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1.
The comparative efficacy of 13 of the sheep dips currently registered in New Zealand was investigated using sheep infested with the louse Bovicola ovis and carrying wool which was about 10 cm long at the shoulder.

With the exception of one synthetic pyrethroid “pour-on” formulation, all products were able to effect a significant reduction in louse populations, relative to untreated controls, for 37 days after treatment. Only four products proved capable of “eradicating” lice and preventing their re-establishment up to 37 days after treatment.

Variations in manufacturers' recommendations relating to the length of wool at dipping, and mode of application of dips are discussed in relation to the results.  相似文献   

2.
Sheep naturally infested with the biting louse, Bovicola ovis were treated with a range of organophosphorus and synthetic pyrethroid dip formulations. The sheep were killed 42 days after treatment and the pelts examined for evidence of cockle, a nodular condition that appears in some sheep as a response to the presence of lice. Sheep treated to saturation with dip formulations produced more high quality pelts than did sheep treated with low volume, pour-on or spray-on dips. These differences are suspected to arise because louse populations decline more slowly after treatment with pour-ons or spray-ons than with saturation dips. The removal of lice and regression of cockle resulted in a high percentage of first grade pickled pelts. However, processing through to the dyed crust leather stage highlighted lesions in the same pelts that were not apparent at the pickle stage and lead to a substantial increase in the number of downgraded pelts.  相似文献   

3.
Pruritic behaviour and deranged fleece are often used as indicators of sheep louse infestation but the exact relationship between infestation and the observation of signs of pruritis was unclear. Two studies were conducted to examine this association. In the first, 24 castrate Merino sheep were randomly assigned to six pens in groups of four and the sheep in three pens infested with 10 lice each on the right mid-side. Louse numbers were counted, fleece derangement scored and pruritic behaviour assessed periodically on each sheep until 38 weeks after infestation. In the second study a single moderately infested sheep was paddocked for 15 weeks with 32 uninfested sheep and louse numbers and fleece derangement monitored for 41 weeks. In the pen studies, differences between infested and non-infested sheep in fleece derangement and pruritic behaviour first became significant (p<0.05) at 8 and 14 weeks, respectively and at louse densities of 0.06 and 0.27 per 10 cm wool part. Some sheep showed definite signs of deranged fleece as early as 5 weeks after initial infestation. In the paddock studies, it took 37 weeks until lice were detected on all sheep in the flock. The correlation between louse numbers and fleece derangement score first became significant (r=0.44 and p<0.05) at 9 weeks after introduction of the lousy sheep, reached a maximum of r=0.79 (p<0.001) at 22 weeks when 84% of sheep had lice detected and the mean louse density was 0.29 per part, and then declined to r=0.12 (n.s.) at 41 weeks when all sheep were infested and the mean louse density was 3.04 per part. It is concluded that fleece derangement is a powerful early indicator of the presence of lice and that sheep may exhibit signs of pruritis well before lice can be readily found by direct inspection. Fleece derangement may be useful as a basis for establishing economic thresholds for the application of long wool treatments in developing louse infestations but appears to be a poor indicator of louse numbers once the infestation is advanced.  相似文献   

4.
The in vivo pediculicidal effectiveness of 1% and 2% formulations of tea tree (Melaleuca alternifolia) oil (TTO) against sheep chewing lice (Bovicola ovis) was tested in two pen studies. Immersion dipping of sheep shorn two weeks before treatment in both 1% and 2% formulations reduced lice to non detectable levels. No lice were found on any of the treated sheep despite careful inspection of at least 40 fleece partings per animal at 2, 6, 12 and 20 weeks after treatment. In the untreated sheep louse numbers increased from a mean (±SE) of 2.4 (±0.7) per 10cm fleece part at 2 weeks to 12.3 (±4.2) per part at 20 weeks. Treatment of sheep with 6 months wool by jetting (high pressure spraying into the fleece) reduced louse numbers by 94% in comparison to controls at two weeks after treatment with both 1% and 2% TTO formulations. At 6 and 12 weeks after treatment reductions were 94% and 91% respectively with the 1% formulation and 78% and 84% respectively with the 2% formulation. TTO treatment also appeared to reduce wool damage in infested sheep. Laboratory studies indicated that tea tree oil 'stripped' from solution with a progressive reduction in concentration as well as volume as more wool was dipped, indicating that reinforcement of active ingredient would be required to maintain effectiveness when large numbers of sheep are treated. The results of these studies suggest significant potential for the development of ovine lousicides incorporating TTO.  相似文献   

