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.     

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.     

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.     

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.     

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.     

Dermal and serological response against Pseudomonas aeruginosa in sheep bred for resistance and susceptibility to fleece-rot

Genetically select lines of Merino sheep have been bred at Trangie (NSW Agriculture and Fisheries) for resistance (R) or susceptibility (S) to fleece-rot and flystrike. It is believed that fleece characters are primarily responsible for the R or S phenotype. When transferred to the wetter coastal environment of Sydney, R and S sheep with no more than 6 weeks wool cover, continued to show significant differences in the incidence and severity of fleece-rot dermatitis. To test the hypothesis that these sheep might also exhibit differences in their local skin reactions and immune responsiveness, 3 intradermal injections of killed Pseudomonas aeruginosa were administered at monthly intervals. After primary intradermal challenge, R sheep had a higher incidence of skin induration and a stronger inflammatory response (increased induration diameter) than S sheep. Compared to S sheep, R sheep also developed higher levels of circulating antibodies against whole cell antigen and both inner and outer membrane proteins of P. aeruginosa. These responses were maintained in R sheep with each consecutive challenge while S sheep showed a decline in their immune responsiveness. Differences in antibody response against outer membrane proteins were also detected when antigenically naive sheep from each genetic line were sensitised by epicutaneous challenge with P. aeruginosa under experimental wetting conditions. Intradermal challenge of these animals 6 months later with outer membrane proteins, revealed a late maximum (72 h) in the development of induration diameters for R sheep while S animals showed maximal induration diameters by 24 h. However, there was no significant difference in induration response between 24 h and 72 h within each group of sheep.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Efficacy of ivermectin in a controlled-release capsule for the control of breech strike in sheep

Objective To investigate the efficacy of ivermectin in an intraruminal controlled-release capsule (CRC) against blowfly strike.
Design Pen and field trials with controls.
Animals Pen studies: Two breech strike trials involving 60 Romney and 60 Merino sheep. One body strike trial using 100 Merino sheep.
Field trials: Eight trials in New Zealand used 1000 Romney and Romney-cross sheep. Fifty Merino lambs in one trial in Australia.
Procedure Pen studies: Sheep were allocated to two equal groups. One was not treated, the other sheep received a CRC that delivered ivermectin at 20 μg/kg/day for 100 days. In the breech strike trials, each animal was given an oral laxative 2 days before exposure to adult Lucilia cuprina . In the body-strike trial, the sheep sheep were kept wet to increase susceptibility prior to the release of blowflies.
Field trials: Fifty or 200 sheep allocated to equal groups of nontreated or treated with the CRC and grazed at pasture exposed to natural blowfly challenge.
Results Pen studies: Breech strikes developed in 24 of 60 controls but in none of 60 CRC-treated sheep. There was a 35% reduction in the number of CRC-treated sheep struck on the body.
Field trials: The average number of breech strikes in CRC-treated sheep was reduced by 86% (P < 0.001). The number of body strikes in the treated groups was a reduced by 27% (P < 0.05).
Conclusion The ivermectin CRC is a useful aid in controlling breech strike, but provides only moderate reduction in the incidence of body strike.     

THE EFFECT OF ANTHELMINTIC TREATMENT AND OTHER MANAGEMENT FACTORS ON THE INCIDENCE OF BREECH STRIKE IN MERINO SHEEP

SUMMARY Repeated scouring and soiling of the breech region with faeces rendered mulesed, Merino sheep susceptible to breech strike. Anthelmintic treatment of ewes before and after lambing and of lambs 6 to 8 weeks old reduced intestinal trichostrongylosis, scouring and consequent breech strike. Wether lambs tended to be more susceptible than ewe lambs and sheep grazing long pastures were struck more frequently than those on short pastures.     

