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Max Murray - One of the best experts on this subject based on the ideXlab platform.
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Pathophysiology of Trypanosoma congolense infection in two breeds of sheep, Scottish Blackface and Finn Dorset.
Veterinary Parasitology, 1997Co-Authors: E. Katunguka-rwakishaya, Max Murray, P.h. HolmesAbstract:The pathophysiology of Trypanosoma congolense infection was studied in two breeds of sheep, the Scottish Blackface (SB) and Finn Dorset (FD), which were known from previous studies to differ significantly in their susceptibility to haemonchosis, in which anaemia is also the primary pathophysiological effect. It was found that infected SB and FD lambs developed similar intensities of parasitaemia. However, infected SB lambs developed a higher degree of anaemia, more severe thrombocytopaenia and hypoalbuminaemia than infected FD. Following infection, the concentrations of plasma cholesterol, serum phospholipids and total lipids decreased. The decline in these lipid components appeared to be greater in infected SB than in infected FD lambs.
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Influence of soyabean meal supplementation on the resistance of Scottish Blackface lambs to haemonchosis
Research in Veterinary Science, 1996Co-Authors: D.s. Wallace, Quintin Mckellar, K. Bairden, Max Murray, P.h. Holmes, G. Fishwick, J. J. Parkins, M. Gill, J.l. Duncan, Michael J. StearAbstract:Abstract Protein supplementation improves the resistance of sheep to haemonchosis. This experiment investigated the Scottish Blackface breed to establish whether dietary protein supplementation is still beneficial in a genetically resistant breed. Lambs were given either a basal diet or a diet supplemented with soyabean meal to give an additional 80 g crude protein kg dry matter −1 . The lambs were given an initial loading dose of Haemonchus contortus , followed by a trickle infection for 10 weeks. The weight gains of the lambs given the supplemented diet were greater and their carcases were leaner, irrespective of infection status. Infected animals on the basal diet were more anaemic and hypoalbuminaemic than animals receiving the supplemented diet, although there were no statistically significant differences in mean worm burdens or faecal egg counts.
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a comparison of the responses to repeated experimental infections with haemonchus contortus among Scottish Blackface lambs
Veterinary Parasitology, 1995Co-Authors: M.j. Stear, K. Bairden, J.l. Duncan, Max MurrayAbstract:Abstract Twenty helminth-naive Scottish Blackface lambs were given three infections with 10 000 infective larvae of Haemonchus contortus at 8 week intervals. An additional six lambs served as uninfected controls and eight lambs were infectivity controls. The lambs were 7 months old at the start of the infection. Four of the 20 lambs developed severe haemonchosis and were put down during the experiment. The remaining 16 lambs plus uninfected controls were necropsied 8 weeks after the third infection. The mean faecal egg count peaked 6–8 weeks after the first infection, gave a second smaller peak 6–8 weeks after the second infection but produced no peak after the third infection. Mean red blood cell counts fell rapidly during the first infection, then rose gradually during the second and third infections. The mean values suggested that the two infections were sufficient to produce effective immunity in the sheep population but they masked considerable individual variation. Eleven animals appeared relatively resistant following the first infection, while two animals were relatively susceptible to even the third infection. The repeatability of mean faecal egg counts or mean red blood cell counts for each animal during the replicate infections were very high, because the rankings of the individual sheep remained remarkably stable. Faecal egg counts were very strongly correlated with red blood cell counts. Multiple regression analysis showed that four factors—faecal egg counts, red blood cell counts, weight and sex—accounted for essentially all of the observed variation in worm burdens among the lambs. Therefore, under these controlled experimental conditions, additional markers appear unnecessary for the detection of resistance status.
