AN IN-VITRO TECHNIQUE FOR STUDYING FLEECE-ROT AND FLY STRIKE IN SHEEP

Fleece-rot was experimentally induced in-vitro by wetting and incubating Merino wool samples embedded in serum-agar. Gravid Lucilia cuprina were readily-attracted to these wool culture plates to oviposit. Where serum was freely available to newly-hatched larvae, fly strike and larval development ensued. Using this technique, fleece-rot and oviposition were found to be markedly influenced by the availability of protein and by bacterial activity, particularly that of Pseudomonas spp. The results indicated that odours emanating from wool culture plates containing the latter species played an important role in oviposition. Furthermore, these events varied according to the type of fleece selected, and could be prevented by the addition of a bactericide.     

Experimental production of dermatitis in sheep with Pseudomonas aeruginosa

SUMMARY The attachment, to sheep skin, for 4 days, of control wool pads saturated with sterile culture medium which contained a bacteriostat, induced only a mild dermatitis, whereas wool pads saturated with Pseudomonas aeruginosa culture induced a subacute dermatitis characterised by scaling, microabscess formation and seropurulent exudate. Changes similar to the latter were observed in skin affected by natural fleece-rot which developed spontaneously after 7 days of artificial wetting and in which P. aeruginosa was the predominant species of bacteria. An exacerbatory, if not causal, role for this organism is suggested in the development of the dermatitis associated with fleece-rot and in the exudation of seropurulent material, a step essential in the development of body strike.     

EFFECT OF DISRUPTION OF THE SEBACEOUS LAYER OF THE SHEEP''S SKIN ON THE INCIDENCE OF FLEECE-ROT

It was postulated that integrity of the sebaceous layer on the skin is important in maintaining resistance to fleece-rot. This hypothesis was tested in an experimenta of a 2 x 2 factorial design in which sebaceous layer disruption and wetting were the 2 treatments. The sebaceous layer was disrupted by applying a light petroleum solvent to the skin of the sheep. Fleece-rot occurred in all sheep (20) that were both wetted and had the sebaceous layer disrupted while 9/19 of those wetted but without the sebaceous layer disrupted developed fleece-rot. The fleece-rot lesions observed were more severe in sheep in the disrupted wetted treatments than in the intact wetted treatment. Interpretation of these differences was complicated by a possible reaction of the skin to the solvent used. The differences were not due to an effect of treatment on fleece wettability. No fleece-rot developed in the sheep not wetted and application of the solvent alone did not induce fleece-rot.     

New infection with Corynebacterium pseudotuberculosis reduces wool production

SUMMARY The effect of natural Corynebacterium pseudotuberculosis infection on wool production and quality in sheep was examined in light of evidence that artificial C pseudotuberculosis infection causes wool production loss. A toxin ELISA was used to identify sheep that had been infected with C pseudo tuberculosis. Greasy and clean fleece weights and fibre diameter were compared in infected and uninfected sheep. C pseudotuberculosis infection caused a 3.8 to 4.8% decrease in greasy wool production and a 4.1 to 6.6% decrease in clean wool production. C pseudotuberculosis infection did not affect fibre diameter. The effects of caseous lymphadenitis (the disease caused by C pseudotuberculosis infection) cause an annual loss of about $17 million in wool production to the Australian wool industry.     

OBSERVATIONS ON FIBRE DIAMETER VARIATION OF SHEEP IN RELATION TO FLEECE-ROT AND BODY STRIKE SUSCEPTIBILITY

SUMMARY: A comparative study of various fleece properties known to influence fleece-rot susceptibility was made in a merino flock consisting of sheep which were found to be either resistant or susceptible to fleece-rot and body strike following heavy rains. The fleece properties measured were fibre diameter, fibre diameter variation, wax content, suint content, wax to suint ratio, suint pH, insoluble nitrogen content, wool colour and wettability. Fibre diameter variation, due mainly to the presence of coarse, secondary fibres in the staple, was the only fleece property which differed significantly (p < 0.001) between resistant and susceptible animals. The coefficient of variation of fibre diameter was lowered from a mean value of 22.7 ± 0.3% in susceptible sheep to 20.0 ± 0.3% in resistant sheep. A causal relationship between high fibre diameter variation and fleece-rot susceptibility is suggested. Sheep with irregular fibre size may retain free moisture in the fleece for longer, and thereby become more susceptible to fleece-rot than sheep with uniform fibre diameter, other predisposing factors being equal.     

