Tarbiat Modares University (TMU) ECOPERSIA 2322-2700 1 4 2013 12 01 Effect of Increasing Dietary Prebiotic GroBiotic®-A Concentration on Growth Performance, Body Indices and Haematological Parameters in Rainbow Trout (Oncorhynchus mykiss) Fingerling 393 406 17105 EN Abdolhamid Azari Laboratory of Feeds and Feeding Management, Aquaculture Research Group, School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia. Roshada Hashim Laboratory of Feeds and Feeding Management, Aquaculture Research Group, School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia. Ghobad AzariTakami Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran. Aboulghasem Roohi Caspian Sea Ecological Research Institute, P.O.Box 961, Khazarabad Boolvar, Sari, Iran. Journal Article 1970 01 01 An 84-day feeding trial was carried out onfingerling (4.44 ± 0.06 g) rainbow trout (<em>Oncorhynchusmykiss, </em>Walbaum, 1792) to evaluate the effect of dietary supplementation with a commercial prebiotic GroBiotic^®-A (G-A) on the growth, feed efficiency, haematology and immunlogical parameters. Ttreatments containing various inclusions of G-A (0 %, 0.5 %, 1.0 %, 1.5 %, 2.0 %, 2.5 %, and 3.0 %) were added to a commercial fish dietand were fed twice daily at 2-6 % of body weight. The highest weight gain (WG), specific growth rate (SGR) and average daily gain (ADG) were obtained in fish fed the diet containing 2.5 % G-A followed by 3.0 % inclusion (<em>P</em><0.05). The highest feed efficiency (FE), protein efficiency ratio (PER) and net protein utilization (NPU) were also recorded in the 2.5 % G-A inclusion (<em>P</em><0.05). Survival was significantly higher (<em>P</em><0.05) in fish fed with 2 % and 2.5 % G-Asupplement (<em>P</em><0.05). Although higher Hb, haematocrit, RBC, WBC, MCH, MCHC, MCV, lymphocytes, and neutrophils were observed at all G-A supplemented diets, the differences among themwerenot significant (<em>P</em>>0.05). On the other hand,significantly higher differencee (<em>P</em><0.05) in lysozyme and immunoglobulin (IgM) concentrations wereobserved in 2.5% G-A inclusion. The results of this study indicated that 2.5 % G-A inclusionhad a better performance on growth and haematoimmunological parameters in rainbow trout fingerling. https://ecopersia.modares.ac.ir/article_17105_172a0351dd06161e7774ba5a3abe865b.pdf