Evaluation of growth and dressing out parameters of experimental scaly crossbreds in 3-year-old common carp (Cyprinus carpio, Linnaeus 1758)

Performance tests of the Pr?erov Scaly Carp (PS), two crossbreds (PS × M72 and PS × ROP) and an internal control group (M2 × M72) were designed to assess their production and dressing out parameters at harvest size for their potential commercial utilization. The fastest growth rate (standard length (SL): 405±21.91 mm, P<0.01) and the highest final live weight (FLW: 2015.70±323.92 g, P<0.01) were recorded in the PS × ROP hybrid. The SL values in this group of carp were 12.5%, 19.12% and 11.57% higher (P<0.01) than those at M2 × M72, PS and PS × M72, respectively, and the FLW values were 21.57%, 62.83% and 24.37% higher (P<0.01) compared with M2 × M72, PS and PS × M72 hybrids respectively. Growth rate parameters of PS × M72 hybrid and control group M2 × M72 were practically identical. The lowest growth rate potential and FLW were recorded in the PS group (P<0.01). The highest (P<0.01) dressing out parameters were found in the control group of mirror carp M2 × M72 with a dressing percentage of 65.64±2.11%. There were practically no differences in this parameter between scaly carp groups (PS: 61.79±2.82%, PS × M72: 61.51±1.72%, PS × ROP: 63.60±1.96%). This study shows evidence for faster somatic growth and bigger final weight in the hybrid line PS × ROP of 3‐year‐old common carp compared with the pure line PS and the crossbreed PS × M72.     

Growth Performance of All-Female and Mixed-Sex Common Carp Cyprinus Carpio L. Populations in the Central Europe Climatic Conditions

The results of a 4-yr study focused on comparing growth performance in all-female and mixed-sex populations of common carp are presented. All-female and mixed-sex populations of purebred Northern mirror carp (M72) and scaly crossbreds of female Ropsha (ROP) and male/neomale M72 carp (ROP × M72) were used for this experiment. Average weight and survival after each growing season and slaughtering value after the third and fourth year of the study were measured. While after 8 wk of rearing no differences between all-female and mixed-sex populations were found, the 1-yr-old all-female mirror carp population (M72) gained 29.7% more weight ( P < 0.0001) than the mixed-sex (68.5:± 15.8 g against 52.8:± 13.9 g; meant S.D.) population. After the second, third and fourth year of rearing, live weight was 9.5% ( P = 0.0062) and 6.8% ( P = 0.0229) and insignificantly 5.1 % higher, respectively, in the all-female population. There was no significant difference, even after the fourth growing season, in live weight between all-females and bisexual scaly crossbreds (2,192 g± 478.3 and 2,206 g± 484.5, respectively). The percentage of the main edible parts (processed body, filleting yield) was significantly higher in both mirror and scaly, all-female populations at 3 yr of age but not significantly different in 4-yr-old fish. No distinct differences in survival and body shape of all-female and bisexual populations were found. The potential of all-female populations for commercial production is discussed.     

Results of comparative growing test of all-female and bisexual population in two-year-old common carp (Cyprinus carpio L.)

The aim of this study was to verify whetherall-female carp populations grow faster thanbisexual ones. All-female mirror and scalypopulations were obtained by crossingmasculinizated females (neomales) of Northernmirror carp (M72) with regular females of M72and scaly Ropsa carp (ROP) purebreds,respectively. All-female and bisexual progenyof both mirror and scaly carps were rearedseparately for one year. However, controlgroups of a distinct phenotype of scalinesswere put in ponds with tested fish to make anadjustment for fish weight, which could becaused by environmental influence. Nodifferences were found after eight weeks ofrearing between all-female and bisexualpopulations, but, all-female mirror carppopulation (M72) gained 29.7% more weight(P < 0.0001) by the end of the first year thanthe bisexual (68.5 g ± 15.8 against 52.8 g± 13.9; mean ± S.D., respectively).Before beginning the second growing season,each group was marked and stocked together intriplicate ponds. Corrected weight after secondgrowing season (P < 0.0062) was 9.9% higher inall-female mirror carps (395.9 g ± 98.6)compared to the bisexual (360.2 g ± 89.0).No significant differences were found incorrected weights between scaly all-female andbisexual crossbreds (522.4 g ± 102.4 and518.3 g ± 95.8, respectively). Nodifferences in survival of all-female andbisexual populations were observed.     

