Oxidative reactions during early stages of beer brewing studied by electron spin resonance and spin trapping

An electron spin resonance (ESR)-based method was used for evaluating the levels of radical formation during mashing and in sweet wort. The method included the addition of 5% (v/v) ethanol together with the spin trap alpha-4-pyridyl(1-oxide)- N- tert-butylnitrone (POBN) to wort, followed by monitoring the rate of formation of POBN spin adducts during aerobic heating of the wort. The presence of ethanol makes the spin trapping method more selective and sensitive for the detection of highly reactive radicals such as hydroxyl and alkoxyl radicals. Samples of wort that were collected during the early stages of the mashing process gave higher rates of spin adduct formation than wort samples collected during the later stages. The lower oxidative stability of the early wort samples was confirmed by measuring the rate of oxygen consumption during heating of the wort. The addition of Fe(II) to the wort samples increased the rate of spin adduct formation, whereas the addition of Fe(II) during the mashing had no effect on the oxidative stability of the wort samples. Analysis of the iron content in the sweet wort samples demonstrated that iron added during the mashing had no effect on the iron level in the wort. The moderate temperatures during the early steps of mashing allow the endogenous malt enzymes to be active. The potential antioxidative effects of different redox-active enzymes during mashing were tested by measuring the rate of spin adduct formation in samples of wort. Surprisingly, a high catalase dosage caused a significant, 20% reduction of the initial rate of radical formation, whereas superoxide dismutase had no effect on the oxidation rates. This suggests that hydrogen peroxide and superoxide are not the only intermediates that play a role in the oxidative reactions occurring during aerobic oxidation of sweet wort.     

Prevalence of gastrointestinal helminths in different poultry production systems

A cross-sectional prevalence study of gastrointestinal helminths in Danish poultry production systems was conducted on 268 adult chickens selected at random from 16 farms in Denmark from October 1994 to October 1995. The trachea and the gastrointestinal tract of each bird was examined for the presence of helminths. In the free-range/organic systems the following helminths were found: Ascaridia galli (63.8%), Heterakis gallinarum (72.5%), Capillaria obsignata (53.6%), Capillaria anatis (31.9%) and Capillaria caudinflata (1.5%). In the deep-litter systems: A. galli (41.9%), H. gallinarum (19.4%) and C. obsignata (51.6%). In the battery cages: A. galli (5%) and Raillietina cesticillus or Choanotaenia infundibulum (3.3%). Exact identification of the cestodes was not possible because of missing scolexices. In the broiler/parent system: C. obsignata (1.6%), and finally for the backyard system: A. galli (37.5%) H. gallinarum (68.8%), C. obsignata (50.0%), C. anatis (56.3%) and C. caudinflata (6.3%). The results confirm the higher risk of helminth infections in free-range and backyard systems but prevalence may also be high in deep litter systems.     

Glucose Homoeostasis and Regulation in Lactating Mink ( Mustela vison ): Effects of Dietary Protein,Fat and Carbohydrate Supply

The ability of lactating mink dams to control glucose homoeostasis, when fed diets containing different ratios of metabolizable energy (ME) from protein, fat and carbohydrates, was studied by measuring plasma concentrations of glucose, insulin, glucagon, urea and free fatty acids (FFA), in the fasted and absorptive state 4 weeks postpartum, in two consecutive years. A total of 36 yearling female mink, fitted with jugular vein catheters and raising litters of six or seven kits, was fed ad libitum lactation diets with different amounts of ME derived from protein, fat and carbohydrates (year 1:61:37:2, 46:37:17 and 31:37:32; year 2:61:38:1, 47:52:1 and 33:66:1). After 3 h fasting the dams were fed 210 kJ ME of the experimental diets. Blood samples were drawn 10 and 5 min before feeding and 30, 60, 90, 120, 150 and 180 min postprandially. The glucose concentration was increased 30 to 150 min postprandially in dams fed the carbohydrate-containing diets (46:37:17 and 31:37:32), whereas the glucose concentration showed no postprandial response in dams fed the carbohydrate-free diets (61:38:1, 47:52:1 and 33:66:1). Plasma insulin concentrations were increased 30 to 120 min postprandially in all dams, irrespective of dietary treatment. Plasma concentrations of glucagon were higher ( P <0.005) in dams fed the low-protein diets (31:37:32 and 33:66:1) than in dams fed the high-protein diets (61:37:2 and 61:38:1). Postprandially, the glucagon : insulin ratios decreased in dams fed the carbohydrate-containing diets, whereas the glucagon:insulin ratios tended to increase in dams fed the carbohydrate-free diets. Plasma concentrations of urea were significantly higher in dams fed the high-protein diets. Plasma concentrations of FFA, measured in the second experiment (year 2) only, showed increased concentrations postprandially, the responses being significant in dams fed the 33:66:1 and 61:38:1 diets. In conclusion, the mink is able to regulate the concentrations of blood constituents involved in maintaining glucose homoeostasis, and thereby to adapt to a wide range of dietary protein and carbohydrate supply.     

