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Increasing the amount of n-3 PUFA in carp meat is one of the most important tasks in enhancing its overall quality. However, the relative influence of supplemental feed and natural feed on the FA profile of cultivated carp flesh is not well documented, making it difficult to choose the most efficient strategy. Carp diet composition and diet and flesh fatty acid profiles were simultaneously followed in order to determine the influence of pelleted feed compared to natural feed on fatty acid profiles of carp tissues. Pelleted feed clearly dominated over zooplankton and Chironomidae in the carp diet, producing carp tissue fatty acid profiles closely resembling those of pelleted feed. However, increase in the abundance of zooplankton over the course of the investigation resulting in concomitant increase of its proportion in feed bulk was in strong positive correlation with increase in n-3 HUFA in the dorsal muscle. n-3 PUFA enrichment of supplemental feed could be the dominant mechanism in production of carp meat rich in n-3 PUFA. However, even a small increase in natural feed availability could significantly change the diet of common carp and result in considerable improvement of meat quality with regard to n-3 HUFA content.

Rezultati prikazani u radu ukazuju na daleko veći značaj prirodne hrane kao izvora polinezasićenih masnih kiselina u odnosu na peletiranu hranu u ishrani šarana u poluintenzivnom sistemu gajenja. Utvrđeno je da su od organizama koji su činili prirodni obrok šaranu: predstavnici familija Chironimidae sa dominaciojm vrste Chironomus plumosus iz faune dna i zooplanktonski organizmi (sa dominacijom Cladocera) imali znatno veći sadržaj omega 3 i omega 6 masnih kiselina nego peletirana hrana. Istraživanja su obavljena u 4 ribnjačka jezera šaranskog ribnjaka „Despotovo“ sa poluintezivnim sistemom gajenja baziranom na prihrani peletiranom hranom. Peletiranu hranu odlikuje najmanja raznovrsnost masnih kiselina i izrazita dominacija linolne i oleinske kiseline. Larve Chironomidae i zooplankton karakteriše veća zastupljenost zasićenih masniih kiselina(SFA: 49.36 ± 1.92 i 38.70 ± 0.67) u odnosu na peletiranu hranu (15.47±0.41), a zooplankton odlikuje i najveća raznovrsnost i zastupljenost n-3 masnih kiselina. Odnos n-3/n-6 masnih kiselina deset puta je veći kod zooplanktona nego kod Chironomidae, a sedam puta veći kod Chironomidae nego kod peletirane hrane.

