457 research outputs found
Genetic aspects of calving, growth, and carcass traits in beef cattle
The aim of this thesis was to learn more about the genetic background of calving, growth and carcass traits of beef cattle breeds in Sweden, and to assess the possibility of including calving traits and commercial carcass traits in the genetic evaluation. In addition, the genetic relationship between field-recorded growth rate and daily weight gain at station performance testing was investigated. The breeds studied were Charolais, Hereford and Simmental. Records of birth weight, pre-weaning gain, post-weaning gain, carcass fleshiness grade, carcass fatness grade, carcass weight, calving difficulty score and stillbirth were analysed using linear animal models. The estimated direct heritabilities were moderate to high for birth and carcass weight, moderate for pre- and post-weaning gain, carcass fleshiness and fatness grades, low for calving difficulty score and very low for stillbirth. Maternal heritabilities tended to be lower than the direct ones. Genetic relationships between direct and maternal genetic effects were generally antagonistic. Moderate to high genetic correlations were estimated between post-weaning gain in the field and at the station, showing considerable breed differences, and the added value of station testing was questioned. Genetic relationships were generally weaker between growth traits and both carcass fleshiness and fatness grade than between growth and carcass weight. Male and female birth weights were found to be the same trait genetically, and strong genetic relationships were estimated between birth weight and calving traits. Less than unity genetic correlations between calving difficulty at first and later parities indicated that partly different sets of genes control these traits. Some antagonistic relationships were found between carcass and calving traits. It was concluded that it would be feasible to include commercial carcass records and calving difficulty score in the genetic evaluation, and that both direct and maternal effects should be considered for pre-weaning traits. Information on correlated traits should be used for selection against stillbirth as direct selection would be inefficient due to small progeny group size and very low heritability. Joint genetic evaluation of pre-weaning gain and carcass weight was recommended to reduce selection bias
Synthetic photometry for carbon-rich giants. IV. An extensive grid of dynamic atmosphere and wind models
The evolution and spectral properties of stars on the AGB are significantly
affected by mass loss through dusty stellar winds. Dynamic atmosphere and wind
models are an essential tool for studying these evolved stars, both
individually and as members of stellar populations, to understand their
contribution to the integrated light and chemical evolution of galaxies.
This paper is part of a series testing state-of-the-art atmosphere and wind
models of carbon stars against observations, and making them available for use
in various theoretical and observational studies.
We have computed low-resolution spectra and photometry (in the wavelength
range 0.35-25 mu) for a grid of 540 dynamic models with stellar parameters
typical of solar-metallicity C-rich AGB stars and with a range of pulsation
amplitudes. The models cover the dynamic atmosphere and dusty outflow (if
present), assuming spherical symmetry, and taking opacities of gas-phase
species and dust grains consistently into account. To characterize the
time-dependent dynamic and photometric behaviour of the models in a concise way
we defined a number of classes for models with and without winds.
Comparisons with observed data in general show a quite good agreement for
example regarding mass-loss rates vs. (J-K) colours or K magnitudes vs. (J-K)
colours. Some exceptions from the good overall agreement, however, are found
and attributed to the range of input parameters (e.g. relatively high carbon
excesses) or intrinsic model assumptions (e.g. small particle limit for grain
opacities).
