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Öğe Antimicrobial activity of trans-cinnamic acid and commonly used antibiotics against important fish pathogens and nonpathogenic isolates(Oxford Univ Press, 2018) Yilmaz, S.; Sova, M.; Ergun, S.Aims Antibiotics and several other chemicals have been used to prevent fish diseases. However, this situation results in economic loss for the companies in the aquaculture industry and most importantly it pollutes the environment. Cinnamic acid is a naturally occurring aromatic acid and is considered to be safe for human consumption. Therefore, in this study, the antibacterial activity of trans-cinnamic acid and commonly used antibiotics, namely chloramphenicol, vancomycin, streptomycin and erythromycin, were tested against 32 bacteria, including fish pathogens, nonpathogenic isolates and collection strains. Methods and Results Trans-cinnamic acid was applied against the bacteria using the disc diffusion and microdilution method under in vitro conditions. Antibiotics were also tested under similar conditions against all tested bacteria using the disc diffusion method. The results show that among 32 bacterial strains trans-cinnamic acid exhibited potent inhibitory effect on the Gram-negative fish pathogen Aeromonas sobria. In addition, a moderate inhibition of trans-cinnamic acid of fish pathogens Aeromonas salmonicida, Vibrio (Listonella) anguillarum, Vibrio crassostreae and Yersinia ruckeri was also observed for trans-cinnamic acid in our study. On the contrary, the majority of nonpathogenic intestinal isolates were resistant to trans-cinnamic acid. Conclusions To the best of our knowledge, this is the first report on the antimicrobial activity of trans-cinnamic acid on 24 of the studied bacteria isolated from fish. In conclusion, trans-cinnamic acid can be used as an environmentally friendly alternative additive to prevent and control primarily A. sobria, as well as other pathogenic bacteria such as A. salmonicida, V. anguillarum, V. crassostreae and Y. ruckeri. Significance and Impact of the Study This study indicated that trans-cinnamic acid may present an environmentally friendly alternative therapeutic agent against A. sobria infections in the aquaculture industry.Öğe Effect of dietary Ulva and Spirulina on weight loss and body composition of rainbow trout, Oncorhynchus mykiss (Walbaum), during a starvation period(Wiley-Blackwell, 2011) Guroy, D.; Guroy, B.; Merrifield, D. L.; Ergun, S.; Tekinay, A. A.; Yigit, M.P>A study was conducted to determine the effect of dietary algal supplementation on weight loss and proximate composition in rainbow trout, Oncorhynchus mykiss, during starvation. An algae-free control diet (C) and four experimental diets, including varying levels of raw Ulva meal (5% = U5; 10% = U10) and Spirulina meal (5% = S5; 10% = S10) were formulated. Fish were fed to satiation for 12 weeks and then subjected to a 3-week starvation period. Body weight, viscerosomatic index (VSI, %), hepatosomatic index (HSI, %), dress-out (DO, %) and chemical composition of carcass were analysed at the end of each starvation week. The accumulated weight loss of the fish fed dietary algae was almost 50% less than the control group (p < 0.05) after 2 and 3 weeks starvation. No significant differences in weight loss were observed among the fish fed different algal diets during the starvation period. Total body protein and ash contents remained constant in all groups throughout the starvation period. Fish in all treatments lost a significant level of total lipids and changes of liver fatty acid profiles were also observed. Results indicate that low level inclusion of algae in aquafeeds may have economical advantages in terms of reducing weight loss in fish when subjected to a short-term fasting period, that sometimes is necessary after a heavy rainfall or when fish stocks are held back to meet market demand.Öğe Effects of dietary protein and lipid levels on growth and feed utilization of wild-caught striped sea bream, Lithognathus mormyrus(Wiley, 2011) Kusku, H.; Bulut, M.; Guroy, D.; Ergun, S.; Bilen, S.; Tekinay, A. A.P>A feeding trial was carried out to determine the effects of dietary protein and lipid levels on the growth performance and feed utilization of wild-caught striped sea bream (Lithognathus mormyrus). The experimental fish were collected from a local lagoon (Cardak Lagoon, Canakkale, Turkey), transferred to the Marine Net Cage Unit and fed by hand to apparent satiation with a commercial sea bream feed (Biomar; 42% crude protein, 16% crude lipid). Approximately 4 weeks were needed to acclimate the fish to