Effects of separate and mixed grazing on trichostrongylosis in first- and second-season grazing calves     

P Nansen  P Steffan  J Monrad  J Gr?nvold  S A Henriksen 《Veterinary parasitology》1990,36(3-4):265-276

This study on natural trichostrongylosis in calves on permanent pasture was designed to evaluate whether susceptible first-season calves would benefit from mixed grazing with second-season calves that were more resistant. The experimental plan allowed a comparison of the effect of mixed grazing with that of separate grazing for each age category. The results showed that the first-season calves already grazing with the older animals at the beginning of the grazing season had lower parasite burdens and less clinical symptoms than first-season calves grazing alone. This effect, experienced in 1987 and characterized by a rather high overwintered parasite population on herbage, could not at this early stage be explained by a parasite "diluting" effect exerted by the older animals, but might perhaps be explained by different grazing behaviour of the two age categories. Later in the summer, the first-season calves continued to benefit from the mixed grazing, most likely because the pasture was less contaminated per unit area due to the very low egg deposition of the older animals. The effect of mixed grazing was most clearly reflected in the differences between worm burdens in tracer calves grazing the respective plots at the end of the season. Apparently, the second-season calves did not suffer parasitologically from grazing together with the younger animals. The paper discusses possible long-term implications with combinations of different age categories of cattle.  相似文献   

Arrested development of Ostertagia ostertagi: effect of the exposure of infective larvae to natural spring conditions of the humid pampa (Argentina)     

Lützelschwab CM  Fiel CA  Pedonesse SI  Najle R  Rodríguez E  Steffan PE  Saumell C  Fusé L  Iglesias L 《Veterinary parasitology》2005,127(3-4):253-262

The aim of this study was to determine the effect of environmental conditions and the time of exposure to the conditions required for Ostertagia ostertagi to become inhibited in development at the early fourth larval stage in the host. Two comparable experiments were conducted from September to January, experiment I in 1997-1998 and experiment II in 1999-2000. Twenty-thousand third-stage larvae (L3), freshly obtained from coprocultures, were spread in different parasite-free grass plots at the beginning of September, October and November in each experiment and exposed to environmental conditions throughout spring and early summer. Duplicate plots for each exposure period were grazed for 3 days by two dewormed tracer calves after 1, 2, 3, 4 weeks of exposure during the corresponding month, and the remaining plots were grazed for 3 days at monthly intervals until the end of the experimental period. For each month in both experiments, control animals were inoculated orally with 20,000 L3 newly recovered from coprocultures (week 0 animals; infection controls). The control and tracer calves were sacrificed and their parasite burdens analysed. The time required to obtain greater than 50% inhibited larvae (IeL4) in the tracer animals during September and October was 3 weeks, whereas during November around 60% of the parasites were inhibited after one week of exposure. During the period tested, greater than 50% inhibition was found in concurrence with a photoperiod ranging between 13 and 14 h. The highest proportion of IeL4 (75% average) in the animals was found concomitant with a 14 h 43 min photoperiod. A high correlation between the percentage of inhibition and day length was established (0.870 p < 0.001 and 0.815 p < 0.001 for experiment I and II, respectively). In both years, the capacity for developmental arrest was lost by the end of December, when the photoperiod begins to decrease, suggesting either a disappearance of the induction stimulus, or that an excess of the stimulus could block the mechanism of inhibition. The induction time was extended 2 weeks in all months tested when the coprocultures were maintained in the dark (experiment II), suggesting that accumulation of the light stimulus contributes to shortening of the induction time. The data presented here would suggest that photoperiod is a key environmental factor for the induction of hypobiosis.  相似文献   

Zum Vorkommen vonCholodkovskya viridana in Nordwestdeutschland (Homoptera: Adelgidae)     

