膳食蛋白源和配料粒度对限制进食且明显饱足的黄尾鰤鱼类性能，排泄废物产量和特性的影响

Recently, yellowtail kingfish (Seriola lalandi) is being cultured in recirculating aquaculture systems (RAS).  Yellowtail kingfish have a poor faecal integrity, which makes the removal of faeces by traditional RAS technology difficult. Reducing the faecal waste load in RAS can be achieved by reducing the amount of faeces  produced (e.g., increasing digestibility) and/or increasing the removal of faeces. This study assessed the effect of  partial fish meal replacement by plant ingredients and the effect of ingredient grinding size on the amount of  faecal waste produced and faecal characteristics, like faecal removal efficiency and particle size distribution  (PSD), in yellowtail kingfish. This was investigated during two 35-d experiments, where fish were fed restrictively (experiment R) or to apparent satiation (experiment S). For each experiment, individual batches of four  experimental diets were produced according to a 2 × 2 factorial design (protein source × ingredient grinding  size). The formulas used were identical for both experiments. FM100 diets contained only fish meal as protein  source, whilst at FM30-P70 diets approximately 70% of the fish meal were replaced by plant protein ingredients.  The effect of ingredient grinding size was tested by including 40% of either a fine or coarse grinding mixture.  Tanks were stocked with 20 fish and 27 fish for experiment R and experiment S, respectively. For each tank, fish  performance, faecal waste production, faecal removal efficiency and faecal PSD were measured. During both  experiments, ingredient grinding size did not affect the faecal removal efficiency or PSD, whilst fish fed the fine  FM30-P70 diets restrictively showed a lower faecal waste production. The inclusion of plant ingredients resulted  in a lower absolute growth and higher FCR. Furthermore, fish fed the FM30-P70 diets showed a higher faecal  waste production, a smaller PSD and a lower faecal removal efficiency. This ultimately resulted in a higher  amount of non-removed faeces by 58.3% and 37.1% compared to FM100 diets for the experiment R and  experiment S, respectively. In conclusion, the replacement of fish meal with plant ingredients in yellowtail  kingfish diets is challenging due to the adverse effects on fish performance, faecal waste production and faecal  characteristics. However, feeding yellowtail kingfish to apparent satiation partly reduced these adverse effects of  plant ingredient inclusion in terms of faecal waste production and faecal characteristics. Reducing the ingredient  grinding size of yellowtail kingfish diets tended to lower the faecal waste production, whilst not negatively  affecting the fish performance or faecal characteristics.  

近年来，黄尾鰤正在循环养殖系统（RAS）中养殖。黄尾鰤的排泄物完整性较差，这使得用传统的RAS技术去除排泄物变得困难。可以通过减少排泄物产生的量（如增加消化率）和/或增加排泄物的清除量来减少RAS中的排泄物废物负荷。本研究评估了植物成分替代部分鱼粉的影响，以及成分研磨大小对黄尾鰤排泄物特性的影响，如排泄物去除效率和粒径分布（PSD）。这在两个35天的实验中进行了研究，在这些实验中，鱼被限制性地喂食（实验R）或表观饱足感（实验S）。对于每个实验，根据2×2因子设计（蛋白质源×成分研磨尺寸）生产4个实验饲粮。两个实验所使用的公式是相同的。FM100饲粮中只含有鱼粉作为蛋白质来源，而在FM30-P70饲粮中，我们大约含有70%的鱼粉被植物蛋白成分所取代。通过加入40%的细研磨或粗研磨混合物来测试成分研磨粒径的影响。实验R和实验S分别饲养了20条鱼和27条鱼。测量了每个鱼缸的鱼类性能、排泄物废物产生、排泄物去除效率和排泄物PSD。在两个实验中，成分研磨尺寸均不影响排泄物去除效率和PSD，而严格饲喂FM30-P70精细饲粮的鱼的排泄物废物产量较低。加入植物成分导致了较低的绝对生长和较高的FCR。此外，饲喂FM30-P70饲粮的鱼的排泄物废物产量较高，PSD较小，排泄物清除效率较低。与实验R和实验S的FM相比，FM100饲粮中，未去除的排泄物量分别增加了58.3%和37.1%。综上所述，黄尾鰤鱼饲粮中用植物成分替代鱼粉，由于对鱼类生产性能、排泄物废物产生和排泄物特性的不利影响，具有挑战性。然而，喂食黄尾鰤明显的饱足在一定程度上减少了植物成分在排泄物废物产生和排泄物特性方面的不利影响。减少黄尾鰤饲粮的成分粉磨尺寸往往会降低排泄物废物的产生，同时不会对鱼的生产性能或排泄物特性产生负面影响。