Effect of monosodium glutamate dietary supplementation on some productive traits of common carp (Cyprinus carpio L.), cultivated in net cages

  1. G. Zhelyazkov*

 

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

 

DOI: 10.15547/ast.2018.03.039

(Manuscript received 30 May 2018; accepted for publication 15 August 2018)

 

Abstract. The aim of the study was to determine the effect of a monosodium glutamate dietary supplementation on the survival rate, growth performance, feed conversion ratio and economic efficiency of common carp (Cyprinus carpio L.), cultivated in net cages. Two hundred carps were allotted into two experimental variants, each of them comprising two replications (Control groups – CG and CG1; Experimental groups – EG and EG1), with 50 fish in a group. The average initial live weight of fish from the control and experimental groups was 1141.62±79.62g and 1129.54±71.47g, respectively (P>0.05). The carps were cultivated in net cages with a size 3.0/3.0/2.0m. The fish were fed with extruded feed Aqua garant VITAL, a product of Garant-Tiernahrung Gesellschaft m.b.H. – Austria, with 6mm size of pellets. Monosodium glutamate in amount of 1% was added to the feed of carps from the experimental groups. The fish from the control groups received no monosodium glutamate supplementation of the diet. The feed given to the fish was 2% of the total biomass. The trial period was 60 days, control catch at 30th day were done in order to study the influence of the monosodium glutamate supplementation on the weight gain and feed conversion ratio of the common carp, cultivated in net cages. The initial (1st day), control (30th day) and final (60th day) live weights (g) were determined by individual weighing. The final live weight of the fish from both replications of the experimental and the control groups was as follows: 1699.36±78.43g and 1597.27±74.66g, the differences were significant (P<0.001). The survival rate of carps from both control and experimental group replications was 100%. The average individual weight gain of fish from the two replications (supplemented with 1% monosodium glutamate) was 569.82±3.75g which was higher than that of controls by 20.04%, the differences were significant (P<0.001). At the end of the trial, the analysis of consumed feed amount showed that feed conversion ratio in the group supplemented with 1% monosodium glutamate was 1.76±0.12, i.e. by 25.57% lower than that of control carps (P<0.001). The economic efficiency in the experimental groups exhibited better economic conversion ratio (0.936), by 22.65% lower than that of the non-supplemented groups.

Effect of nutmeg extract supplementation on some productive traits and economic efficiency of common carp (Cyprinus carpio L.) cultivated in recirculation system

  1. Zhelyazkov*, S. Stoyanova, I. Sirakov, K. Velichkova, Y. Staykov

 

Department of Biology and Aquaculture, Faculty of Agriculture, Trakia University,

6000 Stara Zagora, Bulgaria

(Manuscript received 21 December 2017; accepted for publication 16 February 2018)

 

Abstract. The aim of the present study was to evaluate the effect of a dietary nutmeg extract supplement on the survival rate, growth performance, feed conversion ratio and economic efficiency of common carp (Cyprinus carpio L.) reared in a recirculation system. Thirty-two carps were allotted into two experimental variants, each of them comprising two replications with 8 fish in a group. The average initial live weight of carps from the control group (CG) and experimental group (EG) was 866.56±113.99g and 868.50±111.18g, respectively (P>0.05). Fish were reared in concrete tanks with efficient volume of 0.8m3, elements of the recirculation system. They were fed pelleted carp feed with 25% crude protein produced by “Top mix” company, with pellet size of 6mm. The feed of fish from the EG was supplemented with 1% powdered nutmeg extract after lubricating the pellets with 5ml sunflower oil per 100g feed. Control carps received the same amount of sunflower oil-lubricated feed. The daily ration of fish from both replications was 1.8% of their live weight. The experiment duration was 45 days. The initial and final live weights were determined by individual weighing. By the end of the experiment, there was a tendency towards statistically insignificant higher average live weight in fish supplemented with 1% nutmeg extract – 986.44±125.91g vs 964.94±92.04g in non-supplemented controls (P>0.05). The survival rate of carps from both control and experimental group replications was 100%. The average individual weight gain of carps from the two EG replications (supplemented with 1% nutmeg extract) was 117.94±31.24g which was higher than that of controls by 16.58% but the differences were not statistically significant (P>0.05). At the end of the trial, the analysis of consumed feed amount showed that feed conversion ratio in the group supplemented with 1% nutmeg extract was 3.05±0.78, i.e. by 23.28% lower than that of control carps (P>0.05). The group that received 1% nutmeg extract exhibited better economic conversion ratio (2.71), by 4.06% lower than that of the non-supplemented group.

Growing of common carp fingerlings in net cages at different stoking densities

Y. Staykov*, S. Stoyanova
Department of Biology and Aquaculture, Faculty of Agriculture, Trakia University, Stara Zagora, Bulgaria

Abstract. The stocking density is one of the most important parameters of fish growth and productivity in farming activities. The aim of the study was to evaluate the effects of different stocking densities on growth rate and body indices of common carp fingerlings /Cyprinus caprio L./, reared in net cages. The trial was set up as a complete randomized design, with three different stocking densities (SD1 – 300, SD2 – 500 and SD3 – 700 fish/m3), each of them with three replications. The initial body weight of fish was 0.9 g. The size of net cages was 1.50 х 1.50 х 1.50 m, with effective depth of the mesh 1.0 m and water volume – 2.25 m3. The trial lasted 122 days. The highest final body weight was attained by fish with stocking density of 300 fish/m3 – 75.55 g. The increased stocking density resulted in lower final weight of fingerlings SD2 and SD3 (p<0.05, p<0.001). The higher stocking density influences substantially the exterior traits and body indices of carp fingerlings. There were statistically significant differences between mean relative body width between SD1 and SD3 groups (р≤0.001) as well as between relative head length group between one summer old fish from SD1 and SD3 (р≤0.001). The survival of fingerlings decreased as the stocking density increased, but remained within the allowed reference ranges for all three experimental variants. The fish production was the highest for carp fingerlings stocked at SD3, but it was also associated with a large proportion of fingerlings whose size was under the fish farming standards.

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