A. -W. Steffan 《Journal of pest science》1964,37(4):55-59

Zusammeunfassung Auf Grund von Beobachtungen im Sommer 1962 kann dieAdelgidae-SpeciesCholodkavskya viridana (Cholodkovsky 1896) als neu für Nordwestdeutschland nachgewiesen werden. Ihr Auftreten an Lärchen-Anpflanzungen im Oldenburger Baumschulgebiet wird besprochen. Es konnte festgestellt werden, daß der Anholozyklus dieser Art drei voll fortpflanzungsfähige Alata-exsulans-Generationen besitzt, wie sie bisher nur vonGaumont für Populationen in Mittelfrankreich beschrieben worden sind. Auch die 3. Alata-exsulans-Generation, die im September auftritt, bringt noch sich in den Zyklus einfügende Pseudohiemosistentes hervor. Phänologische und morphologische Charakteristika dieser Art werden angeführt und ihre Unterschiede zu den Generationen anderer in Mitteleuropa anLarix decidua Mill. lebenderAdelgidae-Species besprochen.

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Summary Observations in summer 1962 provedCholodkovskya viridana (Cholodkovsky 1896) to be a newAdelgidae-species in northwestern Germany. Its occurrence in larch plantations in the Oldenburg nursery-district is discussed. In the anholocycle of this species three alata-exsulans generations with complete capability of propagation could be identified, as has only been demonstrated byGaumont with populations in central France. Even the third alata-exsulans generation which appears in September, produces pseudohiemosistentes joining in the life-cycle. Phenological and morphological characteristics of this species are described and their differences from otherAdelgidae-species onLarix decidua in central Europe are discussed.

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Résumé Des observations en été de l'année 1962 ont prouvé qu'en Allemagne du Nord-Ouest,Cholodhovskya viridana. (Cholodkovsky 1896)(Homoptera: Adelgidae) est une nouvelle espèce. Son occurrence dans des plantations de mélèzes au district des pépinières oldenbourgiennes est discutée dans cette publication. L'anholocycle de cette espèce consiste de trois générations d'alata-exsulans, bien capables de se propager, comme l'avait décritGaumont seulement pour des populations en France centrale. Même la troisième génération des alata-exsulans, apparaissant en septembre, produit des pseudohiemosistentes qui s'adaptent bien au cycle. Les propriétés phénologiques et morphologiques de cette espèce sont décrites dans cette publication et les differences entre eux et les autres espèces desAdelgidae de l'Europe centrale sur Larix decidua sont discutées.

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Cattle herd inspections and fly trapping for the detection of the Old World screw‐worm fly (Chrysomya bezziana)     

R Urech  S Muharsini  RS Tozer  Sumartono  PE Green  GW Brown  JP Spradbery  DG Mayer  Y Tack Kan  A Kison 《Australian veterinary journal》2014,92(1-2):28-32

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Dose–Response Studies for Pituitary and Testicular Function in Male Dogs Treated with the GnRH Superagonist, Deslorelin     

A Junaidi  PE Williamson  GB Martin  MA Blackberry  JM Cummins  TE Trigg 《Reproduction in domestic animals》2009,44(5):725-734

We tested the effect of dose of GnRH superagonist on pituitary and testicular function in a study with four groups of four male dogs. The Controls received blank implants and the other three groups received implants containing 3, 6 or 12 mg deslorelin (d ‐Trp⁶‐Pro⁹‐des‐Gly¹⁰‐GnRH ethylamide). In all deslorelin‐treated groups, there was initially an acute increase in plasma concentrations of LH and testosterone, followed by declines such that both hormones became undetectable after approximately 12 days. There was a dose–response in some of these early aspects of the hormone profiles. With respect to long‐term effects of treatment, the 12‐mg dose had significantly greater effects than the smaller doses for the duration of minimum testicular volume [366 ± 77, mean ± SEM (3 mg), 472 ± 74 (6 mg), and 634 ± 59 (12 mg) days], absence of ejaculate [416 ± 88 (3 mg), 476 ± 83 (6 mg), and 644 ± 67 (12 mg) days], undetectable plasma concentrations of LH and testosterone [367 ± 64 (3 mg), 419 ± 72 (6 mg), and 607 ± 69 (12 mg) days], the delay until complete recovery of LH and testosterone secretion [394 ± 65 (3 mg), 484 ± 72 (6 mg) and 668 ± 47 (12 mg) days], and the delay until testes had regrown to normal volume [408 ± 77 (3 mg), 514 ± 74 (6 mg), 676 ± 59 (12 mg) days]. The time taken to restore full ejaculates was also longest for the 12‐mg dose: 716 ± 67 (12 mg) days vs 440 ± 66 (3 mg) and 538 ± 83 (6 mg) days after implantation. There was no correlation between delay to recovery of normal ejaculate quality and body mass. We conclude that the dose–response relationship with deslorelin implants is not expressed with respect to the degree of suppression of reproduction, but on the maximum duration of suppression and thus to delay until recovery.  相似文献   

