Mayrhofer Richard, Menanteau-Ledouble Simon, Pucher Johannes, Focken Ulfert, El-Matbouli Mansour
Clinical Division of Fish Medicine, University of Veterinary Medicine, Vienna, Austria.
Life Science Centre, University of Hohenheim, Stuttgart, Germany.
BMC Vet Res. 2017 Nov 10;13(1):329. doi: 10.1186/s12917-017-1255-5.
The ubiquitous and opportunistic bacterial pathogen Aeromonas hydrophila has been associated with ulcerative dermatitis in fish, especially under stressful conditions. It can cause severe losses in fresh water aquaculture and is particularly prevalent in tropical and subtropical regions. Fresh leaves from maize and bananas have been used as feed supplement by fish farmers in Vietnam and it has been reported that they may have phyto-prophylactic benefits. In the present study, a feeding trial was conducted to investigate the benefits of providing maize and banana leaves as feed supplement: to determine if they were taken up and digested by grass carp (Ctenopharyngodon idella), if this uptake resulted in improved growth performance, and if leaf supplementation protected fish when challenged with A. hydrophila by intramuscular injection.
All fish were fed an identical ratio of commercial pelleted feed relative to biomass. However, in 12/18 tanks, this diet was supplemented with either fresh banana leaves or fresh maize leaves; offered ad libitum. Addition of leaves increased the overall feed conversion ratio (FCR) significantly. However, if only the pellet were taken into account, then no difference was found between treatments. Changes to the isotopic composition of the fish showed leaf nutrient uptake occurred. No prophylactic effects of feeding banana or maize leaves were detected against infection with A. hydrophila, and the diet did not induce changes in the fish haematocrit. However, addition of the maize leaves was associated with significantly reduced severity of the skin lesions, which could improve the market value of the fish.
Addition of the leaf supplement did not result in significantly improved growth performance. Similarly, the effect of the supplement on the fish survival to infection was not significant.
嗜水气单胞菌是一种常见的机会致病菌，与鱼类溃疡性皮肤病有关，尤其是在应激条件下。它会给淡水养殖造成严重损失，在热带和亚热带地区尤为普遍。越南的养鱼户已将玉米和香蕉的新鲜叶子用作饲料补充剂，据报道它们可能具有植物预防作用。在本研究中，进行了一项饲养试验，以调查提供玉米叶和香蕉叶作为饲料补充剂的益处：确定草鱼（Ctenopharyngodon idella）是否摄取并消化了这些叶子，这种摄取是否能提高生长性能，以及补充叶子是否能在草鱼受到嗜水气单胞菌肌肉注射攻击时保护它们。
所有鱼喂食的商业颗粒饲料与生物量的比例相同。然而，在18个水箱中的12个水箱中，这种饲料添加了新鲜香蕉叶或新鲜玉米叶，随意投喂。添加叶子显著提高了总体饲料转化率（FCR）。然而，如果只考虑颗粒饲料，则各处理之间没有差异。鱼的同位素组成变化表明发生了叶子养分摄取。未检测到喂食香蕉叶或玉米叶对嗜水气单胞菌感染有预防作用，且饲料未引起鱼的血细胞比容变化。然而，添加玉米叶与皮肤损伤严重程度显著降低有关，这可能会提高鱼的市场价值。
添加叶子补充剂并未显著提高生长性能。同样，补充剂对鱼感染后的存活率影响也不显著。
