Inovace chovu larev candáta obecného (Sander lucioperca L.) při použití vířníků druhu Branchionus plicatilis

Pikeperch (Sander lucioperca L.) has been realized as one of the promising candidates. Currently one of the crucial bottlenecks in pikeperch larviculture is larval first feeding when high mortalities occur. Since recognition of rotifers as potential candidate for larvae culture, its value has grown tremendously in fish hatcheries. Although using rotifers and Artemia as a starter food items has become a common practice in hatcheries, yet rotifers has not been used for pikeperch larval culture. Many questions regarding introduction of rotifers during pikeperch larval first exogenous feeding are still not answered. The aim of this Ph.D. thesis was to maximize survival, growth and fitness of pikeperch larvae during first exogenous feeding by using rotifers Brachionus plicatilis. The effects of B. plicatilis on survival rate, growth performance and fitness of pikeperch larvae during first feeding were evaluated in the first study. Larvae were reared under three different diets (Artemia; Art /rot; rotifers) from 3 till 17 days post hatch (DPH). Using rotifers as first diet for pikeperch larvae was shown to benefit survival and growth rates. Larvae fed on rotifers only or combined diet (rot/Art) obtained higher survival and growth compared to Artemia diet. It was found that essential fatty acids of rotifers and their smaller size had a crucial effect on the larval survival and performance. The findings of the first study showed that the mixed diet (rot/Art) could be recommended as innovated first exogenous feeding in pikeperch larvae. The objective of the second study was to optimize the first exogenous feeding regime for pikeperch larvae using rotifers and Artemia. Larvae were fed with rotifers for 3 days and afterwards from 8 to 17 DPH they were adopted to 5 different regimes. It was found that feeding pikeperch with rotifers from 5 to 8 DPH and afterwards exclusively with Artemia or mixed of rotifers and Artemia till 17 DPH can ensure high survival and growth rates, and better development of digestive organs. Feeding larvae with rotifers from 5 to 8 DPH and afterwards replacing with Artemia till 17 DPH is recommended as an optimum feeding regime because larval survival and growth were satisfying, and it reduces the costs for production. The main aim of the third study was to determine the optimal salinity for rearing of pikeperch larvae using B. plicatilis. Rotifers were stocked under different salinities and motility was investigated over a 6-h period. The same salinities were used in second trial of this study to quantify the effect on pikeperch gut fullness over the course of 11 h. In the third trail, the survival and growth rate of larvae from 4 to 11 DPH at low and medium salinities were analyzed. Results of this study showed that rotifers stocked at all tested salinities, except for freshwater retained motility for over a 6-h period. Pikeperch larvae reared at 2? and 4 ? showed higher survival and growth rate during trial compared to freshwater. The results of this study showed that larvae in low salinity water had higher survival and growth rate during initial exogenous feeding with B. plicatilis. The aim of fourth study was to determine the optimal rotifers density for pikeperch larvae at the beginning of exogenous feeding. Larvae were divided into 4 groups at different rotifers densities from 5 to 9 DPH. The best growth performance was achieved at the highest rotifers density, however survival rate did not significantly differ among the groups. The results suggested that B. plicatilis at density of 6 ind/mL can be considered optimal for larval growth from 5 to 9 DPH when balancing production and costs, compared to higher prey densities

A contribution on the morphometrics of the thick-clawed crayfish Pontastacus pachypus (Rathke, 1837) (Decapoda, Astacoidea, Astacidae)