5.
Summary The relative efficacy of 6 shower dip chemicals most frequently used for the treatment of sheep lice (Bovicola ovis) in Western Australia was examined. Groups of 20 sheep infested with lice were treated with products containing either alphamethrin, cyhalothrin, diazinon or diazinon plus piperonyl butoxide and rotenone, formulated as emulsifiable concentrates, and with products containing either coumaphos or magnesium fluorosilicate, formulated as wettable powders. All treatments were applied through a shower dip (Sunbeam model SSD). Inspections for lice were conducted until 9 months after dipping. No lice were found on sheep treated with the 4 emulsifiable concentrate products. In contrast, treatment with the wettable powders, which contained either coumaphos or magnesium fluorosilicate as the active ingredient, did not eradicate the lice infestations. The degree to which the fleece was wetted was assessed 20 minutes after dipping and showed that the wettable powder dips penetrated the fleece less than the emulsifiable concentrate dips. Less fluid was retained by wool staples in an in-vitro test when dip wash was made with the wettable powders. It was concluded that the degree of wetting attained at dipping was an important factor in achieving eradication of sheep lice.  相似文献   

6.
Polymer matrix ear tags containing 13.7% w/w tetrachlorvinphos or 8.5% w/w cypermethrin were applied to Merino wethers infested with lice and carrying two months wool. The cypermethrin tags reduced louse numbers by a maximum of 89% in comparison to controls at 16 weeks after treatment and by 85% at the conclusion of the experiment 38 weeks after application. Lice were not eradicated from any sheep. The number of lice counted on sheep treated with tetrachlorvinphos-impregnated tags was not significantly different from controls.  相似文献   

7.
Infestation of sheep with the biting louse Damalinia ovis is a potentially serious problem which can effect the quality and quantity of wool produced and may reduce weight gains. In this trial treated sheep produced 34 per cent more wool than louse-infested controls and the wool from the treated sheep was of a better quality. The mean liveweight gain in the treated groups was 18 per cent more than that in the untreated group. Treatment with a pour-on formulation of propetamphos at 25 to 50 mg kg-1 gave more than 99 per cent control of lice and protected against reinfestation for four months.  相似文献   

8.
Objective To determine practices for control of louse infestation and blowfly strike in Queensland sheep flocks that are associated with organophosphorous and synthetic pyrethroid residues on wool.
Design Information on residues was obtained from a survey of Queensland wool clips. Information on pesticide use was obtained from a trace-back postal survey. The association between pesticide use and residues was assessed using generalised linear models, controlling for potential confounding by flock location.
Procedure Between 1995 and 1997 Queensland wool clips were randomly sampled. Samples were tested for the presence and amount (mg per kg of greasy wool) of organophosphorous and synthetic pyrethroid pesticides. A questionnaire seeking information on flock characteristics and pesticide use was sent to the manager of each flock from which a wool sample was tested.
Results The median amount of OP and SP residue was 0.8 and 0.25 mg/kg, respectively, and 91 and 95% of wool samples contained < 8 mg/kg of OP and SP residues, respectively. The frequency of OP pesticide use for louse control was significantly (P = 0.005) associated with mean OP residue amount, and the timing of SP use for louse control, in relation to shearing, was significantly (P < 0.001) associated with mean SP residue amount.
Conclusion Most Queensland wool clips have acceptable amounts of residues after the use of OP and SP pesticides, but wool growers can further reduce residues by effectively controlling louse infestation with pesticide applications early after shearing and the use of non-chemical methods of ectoparasite control.  相似文献   

9.
The eradication of lice from Merino sheep with wool up to 65 mm long was achieved by spraying insecticide onto the tip of wool over the sides and back. The insecticides used were cyhalothrin and diazinon in small volumes and at high concentration. When infested sheep were sprayed with 100 ml of cyhalothrin 1,500 ppm or diazinon 36,000 ppm, no live lice were seen 23 days after treatment. When treated sheep were challenged with live lice 100 days after treatment an infestation did not establish. Cyhalothrin at a lower concentration of 1,000 ppm gave excellent control but at 500 ppm only fair control was obtained. Diazinon at 24,000 ppm gave probable eradication and at 12,000 ppm excellent control. If a practical method of applying the insecticide to the tip of wool can be developed, then this technique should provide an effective means of eradicating lice in sheep with long wool. This would greatly assist the sheep industry in controlling and eradicating sheep lice.  相似文献   

