Appraisal of a high protein distiller’s dried grain (DDG) in diets for European sea bass,Dicentrarchus labrax fingerlings on growth performance,haematological status and related gut histology

High protein distiller's dried grains (HP‐DDG) are co‐products of ethanol production that uses prefractionation technology. An 8‐week growth trial was conducted to investigate the effect of partial replacement of soybean meal (SBM) by three levels of HP‐DDG (30%, 40% and 50%) on growth performance, physiological parameters and histological changes of the intestine of European sea bass, Dicentrarchus labrax. The results indicated that an increased dietary level of HP‐DDG of more than 30% significantly increases growth performance and improved the FCR of sea bass. In addition, replacement of SBM by HP‐DDG enhanced feed intake efficiency and the health status of fish. Haematology and serum biochemistry (haemoglobin (Hb), red blood cells (RBCs), white blood cells (WBCs), packed cell volume (PCV %) and humeral immune parameters including total protein, albumin, globulin, cholesterol, lysozyme activity and total antioxidant capacity significantly increased with increase HP‐DDG inclusion levels. The findings of this study indicated that HP‐DDG is a good complementary protein source for inclusion aquaculture diets and levels above 30% as a replacement of SBM did not compromise growth performance and physiological parameters of sea bass while enhancing some important indices of health status in this species.     

A brown trout (Salmo trutta) population faces devastating consequences due to proliferative kidney disease and temperature increase: A case study from Austria

Proliferative kidney disease (PKD) is an emerging parasitic disease that affects wild and farmed salmonid fishes worldwide. Currently, it is widespread in Europe with records in many countries. This study assessed the status of PKD in the river Wulka, a small Austrian river, which was known to host a vital brown trout population despite having high water temperatures. Contrary to the initial hypothesis that the river was free from PKD, we observed an overall PKD prevalence of 92%. Noninfected fish were restricted to the uppermost river section. Twenty-two out of 87 PKD-positive fish of all age classes showed clinical signs, while five individuals exhibited signs of recovering from PKD infection. The severity of clinical signs was significantly dependent on the fish length and age, with smaller or younger individuals being more severely affected. Comparison of data from the earlier fish sampling events with those results from 2017 and 2018, together with the analyses of the pattern of water temperature since 2010, indicates that Wulka's brown trout population might become extinct in the near future.     

Effects of different carotenoid supplementation sources with or without sodium taurocholate on growth,feed utilization,carotenoid content and antioxidant status in fry of the European seabass,Dicentrarchus labrax

A total of 210 European seabass fry with an average body weight of 0.51 ± 0.03 g were divided into seven experimental treatments (three replicates per treatment). The seven experimental diets (45.64% CP) were formulated to contain synthetic astaxanthin (SA; 0.1 g kg^?1), marigold flower meal (MFM; 0.2 g kg^?1) or crab waste meal (CM; 10 g kg^?1), with or without sodium taurocholate (ST; 0.4 g kg^?1); the control diet contained no supplementation. The experiment was conducted for 8 weeks. The results show that seabass fry fed the diets containing different sources of carotenoids, especially with ST, demonstrated higher growth efficiency, survival (%), feed efficiency, protein and ether extract contents of fish body. The best results were found with Diet_MFM+ST. Whole‐body carotenoid levels increased significantly with all supplementation treatments; the highest level was observed with SA, followed by fish fed Diet_MFM and Diet_CM, especially with ST co‐supplementation. Moreover, thiobarbituric acid‐reactive substances were significantly reduced in fish fed the diets containing different sources of carotenoids compared to the control diet. The total antioxidant status significantly increased in fish fed Diet_SA and Diet_CM alone or with ST compared to the control group. In conclusion, these results reveal that Diet_MFM+ST is the most suitable treatment for improving growth, feed efficiency, and the protein and ether extract contents of seabass fry compared to other sources of carotenoids. The best oxidant/antioxidant balance and carotenoid content were achieved using SA, CM and MFM with ST supplementation.     

Effect of dietary mannan oligosaccharide (MOS) on growth performance, survival, body composition, and some hematological parameters in giant sturgeon juvenile (Huso huso Linnaeus, 1754)

The effect of dietary mannan oligosaccharide (MOS; activeMOS^®) on growth, survival, and body composition in giant sturgeon juvenile (Huso huso) with initially average weight 46.89 ± 2.57 was investigated for a period of 46 days. Basal diet were supplemented with 0 (control), 2, and 4 g kg^?1 MOS in a totally randomized design trial in triplicate groups. The results showed no significant differences in growth and feeding parameters between control and treatment groups (MOS supplementation diets) (P > 0.05). There was a statistically significant decrease (P < 0.05) in feed per fish level in only group treated with 4 g kg^?1 MOS. The highest and the lowest growth performances were observed in 2 and 4 g kg^?1 MOS, respectively. There were no significant differences in survival rate among all treatment groups (P > 0.05). In group treated with 2 g kg^?1 MOS was a significant difference in lipid carcass (P < 0.05), whereas protein, ash, and moisture remained unaffected (P > 0.05). However, no significant difference was observed in intestinal lactic acid bacteria between all treatment groups (P > 0.05). There were no significant differences in hematological parameters between control and MOS treatment groups (P > 0.05). These results suggested that the prebiotic mannan oligosaccharide did not influence the growth performance in giant sturgeon juvenile, and it is not appropriate for supplementation in the diet of cultured juvenile giant sturgeon.     