While current results indicate that some changes in model assumptions and
parameter ranges should be made in the future to bring certain synthetic
observables into better agreement with observations, it seems unlikely that
these pending improvements will significantly affect the mass-loss rates of the
models.Comment: 28 pages, 15 figures. Table B.1, an 11-page table, is only available
at CD
Synthetic photometry for carbon-rich giants. V. Effects of grain-size-dependent dust opacities
The properties and the evolution of asymptotic giant branch (AGB) stars are
strongly influenced by their mass loss through a stellar wind. This is believed
to be caused by radiation pressure due to the absorption and scattering of the
stellar radiation by the dust grains formed in the atmosphere. The optical
properties of dust are often estimated using the small particle limit (SPL)
approximation, and it has been used frequently in modelling AGB stellar winds
when performing radiation-hydrodynamics (RHD) simulations. We aim to
investigate the effects of replacing the SPL approximation by detailed Mie
calculations of the size-dependent opacities for grains of amorphous carbon
forming in C-rich AGB star atmospheres. We performed RHD simulations for a
large grid of carbon star atmosphere+wind models with different effective
temperatures, luminosities, stellar masses, carbon excesses, and pulsation
properties. Also, a posteriori radiative transfer calculations for many radial
structures (snapshots) of these models were done, resulting in spectra and
filter magnitudes. We find, when giving up the SPL approximation, the wind
models become more strongly variable and more dominated by gusts, although the
average mass-loss rates and outflow speeds do not change significantly; the
increased radiative pressure on the dust throughout its formation zone does,
however, result in smaller grains and lower condensation fractions (and thus
higher gas-to-dust ratios). The photometric K magnitudes are generally
brighter, but at V the effects of using size-dependent dust opacities are more
complex: brighter for low mass-loss rates and dimmer for massive stellar winds.
Given the large effects on spectra and photometric properties, it is necessary
to use the detailed dust optical data instead of the simple SPL approximation
in stellar atmosphere+wind modelling where dust is formed.Comment: 14 pages, 24 figures. Accepted for publication in Astronomy \&
Astrophysic
Effect of co-twin gender on neurodevelopment symptoms : a twin register study
Background: Autism spectrum disorder (ASD) and attentionâdeficit/hyperactivity disorder
(ADHD) are neurodevelopmental disorders thought to have both genetic and environmental
causes. It has been hypothesized that exposure to elevated levels of prenatal testosterone is
associated with elevated traits of ASD and ADHD. Assuming that testosterone levels from a
dizygotic male twin fetus may lead to enhanced testosterone exposure of its coâtwins, we aimed
to test the prenatal testosterone hypothesis by comparing sameâsex with oppositeâsex dizygotic
twins with respect to neurodevelopmental symptoms.
Methods: Neuropsychiatric traits were assessed in a populationâbased twin cohort from the
Child and Adolescent Twin Study in Sweden (CATSS). Parental interviews were conducted for
16,312 dizygotic twins, 9 and 12 years old, with the AutismâTics, ADHD, and other Comorbidities
inventory (AâTAC).
Results: Girls with a female coâtwin had an increased risk of reaching the cutâoff score for ADHD
compared with girls with a male coâtwin. Both boys and girls with a female coâtwin displayed a
larger number of traits related to attention deficit and repetitive and stereotyped behaviors
than those with a male twin. In girls, this also extended to social interaction and the combined
measures for ASD and ADHD, however with small effect sizes.
Conclusions: Our results are reverse to what would have been expected from the prenatal
testosterone hypothesis but consistent with a previous study of ASD and ADHD traits in
dizygotic twins. The seemingly protective effect for girls of having a twin brother may be an
effect of parent report bias, but may also be an unexpected effect of sharing the intrauterine
environment with a male coâtwin.The Swedish Research CouncilThe Brain FoundationBertil HĂ„llstenâs FoundationSöderströmâs foundationThe Swedish Council for Health, Working Life and WelfareStockholm County Council (ALF)The Söderström-Königska FoundationManuscrip
Changes in genomic inbreeding and diversity over half a century in Swedish Red and Swedish Holstein dairy cattle