Determination of Lipid Peroxidation and Fatty Acid Compositions in the Caviars of Rainbow Trout and Carp

In this study, roes obtained from carp (Cyprinus carpio carpio) that were caught in Keban Dam Lake (Turkey) and cultured rainbow trout (Oncorhynchus mykiss) were processed as caviar, and the products were stored at + 4 C°. Lipid peroxidation and the compositions of fatty acids of these products were assessed during production and storage period. The result of fatty analyses showed that palmitic acid (16:0), stearic acid (18:0), palmitoleic acid (16:1), oleic acid (18:1), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), which are all essential fatty acids, were determined in the caviars of the roes obtained from rainbow trout and carp. According to results of chemical analyses, there were no significant differences in thiobarbituric acid reactive substances (TBARs) between rainbow trout and carp caviars (p > 0.05), but malondialdehyde (MDA) levels were found to be statistically significant (p < 0.01). It can be concluded that caviars obtained from both rainbow trout and carp roes are rich in fatty acids and take a part in a balanced and healthy diet.     

Testing of performance in common carp Cyprinus carpio L. under pond husbandry conditions I: top-crossing with Northern mirror carp

Performance tests of Northern mirror carp (M72) and three different crossbreds were conducted in semi‐intensive pond conditions from the larval stage up to market size. The aim of this study was to evaluate the possible utilization of new hybrid combinations (M72 × PL – Poho?elice mirror carp) and (M72 × Dor – Israeli mirror carp), and to compare them with a hybrid widely reared as a commercial product (M72 × M2 – Hungarian mirror carp) and with M72 purebred. The testing model was derived from similar studies carried out in the conditions of the Czech Republic, where an internal control of different scale cover is used to eliminate all non‐genetic effects. ancova revealed at market size significantly better growth in M72 × Dor (1 619±28.3 g; LS mean±SE) and M72 × PL (1475±29.8 g) compared with M72 (1278±26.3 g). Survival during the test of 3 years duration was significantly the best in the M72 × Dor hybrid as were the dressing out parameters measured at market size, even if these were significantly different only in proportion of fillets with skin (39.1±0.28%). Interestingly, the crossbred M72 × M2 commonly used by Czech fishermen showed for both, growth (1371±26.2 g) and survival, the lowest values among crossbreds and with regard to dressing out parameters mostly among all tested groups.     

Cryopreservation of scaly carp (Cyprinus carpio) sperm: effect of different cryoprotectant concentrations on post-thaw motility, fertilization and hatching success of embryos

The aim of the present study was to determine the effect of various cryoprotectants on post-thaw sperm quality and fertilizing capacity of cryopreserved scaly carp (Cyprinus carpio) semen. The present study focused on freezing of scaly carp sperm utilizing a practical and inexpensive protocol for aquaculture. Semen was diluted with Kurokura’s extender composing 3.6 g/l NaCl, 10 g/l KCl, 0.22 g/l CaCl₂, 0.08 g/l MgCl₂ and 0.2 g/l NaHCO₃. The extender contained three different cryoprotectants (DMSO, DMA and egg yolk) at ratios of 5, 10 and 15 %. Semen was placed into 0.25-ml straws and exposed to liquid nitrogen vapor (?120 °C) using an insulated box with an adjustable tray for 10 min and then plunged into liquid nitrogen (?196 °C) tank. The thawing process was performed in a water bath at 40 °C for 10 s. The results indicated that type of cryoprotectants and their concentrations are rather effective in scaly carp sperm cryopreservation on post-thaw sperm quality, while they are very important in order to obtain high fertilization rates. The highest fertilization rate was determined as 96.4 ± 0.15 % with 15 % egg yolk, while the highest hatching rate was determined as 99.3 ± 0.80 with 15 % DMA. In conclusion, the applied cryopreservation method for scaly carp sperm is suitable to fertilize high amounts of eggs.     

