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A F Carson - One of the best experts on this subject based on the ideXlab platform.

  • effects of crossbred ewe genotype and ram genotype on lamb meat quality from the lowland sheep flock
    The Journal of Agricultural Science, 2002
    Co-Authors: L E R Dawson, A F Carson, B W Moss
    Abstract:

    A study was carried out on five lowland farms in Northern Ireland over 2 years to investigate the effects of crossbred ewe and ram genotype on lamb meat quality. Four ewe genotypes were sourced from six hill farms - Bluefaced Leicester x Blackface (BLXB), Texel x Blackface (TXB), Suffolk x Cheviot (SXCH) and Texel x Cheviot (TXCH). On each farm groups of 20-30 of each crossbred ewe genotype were crossed with Suffolk or Texel sires. Within each of the ram breeds, high lean growth index rams sourced from UK sire reference schemes (SRS) were compared with rams sourced from flocks not involved in objective genetic improvement programmes (control). Throughout the 2 years of the study the ewes lambed at 1 and 2 years of age. Lambs from each of the crosses were slaughtered at 36, 44 and 52 kg live weight. Meat from lambs slaughtered at 36 kg had lower a* values (15.1) than meat from lambs slaughtered at 52 kg (17.0 S.E. 0.47) (P < 0.05). Ewe genotype had no effect on any parameter of meat quality measured. The carcasses of lambs sired by Suffolk rams had a higher pH v than lambs sired by Texel rams (5.70 v. 5.65; S.E. 0.014; P < 0.05) and hue angle was lower (P < 0.05) in Suffolk-sired lambs (32.9°) compared with Texel-sired lambs (35.1°) (S.E. 0.62°). Warner-Bratzler shear force was lower in SRS-sired lambs (2.05 kg/cm 2 ) compared with control-sired lambs (2.36 (S.E. 0.096) kg/cm 2 ; P < 0.05). Carcasses from male lambs had a greater cooking loss (217 g/kg) than from female lambs (196 S.E. 5.7 g/kg) (P < 0.01) and meat from male lambs had greater values for Warner-Bratzler shear force (2.44 kg/cm 2 ) than from female lambs (1.97 S.E. 0.098 kg/cm 2 ) (P < 0.001). Low, but statistically significant (P < 0.05) correlations were obtained between carcass fat measurements and meat quality parameters (r = -0.29 for the relationship between cooking loss and fat depth over the glutens medius P<0.001); r=0.21 for the relationship between fat classification and C* values P < 0.01). When meat quality parameters for each of the fat classes were averaged, significant linear regressions (P < 0.05) were obtained between fat classification and pH v , a* and C* values.

  • effects of crossbred ewe genotype and ram genotype on lamb carcass characteristics from the lowland sheep flock
    The Journal of Agricultural Science, 2002
    Co-Authors: L E R Dawson, A F Carson
    Abstract:

    A study was carried out on five lowland farms in Northern Ireland over 2 years to investigate the effects of crossbred ewe and ram genotype on lamb carcass characteristics. Four ewe genotypes were sourced from six hill farms - Bluefaced Leicester x Blackface (BLXB), Texel x Blackface (TXB), Suffolk x Cheviot (SXCH) and Texel x Cheviot (TXCH). On each farm groups of 20 to 30 of each crossbred ewe genotype were crossed with Suffolk or Texel sires. Within each of the ram breeds, high lean growth index rams sourced from UK sire reference schemes (SRS) were compared with rams sourced from flocks not involved in objective genetic improvement programmes (control). Throughout the 2 years of the study the ewes lambed at 1 and 2 years of age. Lambs from each of the crosses were slaughtered at 36, 44 and 52 kg live weight. Assessed on a 5-point scale, lambs from BLXB ewes had the poorest conformation classification values (2.8) (P < 0.001) compared with 3.0-3.2 (S.E. 0.051) for lambs from the other ewe genotypes. Lambs from TXB, SXCH and TXCH ewes had similar conformation classification values. The differential in conformation classification values between lambs from BLXB ewes and those from the other genotypes was greater when the ewes were crossed with Texel (0.6 units) compared with Suffolk rams (0.3 units) (P<0.05). Differences in conformation between the sire breeds varied according to ewe genotype (P < 0.05). When crossed with BLXB ewes there was no difference between Texel and Suffolk-sired lambs in terms of conformation classification values (2.7 v. 2.8 (S.E. 0.07), while with all the other ewe genotypes, Texel-sired lambs had a significantly higher conformation classification than Suffolk-sired lambs (3.5 v. 3.0 when crossed with T × B; 3.2 v. 2.9 when crossed with SXCH; 3.4 v. 3.0 when crossed with TXCH (S.E. 0.07)). Sire reference scheme-sired lambs had greater growth rates from birth to slaughter (203 g/day) compared with control-sired lambs (193 g/day) (S.E. 3.7 days) (P < 0.05) and were of an improved conformation classification (3.1 v. 3.0 (S.E. 0.04)) (P < 0.01). There was a significant interaction (P < 0.01) between ram breed and ram source on lipid content of the carcass. Within the Suffolk-sired lambs, there was no significant difference between SRS-sired lambs (197 g/kg) and control-sired lambs (190 g/kg) (S.E. 6.2 g/kg). However, within the Texel-sired lambs, SRS-sired lambs had a lower lipid content (174 g/kg) than control-sired lambs (204 g/kg) (S.E. 6.2 g/kg) (P < 0.01).

  • a comparison of scottish blackface and Cheviot ewes and five sire breeds in terms of lamb output at weaning in hill sheep systems
    The Journal of Agricultural Science, 2001
    Co-Authors: A F Carson, D Irwin, D J Kilpatrick
    Abstract:

    A study was carried out on six hill farms in Northern Ireland over 2 years (1996–1998) to investigate the effect of ewe and ram breed on ewe prolificacy, lamb viability and weaned lamb output. On each farm, groups of 40 Scottish Blackface ewes (mature weight of 53·8 kg) were mated to Scottish Blackface, Blue-Faced Leicester and Texel rams. Similarly, groups of 40 Wicklow Cheviot ewes (mature weight 63·7 kg) were mated to Cheviot, Suffolk and Texel rams. All ewe×ram breed combinations were present on each farm. Overall, ewe prolificacy was similar in Blackface and Cheviot ewes (1·52 and 1·55 (S.E. 0·026) lambs born/ewe lambed). However, there was a farm×ewe breed interaction (P < 0·001) indicating that, whilst prolificacy was similar in Blackface and Cheviot ewes on the majority of farms (4 out of 6), on one farm prolificacy was higher in Blackface and on another lower, compared with Cheviot ewes. There were no farm×breed interactions for any of the other main production traits. The proportion of ewes lambing without assistance was higher in Cheviot compared with Blackface ewes when crossed with Texel sires (P < 0·001). Cheviot ewes produced heavier Texel-sired lambs compared with Blackface ewes (4·76 versus 4·51 (S.E. 0·076) kg; P < 0·05). Mortality levels were similar in lambs produced from Blackface and Cheviot ewes. The weight of lamb weaned per ewe was higher in Cheviot compared with Blackface ewes (41·5 versus 38·8 (S.E. 1·01) kg/ewe lambed; P < 0·05). However, the weight of lamb weaned per kg of ewe metabolic weight did not differ significantly between the breeds.With Blackface ewes, the proportion of ewes lambing without assistance was lower for Blue-Faced Leicester compared with Blackface sires (P < 0·001). In addition, the proportion of ewes lambing without assistance was lower (P < 0·001) for Texel compared with both Blackface and Blue-Faced Leicester-sired lambs. Lamb birth weights were higher in Blue-Faced Leicester (P < 0·05) and Texel (P < 0·001) compared with Blackface-sired lambs (4·38, 4·51 and 4·09 (S.E. 0·076) kg, respectively). Similarly, the weight of lamb weaned per ewe lambed was higher (P < 0·001) with Blue-Faced Leicester and Texel compared with Blackface sires (39·8, 38·8 and 33·8 (S.E. 1·01) kg, respectively). The carcass weight of the male lambs 3 weeks post-weaning was significantly higher (P < 0·001) in Blue-Faced Leicester and Texel compared with Blackface-sired lambs (12·5, 12·0 and 10·2 (S.E. 0·20) kg, respectively). Carcass conformation classification was higher in Texel compared with Blue-Faced Leicester and Blackface-sired lambs (P < 0·001). Fat classification was higher in Texel (P < 0·01) and Blue-Faced Leicester (P < 0·05) compared with Blackface-sired lambs. With Cheviot ewes, a greater number of ewes lambed unaided (P < 0·05) with Cheviot and Texel compared with Suffolk-sired lambs. The number of lambs born dead was higher (P < 0·01) with Suffolk compared with Cheviot and Texel-sired lambs (0·14, 0·08 and 0·07 (S.E. 0·016) lambs born dead/ewe lambed, respectively). Growth rates were higher in Suffolk compared with Cheviot-sired lambs (P < 0·05). Overall, Suffolk (P = 0·06) and Texel (P < 0·001) sires produced a greater weight of lamb at weaning compared with Cheviot sires (40·0, 41·5 and 36·9 (S.E. 1·01) kg, respectively). Carcass weight of lambs 3 weeks post-weaning was higher for Suffolk (P < 0·05) and Texel (P < 0·01) compared with Cheviot-sired male lambs. Carcass conformation classification was higher in Texel and Suffolk compared with Cheviot-sired (P < 0·001) lambs. Fat classification was also higher in Texel compared with Cheviot-sired lambs (P < 0·05). Carcass chemical composition was not significantly affected by lamb genotype.

