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排序方式: 共有114条查询结果,搜索用时 15 毫秒
1.
Caecal intussusceptions and typhlocolitis in horses with severe Gastrodiscus aegyptiacus infestation 下载免费PDF全文
Z. Gratwick C. Donnellan P. C. Page A. Viljoen J. Williams C. H. Lyle 《Equine Veterinary Education》2018,30(5):247-254
The intestinal trematode Gastrodiscus aegyptiacus (G. aegyptiacus) has been recognised in equids around the world for many years, but its pathogenicity is yet to be confirmed. This report describes seven cases of severe G. aegyptiacus infestation, including six cases of caecal intussusception. 相似文献
2.
Lindy Joy Rose Sheila Okoth Ilze Beukes Abigael Ouko Marili Mouton Bradley Charles Flett Dan Makumbi Altus Viljoen 《Euphytica》2017,213(4):93
Fusarium verticillioides and Aspergillus flavus cause Fusarium ear rot (FER) and Aspergillus ear rot (AER) of maize, respectively. Both pathogens are of concern to producers as they reduce grain yield and affect quality. F. verticillioides and A. flavus also contaminate maize grain with the mycotoxins fumonisins and aflatoxins, respectively, which has been associated with mycotoxicosis in humans and animals. The occurrence of common resistance mechanisms to FER and AER has been reported. Hence, ten Kenyan inbred lines resistant to AER and aflatoxin accumulation were evaluated for resistance to FER, F. verticillioides colonisation and fumonisin accumulation; and compared to nine South African lines resistant to FER and fumonisin accumulation. Field trials were conducted at three localities in South Africa and two localities in Kenya. FER severity was determined by visual assessment, while F. verticillioides colonisation and fumonisin content were quantified by real-time PCR and liquid chromatography tandem mass spectrometry, respectively. Significant genotype x environment interactions was determined at each location (P ≤ 0.05). Kenyan inbred CML495 was most resistant to FER and F. verticillioides colonisation, and accumulated the lowest concentration of fumonisins across localities. It was, however, not significantly more resistant than Kenyan lines CML264 and CKL05015, and the South African line RO549 W, which also exhibited low FER severity (≤5%), fungal target DNA (≤0.025 ng μL?1) and fumonisin levels (≤2.5 mg kg?1). Inbred lines resistant to AER and aflatoxin accumulation appear to be promising sources of resistance to F. verticillioides and fumonisin contamination. 相似文献
3.
Piet?C.?N.?GroenewaldEmail author Carin?S.?Viljoen 《Journal of Agricultural, Biological & Environmental Statistics》2003,8(1):75-83
This article aims to determine the effect of certain covariates, such as season of kidding, parity, and time of kidding on
the characteristics of the lactation curve of Saanen dairy goats. Characteristics investigated are peak milk yield, time of
peak milk yield, total milk production, persistency, and the relationship between fat and protein in milk composition, as
well as between lactation curves of the same animal in successive years. The analysis is carried out using a hierarchical
Bayesian approach, together with Wood’s model, to model lactation. Posterior distributions of quantities of interest are obtained
by means of the Markov chain Monte Carlo (MCMC) methods. These clearly illustrate the significant effect of especially parity,
but also season and time of kidding on the characteristics of the lactation curve. Total and peak milk yield increase with
increasing parity up to about the third or fourth parity, while peak yield is later for first than for later parities. The
analysis also enables estimation of lactation characteristics of untested animals, prediction of future characteristics and
identification of exceptional animals. 相似文献
4.
5.