Swedish Red (SR) and Swedish Holstein (SH) are the dominating commercial dairy cattle breeds in Sweden. Both breeds have undergone substantial changes during the last half century due to intensive selection for breeding goal traits, but also resulting from increased international exchange of breeding animals and genetic drift. The aim of this study was to learn more about changes in genomic diversity and inbreeding in these two breeds over time. Therefore, semen samples from old bulls were genotyped using the 150K Genomic Profiler SNP array and combined with 50K SNP array genotype data, obtained for more recent bulls from the Nordic Cattle Genetic Evaluation. Different measures of level of homozygosity, genomic inbreeding, relatedness and changes in allele frequency were estimated for bulls born during different time periods from the 1950s until 2020. In total, more than 33,000 SNPs for 9737 SR and 5041 SH bulls were included in the analysis using PLINK v1.9. The results showed higher average homozygosity for SR than for SH bulls up to around 2000, but the difference was very small after that. The average inbreeding coefficients based on deviation from expected homozygosity as well as on runs of homozygosity decreased until the early 1980s in both breeds, whereafter they started to increase again for SH, but stayed more stable for SR. From the 1990s onwards, SH displayed higher average inbreeding coefficients than SR. In the last studied birth year group (2015-2020), the mean inbreeding coefficient based on runs of homozygosity was 5.9% for SH and 3.7% for SR. A principal component analysis showed a pattern of genetic relationships related to the birth year period of the bulls, illustrating the gradual change of the genetic material within each breed. The change in allele frequency over time was generally larger for SH than for SR. The results show that the inbreeding level was higher half a century ago than at present, and the inbreeding levels were lower than in some other studied populations. Still, the increase seen for inbreeding coefficients and homozygosity, especially in SH during recent years, should be considered in future breeding strategies
Activities by Hediste diversicolor under different light regimes: experimental quantification of particle reworking using time-resolved imaging
Particle reworking by the ragworm Hediste diversicolorwas assessed by quantifying the transport of fluorescent particles (luminophores) added to the surface sediment during a 10 day experiment. Plexiglass cores and thin glass aquaria with fauna and controls were exposed to either 12 hour light/dark cycles or constant darkness. Luminophore distributions were evaluated by side-view imaging of the aquaria together with destructive sectioning and quantification of tracer distributions in both types of microcosms at the end of experiments. Tracer distributions were evaluated by the gallery-diffusor model, from which the biodiffusion (Db) and the non-local transport (r) coefficients were determined. In addition, the maximum penetration depth (MPD) of luminophores, the 2-D redistribution coefficient, and the transport ratewere used as a suite of proxies to quantify particle reworking by fauna. All measured reworking proxies demonstrated a general decrease in transport of luminophores in darkness compared to light/dark cycles. The difference was significant for proxies determined from sectioning. Imaging of particle transport demonstrated that rates were ~30% higher during light/dark cycles, with ~constant amount of particles transported on a daily basis. The effect of light was consistent in the two microcosm types. However, there was a significant difference in Db, while r and MPD were not significantly different between the cores and aquaria. Overall, these results suggest a light-triggered surface feeding by H. diversicolor. Our study highlights the importance of experimental settings for quantification of particle transport by fauna, and that light conditions and types of experimental microcosms need to be carefully considered during investigations of bioturbation in illuminated environments
Cardiac resynchronization therapy in the presence of total atrioventricular block reduces long-lasting atrial fibrillation episodes
BACKGROUND
There is an ongoing debate on how cardiac resynchronization therapy (CRT) in the presence of total AV block affects atrial fibrillation (AF) episodes and symptoms in patients with AF.
METHODS
Seventy-five patients with symptomatic, drug and ablation refractory AF received, irrespective of their left ventricular ejection fraction (EF), either a CRT device and underwent subsequent atrioventricular node (AVN) ablation or already had a total AV block and underwent CRT upgrade. Long-lasting AF episodes (>48Â h), left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVEDD), left atrial diameter (LAD), NTproBNP levels, EHRA score, and NYHA class had been monitored on the follow-up.
RESULTS
The number of patients experiencing long-lasting AF episodes (>48Â h) and symptoms decreased significantly within 24Â months after CRT implantation in the presence of total AV block (pâ<â.001) from 57 (76%) to 25 (33.3%). Mean LAD decreased from 52âmm (IQR 48.0-56.0) to 48âmm (IQR 42.0-52.0, pâ<â.001) and LVEDD from 54âmm (IQR 49.0-58.0) to 51âmm (IQR 46.5-54.0, pâ<â.001).
