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dc.contributor.advisorFourie, L. J.
dc.contributor.advisorKok, D. J.
dc.contributor.authorMeintjes, Theresa
dc.date.accessioned2017-03-20T09:17:26Z
dc.date.available2017-03-20T09:17:26Z
dc.date.issued1999-09
dc.identifier.urihttp://hdl.handle.net/11660/5937
dc.description.abstractEnglish: Sheep scab, which is caused by the mite Psoroptes ovis, has been and is still today an impediment to sheep husbandry in many countries throughout the world. Despite the economic impact, sheep scab remains a serious veterinary problem in South Africa. The broad objectives of this study were to determine the adverse effects of P. ovis on the host, with special reference to Merino and Dorper sheep, and to examine various possible foci of infestation and host specificity. Furthermore, the effects of abiotic factors (relative humidity and temperature) on the off-host survival of P. ovis were determined. The nature and extent of sheep scab in small scale, predominantly black farming communities, were assessed and compared to commercial predominantly white farming communities. The results revealed the following: With the exception of neutrophils, haematological values remained within the normal range for infested Merino and Dorper sheep, during a 14 week assessment period. For both sheep breeds the albumin and globulin values were higher than the normal range during the entire 14 week observation period. Both sheep breeds displayed a slight decrease in albumin values and a slight increase in globulin values. At the termination of a 16 week assessment period, uninfested control Merino sheep gained a mean ·body mass of 3.44 kg which represented a Il. 60% increase in body mass, compared to the mean body mass decrease (6.4 kg) of infested Merino sheep. This represented a 23.43% decrease in body mass. The mean body mass of the infested Dorper sheep increased over the 16 week period by 4.56 kg (15.11%) compared to the 5.88 kg (18.28%) of the uninfested control Dorper sheep. Comparative studies on the rate of sheep scab lesion development indicated that there were profound differences between sheep breed and season. During the summer assessment of 1997 the mean lesion size on the Merino sheep expanded from 1.0 cm2 at two weeks post infestation to 342.2 cm2 at eight weeks post infestation, compared to the mean lesion size of 0.406 cm2 and 59.0 cm2, respectively, recorded at two and eight weeks post infestation on the Dorper sheep. Lesion growth for both sheep breeds were greater during the winter. Attempts to artificially infest Boer and Angora goats failed. No clinical signs of sheep scab developed on the goats during a nine week observation period. When a single artificially infested Merino and Dorper sheep were introduced during winter into a flock of nine uninfested sheep for each breed, it took 14 and 8 weeks, respectively, before all the sheep in the flocks displayed clinical signs of sheep scab. During summer it took 10 and 12 weeks, respectively, before all sheep in the two flocks displayed clinical signs of sheep scab. All developmental stages of the mites were found in proximal and distal parts of wool / hair tufts clipped from Merino and Dorper sheep. Immature and mature mites were readily transferred to wool/hair tufts placed onto, and later removed from infested sheep, confirming that direct contact between hosts is most probably the main means of transfer. A maximum mean off-host survival time of 15 days (T = 10°C and RH = 33% and 75%), 10.5 days (T = 10°C and RH = 75% and 90%) and 11.25 days (T = 10°C and RH = 90%) were recorded for nymphs, males and ovigerous females, respectively. The mean egg incubation time varied from 5.9 (±2.58) to 22.14 (±6.53) days. The longest time eggs took to hatch was 31 days (T = 10°C and RH = 75%). The longest mean larval longevity was 9.25 days (T = 10°C and RH = 90%). Under natural fluctuating conditions ovigerous females in glass vials containing Merino wool survived 20 days, compared to a maximum of 17 days of females in glass vials without Merino wool. A survey indicated that 36.36% of the sheep flocks in Botshabelo and 38.46% in Thaba Nchu, respectively, were infested with sheep scab. This high incidence was believed to be due to factors such as communal grazing systems, ignorance on the part of the farmers and the lack of financial means to purchase effective remedies to treat their sheep flocks.en_ZA