The thick–clawed crayfish Pontastacus pachypus (Rathke, 1837) is an endangered, and the least known, crayfish species in Europe. Currently, detailed information regarding the morphology, ecology and reproduction of thick–clawed crayfish is outdated. This study presents, for the first time, detailed photographs of the thick-clawed crayfish, and updated information on distinctive morphological characters and morphometric analysis. New specifications of the carapace and appendage morphological characteristics were established as: 1) the rostrum is long, sharply pointed and has three pairs of distinctive sub-apical lateral spines, 2) two well–developed pairs of post–orbital ridge on the carapace are ended by prominent spine; 3) each finger of chelae ends with a black sharp tip. Among the 18 morphometric indices, carapace width to the total length (CPW/TL), abdomen width to the total length (ABW/TL) and claw height to the claw width (CLH/CLW) clearly differentiate P. pachypus from the other representatives of Astacus genus (A. colchicus and A. astacus) and P. leptodactylus (P<0.05). Comparison of individual indices between P. pachypus and P. leptodactylus revealed that almost all indices differed significantly except head length to the total length (HEL/TL) and rostrum length to the total length (ROL/TL). This study contributes to the identification of the thick–clawed crayfish for the purpose of conservation and protection of its localities

Considering Two Aspects of Fish Welfare on African Catfish (<i>Clarias gariepinus</i>) Fillet throughout Postmortem Condition: Efficiency and Mechanisms

Knowledge about fish welfare and its impact on fish fillet quality is still insufficient. Therefore, the influence of two aspects of fish welfare (slaughtering method: bled and unbled fish; fish stock densities: 90, 120, and 150 kg·m−3) on African catfish fillet quality during postmortem conditions was investigated. The aim of study was to determine (i) the efficiency of bleeding on oxidation progress and (ii) the influence of stock density on fillet quality. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS–PAGE) showed a higher protein loss in the unbled than in the bled groups, especially in the heavy myosin chain (MHC) band. However, density did not show any influence on protein profile. Western blot analysis showed fewer oxidized carbonyls in the bled than in the unbled groups; higher oxidation development, microbial growth, and lower hardness were observed in unbled fillets. Additionally, hardness was higher at 90 and 120 kg·m−3 densities in bled fillet compared to 150 kg·m−3. The first three days of storage showed a higher oxidation rate in unbled fillets than in bled fillets, confirming the contribution of hemoglobin to oxidation development with different mechanisms of protein oxidation. The obtained results revealed the same fillet quality in all aspects at either 90 or 120 (kg·m−3) stock densities, which would suggest 120 kg·m−3 for the fishery industry. However, higher stocking density in this study would not be appropriate for fish welfare

Effects of first feeding regime on growth performance, survival rate and development of digestive system in pikeperch (Sander lucioperca) larvae

This study evaluated the effects of first feeding regime on growth performance, survival rate, and development of digestive organs (intestine, liver and pancreas) in pikeperch (Sander lucioperca) larvae. The fish larvae at 5 days post-hatch (DPH), were initially fed with rotifers (Brachionus plicatilis) for 3 days and from 8 to 17 DPH were fed with rotifers/Artemia for different time periods as follows: (A) only rotifers; (B) 8-13 DPH rotifers/14-17 DPH Artemia; (C) 8-10 DPH rotifers/11-17 DPH Artemia; (D) only Artemia; (E) a combination of rotifers and Artemia. Growth performance, survival rate and histological features of intestine, liver and pancreas were assessed at 11, 14 and 17 DPH to examine the effects of feeding regime. The groups fed rotifers for initial 3 days followed by feeding on Artemia (group D) (53 +/- 5.43%) and combination of rotifers and Artemia (group E) (68 +/- 5.51%), respectively, for the following 9 days showed significantly (P lt .05) higher survival rates than the other groups (36-50%). The group fed merely on rotifers (groups A) exhibited significantly lower specific growth rate (SGR) than the other groups, and the highest SGR was found in the group fed with combination of rotifers and Artemia after 3 day rotifer feeding. Moreover, the highest total length (8.57 +/- 0.57 mm), myotome height (0.75 +/- 0.09 mm) and eye diameter (0.58 +/- 0.05 mm) were obtained by combined feeding of rotifers and Artemia after 3 day of initial rotifer feeding. Significant differences among groups were found in morphometric parameters in the anterior intestine and liver. The results of histological examination of the liver, intestine and pancreas did not show any obvious pathological changes in all groups. In conclusion, feeding with rotifers from 5 to 8 DPH and afterwards with Artemia could be suggested as an economical feeding regime for first feeding of pikeperch larvae as comparable survival and growth to co-feeding with rotifers and Artemia were achieved

