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71.
Magnus Vikan Rsg Espen Rimstad Arne Guttvik Brd Skjelstad Eldar sgard Bendiksen se Helen Garseth 《Journal of fish diseases》2019,42(1):97-108
Salmonid alphavirus (SAV) causes pancreas disease (PD) in farmed Atlantic salmon (Salmo salar L.), and exocrine pancreas tissue is a primary target of the virus. Digestive enzymes secreted by the exocrine pancreas break down macromolecules in feed into smaller molecules that can be absorbed. The effect of SAV infection on digestion has been poorly studied. In this study, longitudinal observations of PD outbreaks caused by SAV subtype 2 (SAV2) in Atlantic salmon at two commercial sea sites were performed. The development of PD was assessed by measurement of SAV2 RNA load and evaluation of histopathological lesions typical of PD. Reduced digestion of both protein and fat co‐varied with the severity of PD lesions and viral load. Also, the study found that during a PD outbreak, the pen population comprise several subpopulations, with different likelihoods of being sampled. The body length of sampled fish deviated from the expected increase or steady state over time, and the infection status in sampled fish deviated from the expected course of infection in the population. Both conditions indicate that disease status of the individual fish influenced the likelihood of being sampled, which may cause sampling bias in population studies. 相似文献
72.
Nitrogen transformation rates and N<Subscript>2</Subscript>O producing pathways in two pasture soils
Ting Lan Helen Suter Rui Liu Xuesong Gao Deli Chen 《Journal of Soils and Sediments》2018,18(9):2970-2979
Purpose
Better understanding of N transformations and the regulation of N2O-related N transformation processes in pasture soil contributes significantly to N fertilizer management and development of targeted mitigation strategies.Materials and methods
15N tracer technique combined with acetylene (C2H2) method was used to measure gross N transformation rates and to distinguish pathways of N2O production in two Australian pasture soils. The soils were collected from Glenormiston (GN) and Terang (TR), Victoria, Australia, and incubated at a soil moisture content of 60% water-filled pore space (WFPS) and at temperature of 20 °C.Results and discussion
Two tested pasture soils were characterized by high mineralization and immobilization turnover. The average gross N nitrification rate (ntot) was 7.28 mg N kg?1 day?1 in TR soil () and 5.79 mg N kg?1 day?1 in GN soil. Heterotrophic nitrification rates (nh), which accounting for 50.8 and 41.9% of ntot, and 23.4 and 30.1% of N2O emissions in GN and TR soils, respectively, played a role similar with autotrophic nitrification in total nitrification and N2O emission. Denitrification rates in two pasture soils were as low as 0.003–0.004 mg N kg?1 day?1 under selected conditions but contributed more than 30% of N2O emissions.Conclusions
Results demonstrated that two tested pasture soils were characterized by fast N transformation rates of mineralization, immobilization, and nitrification. Heterotrophic nitrification could be an important NO3?–N production transformation process in studied pasture soils. Except for autotrophic nitrification, roles of heterotrophic nitrification and denitrification in N2O emission in two pasture soils should be considered when developing mitigation strategies.73.
Beth CLARK Glyn D. JONES Helen KENDALL James TAYLOR Yiying CAO Wenjing LI Chunjiang ZHAO Jing CHEN Guijun YANG Liping CHEN Zhenhong LI Rachel GAULTON Lynn J. FREWER 《农业科学与工程前沿(英文版)》2018,5(4):485
Precision agriculture (PA) technologies have great potential for promoting sustainable intensification of food production, ensuring targeted delivery of agricultural inputs, and hence food security and environmental protection. The benefits of PA technologies are applicable across a broad range of agronomic, environmental and rural socio-economic contexts globally. However, farmer and land-manager adoption in low to middle income countries has typically been slower than that observed in more affluent countries. China is currently engaged in the process of agricultural modernisation to ensure food security for its 1.4 billion population and has developed a portfolio of policies designed to improve food security, while simultaneously promoting environmental protection. Particular attention has been paid to the reduction of agricultural inputs such as fertilisers and pesticides. The widespread adoption of PA technologies across the Chinese agricultural landscape is central to the success of these policies. However, socio-economic and cultural barriers, farm scale, (in particular the prevalence of smaller family farms) and demographic changes in the rural population, (for example, the movement of younger people to the cities) represent barriers to PA adoption across China. A framework for ensuring an acceptable and accelerated PA technology trajectory is proposed which combines systematic understanding of farmer and end-user priorities and preferences for technology design throughout the technology development process, and subsequent end-user requirements for implementation (including demonstration of economic and agronomic benefits, and knowledge transfer). Future research will validate the framework against qualitative and quantitative socio-economic, cultural and agronomic indicators of successful, or otherwise, PA implementation. The results will provide the evidence upon which to develop further policies regarding how to secure sustainable food production and how best to implement PA in China, as well as practical recommendations for optimising end-user uptake. 相似文献
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76.