10.
The accuracy of visual inspection of wool lots for lice as a test for louse infestation was estimated using information provided by 178 woolgrowers in Queensland, Australia. The estimated sensitivity of inspection was 36% (95% confidence interval, 19-58%) and the specificity was 95% (95% CI, 88-98%). Accuracy was influenced by timing, after shearing, of pesticide application for louse control and by class of pesticide last applied after shearing. Visual inspection was less sensitive (29%) if pesticides were applied >3 months after shearing and less sensitive (21%) if an insect growth regulator was the class of pesticide last used after shearing. Based on 36% sensitivity, it was estimated that 16 inspections would have to be conducted to reduce the false negative test rate to <20% in the study population. We suggest that visual inspection of wool lots could be used to efficiently monitor the prevalence of louse infestations in Queensland sheep flocks. Positive inspection results are more likely to represent real louse infestations, rather than a false test result, in flocks grazed in the more extensive regions of Queensland.  相似文献   

11.
Information provided by wool growers in Queensland, Australia between 1995 and 1997 was used to assess the prevalence and spatial distribution of louse (Bovicola ovis) infestation in sheep flocks. The estimated prevalence of louse-infested flocks was 40% (95% confidence interval, 35-46%). Although the prevalence of infestation was higher in western regions (41-50%) compared to the south region of Queensland (31%), the difference was not statistically significant (P > 0.05). Significant (P = 0.02) clustering of infested flocks was detected in the south region where two foci were apparent. We conclude that Queensland sheep flocks have a moderate prevalence of louse infestation, and that clustering of infestation is not strong. The control of lice is an industry-wide issue that needs to be addressed by most wool growers in Queensland.  相似文献   

12.
The introduction of systemic injectable products, belonging to the avermectin/milbemycin class of antiparasitic compounds, has provided an alternative to dips for sheep scab control. Their main advantages are that they are quicker and safer to use, cause less stress to the sheep (hence can be used in heavily pregnant ewes), do not require any special handling facilities for their use and do not present the same environmental concerns over disposal of spent product. Moxidectin, a second generation milbemycin, has recently been registered as an injectable product for the prevention and treatment of sheep scab. Laboratory and field studies carried out in the UK and Ireland have shown that two injections at a dose rate of 200 mg/kg bwt., 10 days apart, are 100% effective in the treatment of scab. Further studies have shown that a single injection at the same dose rate will protect against infestation or reinfestation for a period of at least 28 days. This long persistent activity has been evaluated in two large-scale field prophylactic trials, one in Ireland and one in the UK, involving over 16,000 sheep, in which it was demonstrated that a single injection of moxidectin is a safe and effective alternative to dips for routine prevention of scab.  相似文献   

13.
Transmission of sheep lice is thought to occur mainly by sheep to sheep contact although the possibility of other sources of infestation is often suggested. This study investigated the period of survival of Bovicola ovis after removal from sheep under varying conditions and assessed the likelihood of new infestations arising from contaminated facilities, wool caught on fences and shearers' footwear.In laboratory studies with lice held away from sheep at 4, 20, 25 and 36.5 degrees C, adults and nymphs survived longest at 25 degrees C (LT90 of 11.7 and 24.1 days for adults and large nymphs, respectively). Nymphs survived longer than adults and lice provided with raw wool survived longer than lice provided with wool that had been degreased. Nymphal lice survived for up to 29 days on unscoured wool at 36.5 degrees C, but the LT50 was less than 9 days in most experiments. In shearing sheds in winter and early spring lice survived for up to 14 and 16 days, respectively. These periods of survival are considerably longer than previously indicated for B. ovis. Most lice dropped out of wool staples attached to a fence within 1 h and only two of a total of 225 lice were still present after 24 h, suggesting that sheep are unlikely to become infested from wool caught on fences. Adult and nymphal lice readily transferred to shearers' moccasins and survived there for up to 10 days, indicating that transmission of lice on the footwear of shearers or other sheep handlers may be a cause of new infestations. Microwaving each moccasin for 5 min killed all lice and may provide a simple method of reducing the likelihood of transmission of B. ovis between properties.  相似文献   