Nora Hunter - One of the best experts on this subject based on the ideXlab platform.

  • comparative susceptibility of sheep of different origins breeds and prnp genotypes to challenge with bovine spongiform encephalopathy and scrapie
    PLOS ONE, 2015
    Co-Authors: Fiona Houston, James Foster, Martin Jeffrey, Lorenzo González, Wilfred Goldmann, Nora Hunter
    Abstract:

    Sheep are natural hosts of the prion disease, scrapie. They are also susceptible to experimental challenge with various scrapie strains and with bovine spongiform encephalopathy (BSE), which affects cattle and has been accidentally transmitted to a range of other species, including man. Incidence and incubation period of clinical disease in sheep following inoculation is controlled by the PRNP gene, which has different alleles defined on the basis of polymorphisms, particularly at codons 136, 154 and 171, although other codons are associated with survival time, and the exact responses of the sheep may be influenced by other breed-related differences. Here we report the results of a long term single study of experimental scrapie and BSE susceptibility of sheep of Cheviot, Poll Dorset and Suffolk breeds, originating from New Zealand and of a wide range of susceptible and resistant PRNP genotypes. Responses were compared with those of sheep from a closed Cheviot flock of UK origin (Roslin Cheviot flock). The unusually long observation period (6–8 years for most, but up to 12 years for others) allows us to draw robust conclusions about rates of survival of animals previously regarded as resistant to infection, particularly PRNP heterozygotes, and is the most comprehensive such study reported to date. BSE inoculation by an intracerebral route produced disease in all genotype groups with differing incubation periods, although M112T and L141F polymorphisms seemed to give some protection. Scrapie isolate SSBP/1, which has the shortest incubation period in sheep with at least one VRQ PRNP allele, also produced disease following sub-cutaneous inoculation in ARQ/ARQ animals of New Zealand origin, but ARQ/ARQ sheep from the Roslin flock survived the challenge. Our results demonstrate that the links between PRNP genotype and clinical prion disease in sheep are much less secure than previously thought, and may break down when, for example, a different breed of sheep is moved into a new flock.

