Effect of feed type and essential oil product on equine chewing activity

The ingestive and post-digestion effect of a blend of special essential oil compounds (EO) on eating, chewing and faecal parameters were measured in horses. Ingestive effects appear after no adaptation. Post-digestion effects appear after adaptation. Six Icelandic horses were assigned to two groups in a Latin Square subplot design with EO treatments to four different roughage types and four different concentrates. The horses were fed four different roughage meals and two different concentrate meals on each of the four sampling days. Eating time and saliva were observed during meals. Jaw movements (JM) were recorded using a special chewing halter. Eating time was derived from JM and related to DM intake. The size characteristics of faecal particles were measured by using image analysis. All chewing characteristics measured were significantly affected by roughage (p < 0.001) and concentrate type (p < 0.01). EO had a significant ingestive effect on the frequency of observed saliva during concentrate meals. No significant (p < 0.05) post-digestive or ingestive effect of EO was found for any measured chewing characteristic, which was reflected in the absence of effect on faecal particle dimensions. In conclusion, effect of type of roughage and concentrate was more significant than potential effects of EO.     

In vitro heparinization of canine whole blood with low molecular weight heparin (dalteparin) significantly and dose‐dependently prolongs heparinase‐modified tissue factor‐activated thromboelastography parameters and prothrombinase‐induced clotting time

Background: Low‐molecular‐weight heparin (LMWH) is being used increasingly in veterinary medicine for both treatment and prophylaxis of thromboembolic disease, but no predictable patient‐side method exists to monitor its effect. Objectives: The aim of this study was to evaluate thromboelastography (TEG) and prothombinase‐induced clotting time (PiCT) assays for detecting hemostatic alterations following in vitro heparinization of canine whole blood with dalteparin (Fragmin). Methods: Citrated whole‐blood samples were collected from 7 clinically healthy dogs. Dalteparin was added at concentrations of 0, 0.156, 0.625, 1.25, and 2.5 U/mL of whole blood. TEG was performed using heparinase cups with tissue factor (TF, 1:50,000) and kaolin as activators. Reaction time (R), clotting time (K), angle (α), and maximum amplitude (MA) were recorded. PiCT and anti‐FXa activity were measured in plasma. Results: With TF, increasing concentrations of dalteparin significantly prolonged R and K and significantly decreased α and MA. K, α, and MA ratios were significantly different from baseline at all dalteparin concentrations and R was significantly different from baseline at concentrations of 0.625, 1.25, and 2.5 U/mL. With kaolin, only R was significantly different from baseline at dalteparin concentrations of 0.625 and 2.5 U/mL. PiCT detected dalteparin concentrations ≤ 0.625 U/mL, with a good linear correlation (r²=.96, P<.0001). Conclusion: These results suggest that TF‐activated TEG and PiCT assays should be further evaluated as promising new methods for evaluating the effect of LMWH, using doses in the recommended clinical range and prospective clinical studies.     

QTL analysis of Cercospora leaf spot resistance in sugar beet

The inheritance of Cercospora leaf spot resistance in sugar beet was investigated by means of quantitative trait loci (QTL) analysis of a segregating population of 193 individuals, using 110 AFLP and 35 restriction fragment length polymorphism (RFLP) markers. Five QTL were found through composite interval mapping on linkage groups 1, 2, 3, and 9, respectively, two of which were linked on linkage group 3. The significance of these QTL was tested by permutation analysis The QTL had mostly additive, but also certain negative dominance effects; all the resistance alleles came from the Cercospora-resistant parent. Each quantitative trait locus accounted for 7-18% of the phenotypic variation, leaving 37% of the variation unexplained. The results are discussed in relation to the potential use of marker-assisted breeding for Cercospora leaf spot resistance in sugar beet.     