Normal electrocardiographic QT interval in race-fit Standardbred horses at rest and its rate dependence during exercise

ObjectivesCardiac repolarization, measured as QT and T_peak to T_end (T_pT_e) intervals on the ECG, is important, as irregularities caused by diseases, ventricular hypertrophy, drugs and genetic defects can trigger arrhythmias which predispose human patients to syncope and sudden cardiac death. In horses, repolarization is not well described and therefore QT analysis cannot yet be used diagnostically. Therefore, we sought to describe reference values for the normal QT and T_pT_e intervals in Standardbreds and to determine the best method for heart rate (HR) correction.Animals30 Standardbreds.MethodsQT and T_pT_e intervals were measured during rest and exercise and plotted against HR converted to R_peak to R_peak interval (RR). Data were fitted with relevant regression models. Intra- and inter-observer agreement was assessed using Bland–Altman analyses.ResultsData were best described by a piecewise linear model (r² > 0.97). Average prediction error of this model was smaller than for both Bazett and Fridericia corrections. Coefficient of repeatability of intra- and inter-observer variability was 8.76 ms and 5.64 ms respectively and coefficient of variation was 1.77% and 2.76% respectively. T_pT_e increased with RR in stallions.ConclusionsThe QT interval in Standardbred horses shortens with decreasing RR interval (increasing HR) as in humans, but in a markedly different order as it clearly follows a piecewise linear model. The equine QT interval can be measured easily and there is small intra- and inter-observer variability. This model of the equine QT interval provides clinicians with a method that could support a diagnosis of repolarization disturbances in horses.     

AFLP analysis of genetic diversity in leafy kale (<Emphasis Type="Italic">Brassica oleracea</Emphasis> L. convar. <Emphasis Type="Italic">acephala</Emphasis> (DC.) Alef.) landraces,cultivars and wild populations in Europe

AFLP markers were used to characterize diversity and asses the genetic structure among 17 accessions of kale landraces, cultivars and wild populations from Europe. The range of average gene diversity in accessions was 0.11–0.27. Several landraces showed higher levels of diversity than the wild populations and one cultivar had the lowest diversity measures. The landraces that were most genetically diverse were from areas where kales are known to be extensively grown, suggesting in situ conservation in these areas as a supplement to storage of seeds in gene banks. An analysis of molecular variance (AMOVA) showed that 62% of the total variation was found within accessions. For most accessions, genetic distance was not related to geographic distance. Similarities among accessions were probably not caused by recent gene flow since they were widely separated geographically; more likely the relationship among them is due to seed dispersal through human interactions. Our results indicate that a kale population found in a natural habitat in Denmark was probably not truly wild but most likely an escape from a cultivated Danish kale that had subsequently become naturalized.     

Risk factors for infection of sow herds with porcine reproductive and respiratory syndrome (PRRS) virus

In 1992, the porcine reproductive and respiratory syndrome virus (PRRSV) of European type (PRRSV-EU) was introduced in Denmark. By 1996, the virus had spread to approximately 25% of the Danish herds. In January 1996, a modified-live vaccine based on the American type of the virus (PRRSV-US) was used in replacement boars for Danish artificial insemination (AI) centres and from July 1996, the vaccine was used in PRRSV-EU infected herds for prevention of disease. Soon after vaccine introduction, PRRSV non-infected herds experienced outbreaks of disease due to infection with PRRSV-US. In this study, we investigated the risk factors (biosecurity level, animals, exposure from PRRSV-US-infected neighbour herds, semen, herd size, pig density and herd density) for infection with PRRSV-US in a cohort of 1071 sow herds; we used a nested case-control study. The retrospective observation period lasted from June 1996 (when they all were non-infected) to October 1997. Seventy-three non-vaccinated, closed sow herds became infected with the vaccine strain during this period. Each case herd was matched with two control herds from the cohort (controls had not been infected at the time of infection in the case herds). The data were analysed using a Cox-regression model. The hazard of infection increased significantly with exposure from PRRSV-US-infected neighbouring herds, purchase of animals from herds incubating PRRSV-US infection, increasing herd size and purchase of semen from boars at PRRSV-US-infected AI centres. The results are consistent with the modified-live vaccine strain spread to other herds by trade with animals and semen and by neighbour (area) transmission. We suggest that virus spread by aerosols was a frequent mode of transmission.     

Anemia and Growth Retardation in Totally Gastrectomized Swine

The effects of total gastrectomy in six young swine were followed and described during an experimental period up to 18 months. Two of the gastrectomized pigs (Nos. 1 and 2) were medicated with cycobemin every second week. Two other gastrectomized pigs (Nos. 11 and 14) were medicated with iron-dextran twice a week. Three non-gastrectomized swine receiving the same feed as the gastrectomized animals were observed as controls for up to eight months.One of the gastrectomized non-medicated pigs (No. 4) did not gain weight, while the other gastrectomized animals had a normal appearance and gained weight but less than the controls. The non-medicated as well as the cycobemin-medicated gastrectomized animals developed a microcytic hypochrome anemia corresponding to the anemia in iron deficiency. Histochemically loss of iron in the depots (liver, spleen, bone marrow and intestine) was demonstrated in the gastrectomized animals except those treated with iron-dextran. Histological and histochemical examinations of the nervous system did not show any abnormalities.     