  • quantification of peyer s patches in Cheviot sheep for future scrapie pathogenesis studies
    Veterinary Immunology and Immunopathology, 2007
    Co-Authors: Suzanne G St Rose, James Foster, Nora Hunter, D Drummond, Calum Mckenzie, David Parnham, R G Will, Mark E J Woolhouse, Susan Rhind
    Abstract:

    Abstract Peyer's patches (PPs) are the most probable sites of intestinal uptake of the transmissible spongiform encephalopathy (TSE) agent. The amount of PP tissue varies considerably between different age groups of individuals, and whether this variation is related to susceptibility to TSE infection raises an intriguing possibility. The purpose of this study was to determine the surface area of PP tissue and the number of associated lymphoid follicles in different age groups of Neuropathogenesis Unit (NPU) Cheviot sheep. Terminal ilea were obtained from 33 sheep of different ages. Samples of ileal tissue were collected for immunocytochemistry and immunolabelled for prion protein (PrP). Specimens were then fixed in acetic acid, stained with methylene blue and transilluminated. Image analysis software was used to calculate the area of intestinal and PP tissue. The number of associated lymphoid follicles was determined using a dissecting microscope. Results showed a marked fall in surface area of PP tissue and lymphoid follicle density around puberty (about 8–9 months of age in NPU Cheviot sheep) and both measures remained low throughout adulthood. Using the Spearman's rank correlation coefficient, r s , these two measures were found to be closely correlated ( r s  = 0.899, n  = 33, P r s  = −0.879 ( n  = 33, P r s  = −0.943 ( n  = 33, P

  • vacuolar lesion profile in sheep scrapie factors influencing its variation and relationship to disease specific prp accumulation
    Journal of Comparative Pathology, 2002
    Co-Authors: I Begaramcgorum, Lorenzo González, Nora Hunter, Fiona Houston, M M Simmons, M Jeffrey
    Abstract:

    Abstract Detailed neuropathological examination for vacuolar lesions was performed on the brains of 42 sheep with clinical signs compatible with scrapie. The sheep were grouped according to their breed (Poll-Dorset, Cheviot, Welsh Mountain, Shetland and Suffolk), their PrP genotype at codons 136, 154 and 171 (VRQ/VRQ, VRQ/ARQ, VRQ/ARR and ARQ/ARQ) and the type of infection (experimental infection with SSBP/1, or natural disease). Twenty-two neuroanatomical sites from seven brain regions were examined for vacuolation in the neuropil and five sites at the level of the obex were examined for intraneuronal vacuolation. In 36 sheep, immunohistochemical examination for disease-specific PrP (PrPd) accumulation had also been performed in the same brain regions in an earlier study. The magnitude of total neuropil vacuolation was highest in the naturally affected ARQ/ARQ Suffolk sheep and lowest in the experimentally infected VRQ/VRQ Cheviot sheep and VRQ/ARR Poll-Dorset sheep. The severity of neuropil vacuolation at nine of the 22 neuroanatomical sites examined was used to generate a vacuolar lesion profile, which showed variations between the different sheep groups. These variations could be attributed to both PrP genotype and sheep breed and also possibly to scrapie agent; there was, however, considerable individual variation in lesion profile within sheep groups. All groups showed a similar ratio of neuropil vacuolation to neuronal vacuolation at the level of the obex. Although a positive correlation between neuropil vacuolation and PrPd deposition was generally observed, it was low except for the astrocyte-associated pattern of PrPd accumulation. The study suggests that vacuolar lesion profiles in sheep are affected by several factors and, by comparison with lesion profiles in mice, are of no more than limited value for discriminating between scrapie strains.

  • scrapie free merino and poll dorset sheep from australia and new zealand have normal frequencies of scrapie susceptible prp genotypes
    Journal of General Virology, 1998
    Co-Authors: Nora Hunter, Dorothy Cairns
    Abstract:

    As natural scrapie occurs only in sheep of specific PrP genotypes, one proposed aetiology was that scrapie is simply a genetic disease. However, Cheviot and Suffolk sheep of scrapie-susceptible genotypes are found in Australia and New Zealand, both generally accepted to be scrapie-free countries. A study of more common Australia and New Zealand sheep breeds (Merinos and Poll Dorsets) was carried out in order to obtain more generally applicable estimates of Australia and New Zealand sheep PrP genotype frequencies. We have confirmed that animals of highly susceptible PrP genotypes are found in Australia and New Zealand. Interestingly, the Poll Dorset sheep, although born in New Zealand, were brought to the UK as young adult animals and subsequently remained free of clinical scrapie despite 21% of the sheep having scrapie-susceptible genotypes. These results have implications for the genetic control of occurrence of the equivalent human diseases.