farming conditions. No pathological signs were observed and no fish losses occurred during the adaptation period. For the test trials four test diets with different levels of protein and lipid were formulated [low protein and low lipid (LP:LL), low protein and high lipid (LP:HL), high protein and low lipid (HP:LL), and high protein and high lipid (HP:HL)] and fed to L. mormyrus (mean weight 85.0 +/- 4.6 g SEM) in the net cages (circle divide 2 m, depth 2.5 m) for 60 days. During the experiment water temperature varied between 21.1 and 26.4 degrees C; dissolved oxygen 8.4-9.6 mg L-1; pH 7.2-8.6; and salinity 23.3-25.6 parts per thousand. Growth performances of fish fed high protein diets were higher compared to fish fed low protein diets, irrespective of the dietary lipid level (P < 0.05). Feed conversion ratio (FCR) and protein efficiency ratio (PER) were not influenced by dietary protein or lipid levels (P > 0.05). Preliminary results indicate that striped sea bream can be easily adapted to farming conditions in net cages, and that a diet containing 50% crude protein and 15% crude lipid (HP:LL) levels with 23.0 g protein MJ-1 gross energy of protein/energy ratio would be suitable for striped sea bream growth.Öğe Influence of Tribulus terrestris extract on the survival and histopathology of Oreochromis mossambicus (Peters, 1852) fry before and after Streptococcus iniae infection(Wiley, 2014) Yilmaz, S.; Ergun, S.; Kaya, H.; Gurkan, M.The aim of this study was to determine the effects of Tribulus terrestris extract (TT) on growth performance, disease resistance and histopathological changes in intestine and liver tissues of Oreochromis mossambicus (Peters, 1852) first-feeding fry before and after exposure to Streptococcus iniae. Five iso-nitrogenous and isocaloric diets were formulated to contain 0 (control), 200, 400, 600, and 800 mg kg(-1) TT. After feeding for 45 days, fish were infected with S. iniae and mortalities recorded. Final weight, weight gain and SGR of tilapia fry fed the 400 mg kg(-1) TT diet were significantly greater than that of control diet. In the challenge experiment, the best survival rate was obtained with 400 mg kg(-1) TT supplementation. Infection by S. iniae appeared to have a negative effect on histopathological findings and outcome than did TT-800 used alone. However, administration of TT (200 or 400 mg extract kg(-1)) resulted in overall improvement in the intestine and liver histopathology, emphasizing the protective potential of TT. The present study suggests the protective potential of TT in alleviating intestinal and hepatic damage that can occur after a S. iniae infection. It was concluded that 400 mg kg(-1) TT can enhance growth and disease resistance during first-feeding of O. mossambicus fry. This suggests that TT may be an alternative to antibiotics in controlling streptococcal disease in tilapia culture.Öğe Substituting fish meal with poultry by-product meal in diets for black Sea turbot Psetta maeotica(Wiley, 2006) Yigit, M.; Erdem, M.; Koshio, S.; Ergun, S.; Turker, A.; Karaali, B.A 60 days feeding experiment was carried out with Black Sea turbot Psetta maeotica to determine the amount of poultry by-product meal (PBM) that could replace fish meal (FM) in formulated diets without reducing growth performance. Juvenile Black Sea turbot (initial average weight, 30 g) were fed five isoenergetic (gross energy, 20.5 +/- 0.21 kJ g(-1) diet) and isonitrogenous diets (protein content, 550 +/- 0.35 g kg(-1)). The control diet used white FM as the sole protein source, the other four diets were prepared to replace FM protein at levels of 25%, 50%, 75% and 100% with PBM. The fish readily accepted all experimental diets and no mortality were recorded during the trial. There were no significant differences in growth performance of turbot (P < 0.05) fed the diets with 25% and 50% replacement levels compared with fish offered the control diet (100% FM), however, final body weight and specific growth rate values in the 50% replacement diet were about 8% lower than those of the control. Total nitrogen excretion in fish fed 50% replacement diet were about 10% higher than the control group, even though these parameters were not found to be statistically different. At the levels of 750 and 1000 g kg(-1) of the protein, PBM inclusion caused a severe decrease in growth performance, feed utilization, protein efficiency ratio and per cent nitrogen retention. The results in the present study indicate that up to 25% of FM protein can be replaced by PBM protein without causing reduction in growth performance, nutrient utilization and nitrogen retention.
