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Full-Text Articles in Animal Sciences
Genotype By Environment Interaction And Heteroscedasticity Influence The Expression Of Parasite Resistance In Katahdin Sheep, Brian C. Arisman, Joan M. Burke, James L. M. Morgan, Ronald M. Lewis
Genotype By Environment Interaction And Heteroscedasticity Influence The Expression Of Parasite Resistance In Katahdin Sheep, Brian C. Arisman, Joan M. Burke, James L. M. Morgan, Ronald M. Lewis
Department of Animal Science: Faculty Publications
Increasingly, sheep producers are choosing breeds that express resistance to gastrointestinal parasites due to reduced efficacy of anthelminthic drugs. One such breed is Katahdin. Katahdins are raised in various climates and management systems in the United States, which can be combined into eco-management clusters to describe production environments more holistically. The objectives of this study were to determine if genotype by environment interaction (G × E) and heteroscedasticity existed across these eco-management clusters for traits indicative of parasite resistance. Body weights (BW), FAMACHA scores (FAM), and fecal egg counts (FEC) were collected at around 90 d in 3,527 Katahdin lambs …
Clustering Climate And Management Practices To Define Environmental Challenges Affecting Gastrointestinal Parasitism In Katahdin Sheep, Brian C. Arisman, Joan M. Burke, James L. M. Morgan, Ronald M. Lewis
Clustering Climate And Management Practices To Define Environmental Challenges Affecting Gastrointestinal Parasitism In Katahdin Sheep, Brian C. Arisman, Joan M. Burke, James L. M. Morgan, Ronald M. Lewis
Department of Animal Science: Faculty Publications
Gastrointestinal nematodes (GIN) negatively affect the performance and well-being of sheep. Due to anthelmintic resistance, GIN are difficult to control leading producers to choose breeds that can exhibit resistance to parasitism. An example is Katahdin sheep. Katahdins are raised in various climates and management systems in the United States. These environmental factors can be combined to form eco-management groupings or clusters. We hypothesized that GIN challenge varies predictably based on the characteristics of these environmental clusters. Forty Katahdin producers from across the United States were surveyed for management information, with body weights (BW), fecal egg counts (FEC), and FAMACHA scores …
Genetic Structure And Admixture In Sheep From Terminal Breeds In The United States, Kimberly M. Davenport, C. Heimke, S. D. Mc Kay, J. W. Thorne, Ronald M. Lewis, Todd Taylor, B. M. Murdoch
Genetic Structure And Admixture In Sheep From Terminal Breeds In The United States, Kimberly M. Davenport, C. Heimke, S. D. Mc Kay, J. W. Thorne, Ronald M. Lewis, Todd Taylor, B. M. Murdoch
Department of Animal Science: Faculty Publications
Selection for performance in diverse production settings has resulted in variation across sheep breeds worldwide. Although sheep are an important species to the United States, the current genetic relationship among many terminal sire breeds is not well characterized. Suffolk, Hampshire, Shropshire and Oxford (terminal) and Rambouillet (dual purpose) sheep (n = 248) sampled from different flocks were genotyped using the Applied Biosystems Axiom Ovine Genotyping Array (50K), and additional Shropshire sheep (n = 26) using the Illumina Ovine SNP50 BeadChip. Relationships were investigated by calculating observed heterozygosity, inbreeding coefficients, eigenvalues, pairwise Wright’s FST estimates and an identity by state matrix. …
Genome-Wide Association Study To Identify Genetic Loci Associated With Gastrointestinal Nematode Resistance In Katahdin Sheep, G. M. Becker, K. M. Davenport, Joan M. Burke, Ronald M. Lewis, J. E. Miller, J. L.M. Morgan, D. R. Notter, B. M. Murdoch
