Responses of plasma Epo and kidney and liver Epo mRNA to hemorrhage in perinatal pigs

Despite the fact that pig fetuses in late gestation have extensive erythropoiesis, low blood pO₂ and low hemoglobin concentrations, piglets are born without detectable concentrations of plasma erythropoietin (Epo). In the present study, we have examined the hypothesis that long-term hypoxic stimuli are less efficient than short-term stimuli in stimulating Epo production in perinatal pigs. From fetuses collected by hysterectomy 5 days before term, new-born piglets and piglets 2 and 5 weeks old, blood in amounts corresponding to 2% of body weight was withdrawn from the jugular vein. Twenty-four hours later the animals were killed and their kidney and liver Epo mRNA analysed by a competitive RT-PCR assay. Plasma Epo concentration was estimated by a solid-phase, two-site sequential chemiluminescent enzyme immunometric assay. We found that in nearly fully developed fetuses and in new-born piglets, the concentration of Epo mRNA did not increase upon bleeding. This is in contrast to earlier findings in sheep. In 2- and 5-week-old piglets, bleeding was associated with a 12–15-fold increase in kidney Epo mRNA. In the 2- and 5-week-old piglets, bleeding evoked increased translation of Epo mRNA into the protein hormone. Also in new-born piglets, increased plasma levels of Epo accompanied bleeding, whereas significant changes in gene Epo expression were not observed.     

Early marine survival and movements of escaped Atlantic salmon Salmo salar L. juveniles from a land‐based smolt farm during autumn

The aim of this study was to examine early marine survival and movements of simulated escaped Atlantic salmon Salmo salar L. pre‐smolt and smolt from a commercial smolt farm during autumn. One‐third of the pre‐smolt most likely died in the immediate vicinity of the release location, whereas the corresponding mortality for smolts was lower (8.5%) during the 5‐week study period. The surviving pre‐smolt left the farm area after 2–3 days, predominantly along the shore. In contrast, most of the surviving smolts left the farm area during the first day and 54% seemed to move away from the shore and adopt a more pelagic movement pattern than pre‐smolt. The number of surviving fish recorded in the fjord decreased throughout the study period, possibly due to a combination of fish migrating out of the fjord or undetected mortality. Compared with existing knowledge on migration of released farmed smolts during spring, our results indicate less directional and slower movement rates during autumn. Only two of the tagged fish were detected upstream in the rivers following release. A rapid dispersion of escapees indicates that the potential for recapturing escapees is limited unless recapture efforts are initiated immediately after escape. Hence, there is a need for development of technology that detects and prevents escapees to enter the sea.     

The Norwegian minke whale DNA register: a data base monitoring commercial harvest and trade of whale products

The application of genetics for the management of natural resources is expanding, and within this field, DNA registers will play an increasing role. The Norwegian minke whale DNA register, established in 1996, was designed primarily as a control system to detect any attempts at illegal trade of products derived from other stocks of minke whale, or other whale species, under cover of the legal Norwegian harvest originating from the Northeast Atlantic. The register contains genetic data for 7644 of 7751 whales landed in the period 1997–2010. Profiles are established from sequencing part of the mtDNA control region, analysis of 10 STRs and a sex‐determining marker. Probabilities of genotypes matching between two randomly selected whales are 6.0^?04 and 3.0^?08 for five and eight of the STR loci, respectively. This permits verification of traded whale products via match to the register. The register has also been used in a number of ad hoc scientific studies resulting through the accumulation of genetic, demographic and biological data. Here, we review the register’s logistics, specifications and evaluate the potential to apply similar registers to control the exploitation of other marine species.     

Short-term effects of whole-tree harvesting on understory plant species diversity and cover in two Norway spruce sites in southern Norway

Effects of clear-cut harvesting on ground vegetation plant species diversity and their cover are investigated at two Norway spruce sites in southern Norway, differing in climate and topography. Experimental plots at these two sites were either harvested conventionally (stem-only harvesting) or whole trees including crowns, twigs and branches were removed (whole-tree harvesting), leaving residue piles on the ground for some months. We compare the number of plant species in different groups and their cover sums before and after harvesting, and between the different treatments, using non-parametric statistical tests. An overall loss of ground vegetation biodiversity is induced by harvesting and there is a shift in cover of dominant species, with negative effects for bryophytes and dwarf shrubs and an increase of graminoid cover. Differences between the two harvesting methods at both sites were mainly due to the residue piles assembled during whole-tree harvesting and the physical damage made during the harvesting of residues in these piles. The presence of the residue piles had a clear negative impact on both species numbers and cover. Pile residue harvesting on unfrozen and snow-free soil caused more damage to the forest floor in the steep terrain at the western site compared to the eastern site.     

Granulomatous enteritis in rainbow trout (Oncorhynchus mykiss) associated with soya bean meal regardless of water dissolved oxygen level

This study investigated morphological changes associated with soya bean meal‐induced enteritis (SBMIE) in distal intestine (DI) of rainbow trout (Oncorhynchus mykiss) fed a soya bean meal (SBM)‐based diet and exposed to normoxia or hypoxia created by optimal and low water flow rates, respectively. A 28‐day adaption period was followed by a 42‐day challenge period where 600 fish were subjected to dietary challenge and/or hypoxia. Twelve tanks each containing 50 juvenile trout were assigned randomly in triplicate to each treatment. Histopathological and immunohistochemical evaluation revealed pathological features that have not previously been described in association with SBMIE. Vacuolar degeneration of epithelial cells mainly at the base of mucosal folds, epithelial cysts, epithelial dysplasia, necrosis, shedding of necrotic cells, and granulomatous inflammation including infiltration of enlarged, sometimes finely vacuolated or “foamy” macrophages, multinucleated giant cells and increased proliferation of fibroblasts were observed. Acid‐fast bacteria were not detected in enlarged macrophages; however, these cells contained AB‐PAS‐ and sometimes cytokeratin‐positive material, which was interpreted to be of epithelial/goblet cell origin. Hypoxia did not affect the morphological changes in DI. These results suggest that SBM was associated with a granulomatous form of enteritis in DI of rainbow trout regardless of water oxygen level.     

