Melanized focal changes in skeletal muscle in farmed Atlantic salmon after natural infection with Piscine orthoreovirus (PRV)

Melanized focal changes in skeletal muscle of farmed Atlantic salmon (Salmo salar) are a major quality problem. The aetiology is unknown, but infection with Piscine orthoreovirus (PRV) has been associated with the condition. Here, we addressed the pathogenesis of red and melanized focal changes and their association with PRV. First, a population of farmed fish (PRV‐negative prior to sea transfer) was sequentially investigated throughout the seawater period. The fish were autopsied and tested for PRV infection. Muscular changes were described by macroscopy and histology, and a classification system was established. Second, in an experimental infection trial, PRV was injected intramuscularly to induce changes. The farmed fish was gradually infected with PRV. Red focal changes occurred throughout the observation period with a low prevalence regardless of PRV status. Melanized changes were highly diverse and their prevalence increased during the trial. Changes of low macroscopic grade and histological category were more prevalent in PRV‐negative fish. Diffuse granulomatous melanized changes only occurred after PRV infection. No muscular changes were observed in the experimentally challenged fish. Our studies do not indicate that PRV infection causes red focal changes, but seems important in the development of granulomatous melanized changes.     

Association between radiographic assessment of hip status and subsequent incidence of veterinary care and mortality related to hip dysplasia in insured Swedish dogs

Our objective was to evaluate the association between grading of hip status as assessed by radiographic examination (hip screening) and subsequent incidence of veterinary care and mortality related to hip dysplasia (HD) in five breeds of insured dogs in Sweden. Screening results for hip status from the Swedish Kennel Club and data on veterinary care and mortality from the insurance company Agria were merged based on the registration number of the dog. Dogs of five breeds (Bernese Mountain Dogs, German Shepherds, Golden Retrievers, Labrador Retrievers, and Rottweilers) screened during 1995–2004 and covered by an insurance plan for veterinary care or life at the time of screening were included. The study populations included between 1667 and 10,663 dogs per breed. Breed-specific multivariable Cox proportional-hazards analyses were performed to evaluate the impact of radiographic hip status on time from hip screening to first HD-related veterinary and life claim, respectively. The effects of gender, birth season, and a time-varying covariate of year were also studied. Additional analyses, on the five breeds combined, were performed to investigate the effects of hip status, breed, and the interaction between hip status and breed. The effect of hip status was highly significant (P < 0.001) for both life and veterinary claims related to HD in all five breeds with increased hazard ratio (HR) for deteriorating hip status. Dogs with moderate or severe hip status at screening had a markedly increased hazard of HD-related veterinary care and mortality compared with dogs assessed as free or mild. The time-varying covariate of year showed a significantly higher HR in the last time period for German Shepherds and Labrador Retrievers in the analyses of veterinary claims. In the analyses on all five breeds, German Shepherds had the highest HR for both veterinary care and mortality related to HD, followed by Bernese Mountain Dogs. Golden and Labrador Retrievers had the lowest HR. The effect of hip status on the hazard was the same irrespective of breed. However, as a consequence of differences between breeds in overall risk, the predictive ability of screening results for subsequent incidence of HD-related problems for individual dogs was breed-dependent. Based on the strong association between radiographic hip status and incidence of HD-related veterinary care and mortality, and the previously reported moderate heritability of hip status, we conclude that selection based on screening results for hip status can be expected to reduce the risk of HD-related clinical problems.     

Piscine orthoreovirus (PRV) in red and melanised foci in white muscle of Atlantic salmon (Salmo salar)

Melanised focal changes (black spots) are common findings in the white skeletal muscle of seawater-farmed Atlantic salmon (Salmo salar). Fillets with melanised focal changes are considered as lower quality and cause large economic losses. It has been suggested that red focal changes (red spots) precede the melanised focal changes. In the present work, we examined different populations of captive and wild salmon for the occurrence of both types of changes, which were investigated for the presence of different viruses by immunohistochemistry and RT-qPCR. The occurrence of red or melanised foci varied significantly between the populations, from none in wild fish control group, low prevalence of small foci in fish kept in in-house tanks, to high prevalence of large foci in farm-raised salmon. Large amounts of Piscine orthoreovirus (PRV) antigen were detected in all foci. No other viruses were detected. Red focal changes contained significantly higher levels of PRV RNA than apparently non-affected areas in white muscle of the same individuals. Some changes displayed a transient form between a red and melanised pathotype, indicating a progression from an acute to a chronic manifestation. We conclude that PRV is associated with the focal pathological changes in the white muscle of farmed Atlantic salmon and is a premise for the development of focal melanised changes.     

油脂天然抗氧化剂研究——Ⅰ、茶叶提取物抗油脂氧化的效果

用茶叶中提取的多酚类物质(TPE)加入油脂中,用烘箱静置法观察油脂过氧化值(POV)的变化。结果表明,茶叶多酚类提取物添加量为0.03-0.04%(按油脂重量计),对猪油、精炼菜油、色拉油和精炼豆油的抗氧化效果相当于0.02%BHT的1.3-2倍和0.02%DL,α-生育酚的4倍,且具有良好的抗氧化稳定性。在有0.02-0.04%柠檬酸增效剂存在下,TPE的抗氧化效果可提高1.6-3倍。红外光谱分析证明,TPE中多酚类组分和柠檬酸产生氢键缔台,形成大的氢给予体,因而增强了抗油脂氧化的稳定性。柱层析分离TPE总共得到六个部分,其中二个部分抗油脂氧化效果最佳。     

Direct genetic, maternal and litter effects on behaviour in German shepherd dogs in Sweden

