ISSN: 1314-6246 Yılmaz et al. J. BioSci. Biotech. 2012, 1(3): 217-222. RESEARCH ARTICLE http://www.jbb.uni-plovdiv.bg 217 Sevdan Yılmaz 1 Sebahattin Ergün 1 Ekrem Şanver Çelik 2 Effects of herbal supplements on growth performance of sea bass (Dicentrarchus labrax): Change in body composition and some blood parameters Authors’ addresses: 1 Department of Aquaculture 2 Department of Basic Science Faculty of Marine Sciences and Technology, Çanakkale Onsekiz Mart University, 17100 Çanakkale, Turkey. Correspondence: Sevdan Yılmaz Department of Aquaculture, Faculty of Marine Sciences and Technology, Çanakkale Onsekiz Mart University, 17100 Çanakkale, Turkey. Tel.: +90 286 2180018 ext. 1589 e-mail: sevdanyilmaz@comu.edu.tr Article info: Received: 20 September 2012 Accepted: 21 December 2012 ABSTRACT This study was conducted to investigate the effects of dietary thyme ( Thymus vulgaris), rosemary (Rosmarinus officinalis) and fenugreek (Trigonella foenum graecum) as feed additives on growth performance, proximate composition and ammonia excretion of European sea bass Dicentrarchus labrax. Four isonitrogenous (48% crude protein) and isocaloric (21 kj/g) diets were formulated to contain 0% (control) or 1% of thyme, rosemary or fenugreek. The thyme supplementation significantly increased protein efficiency ratio, fillet protein levels, protein and energy retentions (P<0.05). The medicinal herb additives did not change serum urea, uric acid, creatinine and ammonia excretion rate (P>0.05). The results indicate that dietary thyme improved the protein and energy retentions of sea bass. Key words: medicinal herbs, growth, proximate composition, ammonia excretion, seabass Introduction Herbs or spices have been reported to promote various functions like growth (Shalaby et al., 2006), appetite stimulation, antistress (Citarasu, 2010), immune functions (Dügenci et al., 2003; Dorucu et al., 2009; Ergün et al., 2011), skin coloration (Yılmaz & Ergün, 2011), egg hatching rates (Yılmaz & Ergün, 2012a), hematological and biochemical status (Yılmaz & Ergün, 2012b) and also increase disease resistance (Yılmaz et al., 2012; Yılmaz et al., 2013) in fish culture due to different active components. Thyme has strong antimicrobial and antioxidant activity due to its very high contents of thymol, p-cymene, carvacrol, eugenol and 4-allylphenol (Lee et al., 2005; Rota et al., 2008). Carnosic acid and rosmarinic acid are the main chemical constituents of rosemary, and they are particularly high antioxidants (Erkan et al., 2008). Fenugreek is rich in flavonoids (such as apigenin, kaempferol and quercetin) and saponins (such as diosgenin and yamogenin). Their characteristic functions are to protect the oxidative damage (Kaviarasan et al., 2004) and immunostimulatory properties (Bin-Hafeez et al., 2003). Several studies have reported that oral administration of fenugreek in Labeo rohita and Oreochromis mossambicus (Paul et al., 2004; Mostafa et al., 2009), rosemary in O. niloticus (Abutbul et al., 2004; Zilberg et al., 2010), thyme, rosemary and fenugreek in O. mossambicus (Ergün et al., 2011) improved growth performance, disease resistance and immunity. The objective of this study was to determine the effects of thyme, rosemary and fenugreek on the growth performance, fillet composition, ammonia excretion, and some serum biochemical parameters in the European sea bass Dicentrarchus labrax. Materials and Methods Fish and experimental conditions Healthy cultured sea bass, Dicentrarchus labrax (20.43±0.03 g) were obtained from a local fish farm (Ida