不同补饲方案对妊娠绒山羊冬春体况及胎儿发育的影响

结合放牧,给妊娠70天的绒山羊补饲精料和粗料,可使其在冬末早春处于增重状态。随着补饲水平的提高,母羊增重、羔羊初生重及初生羔羊皮肤的总体毛囊密度、次级毛囊密度和次级毛囊数与初级毛囊数的比值(S/P)均有不同程度的提高,但初级毛囊密度并不受影响。母体较胎儿对改善营养更敏感,胎儿快速增重与次级毛囊生长同期进行。羔羊出生时绝大多数初级毛囊已进入活动状态,而次级毛囊尚未开始活动。初生羔羊较成年山羊具有较低的S/P值和较高的总体毛囊密度。     

THE OVIPOSITIONAL RESPONSE OF THE AUSTRALIAN SHEEP BLOWFLY, LUCILIA CUPRINA, TO FLEECE-ROT ODOURS

SUMMARY The ovipositional response of Lucilia cuprina flies to odours emanating from fleece-rot lesions of greasy wool in which Pseudomonas aeruginosa bacteria proliferated, was studied. Fractionation of the fleece-rot odours was carried out by bubbling the volatile components through hydrochloric acid and sodium hydroxide solutions to remove basic odours and acidic odours respectively. It was found that the acidic/neutral odours of fleecerot wool, when perfused into wet, greasy wool, stimulated L. cuprina to oviposit. On the other hand, the basic/neutral odours of fleece-rot wool were virtually unattractive to the gravid fly. Similarly, the acidic/neutral odours emanating from fleece-rot lesions of clean wool from which the non-fibre components, wax, suint and epithelial debris, had been removed by scouring, were found to be unattractive to the gravid fly in choice tests.     

THE BLOWFLY STRIKE PROBLEM OF SHEEP IN NEW SOUTH WALES

A field survey was undertaken between 1972-76 to reappraise the nature of the blowfly problem in New South Wales. For 2 years, 1972-1974, some 80,000 sheep were kept under observation and 12,481 strikes were reported, most due to Lucilia cuprina. Breech strike was still the basic problem but tail strike associated with scouring had become an important component where pastures have been improved. Breech strike was controlled at minimal cost by managerial practices such as docking tails the correct length--second joint-space palpable ventrally (midway down the vulval orifice in ewes) for radically mulesed lambs and the third joint-space (tip of vulva in ewes) for all other lambs-mulesing at lamb marking, mid-season crutching, determining the cause of scouring and applying the appropriate preventative or remedial measures. Thus the use of insecticides could be reserved for the control of body strike in young sheep in the odd wet years and poll strike in horned rams. Major outbreaks of body strike occurred in 1973/74. Body strike worried graziers most because of its unpredictability, sudden onset and scale. and only failing insecticides were available for control.     

THE IMPORTANCE OF THE RADICAL MULES OPERATION AND TAIL LENGTH FOR THE CONTROL OF BREECH STRIKE IN SCOURING MERINO SHEEP

SUMMARY While the radical Mules operation reduced the incidence of breech strike from 59% to 13% in scouring sheep, the problem was further alleviated by docking lambs' tails at the correct (medium) length. Docking lambs' tails very short strongly predisposed radically mulesed ewes and wethers to faecal soiling and breech strike (20% struck). Radically mulesed sheep with tails docked midway down the vulval orifice in ewes, and the corresponding length in wethers, were rarely struck (3%) and did not appear to require crutching to prevent breech strike associated with scouring or urine staining.     