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The influence of energy intake on the pathophysiology of Trypanosoma congolense infection in Scottish Blackface sheep
Veterinary Parasitology, 1995Co-Authors: E. Katunguka-rwakishaya, Max Murray, G. Fishwick, J. J. Parkins, P.h. HolmesAbstract:Abstract The intensity of parasitaemia, degree of anaemia, live body weight gains and blood biochemical changes were measured in two groups of Scottish Blackface sheep infected experimentally with Trypanosoma congolense and allowed either a high (9.9 MJ metabolisable energy (ME) day−1) or a low (6.1 MJ ME day−1) energy intake. It was observed that infected animals on the low energy intake had a longer mean prepatent period, but following patency they developed more severe anaemia and greater growth retardation than those on the high energy intake. Both infected groups exhibited significant reductions in serum total lipids, phospholipids, plasma cholesterol and albumin. However, these changes were more severe in the animals on the low energy intake than in those on the high energy intake. It was concluded that adequate energy nutrition enhances the ability of infected animals to withstand the adverse effects of infection, by promoting body weight gains and moderating the severity of the pathophysiological changes associated with ovine trypanosomosis.
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different patterns of faecal egg output following infection of Scottish Blackface lambs with ostertagia circumcincta
Veterinary Parasitology, 1995Co-Authors: M.j. Stear, Stephen Bishop, Quintin Mckellar, K. Bairden, J.l. Duncan, S K Karimi, Max MurrayAbstract:Abstract Faecal nematode egg counts were monitored in 184 Scottish Blackface lambs during natural exposure to a mixed, predominantly Ostertagia circumcincta infection and 12 lambs were selected which showed consistently zero (low count group; nine lambs) or consistently positive faecal egg counts (high count group; three lambs). These lambs were then treated with anthelmintic and challenged with 50 000 infective larvae of O. circumcincta and monitored thrice-weekly for 38 weeks; they were then re-challenged with another 50 000 infective larvae of O. circumcincta and monitored for a further 8 weeks. All sheep gave positive egg counts following deliberate infection. However, there was considerable variation among sheep in the size and timing of the peak in egg production. In particular, the pattern of mean values for faecal egg counts was different in the two groups. Egg counts were lower in the later periods of the extended infection in both groups of sheep. During the first half of the extended infection, egg counts were lower in sheep from the low count group, but during the second half of the infection the pattern was reversed and egg counts were lower in sheep from the high count group. There was a weak positive correlation between egg counts following anthelmintic treatment and 28 days exposure to natural infection and egg counts 28 days after a deliberate infection. Egg counts in the later stages of the deliberate infection were strongly but negatively correlated with egg counts following natural infection. The results of these studies show that differences in egg count following natural infection can be reproduced in experimental infections and that there is substantial variation in the pattern of egg production over time in different sheep. They also suggest that naturally resistant lambs are better able to delay worm development than naturally susceptible lambs.
P.h. Holmes - One of the best experts on this subject based on the ideXlab platform.
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Influence of dietary protein on parasite establishment and pathogenesis in Finn Dorset and Scottish Blackface lambs given a single moderate infection of Haemonchus contortus.
Research in Veterinary Science, 2018Co-Authors: E.m. Abbott, J. J. Parkins, P.h. HolmesAbstract:An experiment was conducted to examine the influence of dietary protein on parasite establishment and pathogenesis of Haemonchus contortus in lambs of two breeds. Finn Dorset and Scottish Blackface. The lambs were introduced to high protein (170 g crude protein (CP) kg-1 dry matter (DM) or low protein (88 g CP kg-1 DM) diets at three months old and infected one month later with 125 larvae (kg bodyweight)-1. Blood and faecal samples were collected for analysis and bodyweights recorded weekly. The lambs were killed 20 weeks after infection. A second experiment was conducted in Blackface lambs solely to determine the influence on parasite establishment of the high and low protein diets following infection with 125 larvae kg-1. These lambs were killed five or 14 weeks after infection. Results showed that in Scottish Blackface lambs dietary protein did not significantly influence the establishment of H contortus. However, in Finn Dorset lambs dietary protein may have influenced parasite establishment since lambs on the low protein diet had a higher faecal egg output four weeks after infection and more severe clinical signs than infected lambs of the same breed on a high protein diet.
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Influence of dietary protein on the pathophysiology of ovine haemonchosis in Finn Dorset and Scottish Blackface lambs given a single moderate infection.
