Growing amago and rainbow trout in duoculture with self-feeding systems: Implications for production and welfare

Aquaculture ◽  
2010 ◽  
Vol 309 (1-4) ◽  
pp. 137-142 ◽  
Author(s):  
Matthew J. Flood ◽  
Chris Noble ◽  
Rem Kagaya ◽  
Børge Damsgård ◽  
G. John Purser ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Feeding Systems

The essential oils of some medicinal plants on the immune system of rainbow trout (Oncorhynchus mykiss)

Planta Medica ◽  
2012 ◽  
Vol 78 (11) ◽  
Author(s):  
A Ghasemi Pirbalouti ◽  
E Pirali ◽  
G Pishkar ◽  
S Mohammadali Jalali ◽  
M Reyesi ◽  
...  
Keyword(s):  
Immune System ◽  
Rainbow Trout ◽  
Medicinal Plants ◽  
Oncorhynchus Mykiss ◽  
Essential Oils ◽  
Rainbow Trout Oncorhynchus Mykiss

An experience of elaboration and implementation of systems of slag-forming mixtures mechanized feeding into CCM moulds

2020 ◽  
Vol 76 (10) ◽  
pp. 994-1003
Author(s):  
S. P. Eron’ko ◽  
M. Yu. Tkachev ◽  
E. V. Oshovskaya ◽  
B. I. Starodubtsev ◽  
S. V. Mechik
Keyword(s):  
Economic Effect ◽  
Three Dimensional ◽  
Movable Part ◽  
High Quality ◽  
Working Zone ◽  
Fine Material ◽  
Mixing Chamber ◽  
Field Samples ◽  
Technical Solutions ◽  
Feeding Systems

Effective application of slag-forming mixtures (SFM), being fed into continuous castingg machine (CCM) moulds, depends on their even distribution on the melt surface. Manual feeding of the SFM which is widely usedd does not provide this condition, resulting in the necessity to actualize the work to elaborate systems of SFM mechanized feedingg into moulds of various types CCM. A concept of the designing of a system of SFM feeding into CCM moulds presented with the ratte strictly correspondent to the casting speed and providing formation of an even layer of fine material of given thickness on the whoole surface of liquid steel. The proposed methods of designing of the SFM mechanized feeding systems based on three-dimensional computer simulation with the subsequent verification of the correctness of the adopted technical solutions on field samples. Informattion is presented on the design features of the adjusted facilities intended for continuous supply of finely granulated and powder mixtuures on metal mirror in moulds at the production of high-quality billets, blooms and slabs. Variants of mechanical and pneumo-mechaanical SFM supply elaborated. At the mechanical supply the fine material from the feeding hopper is moved at a adjusted distance bby a rigid horizontally located screw. At the pneumo-mechanical supply the metered doze of the granular mixture is delivered by a sshort vertical screw, the lower part of which is located in the mixing chamber attached from below to the hopper and equipped with ann ejector serving for pneumatic supply of the SFM in a stream of transporting gas. It was proposed to use flexible spiral screws in the ffuture facilities of mechanical SFM feeding. It will enable to eliminate the restrictions stipulated by the lack of free surface for locatiion of the facility in the working zone of the tundish, as well as to decrease significantly the mass of its movable part and to decreaase the necessary power of the carriage moving mechanism driver. The novelty of the proposed technical solutions is protected by thhree patents. The reduction of 10–15% in the consumption of slag-forming mixtures during the transition from manual to mechanizeed feeding confirmed. The resulting economic effect from the implementation of technical development enables to recoup the costs inncurred within 8–10 months.

