Feline leukaemia. ABCD guidelines on prevention and management

OverviewFeline leukaemia virus (FeLV) is a retrovirus that may induce depression of the immune system, anaemia and/or lymphoma. Over the past 25 years, the prevalence of FeLV infection has decreased considerably, thanks both to reliable tests for the identification of viraemic carriers and to effective vaccines.InfectionTransmission between cats occurs mainly through friendly contacts, but also through biting. In large groups of non-vaccinated cats, around 30–40% will develop persistent viraemia, 30–40% show transient viraemia and 20–30% seroconvert. Young kittens are especially susceptible to FeLV infection.Disease signsThe most common signs of persistent FeLV viraemia are immune suppression, anaemia and lymphoma. Less common signs are immune-mediated disease, chronic enteritis, reproductive disorders and peripheral neuropathies. Most persistently viraemic cats die within 2–3 years.DiagnosisIn low-prevalence areas there may be a risk of false-positive results; a doubtful positive test result in a healthy cat should therefore be confirmed, preferably by PCR for provirus. Asymptomatic FeLV-positive cats should be retested.Disease managementSupportive therapy and good nursing care are required. Secondary infections should be treated promptly. Cats infected with FeLV should remain indoors. Vaccination against common pathogens should be maintained. Inactivated vaccines are recommended. The virus does not survive for long outside the host.Vaccination recommendationsAll cats with an uncertain FeLV status should be tested prior to vaccination. All healthy cats at potential risk of exposure should be vaccinated against FeLV. Kittens should be vaccinated at 8–9 weeks of age, with a second vaccination at 12 weeks, followed by a booster 1 year later. The ABCD suggests that, in cats older than 3–4 years of age, a booster every 2–3 years suffices, in view of the significantly lower susceptibility of older cats.     

Feline rabies. ABCD guidelines on prevention and management

OverviewRabies virus belongs to the genus Lyssavirus, together with European bat lyssaviruses 1 and 2. In clinical practice, rabies virus is easily inactivated by detergent-based disinfectants.InfectionRabid animals are the only source of infection. Virus is shed in the saliva some days before the onset of clinical signs and transmitted through a bite or a scratch to the skin or mucous membranes. The average incubation period in cats is 2 months, but may vary from 2 weeks to several months, or even years.Disease signsAny unexplained aggressive behaviour or sudden behavioural change in cats must be considered suspicious. Two disease manifestations have been identified in cats: the furious and the dumb form. Death occurs after a clinical course of 1–10 days.DiagnosisA definitive rabies diagnosis is obtained by post-mortem laboratory investigation. However, serological tests are used for post-vaccinal control, especially in the context of international movements.Disease managementPost-exposure vaccination of cats depends on the national public health regulations, and is forbidden in many countries.Vaccination recommendationsA single rabies vaccination induces a long-lasting immunity. Kittens should be vaccinated at 12–16 weeks of age to avoid interference from maternally derived antibodies and revaccinated 1 year later. Although some vaccines protect against virulent rabies virus challenge for 3 years or more, national or local legislation may call for annual boosters.     

Relationship between soil microbial biomass determined by SIR and PLFA analysis in floodplain soils

Purpose  

Although the challenge of linking pedology and hydrology has been identified recently, the microbial diversity in floodplain soils has been studied little in comparison to terrestrial soils. In terrestrial soils, the relationship between soil microbial biomass (SMB) determined by substrate-induced respiration (SIR) and phospholipid fatty acids (PLFA) was examined in several studies. Floodplain soils reveal substantially different properties; they are exposed to drastic changes in water regime from flooded to dry conditions. The relation between SMB determined by SIR and PLFA has, up to the present, not been adequately proved in floodplain soils. Thus, this study was conducted to elucidate the relationship between SMB determined with both methods in a set of floodplain soils of eleven study sites from three study areas along the Elbe River (Germany).     

Priming: it’s all the world to induced disease resistance

After infection by a necrotising pathogen, colonisation of the roots with certain beneficial microbes, or after treatment with various chemicals, many plants establish a unique physiological situation that is called the ‘primed’ state of the plant. In the primed condition, plants are able to ‘recall’ the previous infection, root colonisation or chemical treatment. As a consequence, primed plants respond more rapidly and/or effectively when re-exposed to biotic or abiotic stress, a feature that is frequently associated with enhanced disease resistance. Though priming has been known as a component of induced resistance for a long time, most progress in the understanding of the phenomenon has been made over the past few years. Here we summarize the current knowledge of priming and its relevance for plant protection in the field.     