A comparison of growth, survival rate and number of marketable koi carp produced under different management regimes in earthen ponds and concrete tanks

To compare the growth performance of koi carp, Cyprinus carpio var. koi, produced in concrete tanks (2.13 × 0.91 × 1.22 m; capacity: 2,000 l each) and earthen ponds (9.1 × 6.10 × 1.07 m; capacity: 59650 l each), fish larvae (stocking size: 0.12 ± 0.008 g) were cultured for 11 weeks and individual weight gain, survival rate and number of marketable fish produced were compared among four management regimes for each culture system: (1) live zooplankton fed to fish larvae in ponds (PLF) and tanks (TLF); (2) application of poultry manure in ponds (PPM) and tanks (TPM); (3) application of cow manure in ponds (PCD) and tanks (TCD); and (4) a control treatment for ponds (PC) and tanks (TC), where a commercial feed was applied. There were three replicates for each treatment. Weight gain of koi carp was highest in the PLF treatment, followed in decreasing order by TLF, PPM, PCD, TPM, TCD, PC and TC treatments (P < 0.05). There was a significant difference in the survival of koi carp among the treatments, ranging from 67.83% in TC to 95.50% in PLF. The number of marketable fish produced was highest in the PLF treatment, followed in decreasing order by TLF, PPM and PCD treatments. However, none of the fish produced in the TPM, TCD, PC and TC treatments attained marketable size. Significantly higher (P < 0.05) values of pH and dissolved oxygen (for water samples collected weekly at 9 A.M.) were obtained in the live food and control treatments (for both tanks and ponds), compared to the manured treatments. The concentration of total alkalinity, BOD, PO₄-P, NO₃-N and specific conductivity were significantly higher (P < 0.05) in PPM and PCD, compared to other treatments. NO₂-N and NH₄-N values were significantly higher (P < 0.05) in TPM and TCD, than other treatments. The results suggest that introduction of live zooplankton into culture units result in higher growth of koi carp larvae compared to manure based systems. Earthen ponds appeared to be better alternative to concrete tanks for manure application through maintenance of better water quality due to their higher assimilatory capacity and greater abundance of plankton which resulted in better growth of cultured fish.     

Susceptibility of koi × crucian carp and koi × goldfish hybrids to koi herpesvirus (KHV) and the development of KHV disease (KHVD)

Hybrids of koi, Cyprinus carpio × crucian carp, Carassius carassius and koi × goldfish, Carassius auratus, proved to be susceptible to koi herpesvirus (KHV, syn. CyHV‐3) and developed KHV disease (KHVD). While hybrids of koi × goldfish were partly resistant to mortality following infection by immersion, most koi × crucian carp hybrids died after bath infection. KHV DNA was detected in dead fish but also in all surviving animals by different polymerase chain reactions (PCRs). According to these results, hybrid crossbreeding does not seem to prevent severe losses associated with KHV in terms of inducing KHVD. The present study showed severe losses after a waterborne KHV infection of between 35% and 100% in koi × goldfish and koi × crucian carp hybrids as well as in SPF carp.     

Studies on fish heterosis with DNA fingerprinting

One Tilapia hybridization, Oreochromis aureus, (Steindachner) ♂ × Oreochromis niloticus, (Linnaeus) ♀, and two common carp, Cyprinus carpio, (Linnaeus) ♂, hybridizations, Russian mirror carp ♂ × Xingguo red carp ♀, and German mirror carp ♂ × Xingguo red carp ♀ were used to study the feasibility of predicting heterosis using genetic distance from DNA fingerprinting. The results indicated that highly polymorphic DNA fingerprints could be obtained with human minisatellite 33.6 as a probe on the studied varieties. The within‐population similarity indices of O. aureus, O. niloticus, Russian mirror carp, German mirror carp and Xingguo red carp were 0.785, 0.577, 0.432, 0.348 and 0.339 respectively. The similarity indices between F1 and their parents of three hybridization combinations were not significantly different (P > 0.05). There were larger genetic distances between two hybridization combinations, O. aureus♂ × O. niloticus♀ and Russian mirror carp ♂ × Xingguo red carp ♀, which showed heterosis in production and were extensively used in Chinese aquaculture. The genetic distance between O. aureus♂ and O. niloticus♀ was 0.338, and that between Russian mirror carp and Xingguo red carp was 0.344. However, the genetic distance between German mirror carp and Xingguo red carp was 0.129; this corresponded with the fact that their F1 generation did not show heterosis in the Chinese fish hybridization experiment. The study suggested that genetic distance could be used to predict fish heterosis.     