Research in Veterinary Science, 2018Co-Authors: E.m. Abbott, J. J. Parkins, P.h. HolmesAbstract:Two experiments were conducted to examine the influence of dietary protein on the pathophysiology of Haemonchus contortus in lambs of two breeds, namely Finn Dorset and Scottish Blackface. Erythro-kinetic and metabolic studies using 51Cr-red cells, 59Fe-transferrin and 125I-aIbumin, and digestive efficiency and nitrogen balance measurements were conducted between four and six weeks after infection. Identical radioisotopic and nutritional studies were also conducted on pair-fed control lambs of both breeds. The results demonstrated that in normal control animals, there were no significant effects of diet or breed on any of the erythrokinetic, metabolic or nutritional parameters, with the possible exception of red cell survival which was considerably longer in the Finn Dorset lambs. However, in the infected animals diet and breed did influence those parameters. The severest effects were seen in the infected Finn Dorset lambs given the low protein diet. These animals had the highest level of abomasal blood loss and this was associated with low red cell volumes and high levels of both albumin catabolism and plasma iron turnover. These animals were also in negative nitrogen balance which was partly accounted for by a significantly greater urinary nitrogen loss compared with their pair-fed controls and partly due to the poorer digestibility of the crude protein fraction of the diet. In contrast, although the infected Scottish Blackface lambs had high levels of blood loss and associated pathophysiological changes, these did not differ between dietary treatments and were similar to the changes in the infected Finn Dorset lambs given the high protein diet.
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The influence of energy intake on some blood biochemical parameters in Scottish Blackface sheep infected with Trypanosoma congolense.
Veterinary Parasitology, 1999Co-Authors: E. Katunguka-rwakishaya, Maxwell Murray, P.h. HolmesAbstract:The intensity of parasitaemia, degree of anaemia, live body weight gains and blood biochemical changes were measured in two groups of Scottish Blackface sheep infected experimentally with Trypanosoma congolense and allowed either a high (9.9 MJ metabolisable energy (ME) per day) or a low (6.1 MJ ME per day) energy intake. It was observed that infected animals on the low energy intake had a longer mean prepatent period, but following patency they developed more severe anaemia and greater growth retardation than those on the high energy intake. Both infected groups exhibited significant reductions in serum total lipids, phospholipids, plasma cholesterol and albumin. However, these changes were more severe in the animals on the low energy intake than in those on the high energy intake. It was concluded that adequate energy nutrition enhances the ability of infected animals to withstand the adverse effects of infection by promoting body weight gains and moderating the severity of the pathophysiological changes associated with ovine trypanosomosis.
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Pathophysiology of Trypanosoma congolense infection in two breeds of sheep, Scottish Blackface and Finn Dorset.
Veterinary Parasitology, 1997Co-Authors: E. Katunguka-rwakishaya, Max Murray, P.h. HolmesAbstract:The pathophysiology of Trypanosoma congolense infection was studied in two breeds of sheep, the Scottish Blackface (SB) and Finn Dorset (FD), which were known from previous studies to differ significantly in their susceptibility to haemonchosis, in which anaemia is also the primary pathophysiological effect. It was found that infected SB and FD lambs developed similar intensities of parasitaemia. However, infected SB lambs developed a higher degree of anaemia, more severe thrombocytopaenia and hypoalbuminaemia than infected FD. Following infection, the concentrations of plasma cholesterol, serum phospholipids and total lipids decreased. The decline in these lipid components appeared to be greater in infected SB than in infected FD lambs.