The aim of this study was to study genetic (co)variation of broader behavioural traits in German shepherd dogs and to test whether there is maternal and litter influence on these traits. Data were extracted from the Swedish Dog Mentality Assessment (DMA) from 1989 to 2001 on 5959 German shepherd dogs. Based on previous results, personality traits were created from the 15 behavioural variables extracted from the test. These personality traits were (1) Playfulness, (2) Chase-proneness, (3) Curiosity/Fearlessness, and (4) Aggressiveness. A trait Boldness was constructed from all behaviour variables except those included in Aggressiveness. Mixed linear models with fixed effects of sex, test type, test year, test month, age, and judge were used. Models with all combinations of random effects of animal (direct genetic), genetic and non-genetic maternal, and litter were tested. The best model included effects of animal and litter. Direct heritability estimates were between 0.09 and 0.23, highest for Playfulness and Curiosity/Fearlessness. Maternal heritabilities were all low (0.01-0.08), lowest and not significant if litter or non-genetic maternal effects were included in the model. Additive genetic correlations among Playfulness, Chase-proneness, and Curiosity/Fearlessness were higher (0.54-0.74) than genetic correlations with Aggressiveness (0.29-0.40). Litter variance ratios (c²) were larger than the maternal heritabilities (0.03-0.10). Boldness had a direct heritability estimate of 0.27 and a direct genetic correlation with Aggressiveness of 0.37. We conclude that there is substantial additive genetic variation, that the mother has rather little influence (both genetically and environmentally) and that the litter seems to have a larger influence than the mother for these personality traits. Genetic improvement in these behaviour traits is thus possible.     

Challenges of pheromone-based mating disruption of <Emphasis Type="Italic">Cydia strobilella</Emphasis> and <Emphasis Type="Italic">Dioryctria abietella</Emphasis> in spruce seed orchards

Seed orchards function as the primary source of high-quality seeds for reforestation in many European countries, but their seed yields can be severely reduced due to seed- and cone-feeding insects. We evaluated various parameters of pheromone-based mating disruption for control of the moths Cydia strobilella and Dioryctria abietella, which are major pests in European Picea abies seed orchards. We applied different types of pheromone dispensers (rubber septa or wax droplets) at different densities and heights, and with different amounts of active components, covering whole orchards or part of an orchard. The efficacy of the treatment was evaluated by analysing male captures in pheromone-baited assessment traps, and presence of larvae in cones. A dramatic decrease (94–100%) in capture of males in traps occurred in all pheromone-treated plots compared to control plots for both moth species. In contrast, a subsequent reduction in larval numbers in cones was only achieved when wax droplets were used as the dispensing formulation at high density and at the highest pheromone dose tested, and only in half of the trials for each pest species. Electrophysiological recordings using antennae of male C. strobilella indicated elevated pheromone concentrations in a treated plot versus a control plot. Our results show that mating disruption has potential to reduce cone damage in spruce seed orchards caused by C. strobilella and D. abietella, but optimisation of the technique is required to achieve consistent and efficient population suppression of these pests.     

Fall frost resistance in willows used for biomass production. I. Characterization of seasonal and genetic variation

Fast-growing willow clones (six clones of Salix viminalis L. and one clone each of S. viminalis x S. schwerenii E. Wolf and S. dasyclados Wimm.) were compared with respect to growth rhythm and frost hardening in the fall. Frost resistance of stem tissues was assessed by controlled freezing followed by analysis of chlorophyll fluorescence and scoring of visible cambial discoloration. The fluorescence method proved superior to scoring based on visible cambial discoloration because it was more rapid and less subjective, but needed calibration against cambial damage. Frost hardening in mature parts of stems did not start until growth cessation was initiated in the shoot apices, irrespective of whether growth cessation occurred early or late in the fall. Frost resistance varied because of clonal variations in: (1) pre-hardening frost resistance; (2) timing of growth cessation and hence start of frost hardening; and (3) rate of frost hardening. Compared with coastal and southern clones, continental and northern clones started hardening earlier, and a continental clone proceeded through hardening more rapidly at a given temperature. A cross between a continental and coastal clone was intermediate in timing. The pre-hardening frost resistance, however, was unrelated to both growth and frost hardening characteristics.     

Measuring herding behavior in Border collie—effect of protocol structure on usefulness for selection

From 1989 until 2003, the Swedish Sheepdog Society used a standardized method, Herding Trait Characterization (HTC), to describe herding behavior of individual Border collies for breeding purposes. In the HTC, which existed in 2 consecutive versions, the dog’s herding behavior was described using predefined scales typically consisting of 6 classes within each trait. In total, 1,663 dogs participated in the first version and 951 in the second. The main difference between the versions was the structure of the protocols used to record the traits. In the first version, the scales were designed to describe the intensity in the expression of the measured traits. In the second version, the most desirable behavioral expression was placed in the middle of the scale. Another difference was that in the second version, the judges were given more freedom for their own interpretations, that is, the scales were more subjective. The objective of this study was to examine the quality of each version from a breeding perspective, and to analyze the reasons for possible differences in this respect between them. Heritability estimates for the 17 traits of the earlier version of the HTC ranged from 0.14 to 0.50 (weighted average: 0.30), all significantly different from 0. Corresponding heritabilities for the 19 traits in the later version were substantially lower (0.03-0.41, weighted average: 0.16), 3 of them not being significantly different from 0. Owing to the moderate-to-high heritabilities for the traits measured in the earlier version of the HTC, it would be possible to accomplish effective selection of breeding animals for most of the measured traits. It is plausible that the less neutral and more subjective protocol of the later version is the main cause for the lower heritabilities.