Functional amino acids stimulate muscle development and improve fillet texture of Atlantic salmon

Sufficient firmness is essential for consumer appreciation and the suitability for processing of fish fillets. The objective of this study was to investigate the effect of functional amino acids (AA) on fillet texture and muscle development of Atlantic salmon. Triplicate net pens of 105 g salmon were fed a standard diet, or the same diet with added 15 g/kg arginine or 15 g/kg glutamate during a 5‐month rearing period. The growth rate and FCR (0.91–0.92) showed no significant dietary effects (body weight 864–887 g). Glutamate supplementation resulted in delayed postmortem glycogen degradation (pH drop) and rigour development, along with improved fillet firmness and intercellular myofibre integrity. An in vitro study with salmon myosatellite cells showed that exogenous glutamine or arginine increased the expression of muscle growth markers (myog, tnnl2, myl) at both 8 and 16°C culture temperature. The expression of a marker for proteolysis (ctsb), myl and myog were highest for the glutamine treatment at 16°C. Significant interaction between exogenous AA and temperature indicated elevated AA requirement when growth is accelerated. It is concluded that AA from the glutamate family are vital for fillet firmness. The dispensable glutamine and glutamate appear more critical compared to arginine, particularly during high‐performance periods.     

Influence of dietary menadione nicotinamide bisulphite (vitamin K3) and phylloquinone (vitamin K1) on Atlantic salmon (Salmo salar L.) tissue levels,determined by high‐performance liquid chromatography with fluorescence detection

The aim of the present study was to investigate the retention of menadione nicotinamide bisulphite (MNB; vitamin K₃) and phylloquinone (vitamin K₁) in Atlantic salmon (Salmo salar L.). Another objective was to find a reliable method for determination of menadione in fish feed, and to include and validate more matrices in the methods for phylloquinone and menaquinones (vitamin K₂). Duplicate tanks of Atlantic salmon (～93 g) were fed four levels (0–1000 mg menadione kg^?1 feed) of MNB for 9 weeks. The concentration of menadione and phylloquinone in the feed and the concentration of phylloquinone and menaquinone‐4 (MK‐4) in the tissues were determined. The analysed concentration of dietary menadione found in feed indicated a substantial loss of MNB during feed production. This assumption was supported by screening 15 commercial fish feed samples which also revealed menadione concentrations far below the recommended level. MNB fed salmon showed only a minor increase in liver MK‐4 concentration, compared to salmon fed phylloquinone which had a considerably higher level of liver phylloquinone, indicating a higher retention of phylloquinone compared to menadione in Atlantic salmon. Due to highly varying stability and bioavailability of the different vitamin K derivatives, vitamin K supplementation in fish feed needs a revision.     

Fertilization success and blastomere morphology as predictors of egg and juvenile quality for domesticated Atlantic cod,Gadus morhua,broodstock

We investigated if simplified routines based on blastomere morphology and fertilization success can be used as predictors of egg and embryo viability in Atlantic cod, and abnormal blastomere morphology is related to juvenile deformities. Egg morphology data from 312 families that were produced by hand stripping of gametes were used. Fertilized eggs from all families were separately incubated in 25 L incubators. Blastomere morphology and fertilization success were assessed at 16–32 cell stage. Embryo mortality was measured until hatch. Fertilization success showed a significant positive correlation with the proportion of normal blastomere and 74% of the variation in the incidence of blastomere abnormality was explained by fertilization success. Juvenile deformities were positively correlated with blastomere abnormality and 8% of the variation in juvenile deformities was explained by incidences of blastomere abnormality. To our knowledge, this is the first direct evidence showing that incidences of blastomere abnormalities may be related to cod juvenile deformities. Our results suggest that fertilization success and the occurrence of blastomere abnormalities could be easily adopted by commercial cod hatcheries for the early determination of egg quality.     

Effects of dietary levels and ratio of phosphatidylcholine and phosphatidylinositol on the growth,survival and deformity levels of Atlantic cod larvae and early juveniles

Effects of two weaning diets that differed in phospholipid (PL) classes on growth, survival and deformities of cod larvae and early juveniles were evaluated. Cod larvae were fed rotifers until 21 days post hatch (dph) and then weaning onto dry diet started. One group of larvae were fed a control diet with low levels of phosphatidylcholine (PC), PE and phosphatidylinositol (PI) and the other group of larvae were fed with an experimental diet containing higher levels of PC, PE and PI. Larvae fed with the control diet were significantly smaller than larvae fed with the experimental diet at the end of the experiment. Swim bladder abnormalities were significantly higher in larvae fed with control diet at 35 dph than the larvae fed with experimental diet; however, no significant difference was evident at 42 dph. Vertebral deformities were significantly higher in larvae fed with control diet and scoliosis was significantly different between the treatments. Survival was also significantly higher in the experimental group. Our results indicate that dietary levels of PL, PC and PI may affect the cod larval growth, survival and deformities. More detail studies are needed to find out the optimal levels of these important PL classes in larval cod diets.