Persistent activity of a single late-season treatment with ivermectin against gastrointestinal trichostrongyles and lungworm in young calves     

P Steffan  P Nansen 《Acta veterinaria Scandinavica》1990,31(2):237-242

The present study was designed to assess the persistent efficacy of ivermectin against gastrointestinal trichostrongyles and lungworm (Dictyocaulus viviparus) when given late in the season to young calves naturally exposed to infection on permanent pasture. The results suggest that ivermectin prevents the re-establishment of Ostertagia spp. for 2 to 3 weeks, but Cooperia spp. for only 1 to 2 weeks. Re-establishment of lungworm is prevented for a period of at least 3 weeks. The results are discussed in the light of recent studies on the ivermectin effects on experimental or early-season natural infections.  相似文献   

Hepatitis in the green tree frog (Litoria caerulea) associated with infection by a species of Myxidium     

BD HILL  PE GREEN  H A LUCKE 《Australian veterinary journal》1997,75(12):910-911

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SUMO modification of Huntingtin and Huntington's disease pathology     

Steffan JS  Agrawal N  Pallos J  Rockabrand E  Trotman LC  Slepko N  Illes K  Lukacsovich T  Zhu YZ  Cattaneo E  Pandolfi PP  Thompson LM  Marsh JL 《Science (New York, N.Y.)》2004,304(5667):100-104

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Dose tapering for ciclosporin in cats with nonflea‐induced hypersensitivity dermatitis     

Jean Steffan  Elizabeth Roberts  Andrea Cannon  Pascal Prélaud  Peter Forsythe  Jacques Fontaine  Stephen King  Wolfgang Seewald 《Veterinary dermatology》2013,24(3):315-e70

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Sorption/desorption behaviour of sulfonylurea herbicides as affected by the addition of fresh and composted olive cake to soil     

L DELGADO‐MORENO  A PEÑA 《Weed Research》2008,48(5):461-469

The olive industry generates residues which can be applied as amendments to soils in their original form (olive cake) or after composting or vermicomposting processes. The addition, fresh or incubated, of these amendments to soil and of their different organic fractions was studied in relation to the sorption/desorption of three sulfonylurea herbicides, bensulfuron‐methyl, chlorsulfuron and prosulfuron. Herbicide sorption was low or very low, slightly promoted by the addition of the agricultural by‐products, especially olive cake, and mainly affected by pH of the soil solution, with the organic carbon content having no significant effect on herbicide retention. Desorption was only reduced when fresh olive cake was added. The incubation of soil and amendments for 3 months did not modify herbicide sorption, but made desorption reversible except for olive cake. The transformation of the organic matter of the amendments due to humification and maturity processes are likely to be responsible for this behaviour. Different organic fractions were removed to assess the influence of each fraction on sulfonylurea sorption. Only the removal of all studied organic fractions increased herbicide sorption, revealing the role of humin and mineral fractions in this process. Therefore, the use of organic amendments is not useful for reducing the risk of movement of ionisable molecules in soil.  相似文献