Genetic variation for resistance to clinical and subclinical diseases exists in growing pigs

2001 ◽  
Vol 73 (3) ◽  
pp. 375-387 ◽  
Author(s):  
M. Henryon ◽  
P. Berg ◽  
J. Jensen ◽  
S. Andersen
Keyword(s):  
Genetic Variation ◽  
Respiratory Diseases ◽  
Additive Genetic Variance ◽  
Genetic Correlations ◽  
Frailty Model ◽  
Growing Pigs ◽  
Disease Category ◽  
Breeding Values ◽  
Additive Genetic Variation ◽  
Subclinical Disease

AbstractThe objective of this study was to test that genetic variation for resistance to clinical and subclinical diseases exists in growing pigs. A total of 13 551 male growing pigs were assessed for resistance to five categories of clinical and subclinical disease: (i) any clinical or subclinical disease, (ii) lameness, (iii) respiratory diseases, (iv) diarrhoea, and (v) other diseases (i.e. any clinical or subclinical disease with the exception of (ii), (iii), and (iv)). Additive genetic variation for resistance to each disease category was estimated by fitting a Weibull, sire-dam frailty model to time until the pigs were first diagnosed with a disease from that category. Genetic correlations among the resistances to each disease category were approximated as product-moment correlations among predicted breeding values of the sires. Additive genetic variation was detected for resistance to (i) any clinical or subclinical disease (additive genetic variance for log-frailty (± s.e.) = 0·18 ± 0·05, heritability on the logarithmic-time scale = 0·10), (ii) lameness (0·29 ± 0·11, 0·16), (iii) respiratory diseases (0·24 ± 0·16, 0·12), (iv) diarrhoea (0·30 ± 0·27, 0·16), and (v) the other diseases (0·34 ± 0·15, 0·19) and there were generally positive and low-to-moderate correlations among the predicted breeding values (-0·03 to + 0·65). These results demonstrate that additive genetic variation for resistance to clinical and subclinical diseases does exist in growing pigs, and suggests that selective breeding for resistance could be successful.

Genetic variation within and between subpopulations of the Australian Merino breed

2016 ◽  
Vol 56 (1) ◽  
pp. 87 ◽  
Author(s):  
Andrew A. Swan ◽  
Daniel J. Brown ◽  
Julius H. J. van der Werf
Keyword(s):  
Genetic Variation ◽  
Variance Components ◽  
Additive Genetic Variance ◽  
Genetic Correlations ◽  
Fibre Diameter ◽  
Genetic Group ◽  
Additive Variance ◽  
Breeding Values ◽  
Genetic Groups ◽  
Australian Merino

Genetic variation within and between Australian Merino subpopulations was estimated from a large breeding nucleus in which up to 8500 progeny from over 300 sires were recorded at eight sites across Australia. Subpopulations were defined as genetic groups using the Westell–Quaas model in which base animals with unknown pedigree were allocated to groups based on their flock of origin if there were sufficient ‘expressions’ for the flock, or to one of four broad sheep-type groups otherwise (Ultra/Superfine, Fine/Fine-medium, Medium/Strong, or unknown). Linear models including genetic groups and additive genetic breeding values as random effects were used to estimate variance components for 12 traits: yearling greasy and clean fleece weight (ygfw and ycfw), yearling mean and coefficient of variation of fibre diameter (yfd and ydcv), yearling staple length and staple strength (ysl and yss), yearling fibre curvature (ycuv), yearling body wrinkle (ybdwr), post-weaning weight (pwt), muscle (pemd) and fat depth (pfat), and post-weaning worm egg count (pwec). For the majority of traits, the genetic group variance ranged from approximately equal to two times larger than the additive genetic (within group) variance. The exceptions were pfat and ydcv where the genetic group to additive variance ratios were 0.58 and 0.22, respectively, and pwec and yss where there was no variation between genetic groups. Genetic group correlations between traits were generally the same sign as corresponding additive genetic correlations, but were stronger in magnitude (either more positive or more negative). These large differences between genetic groups have long been exploited by Merino ram breeders, to the extent that the animals in the present study represent a significantly admixed population of the founding groups. The relativities observed between genetic group and additive genetic variance components in this study can be used to refine the models used to estimate breeding values for the Australian Merino industry.

scholarly journals The Effects of Drying Temperature and Method of Assessment on the Expression of Genetic Variation in Gross Shrinkage of Eucalyptus globulus Wood Samples

