排序方式： 共有83条查询结果，搜索用时 312 毫秒
51.
52.
In spite of the role of sulphur (S) as an essential plant nutrient, S-turnover processes in agro-ecosystems are only partially known. The present paper highlights the feasibility of the use of stable S-isotope analysis as a tool to evaluate S-turnover in terrestrial ecosystems. Examples of the usefulness of this approach in forest ecosystems and current research activities to evaluate S transformation processes in agro-ecosystems are shown. 相似文献
53.
René Schreiber Anette Küster Ute Feiler Matthias Grote Rolf Altenburger 《Journal of Soils and Sediments》2011,11(8):1419-1431
Purpose
The objective of this study was to modify a sediment contact protocol to a multiwell plate exposure system which supplements measurement of the fresh weight change (FWC) using the non-invasive effective quantum yield of energy conversion at photosystem II (PS II) reaction centres (Y(II)) in parallel. Since Y(II) is a functional parameter and FWC represents a whole-plant structural response, the determination of a more pronounced response in one of these parameters may hint at the mode of action of contaminants. By the observation of Y(II) at different time points, extrapolation of effect development over time may be gained from modelling. 相似文献54.
Stefan Gunnarsson Jana Pickova Anders Hgberg Maria Neil Anette Wichman Isabelle Wigren Kerstin Uvns-Moberg Lotta Rydhmer 《Livestock Science》2009,123(2-3):306-313
Polyunsaturated fatty acids (PUFA) are essential for the development of the nervous system in animals, and increased concentration of n−3 PUFA in maternal diet improves the cognitive development of mammalian foetuses. In this study the effect of maternal diet fatty acid composition in pigs on the development of the central nervous system, monitored as behaviour of piglets, was investigated using three behavioural tests: recognition of the mother's faeces, back test, and hidden door test.Twenty-seven multiparous Yorkshire sows were split into four groups and fed diets with different content of fat and PUFA throughout pregnancy and lactation. LF (n = 6) was fed a standard diet, HFS (n = 4) a high fat and low PUFA diet, HFO (n = 7) a high n−6 PUFA diet, and HFL (n = 10) a high n−3 PUFA diet.Three behavioural tests were performed on 5–7 randomly chosen piglets per litter (n = 167). Recognition of the mother's faeces was tested in a maze two days after birth. Back test was performed twice (2–4 d and 4 w) and a hidden door test was performed at 4 w. In addition, the brain content of docosahexaenoic acid (22:6 n−3, DHA) of the newborn piglets was determined in treatment groups. Data from the tests were analysed with linear mixed models for each of the tests.Piglets from HFL treatment had significantly higher content of DHA (P < 0.001) and the ratio of n−6/n−3 PUFA was significantly lower in brain tissue (P < 0.001), compared to piglets from the other treatments. In parity 3, means for recognition for mother's faeces were for diets LF, HFS, HFO and HFL; 22.2, 37.0, 26.4 and 18.0%, respectively (P < 0.05), but no other significant effect of diet was found. Piglets in HFS treatment had the shortest latency to make escape attempts and HFO piglets the longest latency in the back test (P = 0.030). No significant effect of sow diet was found on piglet performance in the hidden door test, but intermediate piglets weighing 1410–1619 g had a lower probability of success in hidden door test than piglets weighing < 1410 g (P = 0.028), and ≥ 1875 g (P = 0.027), respectively.It was found that sow diet influenced the DHA content in the piglet brains, but there was no clear effect of sow diet on piglet behaviour. In order to draw any conclusions about possible enhancements of the behavioural development of the piglet more studies need to be performed. 相似文献
55.
Anette Krogen?s Vibeke Rootwelt Stig Larsen Lena Renstr?m Wenche Farstad Arve Lund 《Acta veterinaria Scandinavica》2014,56(1):19
Background
Canine herpesvirus-1 (CHV1) causes a fatal hemorrhagic disease in neonatal puppies and is associated with infertility in female dogs. This study was conducted to assess the status of CHV1 infection in bitches in proestrus or estrus and to investigate possible risk factors by a detailed questionnaire. Blood samples were collected from healthy bitches (n = 193) not vaccinated against CHV1, aged one year or older and admitted for estrus control to the Canine Reproductive Clinical Unit, Norwegian School of Veterinary Science. The serum samples were analysed by immunoperoxidase monolayer assay and serum titers were recorded as the reciprocal value of the highest dilution producing specific cell staining.Results
Altogether, 85.5% of the dogs had CHV1 titers ≥ 80 and were classified as positive. Mean age for dogs included in the study was 4.2 years (95% CI 4.0-4.5), and there was no difference in age between seronegative dogs vs seropositive dogs. When grouping the seropositive dogs into three categories according to the magnitude of the titer, a total of 38.8% of the bitches displayed a weakly positive titer of 80, 44.8% had moderately positive titers of 160 or 320 and 16.4% of the dogs fell into the strongly positive category with titer of ≥640. No association was demonstrated when comparing CHV1 antibody titers to fertility parameters such as previous matings, pregnancies, whelpings, puppies born or condition of puppies. Further, there was no difference in seroprevalence between bitches that had been abroad for a period of time and dogs only living within a Norwegian environment. Samples from dogs collected in summer and fall displayed moderate to high antibody titers indicating recent infection with CHV1. Season, previous birth, and participation in competitions/shows explained 67-78% of the variation in antibody titer.Conclusions
This study demonstrates that CHV1 infection is common in breeding bitches in the eastern part of Norway. Associations with putative risk factors were not identified. However, season, previous whelping, and participation in competitions/shows explained 67-78% of the variation in antibody titer. 相似文献56.