Comparison of the difference method and 15N technique for studying the fate of nitrogen from plant residues in soil

We compared the dynamics of net mineralization of nitrogen (N) derived from white clover material (Ndfc) as measured by the difference and the ¹⁵N methods in a pot experiment with a sandy loam (15°C and pF 2.4) planted with Italian ryegrass. On day 22, mineralized Ndfc (soil mineral N plus plant N uptake) was 5.8% and 1.3% of added N for the ¹⁵N and the difference methods, respectively. The discrepancy was reduced on day 43. On day 64, the relationship was reversed, and on day 98 the values given by the two methods were 22.8% and 29.5%, respectively. The results obtained by the two methods were linearly correlated (r = 0.987) and, on average, did not differ significantly. Nevertheless, the different temporal patterns led to appreciably different parameter values as estimated by fitting of a reparameterized Richards model. On day 22, clover amendment reduced mineralized N derived from soil (Ndfs) by 3.4 mg N pot^–1. The reason for this was that the clover amendment led to a reduction in plant growth and uptake of Ndfs, most likely because of allelopathy, while mineral Ndfs did not increase correspondingly. Clover-induced Ndfs in the microbial biomass of 5.1 mg N pot^–1 suggested that the mineral Ndfs not taken up by plants had been reimmobilized. Towards the end of the experiment, clover-induced Ndfs in the biomass declined to 1.5 mg N pot^–1, while mineralized Ndfs due to clover amendment increased to 5.1 mg N pot^–1. The results strongly suggested that this increase was caused by a real stimulation of humus N mineralization by clover amendment rather than by isotope displacement or pool substitution. Received: 5 May 1997     

Three-dimensional deformation measured in an alaskan glacier

Measurements of movement along 28 boreholes reveal the three-dimensional flow field in a 6 million cubic meter reach of Worthington Glacier, a temperate valley glacier located in Alaska. Sliding at the bed accounted for 60 to 70 percent of the glacier's surface motion. Strain rates in the ice were low from the surface to a depth of about 120 meters, but then increased rapidly toward the bed. Ice deformation was not affected by temporal changes in the sliding rate. The three-dimensional pattern of motion indicates that plane strain, which is often assumed by models, is a poor approximation of this viscous flow.     

Dietary zinc concentration and lipopolysaccharide injection affect circulating trace minerals,acute phase protein response,and behavior as evaluated by an ear-tag–based accelerometer in beef steers

To assess plasma trace mineral (TM) concentrations, the acute phase protein response, and behavior in response to a lipopolysaccharide (LPS) challenge, 96 Angus cross steers (average initial body weight [BW]: 285 ± 14.4 kg) were sorted into two groups by BW (heavy and light; n = 48/group), fitted with an ear-tag–based accelerometer (CowManager SensOor; Agis, Harmelen, Netherlands), and stagger started 14 d apart. Consecutive day BW was recorded to start the 24-d trial (days −1 and 0). Dietary treatments began on day 0: common diet with either 30 (Zn30) or 100 (Zn100) mg supplemental Zn/kg DM (ZnSO₄). On day 17, steers received one of the following injection treatments intravenously to complete the 2 × 3 factorial: 1) SALINE (~2–3 mL of physiological saline), 2) LOWLPS: 0.25 µg LPS/kg BW, or 3) HIGHLPS: 0.375 µg LPS/kg BW. Blood, rectal temperature (RT), and BW were recorded on day 16 (−24 h relative to injection), and BW was used to assign injection treatment. Approximately 6, 24 (day 18), and 48 (day 19) h after treatment, BW, RT, and blood were collected, and final BW recorded on day 24. Data were analyzed in Proc Mixed of SAS with fixed effects of diet, injection, diet × injection; for BW, RT, dry matter intake (DMI), plasma TM, and haptoglobin-repeated measures analysis were used to evaluate effects over time. Area under the curve analysis determined by GraphPad Prism was used for analysis of accelerometer data. Body weight was unaffected by diet or injection (P ≥ 0.16), but there was an injection × time effect for DMI and RT (P < 0.05), where DMI decreased in both LPS treatments on day 16, but recovered by day 17, and RT was increased in LPS treatments 6 h post-injection. Steers receiving LPS spent less time highly active and eating than SALINE (P < 0.01). Steers in HIGHLPS spent lesser time ruminating, followed by LOWLPS and then SALINE (P < 0.001). An injection × time effect (P < 0.001) for plasma Zn showed decreased concentrations within 6 h of injection and remained decreased through 24 h before recovering by 48 h. A tendency for a diet × time effect (P = 0.06) on plasma Zn suggests plasma Zn repletion occurred at a greater rate in Zn100 compared to Zn30. These results suggest that increased supplemental Zn may alter the rate of recovery of Zn status from an acute inflammatory event. Additionally, ear-tag–based accelerometers used in this study were effective at detecting sickness behavior in feedlot steers, and rumination may be more sensitive than other variables.     

