Associations between soil texture,soil water characteristics and earthworm populations in grassland

Abstract

The aim of the present study was to investigate the relationships between soil physical characteristics and earthworms in a regional-scale field study in Denmark. The earthworm populations along within-field gradients in soil texture were quantified at five field sites, representing dominant soil types of Denmark. Eleven earthworm species were found, but populations were mainly dominated by Aporrectodea tuberculata and A. longa. Despite considerable variation in soil parameters across the five study sites the results suggest that the biomass of anecic worms (or A. longa as a species) was not causally associated with the soil parameters studied. This indicates that there must be other causal factors associated with the abundance (and composition) of anecic worms that are not among the soil texture and structure parameters studied. On the other hand, soil texture (Coarse sand) was associated with the abundance of the dominant endogeic species, A. tuberculata, but not endogeic worms in general. It was hypothesized that anecic and endogeic earthworms might respond to local soil water characteristics rather than soil texture, but this hypothesis could not be confirmed with the present data.     

Genotype × environment interactions in the expression of net blotch resistance in spring and winter barley varieties

The net blotch resistance of barley varieties widely grown in Denmark was studied using data obtained from naturally infected field plots and inoculated disease nurseries in multiple years and locations. Data were analysed by combining two statistical procedures, 1) joint regression (JR) and 2) additive main effect, multiplicative interactive effect analysis (AMMI). Of the total variation for net blotch disease severity, 61–81% could be explained by plant genotype (G) and environment (E) main effects. Of the remaining variation, 77–86% could be explained by significant G × E interactions that were due to genotype sensitivity to the mean environmental disease level and/or to specific reactions of individual genotypes in particular environments. G × E interactions led to a different ranking of varietal performance across environments. There was evidence for G × E interactions caused by the virulence characteristics of the initial inoculum sources. The spring barley varieties Alexis and Bartok and the winter barley varieties Jolante, Ludo, and Rafiki were identified as varieties with high levels of net blotch resistance in all environments. Their performance was little affected by G × E interactions, suggesting that they represent good sources for non-specific resistance. Combining JR and AMMI reduced the dimensionality of complex G × E problems greatly, identified systematic reaction patterns of varieties possibly pertaining to different resistance mechanisms, and described specific and non-specific resistance of varieties by means of few parameters while maintaining the possibility to reconstruct the original data with little loss of information. This is very useful for improving the evaluation of varietal resistance for breeding and disease management purposes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Endogenous Amino Acid Flow in the Duodenum of Dairy Cows

In an inbred pig family founded by commercial breeds, nine microsatellite markers from porcine chromosome 4 were screened to find associations with weight gain and fat deposition traits. In this family showing a linear decrease in weight gain with inbreeding, an association (P <0.05) was found between average daily slaughter gain and markers S0214 and S0373 located at approximately 88 and 98 cM in the linkage map constructed in this study. No association (P >0.05) between backfat thickness and marker genotypes could be detected. Furthermore, the genotypes of the markers showed a surprisingly high degree of heterozygosity in all of the inbred generations, even though the theoretical inbreeding coefficients reaching 0.59.     

Influence of thermal treatment on black currant (Ribes nigrum L.) juice aroma

The influence of thermal treatment on black currant juice aroma was investigated in temperature and time ranges relevant for black currant juice concentration processes, namely, 45, 60, 75, and 90 degrees C. Forty-nine aroma compounds were quantified, and the thermal treatment resulted in concentration increases of most terpenes, aldehydes, furans, and phenols, whereas the concentration of esters slightly decreased. Higher temperatures and longer exposure times had larger effects on the aroma compounds. Odor triangle tests showed no sensory difference between pasteurized juice and juice heated at 60 degrees C, whereas juice heated at 90 degrees C differed significantly from pasteurized juice. It is concluded that a 90 degrees C thermal treatment of black currant juice, which is in the temperature range used for conventional evaporation of black currant juice, has an effect on the aroma and sensory properties.     

A Lysimeter Study to Investigate the Effect of Dairy Effluent and Urea on Cattle Urine n Losses, Plant Uptake and Soil Retention

Loss of nitrate (NO₃ ^?) from grazing land is a major cause of surface and groundwater contamination. These losses increase when N sources such as fertilizer are applied to grazing land. The objectives of this work were to (1) study the impact of dairy effluent (DE) or urea on N losses and plant uptake when DE or urea was applied with and without cattle urine and; (2) determine the effect of organic C rich DE on the fate of urine N. The experiment was conducted using lysimeters that contained Templeton sandy loam soil extracted from a pasture in New Zealand. Application of DE resulted in significantly less (p < 0.05) NO₃ ^? leaching compared with urea in the first year, but not in the second year. Differences between years could be attributed to the comparatively lower C:N ratio of applied DE in the second year, causing relatively greater N mineralization and greater NO₃ ^? leaching. Differences could also be due to cumulative effects of DE (first year applied) on second year NO₃ ^? leaching. Total annual pasture N uptake was similar for DE and urea treatments. During the first year, the average NO₃ ^? concentration was lower when DE was combined with urine compared to urine alone, but not in the second year. The combination of DE with urine resulted in significantly greater (p < 0.01) annual pasture N uptake compared with the urine alone treatment in both years. Urine plus urea resulted in the greatest leaching losses in both years, but its impact on pasture N uptake was mixed. The total leaching loss of N from urine plus DE (90 kg N ha^?1) was similar to urine alone (77 kg N ha^?1) in the second year. Likewise, the annual percentage of ¹⁵N recovered in the leachate from urine plus DE (9%) was not significantly different from urine alone (6%). However, ¹⁵N recoveries revealed that the contribution of urine N to NO₃ ^? leaching was greater when urine was combined with DE (98.8%) compared to urine alone (83%). The greater NO₃ ^? leaching from urine when combined with DE could be a result of greater nitrification due to the low C:N ratio of DE. Additionally, the annual percentage of urine N uptake by the pasture from urine plus DE (29%) was significantly less than from urine alone (39%) (p < 0.01). The application of organic C rich DE had no significant effect on soil N retention or denitrification when combined with urine.     

