Growth performance,nutrient digestibility and intestinal morphology of rainbow trout (Oncorhynchus mykiss) fed graded levels of the yeasts Saccharomyces cerevisiae and Wickerhamomyces anomalus

In a 10‐week study, we evaluated the effects of replacing 20%, 40% or 60% of fishmeal (present in control diet at 300 g/kg) on a digestible protein basis with yeast Saccharomyces cerevisiae or a yeast mixture of Wickerhamomyces anomalus and S. cerevisiae on growth performance, nutrient digestibility, nutrient retention and intestinal health of rainbow trout (Oncorhynchus mykiss). Triplicate tanks with 35 rainbow trout (144.7 ± 25.1 g mean ± SEM) were fed rations of 1.5% of total biomass per tank. Replacement of 60% of fishmeal with yeast mixture resulted in lower specific growth rate of 1.0% versus 1.2%/day for other diets. Apparent digestibility coefficients for crude protein and most amino acids were highest in fish fed fishmeal‐based diet, with similar values for fish fed the diet with 20% replacement with yeast mixture. Diet with 20% replacement with yeast mixture resulted in highest phosphorus digestibility. Replacement of 60% of fishmeal with S. cerevisiae resulted in oedematous mucosal fold tips in the proximal intestine. The results of this study suggest that these yeasts can replace up to 40% of fishmeal under current inclusion levels in diets for rainbow trout without compromising growth performance, nutrient digestibility or intestinal health.     

Surplus spermine does not protect salmon cells against lipopolysaccharide (LPS)‐induced stress,but excess spermine is eliminated through spermidine/spermine N1‐acetyltransferase (SSAT)

The present trials tested the efficiency of surplus spermine to reduce inflammation and oxidative stress following LPS‐induced stress using an in vitro model of head kidney and liver cells isolated from Atlantic salmon. Spermine did not protect cells from LPS‐induced inflammatory response at either 0.3, 0.6 or 0.9 mM. However, as the gene expression of spermidine/spermine N1‐acetyltransferase (SSAT) increased with increasing spermine concentration, we addressed possible oxidative effects of the increased SSAT using its activator DENSPM or inhibitor of polyamine oxidation of the acetylated polyamines using MDL72527 at a spermine concentration of 0.6 mM. There was no significant effect of DENSPM, but MDL72527 decreased gene expression of GPX‐3 (p = .04), while gene expression of catalase and MnSOD was unaffected by treatment (p = .30 and p = .48, respectively). In conclusion, spermine did not protect cells from LPS‐provoked inflammation. The higher the spermine concentration, the more SSAT producing acetylated spermine occurred. Inhibiting the acetylated polyamine oxidases by MDL72527 improved oxidation status as expected due to a lower endogenous production of H₂O₂ by polyamine and acetylated polyamine oxidases. Probably care should be taken using polyamines or arginine as functional ingredients to avoid any increased oxidation within cells.     

Genetic differentiation between and within ecotypes of pike (Esox lucius) in the Baltic Sea

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Stocking Density and its Influence on Growth of Spotted Wolffish,Anarhichas minor,in Shallow Raceways

We compared growth properties of spotted wolffish with initial mean weight (± SE) 3.65 (± 0.15) kg reared in shallow raceways at three different densities (50, 70, and 90 kg/m², corresponding to approx. 170, 240, and 310 kg/m³) in a 447‐day‐long growth trial at ambient temperature (mean (± SD), 4.2 C ± 1.9). Growth in all three groups was comparable, but there was a trend toward higher growth at the highest density. Final mean weights (kg ± SE) were 4.90 (± 0.15), 4.80 (± 0.16), and 5.05 (± 0.11), at the 50, 70, and 90 kg/m² density, respectively. Initially, growth rates were higher at the 90 kg/m² density group compared to the two other densities, but overall growth rates were similar in all three groups. Feed conversion efficiency differed and was higher at the two highest densities compared to lowest density. The acid–base balance was influenced by the density treatment as there was a general trend toward higher partial pressure of CO₂ and HCO in the 90 kg/m² group. Calculated productivity increased almost linearly with increasing stocking density and was found to be 24, 42, and 66 g/m²/day at 50, 70, and 90 kg/m², respectively. The results show that the optimum density conditions for farming large spotted wolffish, both with respect to growth rate, feed conversion, and productivity are at densities equal to or higher than 90 kg/m².     

Prediction of Starch,Soluble Sugars and Amino Acids in Potatoes (<Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.) Using Hyperspectral Imaging,Dielectric and LF-NMR Methodologies

Handling and processing of potatoes is performed in increasingly large and more automated facilities, and the industry calls for more automated machinery for quality assessment and sorting by concentration of starch, soluble sugars, protein, amino acids etc. of the potato tubers. The present study was designed to evaluate five different scanning methods for their potential use in potato assessment and sorting. Two methods were based on hyperspectral imaging, two were based on dielectric/bio-impedance and one was based on low-field nuclear magnetic resonance. A set of 60 potatoes of 10 different cultivars were simultaneously sampled for analyses of content and scanned by the five different scanning methods. The resulting multivariate dataset was used to estimate the prediction ability of the individual scanning methods on starch-related parameters, selected simple sugars, selected amino acids, conductivity of pressed cell sap and cell sizes. Results showed that most types of spectral analyses had relatively high potential for predicting the starch-related parameters and medium potential for predicting the concentration of the reducing sugars fructose and glucose. Most methods showed medium potential for prediction of several amino acids, including asparagine, which showed particularly promising predictions in the hyperspectral analyses of intact potatoes. The presented screening study enabled us to perform robust choices for the further development and optimization of the methods and instruments for industrial implementation.     

