Sources of bias, genetic trend and changes in genetic correlation in carcass and ultrasound traits in the icelandic sheep population

The goal of this study was to analyze the genetic and environmental factors of selected meat yield indicators in Fleckvieh cattle in the Czech Republic, through the application of station (S) and field (F) testing methods. Data collected from fattened bulls were analyzed for F (n = 9378) and for S (n = 6346). In the F method and the S method, the values of the main meat yield indicators were as follows: carcass weight 402.91 kg (F), 339.37 kg (S); carcass daily gain 626.05 g/day (F), 609.74 g/day (S); SEUROP carcass classification 2.73 (F), 2.19 (S). Environmental factors were found to have a significant impact on the selected meat yield indicators; their heritability ranged from 0.14 (SEUROP classification) to 0.33 (dressing percentage). The genetic trend was significantly positive only in relation to those meat yield traits, which had a positive link to the size or weight of the animal. The genetic correlation between observations obtained in the S and F methods of testing was very high in relation to the carcass daily gain (0.8351) and carcass weight (0.8244), while slightly lower correlations were calculated for the SEUROP classification. A genetic evaluation of the degree of fatness is not routinely performed in Fleckvieh populations, and the newly established heritability for this trait ranges between 0.17–0.20. The genetic correlation between beef yield indicators and the exterior trait of muscularity was also established, and shows a strong link to the net daily gain, the SEUROP classification and body weight (0.79–0.97). The aim of the study was to evaluate the genetic and environmental effects on meat yield and also estimate genetic parameters for new traits. We can also state, based on the results, that a strong positive genetic trend is confirmed, especially in traits related to the size or weight of animals. This result can be used in breeding programs of dual-purpose cattle, where we can genetically improve the meat and milk yield through the body size.

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Analysis of non-genetic and genetic influences underlying the growth of Kajli lambs

South African Journal of Animal Science ◽

10.4314/sajas.v50i4.13 ◽

2020 ◽

Vol 50 (4) ◽

pp. 613-625

Author(s):

A. Ali ◽

K. Javed ◽

I. Zahoor ◽

K.M. Anjum

Keyword(s):

Birth Weight ◽

Genetic Correlation ◽

Fixed Effects ◽

Genetic Correlations ◽

Breeding Value ◽

Season Of Birth ◽

Genetic Trend ◽

Breeding Values ◽

Heritability Estimates ◽

Birth Type

Data on 2931 Kajli lambs, born from 2007 to 2018, were used to quantify environmental and genetic effects on growth performance of Kajli sheep. Traits considered for evaluation were birth weight (BWT), 120-day adjusted weight (120DWT), 180-day adjusted weight (180DWT), 270-day adjusted weight (270DWT), and 365-day adjusted weight (365DWT). Fixed effects of year of birth, season of birth, sex, birth type, and dam age on these traits were evaluated using linear procedures of SAS, 9.1. Similarly, BWT, 120DWT, 180DWT, and 270DWT were used as fixed effects mixed model analyses. Variance components, heritability and breeding values were estimated by restricted maximum likelihood. The genetic trend for each trait was obtained by regression of the estimated breeding values (EBV) on year of birth. Analyses revealed substantial influence of birth year on all traits. Sex and birth type were the significant sources of variation for BWT and 120DWT. Season of birth did not influence birth weight meaningfully, but had a significant role in the expression of 120DWT, 180DWT, and 270DWT. Heritability estimates were generally low (0.003 ± 0.018 to 0.099 ± 0.067) for all traits. With the exception of the genetic correlation of 180DWT and 365DWT, the genetic correlations between trait were strong and positive. Only 365DWT had a positive genetic trend. Although the heritability estimates for almost all weight traits were low, high and positive genetic correlations between BWT and other weight traits suggest that selection based on BWT would result in the improvement of other weight traits as a correlated response.Keywords: bodyweight, breeding value, genetic correlation, sheep

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Genetic parameter and genetic trend estimates for reproductive traits in Wistar rats

Arquivo Brasileiro de Medicina Veterinária e Zootecnia ◽

10.1590/1678-4162-11653 ◽

2020 ◽

Vol 72 (4) ◽

pp. 1479-1486

Author(s):

G. Taroco ◽

J.T. Paiva ◽

G.B. Mourão ◽

J.B.S. Ferraz ◽

E.C. Mattos ◽

...

