Research note: Postnatal development of electrolyte transport in calf rumen as affected by weaning time.

In a previous study we found a positive correlation between early weaning in calves and morphological parameters which were indicative of ruminal development, i.e. the length and width of the papillae. The objective of the present study was to determine to what extent this observation could be reflected by modulations of absorptive and secretory functions of the rumen mucosa. For this purpose the short-circuit currents (Isc) as a measure of electrogenic net ion fluxes and the transepithelial conductances (G(T)) as a measure of the overall tissue permeability were measured in vitro applying the Ussing-chamber technique. Simultaneously, the unidirectional flux rates of sodium and chloride across rumen wall epithelia were determined in the absence of electrochemical gradients. Under these conditions, significant positive net flux rates (Jnet) clearly indicate active mechanisms for electrolyte absorption. For the experiments 12 male Holstein calves 7 d of age were assigned to three groups of 4 animals each: milk group (I, slaughtered after 6 weeks of age), late weaning group (II, slaughtered after 9 weeks of age) and early weaning group (II, weaned after 6 weeks of age and slaughtered after 9 weeks of age). Whereas G(T) values remained unaffected by different age and feeding, Isc values were significantly affected by early weaning but were not influenced by age. Irrespective of weaning time active absorption of Na+ tended to be higher by about 60% in 9 weeks old animals. Active absorption of chloride was significantly increased in milk fed 9 weeke old calves and this effect was further stimulated by early weaning. In conclusion, the data show an increasing active Na+ absorption with age in calf rumen that could not be influenced by early weaning. Similarly, active Cl- absorption was initially increased during postnatal development and this effect could be stimulated further by early weaning.     

Population dynamics and habitat connectivity affecting the spatial spread of populations – a simulation study

In this paper we show how the spatialconfiguration of habitat quality affects the spatial spread of apopulation in a heterogeneous environment. Our main result is thatfor species with limited dispersal ability and a landscape withisolated habitats, stepping stone patches of habitat greatlyincrease the ability of species to disperse. Our results showthat increasing reproductive rate first enables and thenaccelerates spatial spread, whereas increasing the connectivity has aremarkable effect only in case of low reproductive rates. Theimportance of landscape structure varied according to thedemographic characteristics of the population. To show this wepresent a spatially explicit habitat model taking into accountpopulation dynamics and habitat connectivity. The population dynamicsare based on a matrix projection model and are calculated on eachcell of a regular lattice. The parameters of the Leslie matrix dependon habitat suitability as well as density. Dispersal between adjacentcells takes place either unrestricted or with higher probability inthe direction of a higher habitat quality (restricted dispersal).Connectivity is maintained by corridors and stepping stones ofoptimal habitat quality in our fragmented model landscape containinga mosaic of different habitat suitabilities. The cellular automatonmodel serves as a basis for investigating different combinations ofparameter values and spatial arrangements of cells with high and lowquality.This revised version was published online in May 2005 with corrections to the Cover Date.     

Characterisation of and changes in the atmospheric deposition situation in German forest ecosystems using multivariate statistics

Based on the results of the atmospheric deposition classification of the year 1989, a methodical approach should be introduced, which—based on the modelled total deposition rates—enables us to characterise the input situation of forest monitoring plots and to delimit load areas in Germany. In 1989, the deposition situation in nearly 1,800 forest monitoring sites (BZE/extensive Soil Condition Inventory) in Germany could be explained by four factors (or three, excluding sea salt impact) with the help of a factor analysis. The factor values were grouped into six deposition types with typical compounds and regional patterns. The classified input rates of the soil inventory plots adequately represent the stress situation and deposition changes in Germany. The application of the statistical approach on the level of Brandenburg clarifies the special local input situation. Due to the special combination of deposed elements, the sources of emissions can be characterised as well. When the soil inventory is repeated, a project planned for 2006, this approach can be used in order to determine homogenous areas for stratified data evaluation.     

