Ngoh Si Yan, Shen Xueyan, Nankervis Leo, Hua Katheline
Tropical Future Institute, James Cook University, Singapore, Singapore.
Marine Aquaculture Centre, Aquaculture Department, Urban Food Solution Division, Singapore Food Agency, Singapore, Singapore.
Aquac Nutr. 2024 Dec 21;2024:5467206. doi: 10.1155/anu/5467206. eCollection 2024.
Malabar snapper () is an economically important marine fish throughout the Indo-Pacific, with an emerging aquaculture industry. Although generic marine feeds are available for production, these are not optimised for this species. Understanding energy utilisation and balance can provide insight into suitable macronutrient profiles for new species to provide a baseline for future development. This study, therefore, evaluated the effect of dietary macronutrient composition (i.e., protein, fat, and carbohydrate) on the utilisation efficiencies of digestible energy (DE) in juvenile Malabar snapper using two isonitrogenous diets (high fat: HF and low fat: LF) with contrasting fat and carbohydrate content. Each diet was fed at four feeding levels (100%, 75%, 50%, and 25% apparent satiation) for 56 days, creating a 2 by 4 factorial design. The maintenance energy requirement of Malabar snapper was estimated to be 76.7 kJ kg day, while the utilisation efficiencies of digestible protein (DP) and fat were 73.6% and 68.3%, respectively. Fish fed with LF, which has lower dietary fat and higher dietary carbohydrate levels, had significantly reduced energy utilisation efficiency for growth and significantly higher partial energy utilisation efficiency of digestible fat (DF) ( < 0.05). Since body moisture is usually proportional to body fat content in fish, this implies that the energy from carbohydrates preferentially enters lipogenesis rather than being available for somatic growth, and adiposity does not directly result in weight gain. Malabar snapper utilises DF in preference to protein for metabolism, demonstrating a protein-sparing effect from lipids at DE intake levels below the maintenance requirement. Conversely, given the higher efficiency of fat retention than protein retention, protein is likely used before fat when energy intake is above maintenance. These findings suggest that Malabar snapper requires high levels of DP in its diet to support growth and that energy from dietary carbohydrates is diverted towards adiposity, consequently reducing growth.
马拉巴笛鲷（）是整个印度 - 太平洋地区具有重要经济价值的海洋鱼类，其水产养殖业正在兴起。尽管有通用的海洋饲料可用于生产，但这些饲料并非针对该物种进行优化。了解能量利用和平衡可以为新物种合适的常量营养素概况提供见解，从而为未来发展提供基线。因此，本研究使用两种等氮日粮（高脂肪：HF和低脂肪：LF），其脂肪和碳水化合物含量不同，评估日粮常量营养素组成（即蛋白质、脂肪和碳水化合物）对马拉巴笛鲷幼鱼可消化能量（DE）利用效率的影响。每种日粮以四个投喂水平（100%、75%、50%和25%表观饱足）投喂56天，形成2×4析因设计。马拉巴笛鲷的维持能量需求估计为76.7 kJ kg·天，而可消化蛋白质（DP）和脂肪的利用效率分别为73.6%和68.3%。饲喂LF日粮（其日粮脂肪含量较低，碳水化合物水平较高）的鱼，其生长的能量利用效率显著降低，可消化脂肪（DF）的部分能量利用效率显著更高（P < 0.05）。由于鱼体水分通常与鱼体脂肪含量成正比，这意味着碳水化合物中的能量优先进入脂肪生成而非用于体生长，并且肥胖并不直接导致体重增加。马拉巴笛鲷在代谢中优先利用DF而非蛋白质，这表明在低于维持需求的DE摄入量水平下，脂质具有节约蛋白质的作用。相反，鉴于脂肪保留效率高于蛋白质保留效率，当能量摄入量高于维持量时，蛋白质可能先于脂肪被利用。这些发现表明，马拉巴笛鲷的日粮需要高水平的DP来支持生长，并且日粮碳水化合物中的能量会转向肥胖，从而降低生长。