  • prp genotype and agent effects in scrapie change in allelic interaction with different isolates of agent in sheep a natural host of scrapie
    Journal of General Virology, 1994
    Co-Authors: Wilfred Goldmann, Nora Hunter, James Foster, G Smith, James Hope
    Abstract:

    Man and sheep are the two species in which spongiform encephalopathies occur naturally, and in which there are recognized genetic components that predispose an individual person or sheep to clinical disease. In both species mutations/polymorphisms in the PrP gene have been linked to the incidence of natural disease, but only in sheep is it possible to investigate by deliberate exposure to infection whether these polymorphisms are directly correlated with survival time. Cheviot sheep of different PrP genotypes were challenged with one of two isolates of scrapie or an isolate of bovine spongiform encephalopathy and the survival time and incidence of disease were monitored. Genotype analysis showed that dimorphisms in codons 136 and 171 of the ovine PrP gene correlated with control of disease incidence and modulation of incubation time. Crucially, the functional effects of these domains of PrP were shown to alternate depending on the isolate of infecting agent.

W. A Mitchell - One of the best experts on this subject based on the ideXlab platform.

  • Quaternary geology of part of the Kale Water catchment, Western Cheviot Hills
    2016
    Co-Authors: Southern Scotland, W. A Mitchell
    Abstract:

    This study reports on a survey of the middle part of the Kale Water, one of the western Cheviot catchments. Field mapping has revealed the presence of weathered andesite bedrock on many hillslopes. Conversely, evidence for glaciation is limited and restricted to a few exposures of till and meltwater channels suggesting that the last (Late Devensian) ice sheet in this area was cold-based, creating a frozen patch that lay to the east of a thermal boundary related to the Tweed ice stream. A well developed solifluction sheet is found on the lower valley slopes, indicating remobilization of former glacial sediments under periglacial con-ditions when head formed on the upper slopes. A particular feature is the presence of stratified fine gravels forming an upper lithofacies on many hillslopes which appear to be due to reworking of weathered material. Although there has been no dating of these sediments, it is suggested that the upper part of the sequence dates from Late Devensian deglaciation with the soliflucted sediments related to periglacial processes and paraglacial adjustment in association with permafrost degradation at the end of the Dimlington Stadial, and the stratified gravels related to fluvio-nivational processes associated with snowmelt during the subsequent Loch Lomond Stadial

  • quaternary geology of part of the kale water catchment western Cheviot hills southern scotland
    Scottish Journal of Geology, 2008
    Co-Authors: W. A Mitchell
    Abstract:

    Synopsis This study reports on a survey of the middle part of the Kale Water, one of the western Cheviot catchments. Field mapping has revealed the presence of weathered andesite bedrock on many hillslopes. Conversely, evidence for glaciation is limited and restricted to a few exposures of till and meltwater channels suggesting that the last (Late Devensian) ice sheet in this area was cold-based, creating a frozen patch that lay to the east of a thermal boundary related to the Tweed ice stream. A well developed solifluction sheet is found on the lower valley slopes, indicating remobilization of former glacial sediments under periglacial conditions when head formed on the upper slopes. A particular feature is the presence of stratified fine gravels forming an upper lithofacies on many hillslopes which appear to be due to reworking of weathered material. Although there has been no dating of these sediments, it is suggested that the upper part of the sequence dates from Late Devensian deglaciation with the soliflucted sediments related to periglacial processes and paraglacial adjustment in association with permafrost degradation at the end of the Dimlington Stadial, and the stratified gravels related to fluvio-nivational processes associated with snowmelt during the subsequent Loch Lomond Stadial.