Concept and feasibility study for the integrated evaluation of environmental monitoring data in forests

In the 1970s unexpected forest damages, called “new type of forest damage” or “forest decline”, were observed in Germany and other European countries. The Federal Republic of Germany and the German Federal States implemented a forest monitoring system in the early 1980s, in order to monitor and assess the forest condition. Due to the growing public awareness of possible adverse effects of air pollution on forests, in 1985 the ICP Forests was launched under the convention on long-range transboundary air pollution (CLRTAP) of the United Nations Economic Commission for Europe (UN-ECE). The German experience in forest monitoring was a base for the implementation of the European monitoring system. In 2001 the interdisciplinary case study “concept and feasibility study for the integrated evaluation of environmental monitoring data in forests”, funded by the German Federal Ministry of Education and Research, concentrated on in-depths evaluations of the German data of forest monitoring. The objectives of the study were: (a) a reliable assessment of the vitality and functioning of forest ecosystems, (b) the identification and quantification of factors influencing forest vitality, and (c) the clarification of cause-effect-relationships leading to leaf/needle loss. For these purposes additional data from external sources were acquired: climate and deposition, for selected level I plots tree growth data, as well as data on groundwater quality. The results show that in particular time series analysis (crown condition, tree growth, and tree ring analysis), in combination with climate and deposition are valuable and informative, as well as integrated evaluation of soil, tree nutrition and crown condition data. Methods to combine information from the extensive and the intensive monitoring, and to transfer process information to the large scale should be elaborated in future.

Cchuk ber Caatfchulen gegen Päher und Rrähen

Ohne Zusammenfassung     

Relevance of infection with equine herpesvirus 1 (EHV-1) in a German thoroughbred stud: vaccination, abortion and diagnosis

The aim of the present study was to clarify whether an EHV-1 induced abortion can be prognosticated by an increase of antibody titres, virus shedding and/or viraemia and whether the current abortion diagnostic is suitable. In this context the immune response post immunization and a possible reactivation were of great interest. For this purpose blood samples of 32 mares between the ages of 5-21 years were regularly investigated during a period of two years before and after vaccination and pregnancy. Neutralization tests, indirect immunofluorescence tests as well as PCR and virus isolation were used for EHV-1 diagnostics. It could be shown that the horses reacted individually to vaccination. In 14 cases a EHV-1-reactivation was suggested. An abortion prognosis was not possible even using serological, virological and molecular biological parameters. In addition, virus shedding and antibody titres were individual. An acute infection was detectable by a significant rise of antibodies and viraemia as well as virus shedding in the secretions. For the abortion diagnostics the antigen detection in combination with virus isolation and PCR from fetal lungs gave reliable results. In addition, the virological and serological investigation of the mare is recommendable. For prophylaxis we would advise a regular vaccination and strict hygiene.     

Repeated administrations of adrenocorticotropic hormone during gestation in gilts: Effects on growth, behaviour and immune responses of their piglets

This study investigated whether repeated administrations of adrenocorticotropic hormone (ACTH) during mid or late gestation, a treatment which induces endogenous cortisol release, affect growth performance, early vitality, open-field behaviour and immune responses of neonatal pigs. Administrations of ACTH (100 IU per animal, Synacthen^® Depot) were given intramuscularly to gilts every second day either during mid (Day 49 until 75, Experiment 1) or late gestation (Day 85 until 107, Experiment 2). Control gilts received repeated injections of saline. The repeated ACTH stimulation of gilts during late gestation significantly reduced their daily weight gain during this period, but not when applied during mid gestation. Gestation length, number of born piglets and vitality measures of the newborn piglets, such as the rectal temperatures after birth and times elapsed between birth and first udder contact or milk uptake were not affected by the prenatal treatments. Administration of ACTH during late but not during mid gestation significantly increased the birth weights of piglets, and this difference in postnatal body weight was detectable until an age of 21 days. In addition, only the stimulation with ACTH during late gestation had an immunosuppressive effect on the lymphocyte proliferation of piglets 1 day after birth in response to the T-cell mitogen ConA and, in tendency, on the proliferation in response to the B-cell mitogen LPS. Twenty-four day old piglets from gilts treated during late gestation showed significantly more escape behaviour in an open-field than piglets from control litters. In conclusion, elevated maternal glucocorticoid levels during critical periods of prenatal development in pigs may affect prenatal growth, cell-mediated immunity and emotional reactivity in the neonatal piglets. The occurrence of these effects depends on the timing of increased maternal cortisol levels during gestation.     

Pseudomonas syringae pv. aesculi associated with horse chestnut bleeding canker in Germany

Bacteria were isolated from necrotic lesions on a horse chestnut tree (Aesculus hippocastanum) with bleeding canker in Hamburg, Germany. Sequencing of the rDNA-ITS region revealed great similarity to pathovars of Pseudomonas syringae. Pseudomonas syringae pv. aesculi was identified by sequence homology of the gyrase B gene. This is the first report of P. syringae pv. aesculi in Germany. Phytophthora was not detected.