per kg food based on liver choline concentra­tion. Our results suggest that choline chloride supplementation could improve tilapia growth performance, feed efficiency, reduce liver fat content, and promote lipid degradation.