2009 ◽  
Vol 58 (1-6) ◽  
pp. 252-261 ◽  
Author(s):  
Matthew G. Hamilton ◽  
C. E. Harwood ◽  
B. M. Potts
Keyword(s):  
Genetic Variation ◽  
Eucalyptus Globulus ◽  
Genetic Correlations ◽  
Basic Density ◽  
Strongly Correlated ◽  
Drying Temperature ◽  
Additive Genetic Variation ◽  
Tangential Shrinkage ◽  
Drying Treatment ◽  
Method Of Assessment

Abstract Genetic variation in wood-sample gross shrinkage and basic density was examined in a Eucalyptus globulus base population trial growing in Tasmania, Australia. Gross shrinkage, which includes all components of shrinkage including collapse, was assessed in four ways (calliper- and visually-assessed tangential shrinkage, volumetric shrinkage and radial shrinkage) on samples dried at three temperatures (22°C, 60°C and 105°C). Significant differences between subraces were observed using all measures of gross shrinkage for two or more of the three drying treatments. Furthermore, significant additive genetic variation within subraces was observed in calliper- and visually-assessed gross shrinkage under two or more of the drying treatments, with narrowsense heritabilities greater than or equal to 0.35. There was no obvious trend in heritabilities or coefficients of additive genetic variation with drying temperature. Under the 105°C drying treatment, subrace correlations among calliper-, visually- and volume-assessed gross shrinkage were positive and very strong (≥ 0.97), while these measures were less strongly correlated with radial gross shrinkage at the subrace level (≤ 0.77). Withinsubrace genetic correlations among the first three measures were also strongly positive (≥ 0.95). These high genetic correlations suggest that different drying regimes and the calliper, visual and volume methods of assessment could be used interchangeably to select for reduced tangential gross shrinkage. Estimated subrace and genetic correlations between basic density and measures of gross shrinkage were universally negative (i.e. favourable), although not all were significantly different to zero.

Immunological traits have the potential to improve selection of pigs for resistance to clinical and subclinical disease

2006 ◽  
Vol 82 (5) ◽  
pp. 597-606 ◽  
Author(s):  
M. Henryon ◽  
P. M. H. Heegaard ◽  
J. Nielsen ◽  
P. Berg ◽  
H. R. Juul-Madsen
Keyword(s):  
Genetic Variation ◽  
Animal Models ◽  
Serum Concentrations ◽  
Large Sample ◽  
Expression Levels ◽  
Additive Genetic Variation ◽  
Leukocyte Antigens ◽  
Subclinical Disease ◽  
Selection Of

AbstractIt was reasoned that, if we used a large sample of pigs, we could demonstrate that total and differential numbers of leukocytes, expression levels of swine leukocyte antigens (SLA) I and II, and serum concentrations of IgG and haptoglobin show additive genetic variation and are, therefore, potentially useful as criteria to improve selection of pigs for resistance to clinical and subclinical disease. We tested this premise by assessing 4204 male pigs from the Duroc, Landrace, and Yorkshire breeds for total and differential numbers of leukocytes and serum concentrations of IgG and haptoglobin; 1217 of the Duroc and Landrace pigs were also assessed for expression levels of SLA I and II. We estimated the amount of additive genetic variation by fitting linear animal models to the total and differential numbers of leukocytes and serum concentrations of IgG and haptoglobin. We fitted linear sire models to the expression levels of SLA I and II. We detected additive genetic variation for each group of traits. Total and differential numbers of leukocytes were moderately heritable (h2=0·22 to 0·30), expression levels of SLA I and II were moderate-to-highly heritable (h2=0·46 to 1·23), while serum concentrations of IgG and haptoglobin were lowly heritable (h2=0·14 to 0·16). The additive genetic variation shown for the immunological traits is encouraging for pig breeders. It indicates that these traits are potentially useful as criteria to improve selection of pigs for resistance to clinical and subclinical disease.

scholarly journals Plastic responses to novel environments are biased towards phenotype dimensions with high additive genetic variation

2019 ◽  
Vol 116 (27) ◽  
pp. 13452-13461 ◽  
Author(s):  
Daniel W. A. Noble ◽  
Reinder Radersma ◽  
Tobias Uller
Keyword(s):  
Genetic Variation ◽  
Meta Analysis ◽  
Additive Genetic Variance ◽  
Genetic Mutation ◽  
Developmental Systems ◽  
Additive Genetic Variation ◽  
Genetic Constraint ◽  
Novel Environments ◽  
Plastic Responses