Bioethanol production from sweet sorghum bagasse by Mucor hiemalis

The present work deals with production of ethanol from sweet sorghum bagasse by a zygomycetes fungus Mucor hiemalis. The bagasse was treated with phosphoric acid and sodium hydroxide, with or without ultrasonication, prior to enzymatic hydrolysis by commercial cellulase and β-glucosidase enzymes. The phosphoric acid pretreatment was performed at 50 °C for 30 min, while the alkali treatment performed with 12% NaOH at 0 °C for 3 h. The pretreatments resulted in improving the subsequent enzymatic hydrolysis to 79-92% of the theoretical yield. The best hydrolysis performance was obtained after pretreatment by NaOH assisted with ultrasonication. The fungus showed promising results in fermentation of the hydrolyzates. In the best case, the hydrolyzate of NaOH-ultrasound pretreated bagasse followed by 24 h fermentation resulted in about 81% of the corresponding theoretical ethanol yield. Furthermore, the highest volumetric ethanol productivity was observed in the hydrolyzates of NaOH pretreated bagasse, especially after ultrasonication in pretreatment stage.     

Mosquitocidal activity of two Bacillus bacterial endotoxins combined with plant oils and conventional insecticides

The full whole culture (FWC), containing parasporal protein toxins of Bacillus thuringiensis israelinsis (Bti) and Bacillus sphaericus 2362 (Bs), either singly or in combination with plant oils and commercial insecticides, was tested against larval and adult stages of Culex pipiens mosquitoes under controlled laboratory conditions. In terms of LC₅₀ values recorded after 24, 48, 72 and 96 h, the bacterial toxins showed high potency towards both larvae and adults of mosquitoes in a dose-dependent manner. Generally, the Bti toxin seemed to be more potent than the Bs toxin. For example, the Bti toxin showed a 24 h LC₅₀ of 8.2 ppm against mosquito larvae compared to 13.6 ppm for the Bs toxin. In the adult bioassay, the obtained 24 h LC₅₀ values were 0.064 and 0.085 mg/cm², respectively for the two bacterial toxins. The bacterial toxins mixed with plant oils or insecticides at equitoxic doses (e.g., LC₂₅ values) mostly showed potentiation effects, either against larvae or adults of the tested insect. Among a total of 14 paired mixtures, only the joint action estimated for the mixture of malathion + Bti or Bs was accounted as additively. Combining Bti or Bs endotoxins at LC₀ with different plant oils and insecticides at LC₅₀ concentration levels each, has resulted in considerable synergism against either larvae or adults. In the case of larval bioassays, the maximum synergistic factor (SF) obtained (ca. 2.0) was entitled to the mixture of Bti + spinosad. In the adult bioassays, the mixtures containing Curcuma longa or Melia azedarach oil extracts with Bti or Bs toxins achieved a SF accounted to 2.0. The results of the present study may be considered as an additional contribution to the area of joint toxicity of biocidal agents combining bacterial toxins, plant oils and traditional insecticides. The reached findings may encourage future research to elucidate its performance under practical field conditions.     

Genetic variation and evolutionary forces shaping Cucumber vein yellowing virus populations: risk of emergence of virulent isolates in Europe

The genetic variation and evolutionary mechanisms shaping Cucumber vein yellowing virus (CVYV) populations were investigated by analysis of nucleotide sequences coding for P1b, P1b/P3 and coat proteins (CP) from isolates collected in different countries. The complete genome sequence of isolate ISM from Israel was also determined and compared to those of isolates Jor from Jordan and ALM32 from Spain. This isolate had overall nucleotide identities of 94·23 and 94·96% with ALM32 and Jor, respectively. Nucleotide variation among isolates was not homogeneously distributed, with the 5′ half of the genome being more variable than the 3′ half. A Bayesian phylogenetic tree of the CP showed that CVYV isolates clustered into two main clades: isolates from the Middle East region (Lebanon, Israel and Jordan) clustered in both clades whereas the isolate from Tunisia clustered in clade I and the European isolates clustered as a homogeneous phylogroup in Clade II. A similar topology was observed for P1b but with incongruences with respect to the CP, suggesting genetic exchange among virus isolates, which were confirmed with recombination algorithms. The low genetic diversity within the European phylogroup with respect to the other isolates, neutralist tests and genetic differentiation analyses suggest that the Middle East region is the cradle of CVYV and that a unique virus introduction event occurred in Europe, where the virus spread rapidly. Taken together, these findings indicate a risk of emergence of virulent CVYV isolates in Europe either through migration from the Middle East or by genetic changes of the European isolates.     