14.
Objective To determine the amounts of organophosphorous and synthetic pyrethroid residues on Queensland wool sampled between 1995 and 1997, and to study if pesticide use changed during the period.
Design Estimated amounts of residues were obtained from a survey of Queensland wool clips, and information on pesticide use was obtained from a trace-back postal survey of flock managers.
Procedure Trends in amounts of residues over time were assessed using analysis of variance and simple linear regression models, and changes in pesticide use was assessed using x2 tests.
Results Significant linear reductions in organophosphorous (P = 0.0012), synthetic pyrethroid (P = 0.0044) and total (P = 0.0002) residues were detected. The proportion of woolgrowers treating for louse infestation (P = 0.0046) treating twice or more (P = 0.0006) and treating more than 4 months after shearing (P = 0.0001) decreased between 1994 and 1997. However, the proportion of growers who treated for blowfly strike (P = 0.0124) and used insect growth regulator pesticides increased (P < 0.0001). The use of handjetting to apply pesticides for blowfly strike control increased and the use of dips decreased (P < 0.0001).
Conclusion Residues of organophosphorous compounds and synthetic pyrethroids reduced in Queensland wool between 1994 and 1997. Although woolgrowers treated for louse infestation less, pesticide use to control blowfly strike increased. The increasing use of insect growth regulators in the industry needs to be monitored.  相似文献   

15.
The persistence of foot-and-mouth disease virus on wool   总被引：1，自引：0，他引：1  
SUMMARY Five Suffolk sheep, held in a high-security isolation room, were exposed for 2 hours to the aerosol of 3 mature pigs that had been infected with foot-and-mouth disease virus (FMDV), strain O1-BFS. The fleeces of 3 of the sheep were contaminated with FMDV at 2 days post exposure (dpe), while at 5 dpe the fleeces of all 5 sheep were more extensively, and more heavily, contaminated. The persistence of FMDV on contaminated wool was examined in vitro using multiple 0.5 g samples of Merino wool that were each contaminated with one of 3 strains of FMDV in tissue-culture medium: O1-BFS, O-Morocco (O-MOR 9/91) or an Asia 1 strain (TAI 1/90). Wool samples were held at either 4°C, 18°C or 37°C, and decay curves were established for each virus at each temperature. These curves predicted that O1-BFS, O-MOR 9/91 and TAI 1/90 would fall below detect-able levels at 72, 70 and 48 days post contamination (pc), respectively, for wool stored at 4°C; at 11, 12 and 12 days pc, respectively, for wool stored at 18°C; and at 57, 68 and 33 hours pc, respectively, for wool stored at 37°C. For wool contaminated with O1-BFS-infected sheep faeces, urine or blood, or with O1-BFS-infected cattle saliva, decay curves predicted virus to persist for 5 to 11 days pc at 18°C. We demonstrated that the simulated scouring of FMDV-contaminated wool at 60° to 70°C would usually reduce virus to below detectable levels. The detergent component of the scouring process had little, if any, antiviral activity, and scouring at 20°C or 50°C had limited impact on FMDV titres . We recommend that either (1) simple storage of FMDV-contaminated wool for 4 weeks at temperatures of 18°C or higher, or (2) scouring of contaminated wool at 60° to 70°C would be sufficient to remove the threat of FMDV-contaminated wool being infectious to other animals .  相似文献   

16.
A fat soluble dye was identified as a suitable colourant for mixing with approved dips during the statutory winter dipping period. The optimum concentration of the dye was 0.4 per cent. It uniformly dyed the sheep and depending on the breed persisted on the fleece for three to six months. Any dye that remained on the wool at shearing (six to eight months after dipping) was washed out by scouring solutions containing non-ionic and anionic detergents. The dye did not alter the efficacy of the commonly used insecticides.  相似文献   

17.
OBJECTIVE: To assess the efficacy of two formulations of triclabendazole and ivermectin in combination against liver fluke (Fasciola hepatica), gastro-intestinal nematodes and sucking louse species in cattle and sheep. PROCEDURE: A study of 540 cattle and 428 sheep at 18 sites throughout Victoria and New South Wales was undertaken. At each site, one group of cattle or sheep was treated with a combined formulation (Fasimec Cattle or Fasimec Sheep), another received ivermectin and triclabendazole separately. In trials on lice infestation, an additional group remained untreated. Samples for faecal egg counts were collected on days -7, 0 (treatment day), +7, +14 and +21 after treatment. Lice assessments were carried out on days -7, 0, +7, +14, +28, +42 and +56. RESULTS: Both treatments were highly efficacious (> 98% efficacy) against liver fluke in cattle and sheep, against three sucking lice species of cattle and against gastro-intestinal nematodes in sheep. There was also no significant difference between treatments in efficacy. Against gastro-intestinal nematodes, Fasimec Cattle was significantly (P < 0.01) more effective than the separately applied ivermectin and triclabendazole treatment. Mean efficacy for the Fasimec Cattle and Ivomec/Fasinex 120 groups respectively, was 97.6% and 94.2% on Day +7, 98.9% and 91% on Day +14 and 98.5% and 92.6% on Day +21. CONCLUSION: The efficacy of Fasimec' Cattle and Fasimec Sheep was at least equal to that of currently registered products (with the same active ingredients) used to control these parasites.  相似文献   