Environmentally induced phenotypes have been proposed to initiate and bias adaptive evolutionary change toward particular directions. The potential for this to happen depends in part on how well plastic responses are aligned with the additive genetic variance and covariance in traits. Using meta-analysis, we demonstrate that plastic responses to novel environments tend to occur along phenotype dimensions that harbor substantial amounts of additive genetic variation. This suggests that selection for or against environmentally induced phenotypes typically will be effective. One interpretation of the alignment between the direction of plasticity and the main axis of additive genetic variation is that developmental systems tend to respond to environmental novelty as they do to genetic mutation. This makes it challenging to distinguish if the direction of evolution is biased by plasticity or genetic “constraint.” Our results therefore highlight a need for new theoretical and empirical approaches to address the role of plasticity in evolution.

scholarly journals Genetic Parameters of Interspecific Hybrids of Eucalyptus grandis and E. urophylla Seedlings and Cuttings

2015 ◽  
Vol 64 (1-6) ◽  
pp. 291-308 ◽  
Author(s):  
G. J. van den Berg ◽  
S. D. Verryn ◽  
P. W. Chirwa ◽  
F. Van Deventer
Keyword(s):  
Genetic Variation ◽  
Growth Performance ◽  
Hybrid Material ◽  
Genetic Parameters ◽  
Breeding Strategy ◽  
Hybrid Breeding ◽  
Additive Variance ◽  
Breeding Values ◽  
Additive Genetic Variation ◽  
Hybrid Seedling

Abstract The current E. grandis × E. urophylla hybrid breeding strategy of South Africa’s Forestry Industry is to maintain large breeding populations of both parental species in which parents are selected based on their general combining ability (GCA) estimates or predicted individual tree breeding values and are used for interspecific hybrid crosses. The hybrid material is first screened in seedling progeny trials after which superior individuals are selected and tested as clones. Although this strategy has delivered superior clones for commercial production in South Africa, it is a time consuming strategy to follow and more cost effective strategies are being investigated. In order to review the current hybrid breeding strategy, information on the genetic control of the traits of interest is needed for E. grandis × E. urophylla seedling and clonal populations. The main objectives of this study were therefore to firstly estimate genetic parameters for E. grandis × E. urophylla hybrid seedling and clonal populations; secondly to investigate the correlation between E. grandis and E. urophylla parental (GCA) or individual breeding values and their general hybridising ability (GHA); and lastly to determine the correlation between E. grandis × E. urophylla hybrid seedling ortets and their ramets. Results of our study indicated that non-additive genetic variation explained the majority of the total genetic variation in E. grandis × E. urophylla seedling and clonal populations. Due to the pre-eminence of non-additive variance, the pure-hybrid correlations were weak, especially for clonal populations. It would therefore seem that GCA or predicted individual breeding values are not good predictors of GHA for growth performance in the observed populations. Our study also indicated a weak coefficient of correlation between the growth performance of seedling ortets and their ramets. These results suggest that: firstly a hybrid breeding strategy to capture non-additive genetic variation should be adopted; and secondly that the first phase of screening E. grandis × E. urophylla hybrid material as seedlings should be revisited.

Potential for selection to improve efficiency of feed use in beef cattle: a review

1999 ◽  
Vol 50 (2) ◽  
pp. 147 ◽  
Author(s):  
J. A. Archer ◽  
E. C. Richardson ◽  
R. M. Herd ◽  
P. F. Arthur
Keyword(s):  
Genetic Variation ◽  
Beef Cattle ◽  
Feed Intake ◽  
Production System ◽  
Feed Efficiency ◽  
Genetic Correlations ◽  
Total Production ◽  
Breeding Values ◽  
Improve Efficiency ◽  
Estimated Breeding Values

Evidence for genetic variation in feed efficiency of beef cattle is reviewed in this paper, and ways in which this variation might be used in selection programs to improve beef cattle in Australia are discussed. Efficiency of beef production systems is determined by feed and other inputs of all classes of animals in the production system as well as outputs in terms of slaughter progeny and cull cows. Different indices have been used to express aspects of efficiency on cattle over certain periods of the production cycle. Use of these indices is discussed, and then evidence for genetic variation in both growing animals and mature animals is reviewed. Genetic variation in feed efficiency exists in both growing and mature cattle, although information is lacking to determine whether variation in total production system efficiency exists. The physiological basis for observed variation in feed efficiency is discussed, with differences in requirements for maintenance, body composition, proportions of visceral organs, level of physical activity, and digestion efficiency identified as possible sources of variation. Selection to improve efficiency might be achieved by measuring feed intake of growing animals and utilising genetic correlations that are likely to exist between efficiency of growing animals and mature animals. Measurement of feed intake might occur in central test stations, or methods may be developed to measure feed intake on-farm. Ways of utilising information generated in genetic evaluations are discussed, and it is concluded that estimated breeding values for feed intake after a phenotypic adjustment for growth performance would be most practical, although not theoretically optimal. Such estimated breeding values would best be used in an economic selection index to account for genetic correlations with other traits, including feed intake of the breeding herd, and the economic value of feed in relation to other traits. Future research should be directed towards understanding the genetic relationships between feed intake and other traits in the breeding objective, and to find ways to reduce the cost of measurement of feed intake, including a search for genetic markers.