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The patho-physiology of Trypanosoma congolense in Scottish Blackface sheep: influence of diet on digestive function
Animal Science, 1997Co-Authors: Geert Jan Wassink, G. Fishwick, J. J. Parkins, M. Gill, D. L. Romney, D. Richard, P.h. HolmesAbstract:The influence of types of roughage, barley straw (diet B) versus lucerne hay (diet U, on the patho-physiology of a T. congolense infection was compared in eight pairs of Scottish Blackface male twin Iambs. One animal of each twin pair was infected and the other used as a pair1ed control. Voluntary food intake, body weight, digestive function, various blood haematological and biochemical measurements were made. Voluntary organic matter intake decreased significantly after the T. congolense infection, the decrease being greater in the diet L group than in the diet B group lambs (P < 0.01). The apparent digestibility coefficients of crude protein and organic matter were significantly lower in the infected lambs (P < 0.01). Mean retention time of the roughage through the digestive tract in the animals given barley straw was significantly longer (P < 0.05) due to a 10UIer rumen outflow rate constant (P < 0.01). Infection resulted in longer mean retention times (P < 0.01). Packed cell volume (PCV) was significantly lower before infection in the animals given diet B (P < 0.01). After infection, diet (P < 0.01) and infection (P < 0.01) had an additive effect on PCV. The anaemia was both macrocytic (P < 0.05) and hypochromic (P < 0.01). Diet B resulted in higher plasma cholesterol (P < 0.05), but lower plasma urea (P < 0.01) and albumin (P < 0.01) concentrations before infection than diet L. The T. congolense infection significantly lowered plasma cholesterol (P < 0.01) and increased plasma urea (P < 0.01) concentrations compared with the uninfected controls. Plasma albumin concentrations decreased, but were more affected by nutrition (P < 0.01) than by infection (P < 0.05). It was concluded that the patho-physiological effects of the T. congolense infection in the Scottish Blackface Iambs were affected by the type of roughage offered, but that these effects were additive rather than interactive to the effects of infection.
Stephen Bishop - One of the best experts on this subject based on the ideXlab platform.
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Regional Heritability Mapping of Age-dependent Loci Affecting Growth Traits in Scottish Blackface Lambs
2014Co-Authors: Georgia Hadjipavlou, Valentina Riggio, Ricardo Pong-wong, Oswald Matika, Stephen BishopAbstract:Descriptors of growth derived from fitting the Gompertz curve to longitudinal live weights for 735 Scottish Blackface lambs were analysed using Regional Heritability Mapping to identify genetic regions with significant effects on growth. Evidence for loci affecting predicted growth rates and weights at distinct time points was seen on several chromosomes. Three loci on two chromosomes were mapped for age at maximum growth rate and seven regions on five chromosomes had significant associations with predicted growth rates and live weights at the suggestive level (P
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regional heritability mapping of age dependent loci affecting growth traits in Scottish Blackface lambs
Proceedings of the World Congress on Genetics Applied to Livestock Production, 2014Co-Authors: Georgia Hadjipavlou, Valentina Riggio, Oswald Matika, Ricardo Pongwong, Stephen BishopAbstract:Descriptors of growth derived from fitting the Gompertz curve to longitudinal live weights for 735 Scottish Blackface lambs were analysed using Regional Heritability Mapping to identify genetic regions with significant effects on growth. Evidence for loci affecting predicted growth rates and weights at distinct time points was seen on several chromosomes. Three loci on two chromosomes were mapped for age at maximum growth rate and seven regions on five chromosomes had significant associations with predicted growth rates and live weights at the suggestive level (P<2.30x10). QTL significance and effects varied with age, with longitudinal QTL for growth rate often occurring earlier than for live weight. Irrespective of the methodology used to dissect loci affecting growth, the longitudinal nature of the trait, i.e. its evolution over time, needs to be taken into account, especially for genomic predictions at different growth stages.
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Age-dependent quantitative trait loci affecting growth traits in Scottish Blackface sheep.