  • a reconnaissance of the superficial deposits of the kale water Cheviot hills roxburghshire
    2005
    Co-Authors: W. A Mitchell
    Abstract:

    This report was prepared by Dr Wishart Mitchell, University of Durham on behalf of the British Geological Survey (BGS). It describes a brief study to assess and characterise the superficial deposits and landforms of the district around the Kale Water, Hownam, Roxburghshire. The area mapped forms part of 1:63360 scale Sheet Scotland 18 (Morebattle) which was previously surveyed by James Geikie and published by the Geological Survey of Scotland in 1883. No Survey memoir was prepared for this district although Geikie published a series of informal papers in 1886. The study took the form of a two-week field reconnaissance (August-September, 2003), preparation of two 1:10 000 scale field maps (NT71NE and NT71SE) and a literature review. The report presents the results of the survey and describes the superficial deposits and weathered bedrock of the district with reference to logged natural and temporary sections. It also makes recommendations for future research and mapping. The field maps and images including photographs of sections and landscapes have archived at BGS Murchison House Edinburgh. Notable features of the district include the widespread distribution of weathered bedrock and periglacial deposits. Combined with the paucity of well-developed glacial landforms these features make it difficult to set out a regional glacial history. A modern regional synthesis and stratigraphical review could be achieved with a mapping exercise covering a larger area utilising detailed sedimentological analysis, sampling for dating and an assessment of published OSL dates.

L E R Dawson - One of the best experts on this subject based on the ideXlab platform.

  • effects of crossbred ewe genotype and ram genotype on lamb meat quality from the lowland sheep flock
    The Journal of Agricultural Science, 2002
    Co-Authors: L E R Dawson, A F Carson, B W Moss
    Abstract:

    A study was carried out on five lowland farms in Northern Ireland over 2 years to investigate the effects of crossbred ewe and ram genotype on lamb meat quality. Four ewe genotypes were sourced from six hill farms - Bluefaced Leicester x Blackface (BLXB), Texel x Blackface (TXB), Suffolk x Cheviot (SXCH) and Texel x Cheviot (TXCH). On each farm groups of 20-30 of each crossbred ewe genotype were crossed with Suffolk or Texel sires. Within each of the ram breeds, high lean growth index rams sourced from UK sire reference schemes (SRS) were compared with rams sourced from flocks not involved in objective genetic improvement programmes (control). Throughout the 2 years of the study the ewes lambed at 1 and 2 years of age. Lambs from each of the crosses were slaughtered at 36, 44 and 52 kg live weight. Meat from lambs slaughtered at 36 kg had lower a* values (15.1) than meat from lambs slaughtered at 52 kg (17.0 S.E. 0.47) (P < 0.05). Ewe genotype had no effect on any parameter of meat quality measured. The carcasses of lambs sired by Suffolk rams had a higher pH v than lambs sired by Texel rams (5.70 v. 5.65; S.E. 0.014; P < 0.05) and hue angle was lower (P < 0.05) in Suffolk-sired lambs (32.9°) compared with Texel-sired lambs (35.1°) (S.E. 0.62°). Warner-Bratzler shear force was lower in SRS-sired lambs (2.05 kg/cm 2 ) compared with control-sired lambs (2.36 (S.E. 0.096) kg/cm 2 ; P < 0.05). Carcasses from male lambs had a greater cooking loss (217 g/kg) than from female lambs (196 S.E. 5.7 g/kg) (P < 0.01) and meat from male lambs had greater values for Warner-Bratzler shear force (2.44 kg/cm 2 ) than from female lambs (1.97 S.E. 0.098 kg/cm 2 ) (P < 0.001). Low, but statistically significant (P < 0.05) correlations were obtained between carcass fat measurements and meat quality parameters (r = -0.29 for the relationship between cooking loss and fat depth over the glutens medius P<0.001); r=0.21 for the relationship between fat classification and C* values P < 0.01). When meat quality parameters for each of the fat classes were averaged, significant linear regressions (P < 0.05) were obtained between fat classification and pH v , a* and C* values.