Production, behaviour and fertility of Merino wethers, hemi-castrates with reduced testicular parenchyma and induced cryptorchids

Greasy wool production, body weight, behaviour and fertility of male, fine wool Merino sheep were studied from 10 to 21 months of age to assess their suitability for wool production. The males were either castrated (wethers), or were hemi-castrated with a vasectomy and reduction (either partially or in full) of the parenchyma of the retained testicle, or the testicles pushed up into the ingulnal canal and the scrotum shortened (induced cryptorchids). There were significant differences among all groups in body weight, with increases being associated with the larger amounts of testicular tissue present. Fertility was low in the induced cryptorchids at 19 months of age. The hemi-castrates with reduced testicular parenchyma were infertile. The hemi-castrates with reduced testicular parenchyma had significantly heavier greasy fleece weights than the wethers and induced cryptorchids, which had similar fleece weights. The wether group suffered a higher prevalence of posthitis in spring and autumn than the hemi-castrate or induced cryptorchid groups. Those hemi-castrates with the largest amount of testicular parenchyma retained and the induced cryptorchids exhibited masculine behaviour patterns and had an increased incidence of fly strike to the head. The principle of hemi-castration and reduction of the testicular parenchyma is shown to be applicable in wool producing flocks with the potential to increase greasy wool production while minimising the management and marketing limitations previously associated with induced cryptorchids.     

Ectoparasites are the major causes of various types of skin lesions in small ruminants in Ethiopia

Ectoparasites are the major causes of skin lesions in animals. Clinical, skin scraping examination, and histopathological studies were conducted to identify and characterize skin lesions in small ruminants caused by ectoparasites. Mange mites, lice, sheep keds, and ticks were collected from the skin of affected animals for species identification. Skin biopsies were collected from affected part of the skin and fixed in 10% neutral buffered formalin for histopathology. Of 1,000 sheep and 600 goats examined, 815 (81.50%) sheep and 327 (54.5%) goats were infested with one or more types of ectoparasites. Sarcoptes scabiei var ovis, Demodex ovis, Psoroptes ovis, Bovicola ovis, Melophagus ovinus, and Amblyomma variegatum and other tick species were identified from sheep. S. scabiei var caprae, Demodex caprae, Linognathus stenopsis, and A. variegatum and other tick species were identified from goats. Gross skin lesions or defects observed on the skin include stained and ragged wool, loss of wool/hair, nodules, crusts, lichenification, and fissuring. Microscopic evaluation of H and E stained skin sections revealed lesions in the epidermal layer such as hyperkeratosis, acanthosis, and melanin inconsistency on the basal cells of the epidermis. Follicular keratosis, perifolliculitis, frunculosis, perivasculitis, and aggregates of inflammatory cells (of acute and chronic type) with fibrosis were experiential in the dermal layer of the skin. Most of the skin lesions caused by ectoparasites are overlapping. Thus, ectoparasites control program should be executed to reduce skin lesions as skins are the major export commodity of the country.     

THE SIGNIFICANCE OF CERTAIN SKIN CHARACTERS OF SHEEP IN RESISTANCE AND SUSCEPTIBILITY TO FLEECE-ROT AND BODY STRIKE

Micro-anatomical differences in skin structure associated with resistance and susceptibility of sheep to fleece-rot and body strike were identified, and found to be of similar magnitude in 2 genetically divergent flocks of medium-woolled Merino ewes. Susceptible sheep were characterised by smaller follicle groups, resulting in higher densities of follicle populations with greater concentrations of the primary follicles (and sudoriferous glands) than in the resistant sheep. From these smaller follicle groups of susceptible sheep, thicker wool fibres grew than were found in the resistant sheep.
The significance of these findings is discussed in relation to the pathogenesis of fleece-rot and body strike of sheep, and the value of the measured skin characters as a method for identifying resistant sheep.     

THE CHANGES IN PROTEIN CONCENTRATION AND BACTERIA OF FLEECE AND SKIN DURING THE DEVELOPMENT OF FLEECE-ROT AND BODY STRIKE IN SHEEP

The sequence of events in the development of fleece-rot and body strike in sheep is described. When sheep were wetted by rain, vast increases in the numbers on microorganisms on the fleece and skin surface occured. Frequently, only one bacterial genus, Pseudomonas, proliferated and produced a bacteriostat to inhibit the growth of other resident flora. The development of fleece-rot lesions was characterised by a sudden substantial increase od soluble protein, presumably plasma protein, onto the skin surface. Pseudomonas spp proliferated on the skin surface and frequently produced extracellular, green pigment. First instar blowfly larvae were observed subsequently in such lesions.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

THE EFFECT OF FASCIOLOSIS ON THE WOOL PRODUCTION OF MERINO SHEEP

The wool production of 20 Merino sheep, artificially infected with Fasciola hepatica, was compared with that of 20 uninfected controls. Sheep of two different ages, 6 months and 4 years, were fed in pens ad lib on two different diets giving high and low planes of nutrition. The midside tatooed patch technique was used to measure the wool production over periods of 6 weeks prior to the infection date, and 0–6, 6–12, 12–18 and 18–24 weeks after this date. Infection with F. hepatica caused a significant reduction of 20–39% in wool production from 6 weeks after infection, irrespective of the age of the sheep or the plane of nutrition. It was found that a reduction in wool production may occur without symptoms of fasciolosis being apparent.     