Animal Genetics, 2008Co-Authors: Georgia Hadjipavlou, Stephen BishopAbstract:To dissect age-dependent quantitative trait loci (QTL) associated with growth and to examine changes in QTL effects over time, the Gompertz growth model was fitted to longitudinal live weight data on 788 Scottish Blackface lambs from nine half-sib families. QTL were mapped for model parameters and weekly live weights and growth rates using microsatellite markers on chromosomes 1, 2, 3, 5, 14, 18, 20 and 21. QTL significance (using alpha = 0.05 chromosome-wide significance thresholds, unless otherwise stated) varied with age, and those for growth rate occurred earlier than equivalent QTL for live weight. A chromosome 20 QTL for growth rate was significant from 4 to 9 weeks (maximum significance at 6 weeks) and for maximum growth rate. For live weight, this QTL was significant from 8 to 16 weeks (maximum significance at 12 weeks). A nominally significant chromosome 14 QTL was detected for growth rates from birth to week 2 in the same families and location as an 8-week weight QTL. In addition, at the same position on chromosome 14, a QTL was significant for growth rate for 17-28 weeks (maximum significance at 24 weeks). A chromosome 3 QTL was significant for weights at early ages (birth to week 4) and a growth rate QTL on chromosome 18 was significant from 8 to 12 weeks. Fitting growth curves allowed the combination of information from multiple measurements into a few biologically meaningful variables, and the detection of growth QTL that were not observed from analyses of raw weight data. These QTL describe distinct parts of an animal's growth curve trajectory, possibly enabling manipulation of this trajectory.
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Genetic parameters for early lamb survival and growth in Scottish Blackface sheep
Journal of Animal Science, 2008Co-Authors: Valentina Riggio, Raffaella Finocchiaro, Stephen BishopAbstract:The objectives of this study were 1) to estimate the heritability of lamb survival and growth in the Scottish Blackface breed; 2) to examine the relationship between lamb survival and live BW; and 3) to investigate the possibility of using lamb survival in a breeding program for this breed. The data used for the analyses contained information about survival and live BW at different ages on 4,459 animals. The records were collected from 1988 to 2003 in a Scottish Blackface flock. Live BW was recorded every 4 wk from birth to 24 wk. Survival was defined either by perinatal or postnatal mortality (up to weaning at 12 wk), or as cumulative survival to 1, 4, 8, and 12 wk. The pedigree file comprised 1,416 dams and 178 sires. A sire model was used to estimate genetic parameters for binary survival traits. Heritabilities of BW traits, and phenotypic and genetic correlations between BW and between survival and BW were estimated by fitting an animal model. Further, correlations of survival with live BW were estimated by using a Markov chain Monte Carlo threshold model, implemented by Gibbs sampling. The heritability estimates for cumulative lamb survival declined from birth onward (from 0.33 to 0.08), and postnatal survival had a heritability of 0.01. The direct and maternal heritabilities for BW traits ranged from 0.08 to 0.26 and from 0.06 to 0.21, respectively, whereas the maternal environmental component was between 0.04 and 0.16. The genetic correlations between BW traits at different ages were high. The genetic and phenotypic correlations between survival and BW were always positive (ranging from 0.04 to 0.54), so there was no antagonism between these traits. Therefore, it is possible to simultaneously improve both survival and live BW in a breeding program for this breed.
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Genetic analyses of sensory characteristics and relationships with fatty acid composition in the meat from Scottish Blackface lambs
Animal, 2007Co-Authors: E. Karamichou, R. I. Richardson, G.r. Nute, J. D. Wood, Stephen BishopAbstract:Genetic parameters for eating quality assessed by trained taste panellists were estimated on longissimus thoracis et lumborum (LTL) muscle in Scottish Blackface lambs, comprising lines previously divergently selected for carcass lean content (FAT and LEAN lines) as well as crosses between these lines. Also, relationships between eating quality assessments and fatty acid composition were investigated. Eating quality and fatty acid phenotypic measurements were made on 350 male lambs, at ca. 8 months of age. Eating quality measurements included 18 descriptive terms and fatty acid composition measurements included in total 17 fatty acids of three types: saturated, monounsaturated and polyunsaturated. The FAT line had juicier meat and more vegetable flavour than the LEAN line. Most of the eating quality traits were moderately to highly heritable, with heritabilities ranging from 0.21 (lamb flavour) to 0.92 (sweet flavour). Lamb flavour, juiciness and overall liking were strongly negatively correlated with individual polyunsaturated fatty acids, with the correlations being significantly different from zero. Overall liking was strongly positively correlated with the proportion of total monounsaturated fatty acids. This study provides new information on genetic parameters for eating quality traits in sheep, which may lead to novel opportunities for genetically improving these traits.
