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Two hundred Merino wether hoggets were used to examine the effect of Corynebacterium pseudotuberculosis infection (caseous lymphadenitis) on wool production and bodyweight. Sheep which were challenged with C. pseudotuberculosis (artificially infected) and not vaccinated against this disease produced 0.20 kg less clean wool than unchallenged controls during the following 12 months. The incidence of sheep with lesions in the group that was vaccinated prior to challenge was 55% lower than in unvaccinated challenged sheep but their wool production was not significantly different from either the controls or the unvaccinated challenged sheep. Vaccinated sheep were also heavier than unvaccinated sheep 12 months after challenge. These results indicate that caseous lymphadenitis infection may reduce wool production.

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Five groups of 5 shorn and 5 unshorn caseous lymphadenitis (CLA)-free Merino wether weaners were each placed in feedlot pens with 6 Merino ewes, 2 or more of which had CLA lung lesions but no discharging superficial lesions. The sheep were kept together for 5 months. Twenty-eight per cent of the shorn weaners and 20% of the unshorn weaners developed antibodies to Corynebacterium pseudotuberculosis. At slaughter, 8% of the shorn weaners and 12% of the unshorn weaners had CLA lesions in either lungs, lymph nodes or both. In the absence of contact with CLA-infected ewes, a control group of 5 shorn and 5 unshorn weaners failed to develop antibodies to C. pseudotuberculosis or CLA lesions in the same period. This showed that sheep with CLA abscesses in the lungs but no discharging superficial abscesses were a source of C. pseudotuberculosis infection to other sheep.

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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.

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Merino sheep were artificially infested with lice, Damalinia ovis, and the quantity and processing performance of the wool they subsequently produced was compared with those of wool from uninfested sheep. The experiment was conducted in a winter rainfall region of Western Australia, and was repeated yearly for three years. Louse infestation depressed clean wool production by 0.3-0.8 kg per sheep but did not affect live weight. This represented loss of income to the farmer of about $A0.72 to $A1.92 for each louse-infested sheep. The wool from lice-infested sheep, when processed into tops, yielded 4.8 to 7.2% less top and noil, than wool from uninfested sheep and the tops had a lower mean fibre length. This was estimated to cost the processor $A20.79 to $A32.20 per 100 kg of wool processed which originated from lice-infested sheep. Louse populations built up during winter, spring and early summer to reach maximum sizes during mid or late summer when the sheep were shorn and removed from the experiment. In one group of infested sheep retained for the duration of the experiment, louse populations declined after shearing each summer. It appeared that shearing may be more important in limiting growth of louse populations than climatic factors.

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Thirty one isolates of Bacteroides nodosus were obtained from foot lesions observed on cattle at 3 abattoirs. All isolates were similar to the B. nodosus of ovine benign footrot (BFR) in their response to the degrading proteinase test. At one abattoir, where the interdigital lesions were examined in detail, 9 of 10 isolates were obtained from hyperkeratotic lesions with deep fissures. Traceback to 8 of the farms of origin which carried both sheep and cattle, revealed BFR in sheep on 4 farms. The significance of B. nodosus in interdigital lesions in cattle, and its possible pathogenicity, are discussed.

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In a trial to ascertain the effect of dipping on dermatophilosis and production in Merino sheep it was found that sheep which had been dipped had more lesions and produced less wool than undipped sheep. Sheep dipped in water or water plus diazinon had more mortalities associated with dermatophilosis than sheep dipped in arsenic or not dipped. The arsenic appeared to aid healing. There were more mortalities in the sheep dipped in water or water plus diazinon one day after shearing than those dipped 10 days after shearing.

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The removal of course lupin material from lupin stubble paddocks did not reduce the incidence or severity of liver damage caused by the toxins of Phomopsis leptostromiformis. Furthermore, sheep grazing paddocks from which the coarse lupin material had been removed showed body weight changes no different to sheep grazing normal lupin stubbles. In addition, it was found that 6-month old wethers suffered more severe liver damage than 18-month-old wethers, and that lupin material in the paddock remained toxic for a least 6 weeks.

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Tissue removed from nine new cases from 18 hours to 20 weeks after injury by a golf ball contained crystalline and other foreign material to which there was a mild inflammatory reaction followed by macrophagic activity and fibrosis. Optical and electron probe analysis showed that the crystalline material was crushed barytes containing small quantities of muscovite as is typical in natural deposits. The centres of several golf balls were shown to contain essentially identical material. By contrast with previous reports, no zinc sulphide was found. The form and frequent location of the deposits in the conjunctiva as compared with cornea and eyelid is related to the structure of these tissues.

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