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Feed of high quality is one of the most important parameter which influences fish growth, feed conversion and chemical composition of fish meat in conditions of intensive fish farming. Studies on the influence of two commercial diets on nutritional quality and production results in rainbow trout intensive farming conditions in Pond I and Pond II were undertaken. Obtained values for proteins and fats in feed were significantly higher (p<0.001) in Diet II comparing to Diet I. The average water and ash content was significantly higher (p<0.001) in Diet I in relation to Diet II. The average length and mass of fish were higher in Pond I in relation to Pond II. Calculated values for condition factors, Kf, indicate to a higher production results in Pond II (1.81) in relation to Pond I (1.22). There were not significant differences (p>0.05) in the average content of proteins and ash in fillets of fish from Pond I (17.43% and 1.19%, respectively) and Pond II (18.69% and 1.29%, respectively). The average content of water was significantly higher (p<0.001) in fillets of fish from Pond I (79.87%) comparing to fillets of fish from Pond II (75.40%). Average content of fat in fillets of trout from Pond II (4.17%) was around three times higher than the average content of fat in fillets of trout from Pond I (1.41%), (p<0.001). Results for energy values (348.44 kJ/100g- Pond I and 471.38 kJ/100g- Pond II) are in a direct correlation with the content of fat in fish. The average content of cholesterol in fillets of trout from Pond II (70.12 mg/100g) was significantly higher (p<0.001) than in fillets of trout from Pond I (44.11 mg/100g). The obtained data indicate to a positive influence of fat content in the diet on fat content, energy value and production results in rainbow trout production in Pond II. Lower water temperature established in Pond II (8°C) comparing to Pond I (13°C) might have had additional influence on the nutritional quality and production results in Pond II, as well. [ABSTRACT FROM AUTHOR]

With the aim of reinforcement S&T capacities in aquaculture, studies on the influence of three commercial pelleted diets on fatty acid profile in rainbow trout production were undertaken. Commercial diets for rainbow trout contained significantly different quantities of saturated fatty acids (SFA), (p<0.05), ranging from 21.02 to 38.50%. Significant differences between diets (p<0.05) were established in the proportions of monounsaturated fatty acids (MUFA), (29.56- 45.21%) and polyunsaturated fatty acids (PUFA), (31.95 to 36.43%). The established quantities of EPA (C20:5 n-3) and DHA (C22:6 n-3) in diets were 8.69, 9.11, 11.36% and 3.90, 5.30, 8.18%, respectively. The share of n-3 and n-6 fatty acids (FA) ranged from 17.97 to 26.33% and from 10.10 to 13.98%, respectively. The n-3/n-6 ratio was in the range 1.29-2.61. The major SFA (total SFA: 22.17- 35.63%) in fish samples was palmitic acid (C16:0), (15.61-24.65%). Oleic acid (C18:1cis-9) was the most abundant from the MUFA family (21.90-31.89%), (total MUFA: 35.00-43.50%). From PUFA family (total PUFA: 29.38-34.33%), linoleic acid (C18:2 n-6), (10.09-10.97%), EPA (2.95-4.26%) and DHA (7.53-10.39%) were present in significant quantities in trout. Quantities of n-3 FA ranged from 17.08 to 21.12% and significant differences (p<0.05) were established between trout fed Diet I and Diet III. The proportion of n-6 FA ranged from 12.29 to 13.21% and no significant differences were established (p>0.05). The n-3/n-6 ratio ranged from 1.39 to 1.60 and differences were not statistically significant (p>0.05). The obtained results indicate that fatty acid profile of fish reflects the fatty acid composition of fish diets, with some variabilities which indicate that the incorporation of fatty acids in fish tissue is under some metabolic effects. [ABSTRACT FROM AUTHOR]