N. R. Lambe - One of the best experts on this subject based on the ideXlab platform.
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investigation into the presence of genotype by environment interactions g e in Scottish Blackface lamb traits
Small Ruminant Research, 2012Co-Authors: A Mclaren, N. R. Lambe, S Brotherstone, J E Conington, Raphael A. Mrode, L BungerAbstract:Abstract Genotype by environment interactions (G × E) can form a potential source of inefficiency in animal breeding if selection decisions are made without acknowledging their effects. The presence of such interactions between two Scottish hill farms was investigated using performance data collected from 18,459 Scottish Blackface lambs between 1997 and 2010. Pedigree information was available for 27,548 animals. 30 out of 379 sires used during this time period were used on both farms. Farm A is located on the East Coast of Scotland, whereas Farm B is on the West Coast. The farms differ in a number of aspects including annual rainfall, topography, vegetation, temperature and altitude ranges, with Farm B representing a harsher environment overall. Traits studied were birth weight, 8-week weight and weaning weight, ultrasound back-fat and muscle depths at weaning, carcass weight, carcass fat grade and carcass conformation score. Genetic correlations were estimated for each trait, between the two farms, with those significantly different from 1 ( P s.e. 0.31). By taking G × E into account and comparing bivariate and univariate analyses, the maximum selection response observed for birth weight was 0.0016 kg per generation. Overall, the lack of G × E observed for the majority of traits studied suggest that the common sire offspring have performed similarly across both farms. However, the presence of G × E associated with birth weight may have implications for lambing associated problems, or lamb survival, if sires produce lambs with unexpectedly high or low birth weights.
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Investigation into the presence of genotype by environment interactions (G × E) in Scottish Blackface lamb traits
Small Ruminant Research, 2012Co-Authors: A Mclaren, N. R. Lambe, S. Brotherstone, Joanne Conington, Raphael A. Mrode, Lutz BüngerAbstract:Abstract Genotype by environment interactions (G × E) can form a potential source of inefficiency in animal breeding if selection decisions are made without acknowledging their effects. The presence of such interactions between two Scottish hill farms was investigated using performance data collected from 18,459 Scottish Blackface lambs between 1997 and 2010. Pedigree information was available for 27,548 animals. 30 out of 379 sires used during this time period were used on both farms. Farm A is located on the East Coast of Scotland, whereas Farm B is on the West Coast. The farms differ in a number of aspects including annual rainfall, topography, vegetation, temperature and altitude ranges, with Farm B representing a harsher environment overall. Traits studied were birth weight, 8-week weight and weaning weight, ultrasound back-fat and muscle depths at weaning, carcass weight, carcass fat grade and carcass conformation score. Genetic correlations were estimated for each trait, between the two farms, with those significantly different from 1 ( P s.e. 0.31). By taking G × E into account and comparing bivariate and univariate analyses, the maximum selection response observed for birth weight was 0.0016 kg per generation. Overall, the lack of G × E observed for the majority of traits studied suggest that the common sire offspring have performed similarly across both farms. However, the presence of G × E associated with birth weight may have implications for lambing associated problems, or lamb survival, if sires produce lambs with unexpectedly high or low birth weights.
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Muscle fibre characteristics of two contrasting sheep breeds: Scottish Blackface and Texel.