Effects of glutamate in low‐phosphorus diets on growth performance,antioxidant enzyme activity,immune‐related gene expression and resistance to Aeromonas hydrophila of juvenile mirror carp (Cyprinus carpio)

This study investigated the effects of glutamate (Glu) in low‐phosphorus diets on growth performance, haematological indices, antioxidant enzyme activity, immune‐related gene expression and resistance to Aeromonas hydrophila in juvenile mirror carp (Cyprinus carpio) (5.07 ± 0.02 g). Fish were fed either graded levels of Glu (0 g/kg, 5 g/kg,  10 g/kg and 20 g/kg, named G0, G0.5, G1 and G2, respectively) in a low‐phosphorus diet (15 g/kg NaH₂PO_4, 0.49), or a normal phosphorus diet ( 20 g/kg NaH₂PO_4, 0.61) without added Glu (C), for 8 weeks. At the end of the feeding trial, the fish were challenged with A. hydrophila. Compared with G0 group, 10 g/kg and 20 g/kg Glu supplementation of the low‐phosphorus diet significantly improved the final weight, WGR, SGR and PER, and decreased FCR (p < .05). Glu supplementation of the low‐phosphorus diet significantly enhanced the T‐AOC, SOD activity and GSH content in intestine (p < .05). Glu supplementation significantly reduced MDA content in foregut and midgut and increased CAT activity in midgut and hindgut (p < .05). Regarding immune‐related gene expression, Glu supplementation significantly diminished the up‐regulation of intestinal TNF‐α, IL‐1β and IL‐8 mRNA levels induced by phosphorus deficiency (p < .05). The survival rate of the G1 group was significantly higher than that of the G0 group (p < .05). In conclusion, 10 g/kg Glu supplementation in low‐phosphorus diets can improve the growth performance, enhance the activity of intestinal antioxidant enzymes and strengthen the immune function of juvenile mirror carp.     

Effects of graded levels of dietary vitamin C on the growth,digestive capacity and intestinal microflora of juvenile Jian carp (Cyprinus carpio var. Jian)

A 60‐day experiment was carried out to study the effects of vitamin C [ascorbic acid (AA)] on the growth, digestive enzyme activities and intestinal microbial population. Diets with six levels (0.0, 21.4, 45.1, 69.5, 93.6 and 142.1 mg AA kg^?1 diet) of supplemental ascorbyl polyphosphate were fed to juvenile Jian carp (Cyprinus carpio var. Jian) (12.63±0.02 g). The specific growth rate (SGR), feed efficiency and productive protein value were significantly improved with increasing AA levels up to 45.1 mg AA kg^?1 diet (P<0.05). The hepatopancreas and muscle AA concentrations were increased with increasing dietary AA levels up to 69.5 and 45.1 mg kg^?1 diet respectively (P<0.05). The activities of intestinal trypsin, chymotrypsin, lipase, α‐amylase, Na⁺, K⁺‐ATPase, alkaline phosphatase, gamma‐glutamyl transpeptidase and creatinkinase were all positively affected by the AA supplementation (P<0.05). Intestinal Lactobacillus and Bacillus were increased with increasing AA levels up to 45.1 mg AA kg^?1 diet (P<0.05), while intestinal Escherichia coli decreased with increasing AA levels up to 45.1 mg AA kg^?1 diet (P<0.05). In conclusion, AA improve the digestive capacity and intestinal microbial population of Jian carp, and the dietary AA requirement for SGR of juvenile Jian carp was 40.9 mg AA kg^?1 diet.     