  • effects of crossbred ewe genotype and ram genotype on lamb carcass characteristics from the lowland sheep flock
    The Journal of Agricultural Science, 2002
    Co-Authors: L E R Dawson, A F Carson
    Abstract:

    A study was carried out on five lowland farms in Northern Ireland over 2 years to investigate the effects of crossbred ewe and ram genotype on lamb carcass characteristics. Four ewe genotypes were sourced from six hill farms - Bluefaced Leicester x Blackface (BLXB), Texel x Blackface (TXB), Suffolk x Cheviot (SXCH) and Texel x Cheviot (TXCH). On each farm groups of 20 to 30 of each crossbred ewe genotype were crossed with Suffolk or Texel sires. Within each of the ram breeds, high lean growth index rams sourced from UK sire reference schemes (SRS) were compared with rams sourced from flocks not involved in objective genetic improvement programmes (control). Throughout the 2 years of the study the ewes lambed at 1 and 2 years of age. Lambs from each of the crosses were slaughtered at 36, 44 and 52 kg live weight. Assessed on a 5-point scale, lambs from BLXB ewes had the poorest conformation classification values (2.8) (P < 0.001) compared with 3.0-3.2 (S.E. 0.051) for lambs from the other ewe genotypes. Lambs from TXB, SXCH and TXCH ewes had similar conformation classification values. The differential in conformation classification values between lambs from BLXB ewes and those from the other genotypes was greater when the ewes were crossed with Texel (0.6 units) compared with Suffolk rams (0.3 units) (P<0.05). Differences in conformation between the sire breeds varied according to ewe genotype (P < 0.05). When crossed with BLXB ewes there was no difference between Texel and Suffolk-sired lambs in terms of conformation classification values (2.7 v. 2.8 (S.E. 0.07), while with all the other ewe genotypes, Texel-sired lambs had a significantly higher conformation classification than Suffolk-sired lambs (3.5 v. 3.0 when crossed with T × B; 3.2 v. 2.9 when crossed with SXCH; 3.4 v. 3.0 when crossed with TXCH (S.E. 0.07)). Sire reference scheme-sired lambs had greater growth rates from birth to slaughter (203 g/day) compared with control-sired lambs (193 g/day) (S.E. 3.7 days) (P < 0.05) and were of an improved conformation classification (3.1 v. 3.0 (S.E. 0.04)) (P < 0.01). There was a significant interaction (P < 0.01) between ram breed and ram source on lipid content of the carcass. Within the Suffolk-sired lambs, there was no significant difference between SRS-sired lambs (197 g/kg) and control-sired lambs (190 g/kg) (S.E. 6.2 g/kg). However, within the Texel-sired lambs, SRS-sired lambs had a lower lipid content (174 g/kg) than control-sired lambs (204 g/kg) (S.E. 6.2 g/kg) (P < 0.01).

James Foster - One of the best experts on this subject based on the ideXlab platform.

  • comparative susceptibility of sheep of different origins breeds and prnp genotypes to challenge with bovine spongiform encephalopathy and scrapie
    PLOS ONE, 2015
    Co-Authors: Fiona Houston, James Foster, Martin Jeffrey, Lorenzo González, Wilfred Goldmann, Nora Hunter
    Abstract:

    Sheep are natural hosts of the prion disease, scrapie. They are also susceptible to experimental challenge with various scrapie strains and with bovine spongiform encephalopathy (BSE), which affects cattle and has been accidentally transmitted to a range of other species, including man. Incidence and incubation period of clinical disease in sheep following inoculation is controlled by the PRNP gene, which has different alleles defined on the basis of polymorphisms, particularly at codons 136, 154 and 171, although other codons are associated with survival time, and the exact responses of the sheep may be influenced by other breed-related differences. Here we report the results of a long term single study of experimental scrapie and BSE susceptibility of sheep of Cheviot, Poll Dorset and Suffolk breeds, originating from New Zealand and of a wide range of susceptible and resistant PRNP genotypes. Responses were compared with those of sheep from a closed Cheviot flock of UK origin (Roslin Cheviot flock). The unusually long observation period (6–8 years for most, but up to 12 years for others) allows us to draw robust conclusions about rates of survival of animals previously regarded as resistant to infection, particularly PRNP heterozygotes, and is the most comprehensive such study reported to date. BSE inoculation by an intracerebral route produced disease in all genotype groups with differing incubation periods, although M112T and L141F polymorphisms seemed to give some protection. Scrapie isolate SSBP/1, which has the shortest incubation period in sheep with at least one VRQ PRNP allele, also produced disease following sub-cutaneous inoculation in ARQ/ARQ animals of New Zealand origin, but ARQ/ARQ sheep from the Roslin flock survived the challenge. Our results demonstrate that the links between PRNP genotype and clinical prion disease in sheep are much less secure than previously thought, and may break down when, for example, a different breed of sheep is moved into a new flock.