Genome-Wide Association Study To Identify Genetic Loci Associated With Gastrointestinal Nematode Resistance In Katahdin Sheep, G. M. Becker, K. M. Davenport, Joan M. Burke, Ronald M. Lewis, J. E. Miller, J. L.M. Morgan, D. R. Notter, B. M. Murdoch
Department of Animal Science: Faculty Publications
Resistance to gastrointestinal nematodes has previously been shown to be a moderately heritable trait in some breeds of sheep, but the mechanisms of resistance are not well understood. Selection for resistance currently relies upon faecal egg counts (FEC), blood packed cell volumes and FAMACHA visual indicator scores of anaemia. Identifying genomic markers associated with disease resistance would potentially improve the selection process and provide a more reliable means of classifying and understanding the biology behind resistant and susceptible sheep. A GWAS was conducted to identify possible genetic loci associated with resistance to Haemonchus contortus in Katahdin sheep. Forty animals were …
Genetic Structure And Admixture In Sheep From Terminal Breeds In The United States, Kimberly M. Davenport, C. Hiemke, Stephanie D. Mc Kay, J. W. Thorne, Ronald M. Lewis, Todd Taylor, B. M. Murdoch
Genetic Structure And Admixture In Sheep From Terminal Breeds In The United States, Kimberly M. Davenport, C. Hiemke, Stephanie D. Mc Kay, J. W. Thorne, Ronald M. Lewis, Todd Taylor, B. M. Murdoch
Department of Animal Science: Faculty Publications
Selection for performance in diverse production settings has resulted in variation across sheep breeds worldwide. Although sheep are an important species to the United States, the current genetic relationship among many terminal sire breeds is not well characterized. Suffolk, Hampshire, Shropshire and Oxford (terminal) and Rambouillet (dual purpose) sheep (n = 248) sampled from different flocks were genotyped using the Applied Biosystems Axiom Ovine Genotyping Array (50K), and additional Shropshire sheep (n = 26) using the Illumina Ovine SNP50 BeadChip. Relationships were investigated by calculating observed heterozygosity, inbreeding coefficients, eigenvalues, pairwise Wright’s FST estimates and an identity by state matrix. …
Comparative Digestibility By Cattle Versus Sheep: Effect Of Forage Quality, S. A. Soto-Navarro, R. Lancaster, C. Sankey, B. M. Capitan, B. P. Holland, L. A. Balstad, C. R. Krehbiel
Comparative Digestibility By Cattle Versus Sheep: Effect Of Forage Quality, S. A. Soto-Navarro, R. Lancaster, C. Sankey, B. M. Capitan, B. P. Holland, L. A. Balstad, C. R. Krehbiel
Department of Animal Science: Faculty Publications
The objective was to determine the effect of forage quality on apparent total tract digestibility and ruminal fermentation in cattle versus sheep. Five yearling English crossbred (Hereford × Angus) steers (440.4 ± 35.6 kg of initial BW) and 5 yearling whiteface (Rambouillet × Columbia × Debouillet) wethers (44.4 ± 4.6 kg of initial BW), each fitted with a ruminal cannula, were randomly assigned to 1 of 3 forage sources within ruminant specie, and the study was conducted over 3 periods. For forage source, both animal and period served as the blocking factor with all forage sources represented once within each …
Index Selection In Terminal Sires Improves Early Lamb Growth, G. C. Márquez, W. Haresign, M. H. Davies, G. C. Emmans, Rainer Roehe, L Bünger, G. Simm, Ronald M. Lewis
Index Selection In Terminal Sires Improves Early Lamb Growth, G. C. Márquez, W. Haresign, M. H. Davies, G. C. Emmans, Rainer Roehe, L Bünger, G. Simm, Ronald M. Lewis
Department of Animal Science: Faculty Publications
The use of terminal sires (TS) for crossbreeding is integral to the UK sheep industry where approximately 71% of market lambs are sired by TS rams. Early growth of these crossbred lambs affects profitability. The objectives of this study were i) to evaluate the effectiveness of index selection among TS on BW and ADG of their crossbred offspring; and ii) to compare the efficacy of that selection within TS breeds. The most widely used TS breeds in the United Kingdom are Charollais, Suffolk, and Texel. These participated in sire referencing schemes in which they were evaluated on a lean growth …