Growth testing of two breeds of common carp, Cyprinus carpio L. (Hungarian mirror and Třeboň scaly carp), in ponds with low and high stocking density

The growth of two breeds of common carp, Cyprinus carpio L., was tested in ponds under the climatic conditions of South Bohemia. T?eboň scaly carp (TR) and Hungarian mirror carp (M2) were kept in both low and high stocking densities during the second growing season and then stocked together for communal testing during the third growing season. Before the communal testing, the mean initial weights of fish from low‐ and high‐density stocks differed significantly (374.1 vs. 227.7 g for the TR breed and 766.7 vs. 317.3 g for the M2 breed respectively, P<0.01). After communal testing, mean weights of fish from low‐ and high‐density stocks gained 761.8 vs. 543.8 g for the TR breed and 1339.7 vs. 706.7 g for the M2 breed respectively. These observed weights were also significantly different (P<0.01). However, the test of corrected weight gain, i.e. gain not related to the initial weight of fish, revealed insignificant differences (P>0.01) between the weight gains after correction, i.e. the effect of different initial weights was successfully eliminated. These results seem to confirm the applicability of this method for the assessment of growth of purebred common carp under the climatic conditions of Central European fish farms.     

Aerobic Bacterial Flora of Common Carp (Cyprinus carpio L.) Cultured in Earthen Ponds in Saudi Arabia

ABSTRACT

Quantitative and qualitative estimation of bacterial flora present in pond water, sediments, gills, and intestine of healthy common carp Cyprinus carpio cultured in Saudi Arabia were performed and identified to species level where possible. Mean total viable bacterial counts in pond water ranged from 1.2?±?2.9?×?10⁴ to 2.5?±?3.5?×?10⁵ cfu/mL; in sediments, 9.3?±?2.1?×?10⁷ to 2.7?±?3.5?×?10⁹ cfu/g; in gills filaments, 4.3?±?2.9?×?10⁶ to 1.6?±?3.9?×?10⁷ cfu/g; and in intestine, 8.7?±?4.1?×?10⁹ to 5.4?±?3.2?×?10¹⁰ cfu/g. Gram-negative rod-shaped bacteria dominated (76%) the populations. In total, 12 bacterial genera and 15 species were identified. Pond water and sediment bacteria had the reflection on bacterial composition of gills and intestine of carp. Intestinal bacteria showed more diversification in contrast to gill bacteria. Aeromonas hydrophila, Shewanella putrefaciens, Vibrio cholerae, Corynebacterium urealyticum, Vibrio vulnificus, Vibrio sp., and Staphylococcus sp. were the common bacteria in all the populations. In pond water and carp intestine, A. hydrophila, S. putrefaciens, V. cholerae, and C. urealyticum were the most dominant bacteria (prevalence ≥ 10%) where pond sediments and the carp gills experienced with more one dominant bacterium V. vulnificus. Only the A. hydrophila covered one fourth (25%) of the total bacterial populations.     

Optimization of stocking density of freshwater prawn Macrobrachium rosenbergii (de Man) in carp polyculture in Bangladesh

A study was conducted to optimize stocking density of freshwater prawn, Macrobrachium rosenbergii, in carp polyculture for 3 months in 10 experimental ponds of 80 m². Five stocking densities of prawn, 2500, 5000, 7500, 10 000 and 12 500 ha^?1, were assigned to treatments T₁, T₂, T₃, T₄ and T₅ respectively. The densities of catla, Catla catla, rohu, Labeo rohita and silver carp, Hypophthalmicthys molitrix, were 2500, 5000, and 2500 ha^?1, respectively, in each treatment. Each treatment had two replicate ponds. The mean initial weights of prawn, catla, rohu and silver carp were 1.1±0.02, 8.28±0.1, 25.2±1.1 and 36.32±1.2 g respectively. A pelleted diet containing 30% protein was prepared using fish meal, meat and bone meal, mustard oilcake, rice bran, wheat bran and molasses, and was fed twice daily at a rate of 5% of fish biomass. Water quality parameters were measured fortnightly and the ranges of temperature, pH and dissolved oxygen were 27.5–1.3°C, 6.9–8.6 and 4.5–8.6 mg L^?1 respectively. Feed conversion ratios ranged from 2.05 to 2.20 among the treatments. Per cent survival (%) of prawns ranged from 72% to 78%, while it varied from 80% to 93%, 90% to 95% and 90% to 92% for catla, rohu and silver carp respectively. The results showed that there were no significant differences among the weight gains of prawn and carp in different treatments. However, the overall total production of prawn and fish together was significantly (P<0.05) higher in T₃ and T₄ compared with other treatments. The total production for 3 months ranged between 2618 and 2916 kg ha^?1. The production of prawn was significantly higher (361.3 kg ha^?1) in T₅ with a highest stocking density of 12 500 prawn ha^?1. Although there was no significant difference (P>0.05) between the total production of prawn and fish together in T₃ and T₄, the highest net profit (Tk. 69 006 ha^?1) was obtained in T₄. Therefore, from the result of the study it may be concluded that a stocking ratio of 4:1:2:1 of prawn:catla:rohu:silver carp at a total density of 20 000 ha^?1 may be recommended for prawn–carp polyculture in ponds.     