Jedna od najviše gajenih ciprinidnih vrsta riba u svetu je šaran. Gaji se u različitim sistemima, od ekstenzivnih do intenzivnih. Među brojnim načinima gajenja, poluintenzivna proizvodnja je apsolutno dominantna. Ovakva proizvodnja se bazira na kombinaciji prirodne i dodatne hrane. Prirodnom hranom se obezbeđuje proteini, ali i ostali potrebni sastojci neophodni za pravilan rast i razvoj ribljeg organizma, dok se dodatnom prihranom podmiruju energetske potrebe, ali i nedostajući proteini, minerali, vitamini, pre svega u periodima depresije prirodne hrane. Hrana za gajenog šarana u velikoj meri utiče na proizvodne rezultate. Međutim hrana, iako veoma važna, samo je jedna karika u lancu bitnih ključnih tačaka od vodene njive do tanjira. Priprema ribnjačkih jezera pre nasada predstavlja važnu agrotehničku meru, a koja se često izostavlja, pre svega pri gajenju konzumnog šarana. Prezimljavanje ribnjačkog dna na suvom, tanjiranje, zakrečavanje, a potom đubrenje su od velikog uticaja na razvoj prirodne hrane, ali i na proces mineralizacije organskih materija u ribnjačkoj podlozi, kao i na dezinfekciju ribnjaka, čime se obezbeđuje povoljni ambijentalni uslovi za gajenje šarana. Izbor monokulture ili polikulture u velikoj meri može uticati na ostvarenje profita u poluintenzivnoj proizvodnji šarana, ne samo zahvaljujući maksimalnom iskorišćavanju prirodnih potencijala ribnjaka, već i zahvaljujući obezbeđivanju stabilnosti ribnjačkog ekosistema. Kvalitet šaranske mlađi za nasad jedna je od najvažnijih ključnih tačaka. Izbor mlađi dobijene od selekcionisanih matica predstavlja najbolji, a izbor mlađi iz divljeg mresta najlošiji izbor sa nepredvidivim rezultatima. Jedna od dilema je i da li u ribnjačkim objektima gajiti samo jednu uzrasnu kategoriju ili primeniti mešani nasad? Nasad dvogodišnje mlađi za gajenje konzumnog šarana koji je u toku prethodnog perioda bila bolesna zajedno sa jednomesečnom ili jednogodišnjom mlađi predstavljaju loš tehnološki potez. Međutim, mešani nasad, predstavlja dobar izbor ukoliko želimo da maksimalno iskoristimo prirodnu hranu, kao i u ribnjačkim uslovima u kojima prihranu riba obavljamo peletiranom hranom. Nakon dobre pripreme ribnjačkog objekta, kao i izbora mlađi za nasad predstoji nam odluka kojom vrstom hrane prihranjivati šarana. Izbor žitarica u poluintenzivnoj proizvodnji je opravdan u uslovima dobre razvijenosti prirodne hrane, želje da se proizvodi od 1 do 1,5 t/ha, kao i nemogućnosti plasmana veće količine ribe na tržište. Koncentrovane smeše su u prednosti kada se želi proizvesti više od 1,5 t/ha i šaran boljih nutritivnih svojstava. Od koncentrovanih, ekstrudinara hrana je po najvećem broju kriterijuma u prednosti u odnosu na peletiranu.Veoma je važno voditi računa i o činjenici da u različitim periodima proizvodne sezone (pre svega u zavisnosti od temperature i razvijenosti prirodne hrane) gajenom šaranu odgovora hrana različitog sastava (različitog sadržaja proteina, ugljenih hidrata, vitamina, minerala). Jedan od ključnih faktora za dobre proizvodne rezultate je i potreba da se ribe sačuvaju od ihtiofagnih ptica, sisara, pa i čoveka. Pored odabira pravih tehnoloških postupaka stalno praćenje zdravstvenog stanja gajenog šarana, kao i preventivno delovanje su najbolji načini održavanja stabilnosti zdravstvenog stanja gajenih riba. Iako poluintenzivno gajenje šarana u pogledu dobrobiti riba, predstavlja jedan od oblika proizvodnje koji je najbliži idealnom, sam izlov, transport i skladištenje u prodavnicama živog šarana je period „pakla“ za ovu vrstu. Otuda je neophodno posebnu pažnju posvetiti tehnologiji izlova i transporta šarana u cilju unapređenja dobrobiti riba, a sa ciljem smanjenja stresa kod izlovljene šaranske mlađi, što će imati pozitivan efekat na smanjenje mortaliteta, održavanje dobrog zdravstvenog stanja u narednim periodima gajenja šarana, kao i samog kvaliteta mesa konzumnog šarana. Među poslednjim, ali za dalji razvoj šaranskog ribarstva jednim od ključnih faktora je način prometa šaranom. Promet živog šarana sa aspekta ekonomije predstavlja skup način, sa aspekta dobrobiti riba nehuman, a sa aspekta praćenja trendova plasmana ribe zastareli i neusklađen način prodaje sa zahtevima savremenog kupca.