Meat Science, 2008Co-Authors: Lutz Bünger, N. R. Lambe, E A Navajas, A V Fisher, L. Stevenson, C.a. Maltin, Geoff Simm, Kin-chow ChangAbstract:This study evaluates the effects of breed and sex, together with those of birth weight and litter size, on muscle fibre type characteristics in Texel (TEX) and Scottish Blackface sheep (SBF). The M. longissimus thoracis et lumborum (LTL) of TEX had a significantly higher total muscle cross-sectional area (16%), a higher total fibre number (20%) and a higher muscle CT density (5%) than the SBF but had a similar average muscle fibre size. The frequency of slow fibres in the LTL in TEX was lower than in SBF (7.5% vs. 9.6%). Muscle fibre histochemistry similarly demonstrated that the oxidative fibre frequency in TEX was 10% lower than in SBF. The inter-fibre lipid content in TEX was also significantly lower than in SBF. Correspondingly, TEX displayed higher frequency (91.7% vs. 90.9% in SBF) and higher relative total area (92.5% vs. 90.4% in SBF) of fast fibres. These breed differences in muscle fibre traits indicate underlying genetic variation, and future analyses will evaluate the link of these traits to meat quality and assess the usefulness of these traits in breeding programmes.
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Breed and sex effects on muscle fibre characteristics in two contrasting sheep breeds: Scottish Blackface and Texel
Proceedings of the British Society of Animal Science, 2007Co-Authors: L Bunger, N. R. Lambe, G. Simm, E A Navajas, L. Stevenson, C.a. Maltin, Kc ChangAbstract:Lamb production is an important part of UK agriculture, contributing more than 10% of total livestock output. It is crucial for maintaining employment and infrastructure in rural communities, and in managing and enhancing the countryside and biodiversity. For the UK sheep industry to continue as a major producer and exporter of lamb, the improvement of its economic sustainability is essential and requires high product quality.As one of the major terminal sire breeds in the UK, Texel sheep (TEX) have been selected over generations for rapid growth, muscularity and lean meat content. In contrast, Scottish Blackface sheep (SBF) have been selected for their hardiness and maternal ability, with less attention being paid to carcass traits. It is clear therefore that divergent selection goals are driving the breeding of TEX and SBF. Based on work in pigs in particular, where selection for lean tissue growth rate has been used extensively, it might be predicted that these two breeds would have diver-gent muscle fibre characteristics. The proportion of muscle fibre types and their size affect muscularity as well as functional properties of the musculature and meat eating quality (MEQ). Breed differences indicate a genetic basis for these traits. This study evaluates the effects of breed and sex, together with those of birthweight and litter size on fibre type characteristics.
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in vivo prediction of internal fat weight in Scottish Blackface lambs using computer tomography
Journal of Animal Breeding and Genetics, 2006Co-Authors: N. R. Lambe, J. Conington, K A Mclean, E A Navajas, A V Fisher, L BungerAbstract:Summary From a calibration trial involving computer tomography (CT) scanning and dissection of 45 lambs, a prediction equation was derived to estimate total internal fat weight in Scottish Blackface lambs from measurements taken on cross-sectional CT images. Using data from two cross-sectional images (at the hip and loin) internal fat can be predicted with relatively high accuracy (adjusted R2 = 62.2%, r = 0.79). The derived equation was then used to predict internal fat weights in a further 427 Scottish Blackface lambs from a separate trial. Phenotypic correlations were calculated between predicted internal fat weight and weights of total carcass fat, muscle and bone, predicted using previously derived equations. When considering absolute tissue weights, adjusted for fixed effects, internal fat showed the strongest positive correlation with carcass fat (0.58), followed by muscle (0.36), and then by bone (0.32). When tissue weights were adjusted for fixed effects and total carcass weight (so considering tissue weights relative to size), internal fat showed a lower correlation with carcass fat weight (0.36) and negative correlations with muscle (−0.35) and bone (−0.19). These results provide the basis for more complex studies of relationships (phenotypic and genetic) between internal fat in hill lambs and economically important traits, such as carcass composition and survival of lambs, and tissue levels in different depots in hill ewes.