Potential implications of acoustic stimuli as a non‐physical barrier to silver carp and bighead carp

The effectiveness of an acoustic barrier to deter the movement of silver carp, Hypophthalmichthys molitrix (Valenciennes) and bighead carp, H. nobilis (Richardson) was evaluated. A pond (10 m × 5 m × 1.2 m) was divided in half by a concrete‐block barrier with a channel (1 m across) allowing fish access to each side. Underwater speakers were placed on each side of the barrier opening, and an outboard motor noise (broadband sound; 0.06–10 kHz) was broadcast to repel carp that approached within 1 m of the channel. Broadband sound was effective at reducing the number of successful crossings in schools of silver carp, bighead carp and a combined school. Repulsion rates were 82.5% (silver carp), 93.7% (bighead carp) and 90.5% (combined). This study demonstrates that broadband sound is effective in deterring carp and could be used as a deterrent in an integrated pest management system.     

三种鲤对暴发性鱼病抗病力的差异

本文报道三种鲤对嗜水气单胞菌引起暴发性鱼病的抗病力试验结果。当菌液浓度为６．０×１０￣８ＣＦＵ／ｍｌ，采用１０￣０、１０￣（－１）、１０￣（－２）、１０￣（－３）四个稀释度、０．３ｍｌ／尾注射剂量时，建鲤、野鲤和镜鲤的半数致死量（ＬＤ＿（５０））分别为１０￣（－１．３７５）、１０￣（－０．９７６）、１０￣（－０．５６２）。这三种鲤的半数致死量差异显著（Ｆ＞Ｆ＿（０．０５））。从四个方面研究了抗病机理：白细胞吞噬功能和补体替代途径（Ｃ＿３旁路）杀菌能力，镜鲤较强于野鲤和建鲤，但无显著差异（Ｆ＜Ｆ０．０５）；红细胞Ｃ＿（３ｂ）受体花环率和补体总量（单位／ｍｌ），是建鲤＞野鲤＞镜鲤，差异极显著（Ｆ＞Ｆ０．０１）。本研究结果还表明建鲤的红细胞Ｃ＿（３ｂ）受体花环率和补体总量稍高，但对暴发性鱼病病原（嗜水气单胞菌）较易感染。以上结果证明，不同品系鲤鱼对暴发性鱼病有种内特异性。     

Purification and characterization of α<Subscript>1</Subscript>-proteinase inhibitor and antithrombin III: major serpins of rainbow trout (<Emphasis Type="Italic">Oncorhynchuss mykiss</Emphasis>) and carp (<Emphasis Type="Italic">Cyprinus carpio</Emphasis>) blood plasma

The main serine proteinase inhibitors of rainbow trout (Oncorhynchuss mykiss) and common carp (Cyprinus carpio) blood plasma were isolated and purified. The investigated inhibitors, α₁-proteinase inhibitor (α₁-PI) and antithrombin III (AT III), act by forming stable complexes with target proteinases. The association rate constants k _on for the interaction of fish plasma inhibitors with several serine proteinases have been determined: k _on for both carp and rainbow trout α₁-PI were >10⁷ M⁻¹ s⁻¹ for human neutrophil elastase, and in the case of bovine trypsin and chymotrypsin k _on values were 2.0–5.2 × 10⁶ M⁻¹ s⁻¹. Association rate constants k _on for the interaction of carp and rainbow trout AT III with bovine trypsin and thrombin were about 1.3 × 10⁴–7.9 × 10⁵ M⁻¹ s⁻¹ without and >10⁷ M⁻¹ s⁻¹ in presence of heparin; so antithrombins require the presence of heparin to become effective proteinase inhibitors. The high degree of homology of the estimated amino acid sequences of fish inhibitors reactive site loops confirms their similarity with other proteinase inhibitors from the serpin family.     