Molecular Evidence for Persistence of Anaplasma phagocytophilum in the Absence of Clinical Abnormalities in Horses after Recovery from Acute Experimental Infection

Background: Anaplasma phagocytophilum infects several mammalian species, and can persist in sheep, dogs, and calves. However, whether this organism persists in horses or induces long-term clinical abnormalities is not known.
Objectives: To evaluate whether A. phagocytophilum can persist in horses and to document clinical findings for 3 months after complete recovery from acute disease.
Animals: Five clinically normal adult horses that had recovered spontaneously from experimentally induced acute disease caused by a Swedish equine isolate of A. phagocytophilum .
Methods: Horses were monitored for up to 129 days post inoculation (PI) by daily clinical examination and at least alternate day blood sampling for evidence of A. phagocytophilum on polymerase chain reaction (PCR) and blood smears. All horses were euthanized and underwent postmortem examination.
Results: All horses were periodically PCR positive after recovery from acute infection. Before day 66 PI 2 horses were persistently PCR negative whereas 3 horses were intermittently PCR positive. Subsequently, 4 of 5 horses were intermittently PCR positive, particularly after stress mimicking interventions. One animal was positive immediately before postmortem examination. Clinical abnormalities related to persistence of anaplasma were not observed. No specific changes were found at postmortem examination, and all sampled tissues from all horses were negative on PCR for A. phagocytophilum .
Conclusions and Clinical Importance: Infection with A. phagocytophilum can persist in the horse for at least 129 days. However, the continued presence of the organism is not associated with detectable clinical or pathological abnormalities.     

Metabolic characterization of rumen epithelial tissue from dairy calves fed different starter diets using 1H NMR spectroscopy

The metabolic profile of calf rumen epithelial tissue was for the first time characterized by ¹H NMR spectroscopy of chloroform/methanol extracts. The metabolite profiles comprised a number of amino acids, creatine, taurine, short-chain fatty acids and triglycerides. The effects of two dietary interventions; i) four levels of milk allowance with a concomitant different uptake of starter concentrate, and ii) two diets with varying content of starch and fibre in the concentrate, were elucidated. Partial least square regression analysis revealed that the intensity of NMR signals assigned to leucine, isoleucine and valine (0.90  ppm), propionate (1.06 and 2.18  ppm), lactate (1.32  ppm), butyrate (1.56  ppm), acetate (1.93  ppm), glutamine/glutamate (2.18, 2.35 and 3.75  ppm), creatine (3.04 and 3.94  ppm) and glycine (3.55  ppm) decreased with increasing milk allowance. In addition, the analysis revealed that the main difference between the two diets was the content of propionate in the epithelia tissue extracts. Previous morphological analyses of the same rumen epithelia were not able to detect any significant effects of either milk allowance or dietary starch content. Accordingly, the present study demonstrated that ¹H NMR spectroscopy applied on extracts is a useful tool for metabolite profiling of epithelial tissue and for following the development of epithelia tissue in young calves, and that the technique may be more sensitive to dietary effects than morphological studies.     

Use efficiency of nitrogen from biodigested plant material by ryegrass

Apparent nitrogen‐use efficiency of the applied mineral N (NUE_min) in effluent from biodigested plant material (BE; C : N_org ratio 14:1; mineral N–to–total N ratio 0.5:1) and a nitrate‐based inorganic fertilizer (IF), both applied at two rates was investigated in a six‐month pot experiment with Italian ryegrass (Lolium multiflorum Lam.). Dry‐matter (DM) production was 7% lower and total amount of N in aboveground biomass was 8% lower in BE than in IF at 40 d after sowing (DAS), equal at 81 DAS, and higher in BE than in IF at 136 and 172 DAS. NUE_min calculated on the basis of accumulated N in aboveground biomass of ryegrass in fertilized treatments compared to a control without N application was significantly lower in BE than in IF up to the third cut (136 DAS). Total NUE_min, total N recovery, and amount of foliage DM were similar for both fertilizers at the end of the experiment. Root biomass, total DM produced including roots and stubble, the fraction of root N to total plant N, and soil mineral N at 172 DAS were higher for BE than for IF. Mineral N applied with biogas‐reactor effluent was almost as effective as the nitrate‐based mineral fertilizer used for comparison. Within the six‐month experimental period net N mineralization, estimated at 12% of organic N in effluent, was not substantial. Hence, the organic compounds in the effluent were relatively recalcitrant.