The quality of fish feed and its nutritional value are important for fish production. From an economic point of view it is vital to ensure a cheaper final product while from the nutritional aspects it is essential to fulfill the requirements of fish. The aim of this study was to investigate the digestibility and effect of feed mixtures with different protein content on growth of carp fry. The experiment was carried out at the Laboratory for fish nutrition of the Faculty of Agriculture, University of Belgrade, for 90 days. Fish were fed with concentrate mixtures having 38% (A), 41% (B) and 44% (C) of proteins. The bigger share of the protein part in A were plant proteins (PP), in C fish meal (FM), while in B the share of FM and PP was approximately the same. Results showed significant differences between digestibility of different feed mixture. The digestibility of protein and fat were higher in fish fed diets with higher protein content. Digestibility of nitrogen-free extracts (NFE), energy and digestible energy was not statistically significant (p> 0.05) regardless of the level of protein in the diet. The results indicate that the increase in the digestibility of proteins is in accordance with the increase in protein content in the diet e.g. diets with higher content of FM.

Fish nutrition based on combination of natural food (zooplankton and bottom fauna) as main protein source, and added food, mostly cereals, as energy supply, is one of the main features of the world prevailing, semi-intensive farming system. In the recent years in several countries of South East Europe instead of cereals pelleted and extruded feed is used in carp nutrition in periods of depression of natural food. This is the way to overcome the lack of proteins and lipids, of required amino and fatty acids composition. Bottom fauna organisms represent natural food of greatest importance for fry and cultured consumable carp. Because of its mass development in spring and lesser in autumn, Chironomidae larvae are particularly rich source of nutrients for carp. They are an easily noticeable pray because of their body dimensions (till several centimeters) and clear red color (coming from hemoglobin). Chironomidae larvae are invaluable protein source of adequate amino acid composition for carp body growth. Also, this is a source of lipids, particularly rich in omega 3 and omega 6 fatty acids. High omega 3 fatty acid content is present in Chironomidae, especially in Chironomus plumosus, the most frequently observed species in fish ponds. In Chironomus plumosus larvae, omega 6 fatty acids content compared to omega 3 content is higher. This is of particular importance providing higher needs in omega 6 for carp. Considering that omega 3 and omega 6 fatty acids ratio in farmed fish is lower compared to natural populations; that the consumption of farmed fish is increasing together with requirements to increase omega 3 content, and optimally balance omega 3/omega 6 ratio; research in carp meat improvement are of utmost importance. Stimulation of natural food development particularly Chironomidae larvae in carp ponds is one of the approaches for enhancement of farmed carp meat quality.

The aim of this study was to estimate heritability and genetic correlations between weight, length and height of common carp in Serbia (Cyprinus carpio L.) during 3-year growth period. The 50 families of common carp were produced in 2007 and used for the estimation of genetic parameters. The fish were measured at tagging for weight, length and height (W0, L0, H0), then during the first autumn (W1, L1, H1) and during the second autumn (W2, L2, H2). Based on univariate models heritability estimates were high for all traits (0.39, 0.34 and 0.45 for W1, L1 and H1, respectively) and also for the second production year (0.49, 0.47 and 0.44 for W2, L2 and H2, respectively). The genetic correlations were estimated using multivariate models and they were high between W1 and L1 and H1 (0.81 ± 0.06 and 0.91 ± 0.03 for L1 and H1, respectively), while between H1 and L1 were moderately correlated (0.54 ± 0.12). In the second production year genetic correlations were also high, between W2 and L2 and H2 (0.64 ± 0.09 and 0.74 ± 0.06, respectively), while between length and height they were lower (0.24 ± 0.15). Based on the current results improving growth rate of common carp through genetic selection is expected to be effective. Cilj ove studije je bio da se procene heritabilnost i genetičke korelacije telesne mase, dužine i visine šarana u Srbiji u toku trogodišnjeg ciklusa. U toku 2007. godine proizvedeno je 50 familija šarana i ove jedinke iskorišćene su za procenu heritabilnosti i genetičke korelacije. Merenja riba su obavljena za osobine telesna masa, dužina i visina u momentu označavanja (W0, L0, H0), zatim pri starosti riba prva jesen (W1, L1, H1) i pri starosti druga jesen (W2, L2, H2). Na osnovu jednovarijantnih statističkih modela za svaku osobinu procene heritabilnosti su bile visoke (0.39, 0.34 i 0.45 za W2, L2 i H2). Genetičke korelacije su procenjene na osnovu multivarijacionih statističkih modela i bile su visoke između W1 i, L1 i H1 (0.81 ± 0.06 i 0.91 ± 0.03 za L1 i H1), dok su između H1 i L1 bile umereno korelisane (0.54 ± 0.12). U drugoj produkcionoj godini korelacije su takođe bile visoke, između W2 i, L2 i H2 (0.64 ± 0.09 i 0.74 ± 0.06), dok su između osobina dužina i visina, L2 i H2, bile niže (0.24 ± 0.15). Na osnovu navedenih rezultata očekuje se da bi poboljšanje prirasta u navedenoj populaciji šarana u Srbiji, putem selekcije familija, bilo uspešno.