Feed Intake Of Sheep As Affected By Body Weight, Breed, Sex, And Feed Composition, R. M. Lewis, G. C. Emmans
Feed Intake Of Sheep As Affected By Body Weight, Breed, Sex, And Feed Composition, R. M. Lewis, G. C. Emmans
Department of Animal Science: Faculty Publications
The hypotheses tested were that genetic size-scaling for mature BW (A, kg) would reduce variation in intake between kinds of sheep and that quadratic polynomials on u = BW/A with zero intercept would provide good descriptions of the relationship between scaled intake (SI, g/A0.73 d) and degree of maturity in BW (u) across feeds of differing quality. Both sexes of Suffolk sheep from 2 experimental lines (n = 225) and from 3 breed types (Suffolk, Scottish Blackface, and their cross; n = 149) were recorded weekly for ad libitum feed intake and BW; recording of intake was from weaning through, …
Genetic Relationship Between Longevity And Objectively Or Subjectively Assessed Performance Traits In Sheep Using Linear Censored Models, W. Mekkaway, Rainer Roehe, Ronald M. Lewis, M. H. Davies, L. Bünger, G. Simm, W. Haresign
Genetic Relationship Between Longevity And Objectively Or Subjectively Assessed Performance Traits In Sheep Using Linear Censored Models, W. Mekkaway, Rainer Roehe, Ronald M. Lewis, M. H. Davies, L. Bünger, G. Simm, W. Haresign
Department of Animal Science: Faculty Publications
Genetic parameters of longevity in crossbred mule ewes, and genetic relationships among longevity, growth, body composition, and subjectively assessed traits on mule lambs and ewes have been estimated using Bayesian linear censored models. Additionally, the genetic associations between longevity and culling reasons were examined. Data comprised 1,797 observations of mule ewes for longevity, culling reasons, growth, body composition, mouth scores, and type traits. Longevity was defined as the time (in years) from 2 yr of age (the age at first lambing of most ewes) to culling or death. Censored data (i.e., observations for which only the lower bound of the …
Effects Of Food Quality On Growth And Carcass Composition In Lambs Of Two Breeds And Their Cross, R. M. Lewis, J. M. Macfarlane, G. Simm, G. C. Emmans
Effects Of Food Quality On Growth And Carcass Composition In Lambs Of Two Breeds And Their Cross, R. M. Lewis, J. M. Macfarlane, G. Simm, G. C. Emmans
Department of Animal Science: Faculty Publications
The effects offood quality, breed type and sex (ram and ewe) on Iamb growth and carcass composition, and their changes throughout growth, were measured. The three breed typeswereScottish Blackface (B; no. = 24), Suffolk (S; no. = 28) and their reciprocal crosses (X; no. 33). The lambs had free access to a nutritionally non-limiting food, H, or a bulky food, L. Each lamb was scanned using X-ray computed tomography to measure the weights offat, lean and bone in the carcass at three degrees of maturity (0·30, 0·45 and 0·65) in live weight. Live weight and food intake data were recorded …
Effects Of Index Selection On The Performance And Carcass Composition Of Sheep Given Foods Of Different Protein Concentrations Ad Libitum., R. M. Lewis, G. C. Emmans, G. Simm
Effects Of Index Selection On The Performance And Carcass Composition Of Sheep Given Foods Of Different Protein Concentrations Ad Libitum., R. M. Lewis, G. C. Emmans, G. Simm
Department of Animal Science: Faculty Publications
Sheep of a line selected on an index to increase carcass lean content at 150 days of age (selected (S); no. = 90), and an unselected control line (control (C); no. = 90), were given ad libitum foods of three different protein concentrations (192, 141 and 120 g/kg dry matter). Growth was measured from about 21 to 114 kg live weight. The carcasses of each line were analysed for lean, fat and bone at three widely varying weights in both males and females. Level of protein did not affect the extent to tohidi S was superior to C in the …
