Abstract The study examined the interactive effects of choline content (supplied as choline chloride salt (CC); no added CC, 3.0, or 6.0 g CC kg−1 diet) and water temperature (16 °C vs 24 °C) on liver lipid composition, liver histology and plasma biochemistry. Liver and plasma samples were collected from juvenile yellowtail kingfish (Seriola lalandi; YTK; 156 g body weight), fed fishmeal-based practical diets, at the conclusion of an eight-week feeding experiment. The results showed that higher liver lipid content at 24 °C was due to greater triacylglycerol (TAG) accumulation. Liver phospholipids content remained similar regardless of CC supplementation and temperature (P > 0.05). As expected, liver phospholipids were mainly composed of phosphatidylcholine (PC); however, in most cases liver phospholipids were almost completely made up of PC. Phospholipid classes were also not significantly affected by CC supplementation and temperature. The results indicate that these lipid classes were tightly regulated in the liver of juvenile YTK. Fatty acids composition among TAG, FFA, and phospholipids fractions were different; however, within the phospholipids fraction, the long chain polyunsaturated fatty acids (LC-PUFA) proportion in the liver of YTK remained unchanged regardless of treatments. In general, histological examination did not show severe lesions in fish livers across all treatments. Fish also had significantly more hepatocytes with large nuclei at 16 °C than at 24 °C which is a response that requires further research. Plasma analytes were profoundly affected by temperature rather than by CC supplementation; however, there is no strong evidence indicating compromised health in fish reared at either temperature. This study demonstrates that fish fed fishmeal-based practical diets generally had normal looking livers; nevertheless, some liver and plasma health indicators can be affected in juvenile YTK reared at sub-optimal temperatures and fed diets without supplemented choline.

中文翻译：

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日粮胆碱和水温对黄尾鰤鱼幼鱼肝脏脂质成分、组织学和血浆生化的交互作用

摘要 该研究检查了胆碱含量（以氯化胆碱盐 (CC) 形式提供；不添加胆碱、3.0 或 6.0 g CC kg−1 饮食）和水温（16 °C 与 24 °C）对肝脏脂质的交互作用成分、肝脏组织学和血浆生化。在为期八周的喂养实验结束时，从幼鱼（Seriola lalandi；YTK；体重 156 克）中收集肝脏和血浆样本，以鱼粉为基础的实际饮食喂养。结果表明，24°C 时肝脏脂质含量较高是由于甘油三酯 (TAG) 积累较多。无论 CC 补充和温度如何，肝磷脂含量保持相似（P > 0.05）。正如预期的那样，肝磷脂主要由磷脂酰胆碱 (PC) 组成；然而，在大多数情况下，肝磷脂几乎完全由 PC 组成。磷脂类也不受 CC 补充和温度的显着影响。结果表明这些脂质类别在幼年 YTK 的肝脏中受到严格调控。TAG、FFA和磷脂组分的脂肪酸组成不同；然而，在磷脂部分中，YTK 肝脏中的长链多不饱和脂肪酸 (LC-PUFA) 比例保持不变，无论治疗如何。一般而言，组织学检查未显示所有治疗中鱼肝的严重病变。鱼在 16 °C 下的肝细胞也明显多于 24 °C，这是需要进一步研究的反应。血浆分析物受温度而非 CC 补充剂的影响显着；然而，没有强有力的证据表明在任一温度下养殖的鱼的健康都会受到损害。这项研究表明，喂食以鱼粉为基础的实用饮食的鱼通常具有正常的肝脏；尽管如此，一些肝脏和血浆健康指标可能会影响在次优温度下饲养和饲喂不含胆碱的日粮的 YTK 幼鱼。