Effects of glucocorticoids on parameters of lipid metabolism, hepatic metabolism, haematological parameters and milk yield in high-yielding cows in early lactation

Effects of glucocorticoids on lipid metabolism, hepatic metabolism, haematological parameters and milk yield in high-yielding cows in the early stages of lactation. The assumption is widespread that glucocorticoids promote lipolysis and fatty liver in ruminants. But there are contrary experimental results. Therefore we investigated the effects of dexamethasone (in the form of Voren suspension) in cows with very high milk yields (herd average 10.000 kg/year) between 7 and 15 days post partum, when high levels of lipolysis occur. Nine cows were given Voren 7 and 11 days post partum at doses of 0.02 mg/kg body weight. Glucose and insulin concentrations rose whilst FFA concentrations fell. Hepatic lipid levels were unchanged compared to a control group (n=8). There were also no changes in the various liver function parameters tested (beta-hydroxybutyrate, bilirubin, cholesterol, albumin, aspartat-amino-transferase, glutamat-dehydrogenase), which suggests that liver damage did not occur. Each of the two doses of Voren resulted in typical glucocorticoid-related changes in the differential leukocyte count. There was only a very slight reduction in daily milk yield. This studies show that, in ruminants, glucocorticoids have an indirect antilipolytic effect in vivo and do not aggravate or accelerate fatty degeneration of the liver.     

Cross-resistance between antimicrobial agents used in veterinary medicine: molecular background and practical consequences for susceptibility testing

Phenotypic resistance of veterinary pathogens to more than one antimicrobial agent (multi-resistance) may be caused by intrinsic resistance to the antimicrobial agents, acquired cross-resistance, or acquired co-resistance. Known cross-resistances allow to select so-called "representative substances" which are tested and the results of which can also be regarded as being valid for other members of the same class of antimicrobial agents. In general, a limitation in the number of antimicrobial agents to be tested in routine diagnostics is necessary because of capacity and cost efficiency. This is of particular relevance when the broth microdilution method - recommended as the method of choice - with 96-well microtiter plates is used. The knowledge about the relationship between different resistance phenotypes and the corresponding resistance mechanisms is of major value for both, the laboratory personnel and the veterinary practitioner. This review explains how "representative substances" for the most relevant classes of antimicrobial agents used in veterinary medicine are chosen on the basis of known cross-resistances.     

Influence of zeolite A supplementation during the dry period of dairy cows on feed intake, on the macro and trace element metabolism around calving and milk yield in the following lactation

The object of the present study was to determine the influence of zeolite A, a calcium binder from the group of the aluminosilicate, on feed intake, macro and trace element metabolism as well as the milk yield in the following lactation in dairy cows. 46 cows were allotted to 2 groups (A--control group and B--experimental group). They were fed a total mixed ration (TMR) ad libitum 2 weeks before calving. Additionally the cows in group B received 90 g zeolite A/kg dry matter (DM). The individually feed intake was registered daily. The serum was analysed for Ca, Mg, and Pi (inorganic phosphate), Fe, FFA (free fatty acid) and beta-HB (hydroxybutyrate) and the plasma for the trace elements Cu, Zn, and Mn. After calving the milk yield (FCM) and the milk composition (fat, protein, lactose and urea) were analysed. Feed intake of group B, amounting to 6.2 +/- 1.3 kg DM/d was around 48% lower as compared to 12.0 +/- 1.4 kg DM/d for group A. The zeolite addition into the TMR showed a stabilizing effect on the average Ca concentration in the serum around calving. This effect led to a significantly lower Mg concentration on the day of calving and 1 day post partum. The Pi concentration was significantly lower already after the 1st week of zeolite supplementation and on the day of calving as compared to group A. There was no essential effect of zeolite A on the trace element concentration. The depression of feed intake for group B led to a significant increase of FFA one week after beginning zeolite supplementation and of beta-HB around calving. The feed intake post partum as well as the milk yield were not affected by zeolite supplementation. Because decreased feed intake of group B after zeolite supplementation and the occurred hypophosphatemia, it is not acceptable to use zeolite A in the proved dose for preventing milk fever.     

Degradation of scrapie associated prion protein (PrPSc) by the gastrointestinal microbiota of cattle

A food-borne origin of the transmission of bovine spongiform encephalopathy (BSE) to cattle is commonly assumed. However, the fate of infectious prion protein during polygastric digestion remains unclear. It is unknown at present, whether infectious prion proteins, considered to be very stable, are degraded or inactivated by microbial processes in the gastrointestinal tract of cattle. In this study, rumen and colon contents from healthy cattle, taken immediately after slaughter, were used to assess the ability of these microbial consortia to degrade PrP(Sc). Therefore, the consortia were incubated with brain homogenates of scrapie (strain 263K) infected hamsters under physiological anaerobic conditions at 37 degrees C. Within 20 h, PrP(Sc) was digested both with ruminal and colonic microbiota up to immunochemically undetectable levels. Especially polymyxin resistant (mainly gram-positive) bacteria expressed PrP(Sc) degrading activity. These data demonstrate the ability of bovine gastrointestinal microbiota to degrade PrP(Sc) during digestion.     

