Protection against infectious laryngotracheitis by in ovo vaccination with commercially available viral vector recombinant vaccines

Infectious laryngotracheitis (ILT) is a highly contagious respiratory disease of chickens caused by infectious laryngotracheitis virus (ILTV). The disease is mainly controlled through biosecurity and by vaccination with live-attenuated vaccines. The chicken embryo origin (CEO) vaccines, although proven to be effective in experimental settings, have limited efficacy in controlling the disease in dense broiler production sites due to unrestricted use and poor mass vaccination coverage. These factors allowed CEO vaccines to regain virulence, causing long lasting and, consequently, severe outbreaks of the disease. A new generation of viral vector fowl poxvirus (FPV) and herpesvirus of turkey (HVT) vaccines carrying ILTV genes has been developed and such vaccines are commercially available. These vaccines are characterized by their lack of transmission, lack of ILTV-associated latent infections, and no reversion to virulence. HVT-vectored ILTV recombinant vaccines were originally approved for subcutaneous HVT or transcutaneous (pox) delivery. The increased incidence of ILTV outbreaks in broiler production sites encouraged the broiler industry to deliver the FPV-LT and HVT-LT recombinant vaccines in ovo. The objective of this study was to evaluate the protection induced by ILTV viral vector recombinant vaccines after in ovo application in 18-day-old commercial broiler embryos. The protection induced by recombinant ILTV vaccines was assessed by their ability to prevent clinical signs and mortality; to reduce challenge virus replication in the trachea; to prevent an increase in body temperature; and to prevent a decrease in body weight gain after challenge. In this study, both recombinant-vectored ILTV vaccines provided partial protection, thereby mitigating the disease, but did not reduce challenge virus loads in the trachea.     

Clinical and histopathological features of pemphigus foliaceus with and without eosinophilic infiltrates: a retrospective evaluation of 40 dogs

The importance of cellular infiltrates in tissues has been investigated as a diagnostic tool, mechanism of pathogenesis, and prognostic indicator in certain human diseases. Eosinophils, in particular, have a distinct role in the development of cutaneous lesions in human autoimmune diseases. Identification of an eosinophilic infiltrate can aid the diagnosis of immunobullous disease in the early stages of the disease process. In canine pemphigus foliaceus, eosinophils are present to a variable degree within lesional tissue. This study retrospectively evaluated 40 dogs with pemphigus foliaceus, and examined clinical and histologic features and final outcomes in cases with and without eosinophilic infiltrates. Twenty‐five of 40 dogs (63%) had an eosinophilic infiltrate in either the pustules/crust, follicular infundibulum or dermis. There was no statistically significant difference in clinical distribution or appearance of dermatological lesions, response to treatment, or disease outcome in dogs with or without an eosinophilic infiltrate. However, dogs with concurrent disease were significantly more likely to have an eosinophilic infiltrate (P = 0.01). Dogs with adverse effects associated with immunosuppressive therapy were significantly more likely to have an eosinophilic infiltrate (P = 0.05). Fifteen of 40 dogs (38%) had a history of allergic disease and a significantly higher proportion of these dogs had an eosinophilic infiltrate (P = 0.04). An eosinophilic infiltrate was found in more than half of the dogs in this study. These findings justify further studies to investigate the role of eosinophils in the pathogenesis, therapy and prognosis in dogs with pemphigus foliaceus.     

Assessing the value of forestry to the Irish economy — An input–output approach

Input–output analysis was used to evaluate the total economic impact (i.e. the sum of the direct, indirect and induced impacts) of the forestry and wood products sectors on the Irish economy. The total impact of the forestry sector on a number of regional economies was also examined, as were the short-term economic consequences of an afforestation scenario. Only economic activity associated with timber production was considered, and externalities associated with the sector were not accounted for. The results show that in 2003, forestry produced a direct output of €255.4 million. For every euro of output from forestry, a further €0.85 of economic activity was generated, yielding a total output of €472.4 million and total employment level of 7182. The wood products sector generated a total output of €1.6 billion and a total employment level of 12,246. These estimates of the economic impact of the forestry and wood products sectors cannot be added due to an overlap in indirect and induced impacts. The gross total value of an afforestation programme amounting to 15,000 ha per annum over 5 years was shown to be €475.0 million. Accounting for the fact that almost all land currently afforested is in agriculture, the net total value of this afforestation programme ranged from €157.8 million to €340.4 million, depending on the farming system being replaced and whether stacking of direct payments to farmers under the Single Payment Scheme applies to the land being planted.     

The identification,characterization and conservation value of isoetid lakes in Ireland

• 1. Soft‐water, oligotrophic isoetid lakes are vulnerable to eutrophication, acidification and alkalinization. As a result of these pressures a large proportion have undergone substantial deterioration in several European countries. The understanding of these systems has been limited by either a lack of lakes close to natural conditions or through receiving less focus in broader scale macrophyte surveys. This has resulted in a dearth of information on specific lake types in their natural condition. Sixty‐eight soft‐water lakes in Ireland were studied in order to achieve a better understanding of the biological and environmental conditions defining such lakes.
• 2. Eight groups of lakes were identified using cluster analysis and indicator species analysis. Three groups were representative of isoetid‐rich lakes displaying a high frequency of occurrence of Isoetes lacustris, Lobelia dortmanna or Eriocaulon aquaticum together with the almost ubiquitous Littorella uniflora. Canonical variates analysis indicated that alkalinity, total phosphorus (TP), catchment area, altitude, moors and heathlands, mean transect depth, colour and lake area were significant variables discriminating among the eight groups. Soft‐water lakes with high amounts of isoetids tended to be less exposed, have broad shallow littoral zones with a high transparency and be situated in smaller catchments. Total phosphorus and alkalinity were typically low, although one group of isoetid‐rich lakes had higher mean TP and alkalinity values. This group may contain lakes under threat from nutrient enrichment and alkalinization and also lakes that have higher TP and alkalinity naturally.
• 3. Lakes with a prevalence of isoetids supported a greater diversity of macrophytes and chironomids indicating that such lakes may represent suitable conservation targets as they act as surrogates for soft‐water lakes of high biodiversity. Other factors favouring a focus on isoetids in conservation strategies are their importance as a functional component in soft‐water lakes and their sensitivity to lake and catchment environmental change.