Panagiotis E Simitzis Aristeidis Tsopelakos Maria A Charismiadou Alkisti Batzina Stelios G Deligeorgis Helen Miliou 《Aquaculture Research》2014,45(11):1759-1770
The effects of different stunning/killing procedures on flesh quality of European sea bass were investigated: (1) anaesthesia with clove oil, (2) anaesthesia with 2‐phenoxyethanol, (3) percussive stunning, (4) immersion in ice/water slurry, (5) chilling on ice and (6) anaesthesia with clove oil followed by immersion in ice/water slurry. Muscle pH values were significantly lower in sea bass anaesthetized or stunned by a blow to the head compared with fish immersed in ice/water slurry, chilled on ice or immersed in ice/water slurry after clove oil anaesthesia. Lightness was highest in sea bass anaesthetized by 2‐phenoxyethanol or percussively stunned and lowest in ice‐chilled fish. Redness and yellowness were highest in fish chilled on ice and lowest in fish anaesthetized with clove oil. Liquid loss, fat loss and shear values were not significantly different among the procedures. In general, lipid oxidation values during refrigerated or frozen storage did not significantly differ among treatment groups. Combination of clove oil anaesthesia followed by chilling on ice/water slurry appears to improve both flesh quality and welfare of sea bass, although the implementation of further studies is warranted to consolidate this finding. 相似文献
77.
78.
Helen Belefant‐Miller 《Cereal Chemistry》2009,86(1):67-69
Rice can yellow during storage if moisture levels and temperatures are allowed to increase. This postharvest yellowed (PHY), or stackburn, rice is reduced in value but no study has investigated the inherent potential within rice germplasm for limiting PHY. To screen a large number of cultivars for propensity to PHY, a laboratory method for PHY using a small amount of rice was used. Ninety‐eight popular southern U.S. rice cultivars were yellowed under laboratory conditions. Additional samples of the low‐yellowing and high‐yellowing cultivars were retested after two and three years of storage as rough rice using higher amounts and larger containers. All cultivars showed greater color change with the higher amounts of rice and when yellowed as milled rather than as rough rice. Length of time of storage and storage temperature did not affect the degree of PHY. The low‐ and high‐yellowing groups remained distinguishable but the overall high level of coloring in southern U.S. rice cultivars indicates that a more diverse germplasm should be investigated to increase the likelihood of identifying low‐PHY cultivars. 相似文献
79.
Georgios Theodoropoulos Helen Theodoropoulou Georgios Skopelitis Konstantinos Benardis 《Preventive veterinary medicine》2009,89(3-4):277-281
Commission Regulation (EC) No. 2075/2005 of 5 December 2005 lays down detailed conditions for Trichinella-free farms. The objectives of the present study were: (1) to assess the current state of swine farms in Greece in relation to the risk of exposure of pigs to Trichinella as a first step towards certification of Trichinella-free farms in Greece and (2) to identify a profile and characteristics of swine farms and farmers which can be used to formulate appropriate measures to promote good production practices for reducing risk of exposure of pigs to Trichinella. A total of 70 swine farms were inspected using audit components similar to those used by the U.S. Trichinae Certification Programme. Only four farms (6%) complied with all the criteria used for assessing the good production practices for reducing risk of exposure of pigs to Trichinella. A common characteristic of these four farms was that they had a large size (>300 sows) and produced their own feed. The most common issues among the farms that did not meet audit criteria in the present study were related to proper rodent control and accessibility of other animals in the feed storage area and the facility. In addition, the predominant significant differentiating characteristic for the farms not meeting the criteria was their small (<150 sows) size, while for the farmers it was their low educational level. These characteristics, which are linked to poor infrastructure and reluctance for improvements, respectively, will be difficulties that must be dealt with in the promotion of good production practices for Trichinella-free farms in Greece. 相似文献
80.