Visual assessment of post-mortem lesions exhibits little additive genetic variation in growing pigs

2003 ◽  
Vol 83 (2-3) ◽  
pp. 121-130 ◽  
Author(s):  
M. Henryon ◽  
P. Berg ◽  
G. Christensen ◽  
J. Jensen ◽  
M.S. Lund ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Visual Assessment ◽  
Growing Pigs ◽  
Post Mortem ◽  
Additive Genetic Variation

Genetic parameters of carcass quality in Down cross sheep

1968 ◽  
Vol 10 (2) ◽  
pp. 183-191 ◽  
Author(s):  
J. C. Bowman ◽  
J. E. Marshall ◽  
J. S. Broadbent
Keyword(s):  
Genetic Variation ◽  
Genetic Parameters ◽  
Carcass Traits ◽  
Genetic Correlations ◽  
Carcass Quality ◽  
Correction Factors ◽  
Muscle Area ◽  
Eye Muscle ◽  
Additive Genetic Variation ◽  
Commercial Value

This report gives an account of the paternal half-sib analysis of carcass quality, based on commercial joint dissection, on Down cross sheep collected in the four years 1962–65 inclusive. It also includes a discussion of the multiplicative correction factors used, and the phenotypic and genetic correlations between all the traits, estimated from the pooled within-farm, within-year analysis. It shows that there is very little genetic variation for many of the characters but that the percentage leg, percentage best end, age at slaughter and eye-muscle area have much additive genetic variation remaining for worthwhile response to be expected from selection. These three carcass traits are also the most important characters in determining the commercial value and saleability of lamb. From the results obtained it is argued that there is still much genetic variation for fat development in sheep.

scholarly journals Evolutionary potential varies across populations and traits in the neotropical oak Quercus oleoides

2018 ◽  
Vol 39 (3) ◽  
pp. 427-439 ◽  
Author(s):  
José A Ramírez-Valiente ◽  
Julie R Etterson ◽  
Nicholas J Deacon ◽  
Jeannine Cavender-Bares
Keyword(s):  
Climate Change ◽  
Genetic Variation ◽  
Genetic Structure ◽  
Additive Genetic Variance ◽  
Evolutionary Potential ◽  
Heritable Variation ◽  
Narrow Sense Heritability ◽  
Additive Genetic Variation ◽  
Quantitative Genetic ◽  
Quercus Oleoides

Abstract Heritable variation in polygenic (quantitative) traits is critical for adaptive evolution and is especially important in this era of rapid climate change. In this study, we examined the levels of quantitative genetic variation of populations of the tropical tree Quercus oleoides Cham. and Schlect. for a suite of traits related to resource use and drought resistance. We tested whether quantitative genetic variation differed across traits, populations and watering treatments. We also tested potential evolutionary factors that might have shaped such a pattern: selection by climate and genetic drift. We measured 15 functional traits on 1322 1-year-old seedlings of 84 maternal half-sib families originating from five populations growing under two watering treatments in a greenhouse. We estimated the additive genetic variance, coefficient of additive genetic variation and narrow-sense heritability for each combination of traits, populations and treatments. In addition, we genotyped a total of 119 individuals (with at least 20 individuals per population) using nuclear microsatellites to estimate genetic diversity and population genetic structure. Our results showed that gas exchange traits and growth exhibited strikingly high quantitative genetic variation compared with traits related to leaf morphology, anatomy and photochemistry. Quantitative genetic variation differed between populations even at geographical scales as small as a few kilometers. Climate was associated with quantitative genetic variation, but only weakly. Genetic structure and diversity in neutral markers did not relate to coefficient of additive genetic variation. Our study demonstrates that quantitative genetic variation is not homogeneous across traits and populations of Q. oleoides. More importantly, our findings suggest that predictions about potential responses of species to climate change need to consider population-specific evolutionary characteristics.

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