57.
From 1999 til 2003, the influence of pruning intensity on yield, fruit size, and picking efficiency was tested for the ‘Bluecrop’, ‘Bluetta’, ‘Patriot’, and ‘Spartan’ highbush blueberry varieties. The following procedures were compared: no pruning (control), little annual pruning in the late winter, little pruning every 2 years in the late winter, intensive annual pruning in the late winter, intensive pruning every 2 years in the late winter, and complete pruning down to the ground in the late winter before the first vegetation period of the trial. Each kind of pruning led to a decline in yield. Therefore the highest yield was produced by controls, and the lowest yield (40% of the control level) was shown with intensive annual pruning. Pruning also increased the size of the fruits. The smallest size was found for controls, the biggest with little annual pruning. Picking efficiency increased along with fruit size. Little annual pruning seems to be the best pruning method for highbush blueberries. This method indeed leads to a visible decrease in yield, but the positive effects on fruit size and picking efficiency compensate this inevitable disadvantage. So, from the economical point of view, there is a clear advantage for this variant. Both nonpruning and regular intensive pruning have to be avoided. 相似文献
58.
Examination for a viral co-factor in postweaning multisystemic wasting syndrome (PMWS) 总被引：1，自引：0，他引：1
Lohse L Bøtner A Hansen AS Frederiksen T Dupont K Christensen CS Baekbo P Nielsen J 《Veterinary microbiology》2008,129(1-2):97-107
In order to test the hypothesis that a putative co-factor for the development of postweaning multisystemic wasting syndrome (PMWS) in pigs could be of viral origin, we performed extensive virological examinations on organ material from pigs diagnosed with PMWS originating from within a Danish PMWS-transmission study. Virus isolation attempts were carried out on a large panel of different cell types including primary pig kidney cells and lung macrophages, primary rabbit kidney cells and seven established cell lines (MARC-145, ST117, PK15, BHK21, HeLa, Vero, and MDCK). Although these represent cells with susceptibility to a wide range of known viruses, the results did not provide evidence for a specific virus other than PCV2 contributing to the development of PMWS. Furthermore, in order to test whether specific genotypes of PCV2 may trigger the switch from PCV2 infection to clinical disease, we compared complete DNA genome sequences of PCV2 derived from PMWS-positive as well as PMWS-negative pigs. On the basis of the DNA sequences, the PCV2 isolates were divided into two groups. Group 1 consisting of one isolate originating from a herd unaffected by PMWS, with group 2 consisting of nine isolates originating from four PMWS-affected herds, four PMWS-positive pigs plus one unaffected herd. The PCV2 genomes from the two groups showed 95.5% identity. Alignment analyses of the sequences encoding the replicase and capsid protein from group 1 and group 2 PCV2 isolates showed two amino acid differences encoded in the replicase protein, while 19 amino acid differences were predicted among the capsid protein sequences. The PCV2 DNA sequence analysis supports recent observations from studies in USA as well as Europe, which suggest that strain variations may influence the clinical outcome of PCV2 infection. 相似文献
59.
From 2001 to 2005 the influence of the dwarfed apple rootstocks M 9 (clone: Burgmer 984), Fleuren 56, Supporter 1, P 16, P 22, J-TE-F, J-TE-E and M 27 on growth, yield and fruit size of the apple variety ‘Elstar, Elshof’ was investigated on the locations Auweiler, Dresden-Pillnitz, Osnabrück and Wurzen in Germany. All rootstocks induced a less vegetative growth as the rootstock M 9. In comparison with M 9 the crown volume of the trees ranged from 89 (Supporter 1) to 51% (M 27). The highest yield potential showed the rootstock P 16. Her specific yield (kg/m3) was 17% higher than the specific yield of M 9. A higher specific yield and a higher individual fruit size as M 9 only produced the M 9 clonal selection Fleuren 56. J-TE-E produced the lowest specific yield. 相似文献
60.
Irene McNair Michelle Marshall Francis McNeilly Anette Botner Anne-Sofie Ladekjaer-Mikkelsen Isabelle Vincent Brigitte Herrmann Romeo Sanchez Carrie Rhodes 《Journal of veterinary diagnostic investigation》2004,16(2):164-166
A panel of 20 porcine sera was distributed to 5 laboratories across Europe and Canada. Each center was requested to test the sera for the presence of porcine circovirus type 2 antibodies using the routine assays, indirect immunofluorescence assay (IFA) and indirect immunoperoxidase monolayer assay (IPMA), and to determine the titer of each serum. Results from all centers were then compiled and correlated. They demonstrate a wide variation in the titers obtained between laboratories. These differences were dependent on the assay used and the choice of fixative. In general, IPMA gave higher titers than did IFA, and paraformaldehyde gave higher titers than did acetone or ethyl alcohol. This report highlights the need for standardized procedures and biologicals for this virus. 相似文献