Weekly Measurements over One Year of Ammonia Concentrations and Surface Exchange Fluxes at a Danish Heathland with Passive Wind-Vane Flux Samplers in an Aerodynamic Gradient Configuration

The present study aims to establish the annual NH₃ deposition to an inland heathland in Denmark using a micro-meterological approach with passive wind-vane flux samplers. The integrating samplers were replaced at weekly intervals from May 1995 to May 1996. The average concentration, 2.05 μg m^-3 at the heathland is at a moderate level when compared to heathlands in other parts of Europe. The average deposition velocity was 0.83 cm s^-1 which is within the range of depositon velocities found for other heathlands in Europe. The average canopy resistance was found to be relatively high, 61 s ^-1. The measurements yielded a total NH₃-N deposition of 2.4 (± 0.9) kg ha^-1 yr^-1 with a data coverage of 71% for 1995/1996. In 40% of this time the flux is regarded as zero because the flux is not significant different from zero. In 60% of this time the significant fluxes varied from –0.052 μg m^-2 s^-1 (deposition equal 16.4 kg N ha^-1 yr^-1) to 0.089 μg m^-2 s^-1 (emission equal 28.2 kg N ha^-1 yr^-1). The method is only able to direct measure significant fluxes down to the equivalence of 0.010 μg m^-2 s^-1 (approximately 3.2 kg ha^-1 yr^-1). Therefore the exact deposition cannot be determined by the applied method at very low deposition sites such as a coastal heathland in Denmark. In a high-deposition area as in the central Netherlands the method gave significant fluxes with a 100% data coverage for a two month period.     

Empirical modelling of the kinetics of phosphate sorption to macropore materials in aggregated subsoils

Preferential transport of phosphate through macropores increases the significance of phosphate sorption to macropore wall materials compared with bulk soil materials. Therefore we studied the kinetics of phosphate sorption to soil bulk materials from the Ap and Btg horizons, from the iron oxide-poor (Albic) centres and from iron oxide-rich (Red) exteriors of the fractures in a clayey pseudogley in batch at initial phosphate concentrations (P₀) up to a maximum of 650 μm and at sampling times up to 7 days. Uptake of phosphate was least in the phosphate-rich Ap, and the Albic material also adsorbed little. By contrast the Red material sorbed phosphate strongly. By plotting the logarithm of the solution phosphate concentration against log time, two or three different kinetic regions could be distinguished: a fast reaction within the first minute of reaction; a lag period at intermediate to large initial values of phosphate concentration (P₀); and a steady slow reaction. The lag phase cannot be described satisfactorily by the well-known adsorption models. The Langmuir equilibrium expression produced rather good fits at any fixed time of reaction, but the estimated adsorption maximum increased steadily with time. Empirical models were fitted to the data, among them a ‘lag-linear’ model developed to include the lag phase. The relative contribution of the fast reaction to total adsorption during 7 days decreased from 50 to 80% at small P₀ to less than 10% at large P₀ values. The fraction of fast-adsorbed phosphate followed the order Red > Btg > Albic > Ap regardless of P₀; the slow reaction is, by a log–log rate, ranked Albic ? Btg > Red > Ap for P₀ < 20 μm and Red > Btg > Albic > Ap at larger initial concentrations. The Albic material does not minimize the risk of phosphate leaching through macropores, as demonstrated by its small P sorption capacity, the relatively slow adsorption rate and its small actual P content.