云南半细毛羊不同发育阶段皮肤毛囊性状的发育规律研究

本研究选择了 58只母羔 ( 38只单羔、2 0只双羔 ) ,分别于初生、断乳、6月龄、周岁时采取皮肤样品 ,采用横切和纵切连续切片法 ,在皮脂腺水平上观测皮肤毛囊群结构及毛囊性状发育规律。结果表明 :云南半细毛羊皮肤毛囊群结构为三元型 ,毛囊群呈长椭园形 ,皮脂腺较发达 ,毛囊较少弯曲 ,生长方向一致。毛囊性状初生时与断乳、6月龄、周岁时差异极显著 (P <0 0 1 ) ,其余各年龄段间除皮肤厚度和真皮层厚差异显著 (P <0 0 5)外 ,其余差异都不显著 ,说明毛囊性状在断乳 ( 4月龄 )时已基本稳定 ,断乳时的毛囊性状即可代表周岁时的毛囊性状。初生、断乳、6月龄、周岁时的皮肤总毛囊数 (个 /mm2 )分别为4 7 4 4± 7 73、2 9 0 0± 6 4 9、2 9 2 9± 6 4 2和 2 9 79± 6 0 7,S/P值分别为 3 52± 0 91、6 0 0± 1 1 3、6 6 3± 0 95和 7 39± 1 2 6。单双羔在毛囊发育上有不同 ,这种差别差异不显著 ,但数量上的差异一直持续到断乳     

A postal survey of blowfly strike occurrence in two Queensland shires

OBJECTIVE: To describe the occurrence of blowfly strike in sheep flocks in two shires located in south-eastern Queensland. DESIGN: Postal survey of woolgrowers within Stanthorpe and Inglewood shires. PROCEDURE: Questionnaire posted to woolgrowers in June 1999 seeking information on the monthly occurrence of flystrike and number of sheep at risk. RESULTS: Incidence of body strike and breech strike between August 1998 and May 1999 was 1.1 and 0.5%, respectively. The highest incidence of body strike and breech strike was reported in lambs (6.1%) and weaner sheep (1.5%), respectively. The seasonality of the incidence of body strike was bimodal (November and February), whereas the seasonality of the incidence of breech strike was unimodal (April). Occurrence of body strike within a 3-month period in flocks located within 40 to 50 km of each other was significantly (P < 0.05) clustered. CONCLUSION: Body strike appears to be more common than breech strike in the study area, mainly affects lambs and weaners and high-risk periods occur during late spring and autumn. Study results provide valuable information for planning blowfly strike control programs in the area such as timing of management procedures, use of fly traps), and enable the economic impact of flystrike on the industry in this area to be assessed.     

力克斯兔被毛生物学特性研究

力克斯兔的初级毛囊、次级毛囊于胚胎的18－24天先后出现，基皮肤表皮、真皮的发生与分化于胚胎的24天已基本完成，26胎龄时，初级毛囊结构分化完全，并可见到皮脂腺，26胎龄至仔兔出生，是表皮和毛囊分化出的各组成成分的进一步生长阶段。仔兔出生以后，皮肢表皮和毛囊的结构均无明显变化，但表皮厚度稍有增加、毛囊仍继续向真皮，只是远不及胚胎期迅速。表上的增长及毛囊的生长速度，在不同部位之间无显著差异，而不同胎龄（月龄）之间存在显著或极显著的差异。力克斯兔皮肤的毛囊群结构很有规律，每一毛囊群由2－6个扇形分布的亚毛囊群组成，每一亚毛囊群中又含有5－12个分生毛囊和衍生分生毛囊。力克斯兔出生以后，其衍生分生毛囊数的增加几科与体表面积的增大呈比例，致使各月龄之间毛囊密度无显著差异，但不同部位之间，毛囊密度差异显著。力克斯兔被毛因粗毛含量少、分布均匀、直径也小， 毛纤维短、细，且粗细毛长度一致，密度大、强度大、伸度小（与新西兰白兔比较），从而构成了力克斯兔被毛具有弹性强、柔软性好、平整、美观、经久耐磨等特征。通过扫描电镜及光学显微镜对力克斯兔、新西兰白名锿安哥拉兔三个不同类型的兔种的兔毛纤维鳞片排列形态及髓腔结构的观察，发现不同类型之间，鳞片的排列形态不同，但髓腔结构的差异不明显。     

Blowfly strike in sheep flocks as an example of the use of a time-space scan statistic to control confounding