Selective breeding for growth rate in common carp (Cyprinus carpio L.) has not been actively pursued after some early unsuccessful selection experiments. Prerequisite for successful selective breeding is accurate and objective evaluation of genetic parameters used in the planning and implementation of selection methods. The aim of this work was to assess the possibilities of improving production traits (weight, length and height) that are related to the growth of carp, through selection. Estimated variation and heritabilities were significantly high for all examined characteristics. Based on the obtained results can be expected to improve growth rate of common carp through selective breeding.

The aim of this paper was to study the structure of the gills of carp (Cyprinus carpio) fingerlings kept in small ponds during the growing season. In the studied ponds (nine small ponds and one larger pond) water was of good quality and the quantity of natural food monitored regularly in order to determine precisely the quantity of added food. Although nearly all the gill samples analyzed had parts with normal gill structure, a whole range of histological changes, mainly of gill epithelia as well as circulatory changes and parasites infestation, were found pointing out high responsiveness of the branchial apparatus to agrotechnical measures that must be applied in order to obtain successful fish production in the farm. Ispitivana je histološka građa škrga mlađi šarana (Cyprinus carpio) gajenih u malim jezerima - zimovnicima. Ispitivano je devet malih jezera i jedno veliko, svi sa vodom odgovarajućeg kvaliteta za toplovodno ribarstvo i uz kontrolu prirodne i određivanje količine dodatne hrane. Iako su svi analizirani uzorci škrga imali funkcionalno normalne delove, konstatovano je niz promena histološke građe, uglavnom poremećaja na epitelnim tkivima, na krvnim sudovima škrga, kao i infestacija parazitima. Svi poremećaji ukazuju na osetljivost škržnog aparata koji se prilagođava na neminovne varijacije kvaliteta sredine usled primene agrotehničkih mera neophodnih za uspešnu proizvodnju.

In the era of growing demand for sustainable usage of water, all types of aquaculture systems are under reconsideration. Until recently semi-intensive production was concerned to be one of the least polluting. Nowadays, this fact has been reassessed especially in many countries culturing carp in this way. One of the most significant influences on a fish pond ecosystem in semi-intensive carp production is changing its characteristics by adding low quality supplemental feeding. Therefore, the type of fish feed, its physical and chemical characteristics can considerably change the water quality of a fish pond. Aiming to analyze the effect of commonly used feeds (cereals, pelleted and extruded feed) in semi-intensive production on the water quality, an experiment was carried out at three fish ponds during one production season. Even though the results of physical, chemical and biological parameters showed that there were no statistically significant differences in the water quality between fish ponds with different supplemental feed, looking at the overall picture it could be concluded that the pond that had the lowest quality of feed (row cereals), having high organic mater and chlorophyll a during most of the trial period as well as the specific phytoplankton successions including potentially harmful blue-green alga, had consequently the lowest water quality.