Genotyping of bovine Prototheca mastitis isolates from Poland

Bovine mastitis due to unicellular, achlorophyllous algae of the genus Prototheca is a serious and complex ailment that accounts for high economic losses in the dairy industry. Bovine protothecal mastitis has been almost exclusively associated with only one species Prototheca zopfii. Recently, based on the 18S rDNA sequence analysis, P. zopfii has been divided into three genotypes (1-3), of which P. zopfii genotype 3 has been given the status of a new species Prototheca blaschkeae sp. nov. The aim of this study was to investigate the genotypic composition of the population of P. zopfii bovine mastitis isolates from Poland, according to that threefold classification. Of the 44 isolates tested, 43 (98%) were identified as P. zopfii genotype 2. Only one isolate was assigned to the newly established P. blaschkeae species. These findings clearly show the predominance of the P. zopfii genotype 2 in the etiology of bovine mammary protothecosis in Poland, but also underline the involvement of P. blaschkeae in the disease. The study is the first to provide molecular characterization of Polish P. zopfii mastitis isolates, collected from different regions of Poland.     

Re‐visiting potassium‐ and phosphate‐fertilizer responses in field experiments and soil‐test interpretations by means of data mining

Currently, potassium (K)‐ and phosphate (P)‐fertilizer recommendation in Germany is based on standardized soil‐testing procedures, the results of which are interpreted in terms of nutrient availability. Although site‐specific soil and plant properties (e.g., clay and carbon content, pH, crop species) influence the relation between soil nutrient content and fertilizer effectiveness, most of these factors are not accounted for quantitatively when assessing fertilizer demand. Recent re‐evaluations of field observations suggest that even for soil nutrient contents well within the range considered to indicate P or K deficiency, fertilizer applications often resulted in no yield increase. In this study, results from P‐ and K‐fertilization trials (in total about 9000 experimental harvests) conducted during the past decades in Germany and Austria were re‐analyzed using a nonparametric data‐mining procedure which consists of a successive segmentation of the data pool in order to elaborate a modified recommendation scheme. In addition to soil nutrient content, fertilizer‐application rates, nutrient‐use efficiency, and site properties such as pH, clay content, and soil organic matter, have a distinct influence on yield increase compared to an unfertilized control. For K, nutrient‐use efficiency had the largest influence, followed by soil‐test K content, whereas for P, the influence of soil‐test P content was largest, followed by pH and clay content. The results may be used in a novel approach to predict the probability of yield increase for a specified combination of crop species, fertilizer‐application rate, and site‐specific data.     

Transfer of carbon incubation parameters to model the SOC and SON dynamics of a field trial with energy crops applying digestates as organic fertilizers

The fertilization with organic amendments and digestates from biogas plants is increasingly used to increase carbon stock and to improve the soil quality, but little is still known about their long-term effects. A common method to analyse organic amendments and their mineralization is incubation experiments, where amendments get incubated with soil while CO₂ release is measured over time. In a previous study, carbon models have been applied to model the carbon dynamics of incubation experiments. The derived parameters describing the carbon turnover of the CCB model (CANDY Carbon Balance) are used to simulate the SOC and SON dynamics of a long-term field trial. The trial was conducted in Berge (Germany) where organic amendments like slurry, farmyard manure or digestates were systematically applied. To grant a higher model flexibility, the amounts of crop residues were calculated for roots and stubble separately. Furthermore, the mineralization dynamics of roots and stubble are considered by the model parameters for each crop. The model performance is compared when using the dry matter and carbon content received from the field trial and the incubation experiments, to evaluate the transferability. The results show that the incubation parameters are transferable to the field site, with rRMSE < 10% for the modelled SOC and rRMSE between 10% and 15% for the SON dynamics. This approach can help to analyse long-term effects of unexplored and unusual organic fertilizers under field conditions, whereat the model is used to upscale the C dynamics from incubation experiments, considering environmental conditions.     

Simulating the soil phosphorus dynamics of four long-term field experiments with a novel phosphorus model

Phosphorus is a nonrenewable resource, which is required for crop growth and to maintain high yields. The soil P cycle is very complex, and new model approaches can lead to a better understanding of those processes and further guide to research gaps. The objective of this study was to present a P-submodel, which has been integrated in the existing Carbon Candy Balance (CCB) model that already comprises a C and N module. The P-module is linked to the C mineralization and the associated C-pools via the C/P ratio of fresh organic material. Besides the organic P cycling, the module implies a plant-available P-pool (P_av), which is in a dynamic equilibrium with the nonavailable P-pool (P_na) that comprises the strongly sorbed and occluded P fraction. The model performance was tested and evaluated on four long-term field experiments with mineral P fertilization, farmyard manure as organic fertilizer and control plots without fertilization. The C dynamics and the P_av dynamics were modelled with overall good results. The relative RMSE for the C was below 10% for all treatments, while the relative RMSE for P_av was below 15% for most treatments. To accommodate for the rather small variety of available P-models, the presented CNP-model is designed for agricultural field sites with a relatively low data input, namely air temperature, precipitation, soil properties, yields and management practices. The CNP-model offers a low entry threshold model approach to predict the C-N and now the P dynamics of agricultural soils.