Effects of First Feeding Regime on Gene Expression and Enzyme Activity in Pikeperch (Sander lucioperca) Larvae

The present study investigates the effects of different feeding regimes with rotifers (Brachionus plicatilis) and Artemia salina on the gene expression and digestive enzymes in pikeperch (Sander lucioperca) larvae at 17 days post-hatch (DPH) over a period of 13 days. Five experimental feeding protocols were performed in four replicates. At 4 DPH, the larvae (total length= 5.62 ± 0.03 mm, body weight = 0.66 ± 0.16 mg) were divided into five experimental groups (2-L tanks) at initial density of 100 larvae per liter. Light intensity on the water surface was 90-100 lux and photoperiod was set at 13L: 11D (07:00 to 20:00 h). Water temperature, pH, and dissolved oxygen (DO) were measured before each feeding and the values were 17.8 ± 0.17°C, 7.3 ± 0.04 and 88.5 ± 2.53%. The fish larvae at 5 days post-hatch (DPH), were initially fed with rotifers (Brachionus plicatilis) for 3 days and from 8 to 17 DPH were fed with rotifers/Artemia for different time periods as follows: (A) only rotifers; (B) 8–13 DPH rotifers/14–17 DPH Artemia; (C) 8–10 DPH rotifers/11–17 DPH Artemia; (D) only Artemia; (E) a combination of rotifers and Artemia. Frozen paste of algae was added to the larval tanks twice a day (2 x 300,000 cells/mL). Rotifers and Artemia were provided as live feed to larvae three times a day with residual counts prior to each feeding. Feeding densities were steadily increased based on residual counts, performed prior to each feeding. The expression of genes related to intestinal development and maturation (aminopeptidase N, anpep; leucine aminopeptidase 3, lap3; intestinal-type alkaline phosphatase, alpi), together with key pancreatic digestive proenzymes (trypsinogen 1, try1; chymotrypsinogen b, ctrb; carboxyl ester lipase precursor, cel; phospholipase a2, pla2g1b; pancreatic alpha amylase, amy2a), were assessed. Additionally, the activity of six enzymes (trypsin, lipase, alkaline phosphatase, amino peptidase, amylase, and chymotrypsin) were determined. The highest expression of two genes related to intestine (lap3; anpep) were observed in the fish fed a combination of rotifers and Artemia from 8 DPH (Group E). The expression of amy2a, ctrb, pla2g1b, try1 was significantly lower in larvae fed rotifers until 14 DPH and replaced by Artemia afterwards (Group B). The specific activity of brush border membrane enzymes (alkaline phosphatase and aminopeptidase N) increased with combination of rotifers and Artemia in larval diet (Group E), indicating a more efficient functionality of digestive structures. The groups fed only with rotifers till 17 DPH (Group A) (38 ± 4.07%) and larvae fed with rotifers till 14 DPH followed by feeding with Artemia till 17 DPH (Group B) (36 ± 5.25%) showed significantly (P<0.05) lower survival rates than the other groups (54-67%). The group fed only with rotifers (Group A) showed significantly lower specific growth rate (SGR) than the other groups, and the highest SGR was found in the group fed with combination of rotifers and Artemia after 3 day rotifer feeding (Group E). The highest standard length (8.32 ± 0.48 mm) was obtained by combined feeding of rotifers and Artemia after 3 day of initial rotifer feeding. Combination of rotifers and Artemia from 8 DPH (Group E) could be considered a more appropriate diet for first feeding pikeperch larvae compared with later introduction of Artemia, as indicated by the higher expression of genes and activities of digestive enzymes. Our findings provide new insight into the effect of temporal sequence of rotifers and Artemia on the expression of genes and activities of digestive enzymes in pikeperch larvae