  • quantification of peyer s patches in Cheviot sheep for future scrapie pathogenesis studies
    Veterinary Immunology and Immunopathology, 2007
    Co-Authors: Suzanne G St Rose, James Foster, Nora Hunter, D Drummond, Calum Mckenzie, David Parnham, R G Will, Mark E J Woolhouse, Susan Rhind
    Abstract:

    Abstract Peyer's patches (PPs) are the most probable sites of intestinal uptake of the transmissible spongiform encephalopathy (TSE) agent. The amount of PP tissue varies considerably between different age groups of individuals, and whether this variation is related to susceptibility to TSE infection raises an intriguing possibility. The purpose of this study was to determine the surface area of PP tissue and the number of associated lymphoid follicles in different age groups of Neuropathogenesis Unit (NPU) Cheviot sheep. Terminal ilea were obtained from 33 sheep of different ages. Samples of ileal tissue were collected for immunocytochemistry and immunolabelled for prion protein (PrP). Specimens were then fixed in acetic acid, stained with methylene blue and transilluminated. Image analysis software was used to calculate the area of intestinal and PP tissue. The number of associated lymphoid follicles was determined using a dissecting microscope. Results showed a marked fall in surface area of PP tissue and lymphoid follicle density around puberty (about 8–9 months of age in NPU Cheviot sheep) and both measures remained low throughout adulthood. Using the Spearman's rank correlation coefficient, r s , these two measures were found to be closely correlated ( r s  = 0.899, n  = 33, P r s  = −0.879 ( n  = 33, P r s  = −0.943 ( n  = 33, P

  • prp genotype and agent effects in scrapie change in allelic interaction with different isolates of agent in sheep a natural host of scrapie
    Journal of General Virology, 1994
    Co-Authors: Wilfred Goldmann, Nora Hunter, James Foster, G Smith, James Hope
    Abstract:

    Man and sheep are the two species in which spongiform encephalopathies occur naturally, and in which there are recognized genetic components that predispose an individual person or sheep to clinical disease. In both species mutations/polymorphisms in the PrP gene have been linked to the incidence of natural disease, but only in sheep is it possible to investigate by deliberate exposure to infection whether these polymorphisms are directly correlated with survival time. Cheviot sheep of different PrP genotypes were challenged with one of two isolates of scrapie or an isolate of bovine spongiform encephalopathy and the survival time and incidence of disease were monitored. Genotype analysis showed that dimorphisms in codons 136 and 171 of the ovine PrP gene correlated with control of disease incidence and modulation of incubation time. Crucially, the functional effects of these domains of PrP were shown to alternate depending on the isolate of infecting agent.

  • transmission of bovine spongiform encephalopathy to sheep and goats
    Veterinary Record, 1993
    Co-Authors: James Foster, James Hope, H Fraser
    Abstract:

    Spongiform encephalopathy has been confirmed in both 9positive9 and 9negative9 lines of Cheviot sheep (selected for their differential response on experimental exposure to scrapie) after intracerebral injection or oral dosing with brain homogenate derived from cattle with bovine spongiform encephalopathy (BSE). With either challenge the incubation period of the disease ranged from 440 to 994 days in both lines of sheep. In a similar experiment, three Anglo-Nubian goats developed the disease 506 to 570 days after intracerebral infection with the same BSE homogenate, and two of three goats developed the disease 941 and 1501 days after oral dosing; the other goat and some sheep from each of the experimental groups remain alive 1720 days after exposure. This is the first report of the experimental transmission of BSE to sheep and goats.