Copyright © 2008 John Wiley & Sons, Ltd.     

Morphological variation of Solanum elaeagnifolium in south‐eastern Australia

Solanum elaeagnifolium (silverleaf nightshade) is an invasive perennial weed in Australia, with aerial growth commencing in spring from either the perennial root system or the soil seedbank, with senescence occurring in autumn. A total of 642 S. elaeagnifolium individuals were collected at flowering from 92 locations in south‐eastern Australia to study morphological variation and its implications for management. Large morphological variation was found between individuals from different locations. Leaf length, width and area ranged from 1.44 to 10.6 cm, 0.39 to 4.09 cm and 0.41 to 25.8 cm² respectively. Plants from higher rainfall regions were significantly taller and had larger leaves, suggesting a possible correlation between rainfall and morphology. Scanning electron microscopy comparison of leaf surfaces showed lower trichome and stomatal densities on the adaxial surface (67.0 ± 3.3 trichomes mm^?2 and 603.4 ± 29.2 stomata mm^?2 respectively) than on the abaxial surface (131.9 ± 7.2 trichomes mm^?2 and 813.7 ± 30.5 stomata mm^?2 respectively). The morphological plasticity of S. elaeagnifolium highlighted in this study could probably contribute to its adaptability and partly explain its establishment and continuing expansion in Australia.     

Time of emergence impacts the growth and reproduction of silverleaf nightshade (Solanum elaeagnifolium Cav.)

Silverleaf nightshade is one of the worst agricultural weeds on a worldwide basis. Improved understanding of its life cycle will be useful for weed management. This research showed that the growth and reproduction of silverleaf nightshade were affected significantly by the time of emergence. Plants (both root‐ and seed‐generated) that emerged early in the growing season, such as in September or November (spring), were significantly taller and produced more biomass and fruit than plants that emerged in January (summer) and March (autumn). Delayed emergence resulted in a shorter vegetative phase and less fruit production. As a result, the silverleaf nightshade plants that emerged in September produced a large amount of seeds, while the plants that emerged later in the season did not flower. Thus, control of early‐emerging plants is important. The dynamics of fruit production indicated that silverleaf nightshade fruit formed in December and peaked in March, which suggests that a control action is required before December to control the soil seed bank.     

Use of density to predict crop yield loss between variable seasons

Summary Density:yield loss models rely on fixed coefficients, parameterized from a particular site and season to predict the impact of weeds on crop yields. However, the empiricism of this approach and failure to incorporate environmental effects, has major biological and economic implications. In this study, seasonal variability in wheat yield loss and associated economic costs from Avena spp. were quantitated. A competition experiment at Wagga Wagga, NSW, showed large seasonal differences in wheat yield loss from densities of Avena spp. across 2 years. Gross margins, simulated over a 51-year period, decreased as Avena spp. density increased and were more variable at low crop densities and higher weed densities. For example, at a density of 200 Avena spp. plants m⁻², coefficient of variation in crop gross margin ( CV ) was $AUS 47 ha⁻¹ for a crop density of 200 wheat plants m⁻² compared with a CV of $AUS 75 ha⁻¹ for a crop density of 50 wheat plants m⁻². The value of yield loss predictions will be vastly improved by making parameter values in yield loss models a function of seasonal factors such as rainfall.     

Blood-component therapy: selection, administration and monitoring

Transfusion of blood products is a frequent necessity in small animal practice. Transfusion medicine has become more sophisticated with increased access to blood components, knowledge of blood types, and cross-matching requirements. Although potentially life saving, this procedure does carry some risk. In addition to selecting the appropriate blood product, several steps need to be completed to prepare the product for administration and the patient for receiving a transfusion.     

Weed management in canola (Brassica napus L): a review of current constraints and future strategies for Australia

ABSTRACT

Weeds are a major constraint to canola (Brassica napus L.) production, reducing grain yield and quality. The repeated use of pre- and post- emergent herbicides to control several grasses and broadleaf weeds has escalated the problem of herbicide resistance in weeds. The development of herbicide-tolerant canola cultivars has increased the flexibility of weed management but has also increased the risks of outcrossing with wild relatives and weed shifts to resistance. Herbicide-resistant weed species, and the related biological repercussions, pose a major threat to sustainable weed management. These developing risks have led researchers to examine integrated weed management (IWM) techniques for sustainable weed control. Weed control strategies using non-chemical tactics have valid roles for managing weeds. However, in broad-acre commercial fields, the effectiveness of several non-chemical selections are less proven than commercial chemical herbicides. Canola competition and allelopathy for weed suppression are potential components for integrated weed management in canola. This review examines current chemical and non-chemical options available for developing IWM strategies for profitable canola production, as well as future research directions.