Effect of different types of descaling methods on shelf life of air-/vacuum-packaged common carp (<Emphasis Type="Italic">Cyprinus carpio</Emphasis> L.) fillets under refrigerated storage conditions

Microbiological quality, sensory attributes and consumer preferences of common carp (Cyprinus carpio L.) fillets descaled by four different methods under two storage conditions (air packed and vacuum packaged) and refrigerated storage conditions were studied. Farmed common carps (scaly and mirror), of marketable size (2.2 kg, 3 years old), were randomly divided into four experimental groups (n = 10), and filleted and fillets were processed by four descaling methods: without skin, without scales, undercut scales and mirror carp (without any other treatment). Microbiological analyses were determined by total viable counts (TVCs) in logarithm of colony-forming units per gram (log CFU/g), and sensory quality of fillets was classified by odour, flavour, after taste and consistency on storage days 0, 3, 6 and 9. Vacuum packaging conditions affected the growth of microbiota and extended the shelf life of fillets in all experimental groups. Microbial communities grew to between 3.19–3.90, 4.03–6.00 and 6.35–8.28 log CFU/g after 3, 6 and 9 days of storage, respectively, and fillets without skin showed the lowest TVC among all analysed groups throughout storage. Also sensory analyses showed that consistency and odour of carp fillets were influenced by packaging conditions as well as descaling methods. The survey on consumer preferences of carp found out that 58.9 % of customers preferred scaly carp with undercut scales and processed to fillets instead of mirror carp. The results of present study show that different types of descaling methods combined with air/vacuum packaging can significantly prolong the shelf life of carp fillets.     

Differences in the antibody response and survival of genetically different varieties of common carp (Cyprinus carpio L.) vaccinated with a commercial Aeromonas salmonicida/A. hydrophila vaccine and challenged with A. hydrophila

Males of two strains of carp, wild Duna (D), and inbred Szarvas 22 (22), were selected for high and low stress response. Two purebreds of D and 22, from randomly chosen parents and four crosses, 22 × 22-L (low stress response), 22 × 22-H (high stress response), 22 × D-L (low stress response) and 22 × D-H (high stress response) from selected stress response parents were produced and vaccinated with a commercial Aeromonas salmonicida/Aeromonas hydrophila vaccine and their circulating antibody response evaluated 1, 3, 5, and 7 weeks post-vaccination by ELISA. Significantly higher titres of circulatory antibodies against A. hydrophila were found in the families 22 and cross 22 × 22-L compared to other groups. The development of circulatory antibodies against A. hydrophila in all crosses having at least one D parent was low and remained low throughout the experiment. The level of circulatory antibodies against atypical A. salmonicida in the inbred strain increased following a booster vaccination with the highest values measured in inbred strain 22 and cross 22 × 22 L. The different varieties of carp had different levels of survival against experimental challenge with A. hydrophila. The greatest survival was obtained in strain 22 and cross 22 × 22-L, while ~90% of D wild carp and cross 22 × D (independent of their stress response) died. Survival results correlated well with the antibody response of the different groups: 22 and 22 × 22-L had the highest antibody titres against A. hydrophila and the greatest level of survival.     

草鱼出血病细胞培养灭活疫苗的研究——疫苗株的免疫原性及其有效免疫剂量的比较

本文比较了疫苗株FR—854和FR—836—w的免疫原性,及其对三寸左右草鱼种的有效免疫剂量。疫苗株FR—854和FR—836—w均有较强的免疫原性,其保护力可达70%以上。但试验结果初步证明,FR—854疫苗比FR—836—w疫苗免疫原性更强。经统计分析,FR—854疫苗的免疫保护力可达88.9±12.0（6）%,血清中和抗体效价为160.5±58.9（6）;而FR-838-W疫苗分别只有71.3±14.2（6）%、88.3±26.2（6）;二者有显著的差异（0.05>P>0.01）。注射免疫三寸左右的草鱼种,FR—854的免疫剂量在3—5×10^4.5TCID0/尾左右,FR—836—w在3—5×107.5TCID₅₀/尾左右,其免疫保护力可达80%左右,同时我们测得ER—854的半数免疫量为10^5.1TCID₅₀/ml。