Puerarin and conjugate bases as radical scavengers and antioxidants: molecular mechanism and synergism with beta-carotene

The 4'-hydroxyl group of puerarin, a C-glycoside of the isoflavonoid daidzein, was shown, using 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) radical cation and stopped-flow spectroscopy and by comparison with the 7-propylpuerarin (A ring derivative) and 4'-propylpuerarin (B ring derivative), to be a more efficient radical scavenger as compared to the 7-hydroxyl group by a factor of 2, a difference increasing upon deprotonation. The difference in radical scavenging agreed with the oxidation potentials (cyclic voltammetry in acetonitrile, 0.1 M Bu4NBF4 at 25 degrees C): E/mV=862+/-3 for puerarin, 905+/-10 for 7-propylpuerarin, and 1064+/-2 for 4'-propylpuerarin relative to ferrocene/ferricenium. In aqueous solution, the reduction potential was shown to decrease for increasing pH, and deprotonation of the 4'-hydroxyl group increased radical scavenging more than deprotonation of the 7-hydroxyl group. The 7-hydroxyl was found to be more acidic (pKa1=7.20+/-0.01 in puerarin and pKa=7.23+/-0.01 in 4'-propylpuerarin) than the 4'-hydroxyl group (pKa2=9.84+/-0.08 in puerarin and pKa=9.51+/-0.02 in 7-propylpuerarin); aqueous solution, ionic strength of 0.1, and 25 degrees C. In phosphatidyl choline liposome of pH 7.4, puerarin and beta-carotene each showed a modest antioxidant activity measured as prolongation of the lag phase for formation of conjugate dienes and using the water-soluble radical initiator APPH with effects of puerarin and beta-carotene being additive. For the lipophilic initiator AMVN, the antioxidative effect decreased for puerarin and increased for beta-carotene as compared to APPH and showed a clear synergism. A regeneration of beta-carotene, effective in the liposome lipid phase as antioxidant, from the cation radical by deprotonated forms of puerarin was demonstrated in 9:1 chloroform/methanol using laser flash photolysis with k2=2.7x10(4) L mol-1 s-1 for the bimolecular process between the cation radical and the puerarin dianion.     

Risk factors for Campylobacter colonisation during rearing of broiler flocks in Great Britain

We investigated the associations between Campylobacter colonisation and management practices and farm characteristics in 603 housed broiler batches originating from 137 farms in Great Britain. All study batches were the initial batch slaughtered from the selected house on enrolled farms. Between 1 and 15 batches were sampled from each farm throughout the study. A total of 34.2% of the batches was Campylobacter positive and multivariable multilevel logistic regression revealed that the risk of Campylobacter colonisation was highest in July (OR = 3.4, CI_95%:1.8; 6.4), August (OR = 3.4, CI_95%:1.9; 6.2) and September (OR = 3.7, CI_95%:1.9; 7.1). Cattle on or adjacent to the farm increased the risk (OR = 1.7, CI_95%:1.1; 2.7), whereas chlorinated drinking water reduced it (OR = 0.5, CI_95%:0.2; 0.9). If the first removed batch from the previous flock in the house had been Campylobacter positive, the first batch of the following flock was also more likely to be colonised (OR = 3.2, CI_95%:2.1; 4.9). This association was more likely due to a persistent risk practice or source of Campylobacter on the farm than a direct carry-over from previous flock.     

Proton nuclear magnetic resonance spectroscopy based investigation on propylene glycol toxicosis in a Holstein cow

Background

It is unknown which metabolites are responsible for propylene glycol (PG)-induced toxicosis, and a better understanding of the underlying mechanisms explaining incidences of abnormal behaviour of dairy cows fed PG is therefore needed.

Methods

The study included three cows of which one developed PG toxicosis. In order to investigate how the metabolism of PG differed in the cow developing toxicosis, proton nuclear magnetic resonance (NMR) spectroscopy was applied on ruminal fluids and blood plasma samples obtained before and after feeding with PG.

Results

PG toxicosis was characterized by dyspnea and ruminal atony upon intake of concentrate containing PG. The oxygen saturation of arterial blood haemoglobin and the oxygen pressure in arterial blood decreased along with the appearance of the clinical symptoms. NMR revealed differences in plasma and ruminal content of several metabolites between the cow responding abnormally to PG and the two control cows.

Conclusion

It is concluded that PG-toxicosis is likely caused by pulmonary vasoconstriction, but no unusual metabolites directly related to induction of this condition could be detected in the plasma or the ruminal fluid.