Differences between strains of Bacteroides nodosus in their effects on the severity of foot-rot, bodyweight and wool growth in Merino sheep

The effects of 3 ovine and one bovine strains of Bacteroides nodosus on the severity of foot-rot, bodyweight and wool growth were compared in Merino sheep in a field experiment. Based on the severity of the induced foot lesions, one strain was classed as virulent (causing underrunning lesions in most feet), one was benign (causing lesions of the interdigital skin only), and 2, including the bovine strain, were of intermediate virulence (causing underrunning lesions in a small proportion of feet). Differences among strains in their effect on foot-rot severity and bodyweight were significant when compared over the whole experimental period, but were not significant at any single time of measurement, because of large differences between replicates. Bodyweight loss and severity of foot-rot caused by the virulent strain were significantly greater than that caused by the benign strain. The intermediate strains lay between these 2 extremes in terms of both bodyweight and foot-rot scores but were not significantly different from either in a statistical sense. Total greasy wool weight did not differ among groups over the whole experiment, but the rate of wool growth during the period when foot lesions were most prevalent and severe was reduced appreciably by the virulent strain and to a lesser extent by the intermediate strains.     

Selection response to fleece weight,wool characteristics,and heritability estimates in yearling Romney sheep

The juvenile live weights, yearling fleece weight and wool characteristics of 2987 Romney progeny of 114 sires born over 9 breeding seasons in a fleece-weight-selected and a random control line were analysed. The high fleece weight-selected flock performance was higher (P < 0.001) for weaning weight and spring weight (6.9 and 8.4%), higher (P < 0.001) for greasy and clean fleece weight (23.8 and 24.3%), and also higher (P < 0.001) for FD by 1 μm, staple length by 6 mm, and wool yellowness by 0.3 unit than random control yearling sheep. Heritability estimates for weaning and spring live weight, greasy fleece weight, clean fleece weight, yield, fibre diameter, staple length, staple strength, loose wool bulk, brightness and yellowness were 0.15, 0.51, 0.35, 0.36, 0.40, 0.57, 0.41, 0.24, 0.46, 0.12 and 0.14 respectively. The heritability estimates are within the range of the long wool sheep breeds studied previously. The high selection differential achieved in the initial screening commercial flocks however facilitated to approach a selection response peak in a shorter selection duration and thus resulted in a non-significant genetic gain in greasy fleece weight when averaged over the 9 years of selection.     

Efficacy of ivermectin jetting fluid against strike by some primary and secondary blowflies of sheep

SUMMARY Merino sheep, which were hand jetted with ivermectin jetting fluid, and untreated sheep were challenged with larval implants of Lucilia cuprina, Lucilia sericata, Calliphora noclva and Chrysomya ruflfacles at intervals of about 2 weeks from 6 to 16 weeks after treatment. Both Lucilia species produced strike rates of about 90% in untreated sheep; the respective rates were lower for Chr rufifacies (55%) and C nociva (60%). Strike rates for the treated group were about 17, 11, and 9% for L cuprina, L sericata, and Chr rufifacies, respectively. Only 1 implant site in the treated group was struck by C nociva. Treated sheep had significantly (P < 0.01) longer time to first strike than did untreated ones for each species of fly. L sericata, Chr rufifacies, and C nociva larvae implanted on treated animals had significantly (P < 0.05) longer time to first strike than did L cuprina larvae.     

非遗传因素对中国美利奴羊(新疆型)主要经济性状的影响

为探索非遗传因素对中国美利奴羊（新疆型）主要经济性状的影响,试验对拜城种羊场1992-2010年共19年周岁母羊鉴定记录进行统计分析,利用最小二乘方差分析法研究出生年份、群别及出生月份3个非遗传因素对周岁母羊鉴定记录的6个主观鉴定性状（头毛评分、毛密度评分、毛弯曲评分、毛细度评分、体型外貌评分、品种等级评分）和4个客观测定性状（毛长度、鉴定时体重、剪毛后体重、剪毛量）共10个经济性状的影响。结果表明,出生年份和群别对10个性状均有极显著影响（P<0.01）;出生月份对除毛密度评分、毛细度评分、品种等级评分外的其他7个性状均有极显著影响（P<0.01）。从毛细度、毛长度和剪毛量3个最主要的性状来看,2008年毛细度评分最高,显著高于2006、2007和2010年（P<0.05）;1996年毛长度最长,显著高于1994、2002、2004、2006、2007、2008和2010年（P<0.05）,与1995、2003和2009年差异不显著（P>0.05）;1995年剪毛量最多,显著高于1994和2009年（P<0.05）,与1992年差异不显著（P>0.05）;除此之外,其他年份的毛细度评分、毛长度和剪毛量均极显著低于最高值（P<0.01）。除2号群外,不同群别各有优势。1、2月份出生的羊较3、4月份好。由此可见,出生年份、群别和出生月份非遗传因素对中国美利奴羊（新疆型）的主要经济性状存在显著影响,因此,在遗传参数估计和遗传评定时应该综合考虑这些因素,从而为获得更为全面、准确的育种值及制定育种方案提供参考依据。     

Traumatic myiasis of horses caused by Wohlfahrtia magnifica.