The potential of nonpathogenic Fusarium oxysporum and other biological control organisms for suppressing fusarium wilt of banana 总被引:3,自引:0,他引:3
The aim of this study was to evaluate the ability of nonpathogenic F. oxysporum and Trichoderma isolates from suppressive soils in South Africa to suppress fusarium wilt of banana in the glasshouse. Several biological control agents and commercial biological control products were included in the study. The isolates were first screened in vitro on potato dextrose agar. In glasshouse evaluations, the fungal and bacterial isolates were established on banana roots before they were replanted in pathogen-infested soil, while the commercial biocontrol agents were applied as directed by the supplier. Banana plantlets were evaluated for disease development after 7 weeks. In vitro tests showed none of the nonpathogenic isolates suppressed Fusarium oxysporum f.sp. cubense ( Foc ), while slight suppression was observed with the two Trichoderma isolates. Results of the glasshouse evaluations revealed that two of the nonpathogenic F. oxysporum isolates, CAV 255 and CAV 241, reduced fusarium wilt incidence by 87·4 and 75·0%, respectively. The known biological control agent Fo47 did not suppress Foc significantly. Pseudomonas fluorescens strain WCS 417, known for its ability to suppress other fusarium wilt diseases (WCS 417), reduced disease incidence by 87·4%. These isolates should be further evaluated for potential application in the field, independently and in combination. 相似文献
6.
7.
Shirey SB Harris JW Richardson SH Fouch MJ James DE Cartigny P Deines P Viljoen F 《Science (New York, N.Y.)》2002,297(5587):1683-1686
The lithospheric mantle beneath the Kaapvaal-Zimbabwe craton of southern Africa shows variations in seismic P-wave velocity at depths within the diamond stability field that correlate with differences in the composition of diamonds and their syngenetic inclusions. Middle Archean mantle depletion events initiated craton keel formation and early harzburgitic diamond formation. Late Archean accretionary events involving an oceanic lithosphere component stabilized the craton and contributed a younger Archean generation of eclogitic diamonds. Subsequent Proterozoic tectonic and magmatic events altered the composition of the continental lithosphere and added new lherzolitic and eclogitic diamonds to the Archean diamond suite. 相似文献
8.
Summary Observations in outdoor culture beds indicated that food availability and frequency of feeding influenced worm density. In order to study the role of feeding status on the growth and reproduction of Eisenia fetida, pre-clitellate specimens were kept for 180 days under controlled conditions. A control group was regularly provided with freshly produced cattle manure while the experimental groups were fed only sporadically and at some stage even starved by removing some of the substrate. Worm growth, maturation, and cocoon production were monitored. The role of food availability was highlighted by this study. Both worm growth and cocoon production were correlated closely with the feeding pattern that was followed. This study also showed that freshly produced, urine-free, cattle manure proved an excellent food source provided it was added in such a way as to prevent the development of anaerobic conditions. Regular feeding gave high growth and reproduction rates. 相似文献
9.
G J Viljoen S Van Wyngaardt R Gothe L Visser J D Bezuidenhout A W Neitz 《The Onderstepoort journal of veterinary research》1990,57(3):163-168
One-day-old leghorn chickens were used in a laboratory assay to determine the toxicity of crude extracts of the tick Argas (Persicargas) walkerae and of fractions obtained during the isolation procedure. Extracts of unfed and engorged larvae, nymphae and females were tested using this in vivo test system. Only extracts of replete A. (P.) walkerae larvae produced paralysis. A toxic fraction was isolated from replete larval extracts by gel-permeation and ion-exchange chromatography. This fraction with a pI of 4,5, showed 2 major bands corresponding to a Mr of 32 kDa and 60 kDa after SDS-polyacrylamide gel electrophoresis. 相似文献
10.
The filaricidal effects of trichlorphon, arsenic trioxide, sodium antimony biscathecol disulphonate and nitroxynil against Parafilaria bovicola were the subject of this investigation. Levamisole hydrochooride was retested in a separate trial to assess the time required for healing after successful treatment. A comparison of carcass lesions and the percentage of lesion area in untreated controls with those in treated animals reconfirmed the efficacy of levamisole hydrochlorice, while nitroxynil gave more promising results. Both lesions and lesion area were reduced by 76% by the former and by 93% by the latter compound. The other drugs only slightly suppressed P. bovicola activity. After treatment with levamisole hydrochloride, active lesions were still present for 1-4 weeks and visible lesions on slaughter for 8 weeks. Since the visible lesions during the 8 weeks varied from acute to chronic and as they disappeared 9 weeks post treatment, it is suggested that provision should be made for a healing period of at least 9 weeks. 相似文献