DataSheet_1_Effects of First Feeding Regime on Gene Expression and Enzyme Activity in Pikeperch (Sander lucioperca) Larvae.docx

2 pages. -- Supplementary Table 1. Experiment husbandry schedule. Amount of daily feed offered, shading concentration (Nannochloropsis sp.) and recirculation flow changes with time are shown (Imentai, et al., 2020). -- Supplementary Table 2. Oligonucleotides used for QPCR.The present study investigates the effects of different feeding regimes with rotifers (Brachionus plicatilis) and Artemia salina on the gene expression and digestive enzymes in pikeperch (Sander lucioperca) larvae at 17 days post-hatch (DPH) over a period of 13 days. Five experimental feeding protocols were performed in four replicates. At 4 DPH, the larvae (total length= 5.62 ± 0.03 mm, body weight = 0.66 ± 0.16 mg) were divided into five experimental groups (2-L tanks) at initial density of 100 larvae per liter. Light intensity on the water surface was 90-100 lux and photoperiod was set at 13L: 11D (07:00 to 20:00 h). Water temperature, pH, and dissolved oxygen (DO) were measured before each feeding and the values were 17.8 ± 0.17°C, 7.3 ± 0.04 and 88.5 ± 2.53%. The fish larvae at 5 days post-hatch (DPH), were initially fed with rotifers (Brachionus plicatilis) for 3 days and from 8 to 17 DPH were fed with rotifers/Artemia for different time periods as follows: (A) only rotifers; (B) 8–13 DPH rotifers/14–17 DPH Artemia; (C) 8–10 DPH rotifers/11–17 DPH Artemia; (D) only Artemia; (E) a combination of rotifers and Artemia. Frozen paste of algae was added to the larval tanks twice a day (2 x 300,000 cells/mL). Rotifers and Artemia were provided as live feed to larvae three times a day with residual counts prior to each feeding. Feeding densities were steadily increased based on residual counts, performed prior to each feeding. The expression of genes related to intestinal development and maturation (aminopeptidase N, anpep; leucine aminopeptidase 3, lap3; intestinal-type alkaline phosphatase, alpi), together with key pancreatic digestive proenzymes (trypsinogen 1, try1; chymotrypsinogen b, ctrb; carboxyl ester lipase precursor, cel; phospholipase a2, pla2g1b; pancreatic alpha amylase, amy2a), were assessed. Additionally, the activity of six enzymes (trypsin, lipase, alkaline phosphatase, amino peptidase, amylase, and chymotrypsin) were determined. The highest expression of two genes related to intestine (lap3; anpep) were observed in the fish fed a combination of rotifers and Artemia from 8 DPH (Group E). The expression of amy2a, ctrb, pla2g1b, try1 was significantly lower in larvae fed rotifers until 14 DPH and replaced by Artemia afterwards (Group B). The specific activity of brush border membrane enzymes (alkaline phosphatase and aminopeptidase N) increased with combination of rotifers and Artemia in larval diet (Group E), indicating a more efficient functionality of digestive structures. The groups fed only with rotifers till 17 DPH (Group A) (38 ± 4.07%) and larvae fed with rotifers till 14 DPH followed by feeding with Artemia till 17 DPH (Group B) (36 ± 5.25%) showed significantly (P<0.05) lower survival rates than the other groups (54-67%). The group fed only with rotifers (Group A) showed significantly lower specific growth rate (SGR) than the other groups, and the highest SGR was found in the group fed with combination of rotifers and Artemia after 3 day rotifer feeding (Group E). The highest standard length (8.32 ± 0.48 mm) was obtained by combined feeding of rotifers and Artemia after 3 day of initial rotifer feeding. Combination of rotifers and Artemia from 8 DPH (Group E) could be considered a more appropriate diet for first feeding pikeperch larvae compared with later introduction of Artemia, as indicated by the higher expression of genes and activities of digestive enzymes. Our findings provide new insight into the effect of temporal sequence of rotifers and Artemia on the expression of genes and activities of digestive enzymes in pikeperch larvae.Peer reviewe