A survey was carried out in three stud farms with grazing animals, in order to gather data on the prevalence and clinical manifestation of, and the fly species involved in, traumatic myiasis of horses in Hungary. This parasitic disease was recorded in each farm. On the whole, 9.0% (14) of the inspected horses were infested with fly larvae. The affected horses had one infested lesion only, located at the mucosa of the vulva or the vaginal vestibule. The clinical symptoms depended on the age of infestation. Wohlfahrtia magnifica (Diptera: Sarcophagidae) was the only myiasis-causing fly species identified. It was assumed that unknown volatile chemicals might be responsible for the attraction of gravid females to the undamaged vulvar region. These odours are supposed to be produced during different physiological and/or pathological events associated with oestrus, prolonged puerperal period or inflammation of tissues. Daily inspection of grazing horses and early treatment of the affected areas are needed to avert significant damage to the infested horses.     

影响多胎细毛羊主要经济性状的非遗传因素分析

为探索非遗传因素对细毛羊主要经济性状的影响,本文对新疆科创畜牧繁育中心2009—2017年的鉴定记录进行统计分析,利用最小二乘方差分析鉴定年份、年龄及性别3个非遗传因素对多胎细毛羊头部评分、体型评分、密度评分、细度评分、匀度评分、弯曲度评分、油汗评分、总评分8个主观鉴定性状和羊毛长度、剪毛后体重、剪毛量3个客观测定性状的影响。结果表明:鉴定年份对各性状均有极显著影响;性别对密度评分、毛长度、匀度评分、油汗评分、总评分、剪毛后体重、剪毛量均有极显著影响,对头部评分、体型评分、细度评分、弯曲评分的影响均不显著。年龄对细度评分有极显著影响,对头部评分、剪毛量有显著影响,对其他性状的影响均不显著。     

高山美利奴羊重要经济性状遗传参数估计

本研究旨在估计高山美利奴羊重要经济性状的遗传参数,为优化高山美利奴羊选育方案、建设品种完整结构、进行遗传评估及实施育种值选种提供理论技术支撑。采用甘肃省绵羊繁育技术推广站2003—2018年高山美利奴羊核心群数据资料,基于ASReml运用单性状个体动物模型和多性状个体动物模型估计高山美利奴羊体重、产羔数、产毛量、净毛量、净毛率、羊毛纤维直径、羊毛纤维直径变异系数、毛丛长度等重要经济性状的遗传参数。结果表明:高山美利奴羊产羔数为低等遗传力,其他所有性状均为中高等遗传力;大部分经济性状间呈正遗传相关,体重、产毛量、羊毛纤维直径与净毛率间呈负遗传相关,羊毛纤维直径变异系数与体重、产毛量、纤维直径呈负遗传相关。     

Cholinesterase activity in Thysaniezia giardi (Cestoda,Anoplocephalidae)

Summary

The activity of cholinesterase was determined separately in the mature and gravid proglottids of Thysaniezia giardi and its significance is discussed. The mean values of the enzyme in mature and gravid proglottids were respectively 225.60 ± 28.55 and 75.00 ± 11.64 units per gram of wet weight.     

Immunisation of sheep against experimental Pseudomonas aeruginosa dermatitis and fleece-rot associated body strike

Sheep immunised with an experimental Pseudomonas aeruginosa vaccine and unvaccinated control sheep were challenged by induction of experimental dermatitis with the homologous strain. All of 6 control sheep developed ulcerative dermatitis, and 2 of the 6 challenge sites were struck by larvae of Lucilia cuprina. Neither severe dermatitis nor strike occurred in 6 vaccinated sheep. These results were confirmed in an experimental challenge using 3 different serotypes of P. aeruginosa on each of 3 vaccinated and control sheep, although fly-strikes did not occur. In a field trial of the same vaccine, none of 26 vaccinated sheep developed severe exudative, fleece-rot lesions nor were any fly-struck, whereas 61 of 115 control sheep developed severe, exudative, fleece-rot lesions, 21 of these becoming struck by L. cuprina. The isolates of P. aeruginosa recovered from the field challenge experiment were a different serotype to that used in the vaccine.