Effect of Аrtemisia annua L. extract on growth performance, biochemical blood parameters and meat quality of rainbow trout (Oncorhynchus mykiss W.), cultivated in recirculating system

  1. Koshinski*

 

Department of Biology and Aquaculture, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria

 

DOI: 10.15547/ast.2018.03.051

(Manuscript received 30 June 2018; accepted for publication 20 August 2018)

 

Abstract. Medicinal herbs can be used as feed additives to improve animal growth performance and to optimize physiological processes. The purpose of this study was to trace growth performance, meat quality and biochemical blood parameters (glucose, urea, creatinine, total protein, albumin, ASAT, ALAT, Ca, P, Mg, triglycerides, cholesterol) of rainbow trout (Oncorhynchus mykiss W.), fed with additive sweet wormwood (Аrtemisia annua L.) extract. In a recirculation system at the Aquaculture Base of the Faculty of Agriculture at Trakia University, a control group (no added) and an experimental (with added 204 mg.kg-1 of sweet wormwood extract) option were set, each of them with two replicates and mean initial weight of fish 13.32±3.07g and 13.37±2.76g, respectively. Forty specimens of rainbow trouts in good health condition were placed in each tank and cultivated for 60 days. At the end of the experiment average final weight, specific growth rates, feed conversion ratio, meat quality and blood biochemical parameters were calculated. Trouts from the experimental group, fed with supplement had 5.5% higher average final weight compared to this one of individuals from the control (P<0.05). The blood biochemical parameters glucose, ASAT and ALAT in control variant were higher compared to the values of that parameters of the fish from the experimental group (P>0.05). Electrolytes of blood such as phosphorus (P) had higher level in the experimental group (P>0.05) compared to the control group. Better growth performance and blood parameters were measured in trout fed sweet wormwood supplement.

Effect of dietary phytoextracts supplementation on the chemical composition and fatty acid profile of rainbow trout (Oncorhynchus Mykiss w.), cultivated in recirculation system

  1. Georgieva, G. Zhelyazkov, Y. Staykov, D. Georgiev

 

Department of Biology and Aquaculture, Faculty of Agriculture, Trakia University, 6014 Stara Zagora, Bulgaria

 

DOI: 10.15547/ast.2018.03.041

(Manuscript received 7 June 2018; accepted for publication 28 August 2018)

 

Abstract. The present research aimed to examine the effect of dietary phytoextracts supplementation on the chemical composition and fatty acid profile in the meat of rainbow trout (Oncorhynchus mykiss W.), cultivated in a recirculation system. The fish were divided into 6 groups: one control (C) and five experimental groups in the food of which phytoextracts of curcumin (EC), paprika (EP), thyme (ET), oregano (EO) and garlic (EG) were added. The inclusion of phytoextracts had no significant effect on growth parameters of fish from EC, EP, ET, EO and EG groups (P>0.05). No statistical differences on water content, protein and lipids were observed in the meat of fish from the control and the experimental groups (P>0.05). Statistically significantly higher value of the dry matter was established in ET group in comparson with C, EC, EP, EO and EG groups (P≤0.001). The values of ash were significantly lower in fish from all experimental groups compared to the control group. The inclusion of phytoextracts did not affect the fatty acid profile of fish from EP, EO and EG groups (P>0.05). Exceptions are EC and ET groups, which had the lowest value of C18:3n-3 α-linolenic compared to those from the control group (P≤0.05, P≤0.001).

Effect of linseed and sunflower oils in the diet on the growth parameters in rainbow trout (Oncorhynchus mykiss W.) cultivated in a recirculating system

G. Zheliazkov*

Department of Biology and Aquaculture, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria

Abstract. The aim of this study was to determine the influence of linseed and sunflower oils in the diet on the survival rate, weight gain and the feed conversion ratio in rainbow trout, reared in a recirculating system. The fish of the three groups were raised in concrete tanks with effective capacity of 0.8 m3, which were part of the recirculating system. Rainbow trout received extruded feed (6 mm pellets), produced by “Aqua garant”. The feed of the fish from the experimental group (EL) was supplemented with 5% linseed oil, while that of the trout of the group (ES) – 5% sunflower oil. The diet of the fish of the control group (C) did not contain any of the above mentioned oils. The duration of the trial was 60 days. In order to study the effect of linseed and sunflower oils in the diet on the weight gain of the fish, control catches were carried out at 15 days’ interval. The live weight (g) and linear growth (mm) of the control catches were determined as the fish were individually weighed and measured. The final live weights of the trout in the experimental groups as well as that in the control were as follows: EL – 334.79±67.52g, ES – 329.39±70.31 g and C – 323.58±67.77 g. The values of this parameter in EL were higher than those of fish from ES and the control group by 1.64% and 3.47%, respectively, but the differences were not significant (P>0.05). This trend persisted also for the linear measurements – in the trout of EL they were the highest. The fish of EL displayed the lowest feed consumption. This trait had lower values than the ones of the trout of ES and the control group by 2.84% and 5%, respectively, though the differences were not significant (P>0.05). The survival rate of the fish from the groups did not differ substantially.

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Fatty acid composition of common carp, rainbow trout and grey mullet fish species

M. Stancheva, A. Merdzhanova

Abstract. The aim of the present study was to determinate the fatty acid composition of two commercially important freshwater fish species – rainbow trout (Oncorhynchus mykiss) and carp (Cyprinus carpio L.) and one Black Sea fish – grey mullet (Mugil cephalus). Lipid extraction was done according to the Bligh and Dyer method. Methyl esters were prepared according to method EN ISO 5508:2000. The fatty acid (FA) composition was analyzed by GC-MS. The total lipid content in rainbow trout was 11.50 g/100g raw weight (r.w.), in carp – 12.74g/100 g r.w. while grey mullet showed a value of 3.80g/100g r.w. In comparison with other groups, the polyunsaturated FA (PUFA) showed the highest level in trout – 43.13 % including ω3 such as eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids followed by grey mullet –29.1%, whereas the carp presented lowest level – 17.55%. The amounts of total ω6 PUFAs were higher than the total ω3 PUFAs in all analyzed fish samples. A ω3 /ω6 and PUFA/SFA ratios were determined in all three fish species.

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Consumption of dissolved oxygen in rainbow trout (Oncorhynchus mykiss)

I. Sirakov, Y. Staykov , G. Djanovski

Abstract. The purpose of the study was to determine the dissolved oxygen consumption of rainbow trout, cultivated in raceway. The consumption analysis is based on a process automatic oxygen measurement system and compares the theoretically calculated amount of food for trout feeding based on the flow and oxygen consumption of the cultivated fish with wise used in the trout nutrition practice – calculation of feed amount according to water temperature and individual fish weight. The average amount of oxygen consumed by the fish in our trial measured in an interval of 1 minute was 0.295 mg.l-1. The comparison between the calculated amount of food by the equation σ = 0.054.Q. (O in-O out) and quantity of food used in feeding of rainbow trout based on water temperature and individual fish weight did not show statistically significant differences.

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