Swim bladder mycosis in farmed rainbow trout Oncorhynchus mykiss caused by Phoma herbarum and experimental verification of pathogenicity

2020 ◽  
Vol 138 ◽  
pp. 237-246 ◽  
Author(s):  
J Řehulka ◽  
A Kubátová ◽  
V Hubka
Keyword(s):  
Rainbow Trout ◽  
Histopathological Examination ◽  
Periodic Acid ◽  
Bladder Wall ◽  
Swim Bladder ◽  
Cell Reactivity ◽  
Periodic Acid Schiff ◽  
Posterior Portion ◽  
Hepatic Congestion ◽  
Phoma Herbarum

In this study, spontaneous swim bladder mycosis was documented in a farmed fingerling rainbow trout from a raceway culture system. At necropsy, the gross lesions included a thickened swim bladder wall, and the posterior portion of the swim bladder was enlarged due to massive hyperplasia of muscle. A microscopic wet mount examination of the swim bladder contents revealed abundant septate hyphae, and histopathological examination showed periodic acid-Schiff-positive mycelia in the lumen and wall of the swim bladder. Histopathological examination of the thickened posterior swim bladder revealed muscle hyperplasia with expansion by inflammatory cells. The causative agent was identified as Phoma herbarum through morphological analysis and DNA sequencing. The disease was reproduced in rainbow trout fingerlings using intraperitoneal injection of a spore suspension. Necropsy in dead and moribund fish revealed extensive congestion and haemorrhages in the serosa of visceral organs and in liver and abdominal serosanguinous fluid. Histopathological examination showed severe hepatic congestion, sinusoidal dilatation, Kupffer cell reactivity, leukostasis and degenerative changes. Fungi were disseminated to the liver, pyloric caeca, kidney, spleen and heart. Although infections caused by Phoma spp. have been repeatedly reported in fish, species identification has been hampered by extensive taxonomic changes. The results of this study confirmed the pathogenicity of P. herbarum in salmonids by using a reliably identified strain during experimental fish infection and provides new knowledge regarding the course of infection.

Recirculation versus flow-through rainbow trout laboratory Flavobacterium columnare challenge

2020 ◽  
Vol 139 ◽  
pp. 213-221
Author(s):  
C Birkett ◽  
R Lipscomb ◽  
T Moreland ◽  
T Leeds ◽  
JP Evenhuis
Keyword(s):  
Rainbow Trout ◽  
Environmental Parameters ◽  
Cumulative Effects ◽  
Flavobacterium Columnare ◽  
Replacement Rate ◽  
Bacterial Concentration ◽  
Water Replacement ◽  
Dose Concentration ◽  
Flow Through ◽  
And Control

Flavobacterium columnare immersion challenges are affected by water-related environmental parameters and thus are difficult to reproduce. Whereas these challenges are typically conducted using flow-through systems, use of a recirculating challenge system to control environmental parameters may improve reproducibility. We compared mortality, bacterial concentration, and environmental parameters between flow-through and recirculating immersion challenge systems under laboratory conditions using 20 rainbow trout families. Despite identical dose concentration (1:75 dilution), duration of challenge, lot of fish, and temperature, average mortality in the recirculating system (42%) was lower (p < 0.01) compared to the flow-through system (77%), and there was low correlation (r = 0.24) of family mortality. Mean days to death (3.25 vs. 2.99 d) and aquaria-to-aquaria variation (9.6 vs. 10.4%) in the recirculating and flow-through systems, respectively, did not differ (p ≥ 0.30). Despite 10-fold lower water replacement rate in the recirculating (0.4 exchanges h-1) compared to flow-through system (4 exchanges h-1), differences in bacterial concentration between the 2 systems were modest (≤0.6 orders of magnitude) and inconsistent throughout the 21 d challenge. Compared to the flow-through system, dissolved oxygen during the 1 h exposure and pH were greater (p ≤ 0.02), and calcium and hardness were lower (p ≤ 0.03), in the recirculating system. Although this study was not designed to test effects of specific environmental parameters on mortality, it demonstrates that the cumulative effects of these parameters result in poor reproducibility. A recirculating immersion challenge model may be warranted to empirically identify and control environmental parameters affecting mortality and thus may serve as a more repeatable laboratory challenge model.

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