The use of a time-space scan statistic--defined by a cylindrical window with a circular geographic base and height corresponding to time--was investigated as a method of detecting clustering in veterinary epidemiology whilst controlling confounding. The example data set consisted of farmer-recorded occurrence of body strike and breech strike between August 1998 and May 1999 in 26 sheep flocks located in two local government areas of southeastern Queensland, Australia. This information was derived from a questionnaire survey mailed to farmers. Potentially confounding factors included in the investigation were flock size (< or = median, > median), flock structure (proportion of lambs, wethers, ewes and rams), pesticide application for flystrike control (yes, no) and rainfall (< or = median, > median). The total sheep population within selected flocks was 92,660; 1012 (1.09%) and 518 (0.56%) cases of body strike and breech strike were reported in 16 and 10 flocks, respectively.Clustering analyses of body strike and breech strike were undertaken separately, because different predisposing factors are associated with these diseases. Significant clustering of body strike (28.76 degrees S, 151.82 degrees E) during March 1999 and breech strike (28.73 degrees S, 151.16 degrees E) between February and May 1999 was detected. Adjusting for flock structure, flock size, pesticide use and rainfall did not alter the most likely cluster of body strike identified--although the relative risk changed (> 10%) after adjusting for flock structure. Adjustment for flock structure and rainfall resulted in different clusters of breech strike being identified.     

不同品种绵羊皮肤毛囊中角蛋白关联蛋白8-1基因差异表达研究

试验旨在研究不同品种绵羊皮肤毛囊中角蛋白关联蛋白8-1（keratin associated protein 8-1,KAP8-1）基因相对表达量,从而明确KAP8-1基因对绵羊皮肤毛囊发育的调控作用。采用Real-time PCR SYBR GreenⅠ染料法,测定KAP8-1基因荧光定量Ct值,所得结果采用2-△△Ct法计算相对表达量。结果表明,南非肉用美利奴羊（♂）×东北细毛羊（♀）组、南非肉用美利奴羊（♂）×小尾寒羊（♀）组、杜泊羊（♂）×小尾寒羊（♀）组3个品种羊皮肤毛囊内KAP8-1基因均有表达,且三者相对表达量的比值为7.56∶2.19∶1。说明KAP8-1基因对皮肤毛囊发育、羊毛品质差异均具有一定的调控作用,且品种之间存在一定的差异。     

CORYNEBACTERIUM PSEUDOTUBERCULOSIS INFECTION OF SHEEP: ROLE OF SKIN LESIONS AND DIPPING FLUIDS

Caseous lymphadenitis (CLA) infection was established experimentally in a total of 30, 2-tooth merino wethers. In the first experiment a broth culture of the causative organism, Corynebacterum pseudotuberculosis was placed directly on to a freshly shorn area on the right shoulder of 21 sheep after pretreatment with a defatting agent, water or 4 different commercial sheep dips. Within 6–13 days focal skin lesions appeared on 7 sheep and these were followed by abscessation of the right prescapular lymph node. Lung lesions of CLA developed in 6 sheep; 5 of which had skin lesions. In the second experiment C. Pseudotuberculosis broth culture was applied over the right shoulder region of 14 sheep, 24 hours post shearing. The 7 animals had only 1 application of the culture and the remaining 7 had 4 applications on consecutive days. A total of 9 of the 14 sheep developed skin lesions and subsequent CLA in the right prescapular lymph nod but there was no significant difference between the 2 methods of application. As part of the second experiment a broth culture of C. pseudotuberculosis was added to a commercial arsenical sheep dip and 2 hours later sprayed on to the right side of sheep shorn 24 hours or 2 weeks previously. Within 6–13 days all 14 sheep treated in this way developed skin lesions from which C. pseudotuberculiosis was recovered in dense pure growth. Healing time of skin lesions in all affected sheep ranged from 17–72 days post inoculation. A serological test to detect the presence of C. pseudotuberculosis antitoxin was used at regular intervals on all experimental sheep. The earliest positive reaction in an affected sheep was recorded 4 weeks post inoculation. In 23 known affected sheep tested at 35 weeks post inoculation, 10 were positive to the Zaki test. No false positive reactors were recorded. The localisation of focal lung lesions in the interstitial tissue suggests that pulmonary abscessation caused by C. pseudotuberculosis develops via the haematogenous route.