The effect of physiological and environmental conditions on smolt migration in Atlantic salmon Salmo salar

Hydropower development has negatively influenced Atlantic salmon (Salmo salar) populations. Compensatory hatchery‐rearing programmes exist, but released fish suffer from high mortality that may be related to the lack of experience from natural environments in hatchery‐reared smolts and their large body size and high energetic state. Here, we used acoustic telemetry to test how body size, energetic state, and the environmental conditions of the river affect migration in hatchery‐reared smolts. The study was conducted in three consecutive years between 2011 and 2013 in the lower part of the River Umeälven, Sweden. For individual fish, there was no effect of body size but the energetic state of the fish had a negative effect on sea entry. The most important factor affecting sea entry rate was the water discharge in the old river bed that differed among years. Smolts were more likely to enter the sea in years when the discharge was high or when the discharge increased substantially shortly after release. Hatchery‐reared fish had higher migration speed at a slower flowing section compared with a faster flowing section, which was likely a result of large hesitation to enter the rapid section. The increase in water discharge led to an increase in fish migration speed disproportional to the increase in water velocity. Our results highlight the importance of water discharge for the smolts during smolt migration, and we argue that concern should be given to migrating fish when managing regulated rivers.     

To what extent can maternal inherited immunity acquired from a crustacean‐enhanced diet improve the performance and vitality of the offspring and enhance profitability of European Sea bass (Dicentrarchus labrax)?

This study was conducted to investigate the effects of maternal inherited immunity acquired from crustacean‐enhanced diets on the vitality and profitability of sea bass offspring. Newly hatched larvae produced from three groups of broodstock were evaluated. The broodstock were fed (a) a basal diet (BD), (b) a Palaemon‐supplemented diet (PSD), and (c) an Artemia‐supplemented diet (ASD) for 42 days. A total of 400,000 larvae at 3 days posthatch (DPH) produced from each treatment were stocked in larval rearing tanks at 40 larvae/L for 42 days. Survival (%) was improved by 37 and 9.96% in the groups fed ASD and PSD compared with the control group. The growth, swim bladder (%), and condition factor all significantly (p ≤ 0.05) improved in the postlarvae produced from broodstock enhanced with crustacean diets. Compared with the BD group, the serum lysozyme activities of the fish groups fed ASD and PSD increased by 45.6 and 11.7%, respectively. Sea bass fry (90DPH) produced from broodstock fed ASD showed the best tolerance to salinity/temperature stress tests. Furthermore, the profitability improved in ASD and PSD compared with the BD group. In conclusion, sea bass broodstock enhanced with Artemia biomass produced offspring of superior quality with less cost and greater profit margins.     

Ultra-structural changes in the integument induced by the use of three of six forms of allylisothiocyanate tested against Plutella xylostella and Pieris rapae larvae

The insecticidal activity of four forms of Hong Jing (HJ) allylisothiocyanate (AITC), AITC + cypermethrin (HJ_A, HJ_B, and HJ_C) with ratio of (1:1, 4:1, and 2:1), pure AITC (HJ_D), and two forms of Hong Du (HD) AITC, AITC + chlorpyrifos (HD_A and HD_B) with ratio of (2:1 and 2:1), respectively, were studied on the major cruciferous insect larvae Plutella xylostella (L.) and Pieris rapae (L.) by combining both spraying and dipping methods. The P. rapae was more susceptible than P. xylostella larvae. The LC₅₀ values 72 h after treatment of AITC forms (HJ_B, HJ_A, HJ_C, HJ_D, HD_B, and HD_A) on the P. rapae were; 0.07, 0.08, 0.16, 0.83, 0.26, 1.08 gL⁻¹, and 0.69, 0.26, 5.45, 0.93, 3.01, 5.98 gL⁻¹ on the P. xylostella, respectively. The toxicity of some of the AITC forms was very close to or better than that of the commercial contact insecticides such as chlorpyrifos (LC₅₀ = 0.03 and 0.04 gL⁻¹ on P. rapae and P. xylostella, respectively), and cypermethrin (0.65 and 0.78 gL⁻¹, respectively, against P. rapae and P. xylostella). The ultrastructural studies on the integument of the third larval instar of P. xylostella treated by sub-lethal concentration (LC₂₀) of HJ_B, HJ_D, and HD_B were carried out by using transmission electron microscope. The more pronounced alterations in the hypodermis and mitochondria cells. They exhibited changes in all treated samples. The hypodermis was almost completely destroyed, and the mitochondria exhibited morphological alterations, represented by enlargement, matrix rarefaction and vacuolization of the mitochondria matrix, quantity of cristae reduced, and density electron matrix lessened. These AITC forms have potential as contact insecticides, and the ultra structural observations confirm the insecticidal efficiency of different AITC forms on P. rapae and P. xylostella.