Effects of First Feeding Regime on Gene Expression and Enzyme Activity in Pikeperch (Sander lucioperca) Larvae

The present study investigates the effects of different feeding regimes with rotifers (Brachionus plicatilis) and Artemia salina on the gene expression and digestive enzymes in pikeperch (Sander lucioperca) larvae at 17 days post-hatch (DPH) over a period of 13 days. Five experimental feeding protocols were performed in four replicates. At 4 DPH, the larvae (total length= 5.62 ± 0.03 mm, body weight = 0.66 ± 0.16 mg) were divided into five experimental groups (2-L tanks) at initial density of 100 larvae per liter. Light intensity on the water surface was 90-100 lux and photoperiod was set at 13L: 11D (07:00 to 20:00 h). Water temperature, pH, and dissolved oxygen (DO) were measured before each feeding and the values were 17.8 ± 0.17°C, 7.3 ± 0.04 and 88.5 ± 2.53%. The fish larvae at 5 days post-hatch (DPH), were initially fed with rotifers (Brachionus plicatilis) for 3 days and from 8 to 17 DPH were fed with rotifers/Artemia for different time periods as follows: (A) only rotifers; (B) 8–13 DPH rotifers/14–17 DPH Artemia; (C) 8–10 DPH rotifers/11–17 DPH Artemia; (D) only Artemia; (E) a combination of rotifers and Artemia. Frozen paste of algae was added to the larval tanks twice a day (2 x 300,000 cells/mL). Rotifers and Artemia were provided as live feed to larvae three times a day with residual counts prior to each feeding. Feeding densities were steadily increased based on residual counts, performed prior to each feeding. The expression of genes related to intestinal development and maturation (aminopeptidase N, anpep; leucine aminopeptidase 3, lap3; intestinal-type alkaline phosphatase, alpi), together with key pancreatic digestive proenzymes (trypsinogen 1, try1; chymotrypsinogen b, ctrb; carboxyl ester lipase precursor, cel; phospholipase a2, pla2g1b; pancreatic alpha amylase, amy2a), were assessed. Additionally, the activity of six enzymes (trypsin, lipase, alkaline phosphatase, amino peptidase, amylase, and chymotrypsin) were determined. The highest expression of two genes related to intestine (lap3; anpep) were observed in the fish fed a combination of rotifers and Artemia from 8 DPH (Group E). The expression of amy2a, ctrb, pla2g1b, try1 was significantly lower in larvae fed rotifers until 14 DPH and replaced by Artemia afterwards (Group B). The specific activity of brush border membrane enzymes (alkaline phosphatase and aminopeptidase N) increased with combination of rotifers and Artemia in larval diet (Group E), indicating a more efficient functionality of digestive structures. The groups fed only with rotifers till 17 DPH (Group A) (38 ± 4.07%) and larvae fed with rotifers till 14 DPH followed by feeding with Artemia till 17 DPH (Group B) (36 ± 5.25%) showed significantly (P<0.05) lower survival rates than the other groups (54-67%). The group fed only with rotifers (Group A) showed significantly lower specific growth rate (SGR) than the other groups, and the highest SGR was found in the group fed with combination of rotifers and Artemia after 3 day rotifer feeding (Group E). The highest standard length (8.32 ± 0.48 mm) was obtained by combined feeding of rotifers and Artemia after 3 day of initial rotifer feeding. Combination of rotifers and Artemia from 8 DPH (Group E) could be considered a more appropriate diet for first feeding pikeperch larvae compared with later introduction of Artemia, as indicated by the higher expression of genes and activities of digestive enzymes. Our findings provide new insight into the effect of temporal sequence of rotifers and Artemia on the expression of genes and activities of digestive enzymes in pikeperch larvae.publishedVersio