CONCLUSION
A combination of total AVN block and biventricular pacing markedly reduces long-lasting AF episodes, symptoms, left atrial diameter, and left ventricular end-diastolic diameter
Simulation of optimum population structure (population dynamics)
International audienc
Factor analysis of evaluated and linearly scored traits in Swedish Warmblood horses
Assessment protocols to describe the various aspects of conformation, gait and jumping traits on a linear scale were introduced at young horse tests for Swedish Warmblood horses in 2013. The traits scored on a linear scale are assumed to be less subjective and more easily compared across populations than the traditional evaluated traits that are scored relative to the breeding goal. However, the resulting number of traits is considerable, and several of the traits are correlated. The aim of this study was to investigate the interrelationship between the different evaluated and linearly scored traits in Swedish Warmbloods using factor analysis. In total, 20,935 horses born 1996-2017 had information on evaluated traits, and 5450 of these also had linearly scored trait records assessed since 2014 when the protocol was updated. A factor analysis with varimax rotation was performed separately for evaluated and linearly scored traits using the Psych package in R. Height at withers was included in both analyses. A total of four factors for evaluated traits and 14 factors for linearly scored traits were kept for further analysis. Missing values for individual traits in horses with linearly scored trait records were imputed based on correlated traits before factor scores were calculated using factor loadings. Genetic parameters for, and correlations between, the resulting underlying factors were estimated using multiple-trait animal models in the BLUPF90 package. Heritability estimates were on a similar level as for the traits currently used in the genetic evaluation, ranging from 0.05 for the factor for linearly scored traits named L.behaviour (dominated by traits related to behaviour) to 0.59 for the factor for evaluated traits named E.size (dominated by height at withers and conformation). For both types of traits, separate factors were formed for jumping and gait traits, as well as for body size. High genetic correlations were estimated between such corresponding factors for evaluated traits and factors for linearly scored traits. In conclusion, factor analysis could be used to reduce the number of traits to be included in multiple-trait genetic evaluation or in genomic analysis for warmblood horses. It can also contribute to a better understanding of the interrelationships among the assessed traits and be useful to decide on subgroups of traits to be used in several multiple-trait evaluations on groups of original traits
Consequences of specialized breeding in the Swedish Warmblood horse population
In many European warmblood studbooks, clear specialization toward either jumping or dressage horses is evident. The Swedish Warmblood (SWB) is also undergoing such specialization, creating a possible need for separate breeding programs and a discipline-specific Young Horse Test (YHT). This study investigated how far specialization of the SWB breed has proceeded and the potential consequences. Individuals in a population of 122,054 SWB horses born between 1980 and 2020 were categorized according to pedigree as jumping (J), dressage (D), allround (AR), or thoroughbred (Th). Data on 8,713 J horses and 6,477 D horses assessed for eight traits in YHT 1999-2020 were used to estimate genetic parameters within and between J and D horses and between different periods. Future scenarios in which young horses are assessed for either jumping or dressage traits at YHT were also analyzed. More than 80% of horses born in 1980-1985 were found to be AR horses, while 92% of horses born in 2016-2020 belonged to a specialized category. The average relationship within J or D category was found to increase during the past decade, whereas the relationship between these categories decreased. Heritability estimates for gait traits were 0.42-0.56 for D horses and 0.25-0.38 for J horses. For jumping traits, heritability estimates were 0.17-0.26 for J horses and 0.10-0.18 for D horses. Genetic correlations between corresponding traits assessed in J and D horses were within the range 0.48-0.81, with a tendency to be lower in the late study period. In the future scenarios, heritability and genetic variance both decreased for traits that were not assessed in all horses, indicating that estimation of breeding value and genetic progress for these traits could be affected by a specialized YHT. However, ranking of sires based on estimated breeding values (EBVs) and accuracy of EBVs was only slightly altered for discipline-specific traits. With continued specialization in SWB, specialization of the YHT should thus be considered
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