S. C. Bishop - One of the best experts on this subject based on the ideXlab platform.
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Quantitative trait loci associated with parasitic infection in Scottish Blackface sheep
Heredity, 2006Co-Authors: G Davies, Mohamed Ahmed Ezzeddin Benothman, A. Kerr, S. Mitchell, M.j. Stear, O Abuagob, S. C. BishopAbstract:This study aimed to identify quantitative trait loci associated with endoparasitic infection in Scottish Blackface sheep. Data were collected from 789 animals over a 3-year period. All of the animals were continually exposed to a mixed nematode infection by grazing. Faecal samples were collected in August, September and October each year at ca. 16, 20 and 24 weeks of age; Nematodirus spp. eggs were counted separately from the other species of nematodes. Blood samples were collected in October from which immunoglobulin A (IgA) activity was measured and DNA was extracted for genotyping. In total, 139 Microsatellite markers were genotyped across eight chromosomal regions (chromosomes 1, 2, 3, 5, 14, 18, 20 and 21) in the sires and progeny were genotyped for the markers that were polymorphic in their sire. Evidence was found for quantitative trait loci (QTL) on chromosomes 2, 3, 14 and 20. QTL associated with specific IgA activity were identified in chromosomes 3 and 20, in regions close to IFNG (chromosome 3) and the MHC (chromosome 20). QTL associated with Nematodirus FEC were identified on chromosomes 2, 3 and 14. Lastly, QTL associated with non-Nematodirus Strongyle FEC were identified on chromosomes 3 and 20. This study has shown that some aspects of host resistance to gastrointestinal parasites are under strong genetic control, therefore these QTL could be utilised in a marker-assisted selection scheme to increase host resistance to gastrointestinal parasites.
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Body tissue changes in Scottish Blackface ewes during one annual production cycle
Proceedings of the British Society of Animal Science, 2001Co-Authors: N. R. Lambe, J. Conington, M. J. Young, R.m. Lewis, G. Simm, S. C. BishopAbstract:Fat and muscle reserves are mobilised during winter by breeding hill ewes, living in harsh environments, as they conceive and carry their lambs (Russel et al., 1968). Tissue depletion and repletion were studied in Scottish Blackface ewes through one productive cycle using computed tomography (CT). The aim was to use this nondestructive method to quantify patterns of change in carcass fat, carcass muscle and internal fat in ewes of differing age and reproductive status.
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Genetics of maternal behaviour in Scottish Blackface sheep under field conditions: factors affecting maternal behaviour scores and their influence on lamb live weights and survival
Proceedings of the British Society of Animal Science, 2000Co-Authors: N. R. Lambe, J. Conington, A. Waterhouse, S. C. Bishop, G. SimmAbstract:Behavioural studies of sheep have shown that poor maternal behaviour by the ewe immediately postparturition can lead to reduced lamb survival and ewe production (O'Connor et al., 1985). Under field conditions, behaviour may be quantified by the maternal behaviour score (MBS) - a six-point scale assessing ewe flight distance when lambs(s) are handled for the first time, within 24 hours of birth (adapted from O'Connor et al., 1985). Greater scores are awarded to ewes remaining closer to their lamb(s). The objectives of this study were (1) to investigate the factors affecting MBS in Scottish Blackface ewes; (2) to determine if MBS affects the average weight of lambs reared or the number of lambs dying before weaning; (3) to estimate genetic and phenotypic parameters for MBS and correlations between MBS and lamb performance.
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The inheritance of faecal egg count following natural Ostertagia circumcinctainfection in Scottish Blackface lambs
Proceedings of the British Society of Animal Science, 1996Co-Authors: S. C. Bishop, K. Bairden, Q.a. Mckellar, M. Park, M.j. StearAbstract:The use of genetic selection as a means of reducing the welfare and production losses caused by gastrointestinal parasites has hitherto been ignored by the UK sheep industry. The aim of this study is to assess the potential for selection for reduced faecal egg count, as an indicator of parasitism, and to establish relationships with live weight.Faecal egg counts and live weights were measured on approximately 200 predominantly twin born Scottish Blackface lambs each year for three years following natural, predominantly Ostertagia circumcincta , infection on pasture. Measurements were made from one to six months of age, at four week intervals, following anthelmintic treatment. Heritabilities, maternal common environment effects, genetic and phenotypic correlations were calculated using Residual Maximum Likelihood techniques.