18.
The possibility that Damalinia ovis ingests intact epidermis could explain economically important irritation behaviour by infested sheep. To test this, feeding lice were observed on sheep by hand lens and macrophotography and on light and scanning electron microscope preparations. Aspects of feeding behaviour were described, particularly an epidermal ingestion posture. Louse ingesta were examined in paraffin and frozen sections. Lipid-covered stratum corneum squames were identified in crop, midgut, rectum and faeces. Nucleated keratinocytes from inner epidermal strata were not seen, neither were wool fibres. Vertical frozen sheep skin sections, with feeding lice cryofixed by liquid nitrogen, showed mandibles engaged in the outer stratum corneum of the epidermis. The epidermal origin of some ingesta was confirmed by confirming lice over sheep whose skin was stained with Oil Red O, whose colour was seen in crop, midgut, rectum and faeces of harvested lice. Lipase was found in louse midgut. It was concluded that sebaceous secretions may form an important component of the D. ovis diet. The relative contribution from loose scurf or from stratum corneum squames was not determined. Mechanical stimuli by feeding lice did not seem to be the source of host irritation. The role of sensitising agents in louse brei filtrates was investigated with inconclusive results. Intradermal injections of louse faeces did not elicit a demonstrable response.  相似文献   

19.
The synthetic pyrethroid deltamethrin (DM) containing a trace of [(14)C]-DM was formulated with non-oxidised sterol and wax ester fractions (F1) of wool grease and as the commercial preparation 'Clout-S'. These were applied as a 'backline' strip to sheep immediately after shearing and the concentration of [(14)C]-DM at meridians adjacent to the application strip and at 1/4 and 3/4 of the dorsal-ventral distance was determined. The F1 formulation resulted in significantly greater lateral spread of DM with less remaining at the application site (66+/-8% of dose) 98 days after treatment compared to 'Clout-S' (94+/-3% dose). Autoradiographic examination of treated wool demonstrated that there was more DM in the lower half of the wool staple when formulated in F1 compared to 'Clout-S'. Greater mortality occurred when sheep biting lice Bovicola (Damalinia) ovis were exposed in vitro to wool containing DM from F1 compared to 'Clout-S' treated sheep. In field trials there was increased efficacy against synthetic pyrethroid resistant B. ovis with F1 formulation than with 'Clout-S'. The study has demonstrated that synthetic pyrethroid availability, and therefore efficacy, can be significantly increased when the insecticide is formulated in a 'carrier' with the physicochemical characteristics of wool grease.  相似文献   

20.
OBJECTIVE: To measure the residues of spinosad and chlorhexidine in the tissues of sheep after treatment of blowfly strike. PROCEDURE: Fourteen sheep with natural myiasis and 12 with artificial infestations of Lucilia cuprina larvae had the wool removed over their infestations and were treated with an aerosol wound dressing containing spinosad and chlorhexidine. Sheep were killed up to 14 days after treatment and residues of the chemicals measured in tissues. RESULTS: Chlorhexidine was not detected in any tissue. Residues of spinosad were highest in fat, lowest in muscle and intermediate in liver and kidney. The highest residue detected was 0.2 mg/kg spinosad in perirenal fat 7 days after generous treatment of a sheep with a large fly strike. Residues of spinosad in fat peaked 3 to 7 days after treatment and 1 to 3 days after treatment in liver and kidney. CONCLUSION: These studies present a realistic worst-case in struck sheep and at the highest dose studied, equivalent to 5.8 mg spinosad per kg body weight, the maximum residue detected of 0.2 mg/kg in peri-renal fat was 20% of the Australian maximum residue limit. Muscle, liver and kidney residues of spinosad were also below the Australian maximum residue limits at all times.  相似文献   

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