CO2 exploitation and genetic diversity in winter varieties of oilseed rape (Brassica napus); varieties of tomorrow

We investigated the CO_2] exploitation and genetic diversity inthree old and three new winter varieties of oilseed rape (Brassicanapus L.). Plants were cultivated in growth chambers with 360 ppmCO₂ and 700 ppm CO₂ under conditions simulating a normalgrowth season. Exposed to elevated CO₂ the stomatal conductance(g_s) and the maximum photosynthesis capacity (A_max) werereduced and the dry biomass and the total seed-number were increased.The response in seed-yield differed among the varieties; it was increased inthree varieties and decreased in three. The analysis of variance (ANOVA)showed that there were Treatment- and Week-effects on the g_s, andthere were Variety-, Week- and Treatment-effects on the A_max. Itwas also evident that there were a Variety- and Variety-agegroup-effect onthe seed-yield, but the Variety-agegroup-effect could not explain theVariety-effect. When either or both covariates (seed-number andbiomass) were included in the model, the covariates themselves had asignificant effect and it became evident that there was a Treatment-effecton the seed-yield.From AFLP (amplified fragment length polymorphism) markers adendrogram was constructed by the UPGMA method (unweightedpair-group method using the arithmetic averages) and [G _ST wascalculated for all possible subsets of the varieties. The three old varietiescomprised the densest cluster and were also more genetically diverse thantwo of the three new varieties. Varieties with clear changes amongCO₂ levels were rather genetically diverse.Thus, the varieties represent different traits, which could be exploited infuture breeding of oilseed rape.     

Variations in migration behaviour and mortality of Atlantic salmon smolts in four different hydroelectric facilities

Migration behaviour, route selection and mortality of Atlantic salmon, Salmo salar L., smolts were studied at four different hydroelectric facilities in the River Mustionjoki, Finland, in May 2017. Radio-tagged smolts were released upstream of the power stations and tracked by stationary antenna-receiver systems and hand-held receivers. Tracking revealed a general tendency of smolts to move downstream with the main flow, but also variable behaviour and mortality related to diverse conditions characteristic of each power station. Average migration delay at the power stations ranged between 13.8 and 101.1 h (median: 1.7–61.5 h). Estimated mortality ranges were 0%–50% in the forebays, 4%–64% in the power stations and 2–30%/km during river migration after passage of the dam. This study provided essential information on behaviour and mortality in relation to local conditions at each power station required for successful application of fish bypass systems in a salmon restoration project.     

Spatial and temporal variation of nitrous oxide and methane flux between subtropical mangrove sediments and the atmosphere

We quantified spatial and temporal variations of the fluxes of nitrous oxide (N₂O) and methane (CH₄) and associated abiotic sediment parameters across a subtropical river estuary sediment dominated by grey mangrove (Avicennia marina). N₂O and CH₄ fluxes from sediment were measured adjacent to the river (“fringe”) and in the mangrove forest (“forest”) at 3-h intervals throughout the day during autumn, winter and summer. N₂O fluxes from sediment ranged from an average of −4 μg to 65 μg N₂O m⁻² h⁻¹ representing N₂O sink and emission. CH₄ emissions varied by several orders of magnitude from 3 μg to 17.4 mg CH₄ m⁻² h⁻¹. Fluxes of N₂O and CH₄ differed significantly between sampling seasons, as well as between fringe and forest positions. In addition, N₂O flux differed significantly between time of day of sampling. Higher bulk density and total carbon content in sediment were significant contributors towards decreasing N₂O emission; rates of N₂O emission increased with less negative sediment redox potential (E_h). Porewater profiles of nitrate plus nitrite (NO_x⁻) suggest that denitrification was the major process of nitrogen transformation in the sediment and possible contributor to N₂O production. A significant decrease in CH₄ emission was observed with increasing E_h, but higher sediment temperature was the most significant variable contributing to CH₄ emission. From April 2004 to July 2005, sediment levels of dissolved ammonium, nitrate, and total carbon content declined, most likely from decreased input of diffuse nutrient and carbon sources upstream from the study site; concomitantly average CH₄ emissions decreased significantly. On the basis of their global warming potentials, N₂O and CH₄ fluxes, expressed as CO₂-equivalent (CO₂-e) emissions, showed that CH₄ emissions dominated in summer and autumn seasons (82-98% CO₂-e emissions), whereas N₂O emissions dominated in winter (67-95% of CO₂-e emissions) when overall CO₂-e emissions were low. Our study highlights the importance of seasonal N₂O contributions, particularly when conditions driving CH₄ emissions may be less favourable. For the accurate upscaling of N₂O and CH₄ flux to annual rates, we need to assess relative contributions of individual trace gases to net CO₂-e emissions, and the influence of elevated nutrient inputs and mitigation options across a number of mangrove sites or across regional scales. This requires a careful sampling design at site-level that captures the potentially considerable temporal and spatial variation of N₂O and CH₄ emissions.