Curcuminoids form reactive glucuronides in vitro

Curcumin is of current interest because of its putative anti-inflammatory, anticarcinogenic, and anti-Alzheimer's activity, but its pharmacokinetic and metabolic fate is poorly understood. The present in vitro study has therefore been conducted on the glucuronidation of curcumin and its major phase I metabolite, hexahydro-curcumin, as well as of various natural and artificial analogs. The predominant glucuronide generated by rat and human liver microsomes from curcumin, hexahydro-curcumin, and other analogs with a phenolic hydroxyl group was a phenolic glucuronide according to LC-MS/MS analysis. However, a second glucuronide carrying the glucuronic acid moiety at the alcoholic hydroxyl group was formed from the same curcuminoids, but not hexahydro-curcuminoids, by human microsomes. Curcuminoids without a phenolic hydroxyl group gave rise to the aliphatic glucuronide only. The phenolic glucuronides of curcuminoids, but not of hexahydro-curcuminoids, were rather lipophilic and, in part, unstable in aqueous solution, their stability depending strongly on the type of aromatic substitution. The phenolic glucuronide of curcumin and of its natural congeners, but not the parent compounds, clearly inhibited the assembly of microtubule proteins under cell-free conditions, implying chemical reactivity of the glucuronides. These novel properties of the major phase II metabolites of curcuminoids deserve further investigation.     

Agricultural surroundings support flower-visitor networks in an Afrotropical rain forest

Local habitat structure and resource availability appear to be of great importance for the diversity, abundance, and community structure of bees. We examined the contribution of three different habitat types (farmland, forest edge, forest understory) to bee diversity in a tropical forest-agriculture mosaic in Western Kenya and analysed differences and overlap in plant-bee community interactions between nearby habitats. We used network properties (network size and specialization indices) and bee species turnover to examine temporal and spatial variation of flower-visitation interaction networks in general and in bee species composition in detail across habitats. In total we found 121 bee and 89 plant species involved in the interactions. Results suggest that bees were limited by floral resources because the largest networks, highest diversity, and largest abundances were found at the forest edge and in the farmland which hosted higher amounts of flowers and a more homogeneous distribution of resources in space and time. Forest in the study area is characterized by (1) lower flower density and (2) more humid conditions relative to the farmland. We therefore suggest that the species-rich and structurally diverse farmland acts as a “pollinator rescue” which supports bee communities in the natural forest. We advise conservation managers and politicians to conserve the structural richness of the farmland to (1) preserve bee diversity within the farmland and (2) conserve positive effects of the farmland on bee activity in the forest remnant.     

Identification of an aliphatic epoxide and the corresponding dihydrodiol as novel congeners of zearalenone in cultures of Fusarium graminearum

The mycotoxin zearalenone (ZEN) is produced by various Fusarium fungi and frequently found as a contaminant in food and feed. There are reports in the literature that several closely related analogues of ZEN are also formed in cultures of Fusarium species. We have therefore analyzed the organic extract from a 40 day culture of Fusarium graminearum by LC-DAD-MS and detected 15 compounds, which could be congeners of ZEN because of their ultraviolet, mass spectroscopy, and tandem mass spectroscopy spectra. In addition to confirming the previously reported α- and β-stereoisomers of 5-hydroxy-ZEN and 10-hydroxy-ZEN, we identified seven ZEN congeners for the first time. One of the major novel congeners was shown by nuclear magnetic resonance spectroscopy and chemical synthesis to have the structure of an aliphatic ZEN epoxide, whereas two minor products proved to be the corresponding dihydrodiols. In addition, three stereoisomers of a cyclization product of the dihydrodiols, carrying a spiro-acetal group, were identified as fungal products for the first time. The latter may be artifacts, because the ZEN epoxide and dihydrodiol are unstable under acidic conditions and rearrange easily to the spiro-acetal compounds.     

Trace and nutrient elements in manure, dung and compost samples in Austria

In Austria, farm animals are estimated to produce about 20×10⁶ ton of excrements annually. In order to predict possible changes of the inorganic compositions of the target soils from various organic fertilizers, mean compositions of excrements, composts and sewage sludges have been compiled on a dry weight basis. Although the high amounts of K and P were beneficial, there were some high concentrations of Na in biogas residues and pig manures. Intense additions of Cu, Zn, and Se are reflected in high loads in the respective excrements, and these amounts in some instances exceeded the threshold limits for soil contamination. Selenium addition to arable soils can be regarded as beneficial, however, as Austria is a low Se area. Composts and sewage sludges were higher in Al and lithophilic trace elements than were the excrements. Factor analysis traced phosphates as the main source of Cd. Cr in processed matrices was significantly higher, and abrasion from tools should be considered in future investigations. Other unwanted trace elements, like Ni, Pb, As and Hg, were found at a rather low concentration.