Fish production and some traits of meat quality in rainbow trout (Oncorhynchus mykiss) farmed in different production systems

ISSN 1313 - 8820 (print) ISSN 1314 - 412X (online) Volume 8, Number 4 December 2016 2016 Editor-in-Chief Georgi Petkov Faculty of Agriculture Trakia University, Stara Zagora Bulgaria Co-Editor-in-Chief Dimitar Panayotov Faculty of Agriculture Trakia University, Stara Zagora Bulgaria Editors and Sections Genetics and Breeding Tsanko Yablanski (Bulgaria) Atanas Atanasov (Bulgaria) Nikolay Tsenov (Bulgaria) Max Rothschild (USA) Ihsan Soysal (Turkey) Horia Grosu (Romania) Bojin Bojinov (Bulgaria) Stoicho Metodiev (Bulgaria) Svetlana Georgieva (Bulgaria) Nutrition and Physiology Nikolai Todorov (Bulgaria) Peter Surai (UK) Zervas Georgios (Greece) Ivan Varlyakov (Bulgaria) Production Systems Radoslav Slavov (Bulgaria) Dimitar Pavlov (Bulgaria) Bogdan Szostak (Poland) Banko Banev (Bulgaria) Georgy Zhelyazkov (Bulgaria) Agriculture and Environment Ramesh Kanwar (USA) Martin Banov (Bulgaria) Peter Cornish (Australia) Product Quality and Safety Marin Kabakchiev (Bulgaria) Stefan Denev (Bulgaria) Vasil Atanasov (Bulgaria) Roumiana Tsenkova (Japan) English Editor Yanka Ivanova (Bulgaria) Scope and policy of the journal Agricultural Science and Technology /AST/ – an International Scientific Journal of Agricultural and Technology Sciences is published in English in one volume of 4 issues per year, as a printed journal and in electronic form. 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Address of Editorial office: Agricultural Science and Technology Faculty of Agriculture, Trakia University Student's campus, 6000 Stara Zagora Bulgaria Telephone.: +359 42 699330 +359 42 699446 www.agriscitech.eu Technical Assistance: Nely Tsvetanova Telephone.: +359 42 699446 E-mail: Volume 8, Number 4 December 2016 ISSN 1313 - 8820 (print) ISSN 1314 - 412X (online) 2016 AGRICULTURAL SCIENCE AND TECHNOLOGY, VOL. 8, No 4, pp 346 - 350, 2016 10.15547/ast.2016.04.067 Product Quality and Safety Fish production and some traits of meat quality in rainbow trout (Oncorhynchus mykiss) farmed in different production systems St. Stoyanova*, Y.Staykov, G. Zelqzkov, I. Sirakov, G.Nikolov Department of Biology and Aquaculture, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria (Manuscript received 26 October 2016; accepted for publication 22 November 2016) Abstract. The rainbow trout (Oncorhynchus mykiss), an important species in Bulgarian aquaculture, is farmed in different production systems as raceways, net cages etc. The aim of the present study was to evaluate the effect of two different rearing systems on fish production, survival rate, meat chemical, mineral composition and farming economic efficiency of culticated rainbow trout (Oncorhynchus mykiss). The information from a survey on fish production and economic efficiency traits was collected from two national rainbow trout farms using the two commonest fish farming systems: in raceways, Happy Fish Ltd fish farm and in net cages, Forest Group Ltd fish farm. The average individual weight gain (g), total weight gain (kg), feed conversion ratio, production costs of 1 kg fish and the economic efficiency coefficients were determined for the two studied fish farms. The final live weight of rainbow trout in net cages was 0.30 kg vs 0.35 kg in raceways. The average individual weight gain was higher in raceways farming system (0.30 kg) than in net cages farm (0.26 kg). The mortality rate of fish in raceways was considerably lower: only 1% as compared to that in net cages (4%). The feed conversion ratio at the end of the experiment showed identical values for trout in both farms 1.01. The meat water content of fish reared in raceways and net cages was 77.46±0.65% and 74.52±0.52% respectively (P≤0.01).The protein content of fish meat was higher in fish farmed in net cages 18.84±0.29% as compared to fish cultivated in raceways 17.60±0.49% (P≤ 0.05). Meat fat content of rainbow trout, reared in the net cage system was also considerably higher (5.26±0.30%) than the respective parameter in fish farmed -1 in ponds (3.60±0.15%) (P≤0.001). The content of Ca and P was higher in rainbow trouts reared in raceways (138.96±1.12 mg.kg and 2844.32±39.31 mg.kg 1 ) compared with the values of these parameters of fish in net cages (134.46±1.96 mg.kg-1 and 2690.31±42.81 mg.kg-1) (P≤ (...truncated)