dc.description.abstractAfrikaans: Skaapbrandsiek wat deur die myt Psoroptes ovis veroorsaak word was van die vroegste tye reeds, en is nog steeds, 'n belemmering vir die skaapboerdery bedryf Ten spyte van die ekonomiese impak is skaapbrandsiek ook 'n ernstige veeartsenykundige probleem in Suid Afrika. Die oorhoofse doelstellings van hierdie studie was om ondersoek in te stel na die nadelige effek van P. ovis op die gasheer, om die moontlike infestasie bronne en ook gasheer spesifisiteit te ondersoek. Voorts is die effek van abiotiese faktore (relatiewe humiditeit en temperatuur) op die oorlewing van P. ovis weg van die gasheer vasgestel. Die aard en omvang van skaapbrandsiek in klein, oorwegend swart boerdery gemeenskappe was vasgestel deur fisiese ondersoek en vraelysopnames is ook gemaak en vergelyk met soortgelyke vraelysopnames in kommersiële, oorwegend wit boerdery gemeenskappe. Uit die resultate het die volgende aan die lig gekom: Met die uitsondering van neutrofiele, was die hematologiese waardes, gedurende 'n 14 week observasie tydperk, vir beide Merino en Dorperskape binne die normale perke. Vir beide skaaprasse was die albumien and globulien waardes deurgaans, gedurende die observasie tydperk, bokant die normale vlakke. Beide skaaprasse het 'n effense afname in albumien waardes, en 'n effense toename in globulien waardes getoon. Na afloop van 'n 16 week. waarnemingstydperk, het ongeïnfesteerde kontrole Merinoskape 'n gemiddelde liggaamsmassa toename van 3.44 kg (11.60%) getoon, vergeleke met 'n gemiddelde liggaamsmassa afname van 6.4 kg (23.43%) vir geïnfesteerde Merinoskape. Die gemiddelde liggaamsmassa van geïnfesteerde Dorperskape het toegeneem oor' n 16 week periode met 4.56 kg (15.11 %) vergeleke met die 5.88 kg (18.28%) vir die ongeïnfesteerde kontrole Dorperskape. Vergelykende studies tussen Merino- en Dorperskape ten opsigte van die tempo van skaapbrandsiek letselontwikkeling, het aangetoon dat daar merkbare verskille in die : populasie toename van P. ovis is. Gedurende die somer waarnemingstyperk in 1997 het die gemiddelde letselgrootte op Merinoskape toegeneem vanaf 1.0 cm2, twee weke na infestasie, tot 342.2 cm2 agt weke na infestasie. By Dorperskape is gemiddelde letselgroottes van 0.406 cm2 en 59.0 cm2, onderskeidelik, aangeteken twee en agt weke na infestasie. Letselontwikkeling was gedurende die winter vinniger vir beide skaaprasse. Pogings om Boer- en Angorabokke kunsmatig met skaapbrandsiek te besmet, was onsuksesvol. Geen kliniese tekens van skaapbrandsiek het ontwikkelop enige van die twee boksoorte gedurende 'n nege weke observasietydperk nie. Gedurende winter was alle Merinoskape positief geïnfesteer met skaapbrandsiek 14 weke nadat 'n enkele kunsmatig geïnfesteerde Merinoskaap by 'n trop van nege geplaas is. Agt weke na blootstelling (winter) was al die Dorperskape in 'n soortgelyke trop geïnfesteer. Gedurende somer het dit vir Merino- en Dorperskape 10 en 12 weke, onderskeidelik, geneem voordat al die skape in die trop kliniese simptome van skaapbrandsiek getoon het. Alle ontwikkelingsstadiums van die myt is op die proksimale en distale wol- of. haarsnitte, onderskeidelik, van Merino- of Dorperskape gevind. Volwasse asook onvolwasse myte het geredelik oorgedra na wol- en haarsnitte wat op geïnfesteerde skape geplaas is, en later weer verwyder is. Hierdie resultate bevestig die feit dat direkte kontak tussen diere moontlik die hoof metode is waarvolgens die siekte versprei. Die langste gemiddelde oorlewings tydperk weg van die gasheer vir nimfe, mannetjies en vol.wasse wyfies was, 15 dae (T = 10°C en RH = 33% en 75%), 10.5 dae (T = 10°C en RH = 75% en 90%) en 11.25 dae (T = 10°C en RH = 90%), onderskeidelik. Die gemiddelde eierontwikkelingstyd het gevarieër tussen 5.9 (±2.58) en 22.14 (±6.53) dae. Die langste aangetekende tyd vir eiers om uit te broei was 31 dae by T = 10°C en RH = 75%. Die langste gemiddelde larwale oorlewingstyd was 9.25 dae wat aangeteken is by 10ce en RH = 90%. Onder natuurlik veranderende toestande het volwasse wyfies in glasbuisies waarin Merinoskaapwol ingesluit was, oorleef vir 20 dae, vergeleke met die maksimum oorlewingstyd van 17 dae vir volwasse wyfies in glasbuisies sonder Merinowol. 'n Fisiese ondersoek van verskeie skaaptroppe het getoon dat 36.36% van die skape in Botshabelo en 38.46% in Thaba Nchu, onderskeidelik, positief met die skaapbrandsiekmyt besmet was. Hierdie hoë insidensie kan toegeskryf word aan faktore soos gemeenskaplike weidingsareas, onkunde van die boere en die gebrek aan finasieële vermoëns om effektiewe middels vir die behandeling van die skape aan te skaf.af
dc.description.sponsorshipFoundation for Research Developmenten_ZA
dc.description.sponsorshipUniversity of the Free Stateen_ZA
dc.description.sponsorshipBayer Animal Health Divisionen_ZA
dc.description.sponsorshipFort Dodge (Pty) Ltden_ZA
dc.description.sponsorshipHoechst Roussel Vet (Pty) Ltden_ZA
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectSheep scaben_ZA
dc.subjectPsoroptes ovisen_ZA
dc.subjectHaematologyen_ZA
dc.subjectSerum biochemistryen_ZA
dc.subjectHost body massen_ZA
dc.subjectLesion growthen_ZA
dc.subjectMite longevityen_ZA
dc.subjectPsoroptic scabies in sheepen_ZA
dc.subjectSheep -- Parasitesen_ZA
dc.subjectVeterinary parasitologyen_ZA
dc.subjectDissertation (M.Sc. (Zoology and Entomology))--University of the Free State, 1999en_ZA
dc.titleThe bio-ecology of the sheep scab mite Psoroptes ovis (Acari: Psoroptidae) Hering (1835)en_ZA
dc.typeDissertationen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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