Effects Of Two Dried Forages, And A Choice Between Them, On Intake, Growth And Carcass Composition In Lambs Of Two Breeds And Their Cross, R. M. Lewis, J. M. Macfarlane, G. C. Emmans
Effects Of Two Dried Forages, And A Choice Between Them, On Intake, Growth And Carcass Composition In Lambs Of Two Breeds And Their Cross, R. M. Lewis, J. M. Macfarlane, G. C. Emmans
Department of Animal Science: Faculty Publications
The effects of for age type, breed type and sex on lamb growth and carcass composition, and their changes throughout growth, were measured. The three breed types were Scottish Blackface (no. =31), Suffolk (no. =28) and their reciprocal cross (no. =30). The lambs were given ad libitum a pelleted rye grass alone, pelleted lucerne alone or a choice of both. Each lamb was scanned using X-ray computed tomography to measure the weights of fat, lean and bone in the carcass at three proportions of mature body weight (0-30, 0·45 and 0·65). Live weights and food intake data were recorded weekly. …
The Ability Of The N-Alkane Technique To Estimate Intake And Diet Choice Of Sheep, R. M. Lewis, A. M. Magadlela, N. S. Jessop, G. C. Emmans
The Ability Of The N-Alkane Technique To Estimate Intake And Diet Choice Of Sheep, R. M. Lewis, A. M. Magadlela, N. S. Jessop, G. C. Emmans
Department of Animal Science: Faculty Publications
This study assessed the efficacy of the n-alkane technique to estimate intake and diet composition in animals given single foods or a choice of two. In thefirst experiment intakes of pelleted ryegrassand lucerne, given eitheralone or as a choice, were measured in lambshoused indoors in individual pens. Each of the three feeding treatments was given to 12 lambs at two degrees of maturity (0.30 and 0·45 of estimated mature sizes). The 12 lambs were constituted as three replicates of the two sexes of each of two breeds. The measured intakes werecompared with those estimated using the n-alkanes C31 andC33, found …
Genetic Relationships Between Visual And Objective Measures Of Carcass Composition In Crossbred Lambs, H. E. Jones, G. Simm, W. S. Dingwall, R. M. Lewis
Genetic Relationships Between Visual And Objective Measures Of Carcass Composition In Crossbred Lambs, H. E. Jones, G. Simm, W. S. Dingwall, R. M. Lewis
Department of Animal Science: Faculty Publications
The aim of this study was to estimate genetic and phenotypic (coroariances between objective measures and carcass visual scores, as a test of the potential value afvisual scores in selection programmes to improve carcass composition in crossbred lambs. In each of 1986, 1987 and 1988, 22 Suffolk rams were chosen with either high or low scores on an index designed to increase lean growth rate. These rams were joined with 18 to20 crossbred ewes each and theirlambs were grov.J11 on grass to one of three target live weights (35·5, 41·5 and 47·0 kg) for slaughter. The carcasses of 1881 lambs …
Ewe Fertility In The Star Accelerated Lambing System, R. M. Lewis, D. R. Notter, D. E. Hogue, B. H. Magee
Ewe Fertility In The Star Accelerated Lambing System, R. M. Lewis, D. R. Notter, D. E. Hogue, B. H. Magee
Department of Animal Science: Faculty Publications
Effects of environmental factors such as ewe age, season of exposure, and time from lambing to exposure on fertility were evaluated using records on 1,084 Dorset ewes in the STAR accelerated lambing system. The STAR program consisted of five 30-d concurrent breeding and lambing periods per year beginning on January 1, March 15, May 27, August 8, and October 20. Fertility in the flock changed in a cyclic and predictable fashion during the year. Changes in prolificacy were less consistent but also tended to show cyclic variation. Matings that occurred within the typical breeding season (August, October, and January) were …