Keyword(s):

Genetic Correlation ◽

Wistar Rats ◽

Genetic Parameter ◽

Genetic Correlations ◽

Reproductive Traits ◽

Wistar Rat ◽

The Other ◽

Genetic Trend ◽

Genetic Progress ◽

Genetic Trends

ABSTRACT The aim of this study was to estimate genetic parameters and genetic trends for reproductive traits in Wistar rats. A total of 1,167 data records from 283 females over six generations of monogamous mating pairs was used. Heritability and genetic correlation were estimated through Bayesian inference and genetic trends were calculated by linear regression of breeding values over generations. Heritability estimates for litter size at birth (LS), calving interval (CI), pup mortality (PM) and maternal cannibalism (CAN) presented low magnitude, ranging from 0.01 to 0.13. CAN presented high and positive genetic correlation with LS and PM (0.77 and 0.78, respectively). On the other hand, all the other estimated genetic correlations were not significant. Genetic trend was positive for LS (+0.0900 pups per generation), and negative for PM and CAN (-1.0085 and -0.5217 pups per generation, respectively). For CI the genetic trend was not significant. It is recommended to increase selection intensity on dams in this Wistar rat population in order to accelerate the genetic progress.

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Application of single-step GBLUP in New Zealand Romney sheep

Animal Production Science ◽

10.1071/an19315 ◽

2020 ◽

Vol 60 (9) ◽

pp. 1136

Author(s):

M. A. Nilforooshan

Keyword(s):

New Zealand ◽

Single Step ◽

Pedigree Information ◽

Genomic Relationship Matrix ◽

Relationship Matrix ◽

Genomic Relationship ◽

Genetic Trend ◽

Weaning Weight ◽

Sheep Population ◽

Pedigree Relationship

Context In New Zealand, Romney is the most predominant breed and is reared as a dual-purpose sheep. The number of genotypes is rapidly increasing in the sheep population, and making use of both genotypes and pedigree information is of importance for genetic evaluations. Single-step genomic best linear unbiased prediction (ssGBLUP) is a method for simultaneous prediction of genetic merits for genotyped and non-genotyped animals. The combination and the compatibility of the genomic relationship matrix (G) and the pedigree relationship matrix for genotyped animals (A22) is important for unbiased ssGBLUP. Aims The aim of the present study was to find an optimum genetic relationship matrix for ssGBLUP weaning-weight evaluation of Romney sheep in New Zealand. Methods Data consisted of adjusted weaning weights for 2422011 sheep, 50K single-nucleotide polymorphism genotypes for 13304 animals and 3028688 animals in the pedigree. Blending of G and A22 was tested with weights (k) ranging from 0.2 to 0.99 (kG + (1 – k)A22), followed by none or one of the three methods of tuning G to A22. Key results The averages of G and A22 were close to each other for overall, diagonal and off-diagonal elements. Therefore, differently tuned G performed similarly. However, elements of G showed larger variation than did the elements of A22 and, on average, genotyped animals were less related in G than in A22. Correlations between genomic estimated breeding values (GEBV) for the top 500 genotyped animals, as well as the rank correlations, were almost 1 among ssGBLUP evaluations using tuned G. The corresponding correlations with BLUP evaluations were increased by blending G with a larger proportion of A22, and were further increased by tuning G, indicating improved compatibility between G and A22. Blending and tuning G suppressed the inflation of GEBV and bias and it moved the genetic trend closer to the genetic trend obtained from BLUP. Conclusions A combination of blending and tuning G to A22, with a blending rate of 0.5 at most, is recommended for weaning weight of Romney sheep in New Zealand. Failure to do that resulted in inflated GEBV that can reduce the accuracy of selection, especially for genotyped animals. Implications There is a growing interest in the single-step GBLUP method for simultaneous genetic evaluation of genotyped and non-genotyped animals, in which genomic and pedigree relationship matrices are admixed. Using data from New Zealand Romney sheep, we have shown that adjustment of the genomic relationship matrix on the basis of the pedigree relationship matrix is necessary to avoid inflated evaluations. Improving the compatibility between genomic and pedigree relationship matrices is important for obtaining accurate and unbiased single-step GBLUP evaluations.

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Joint estimation of (co) variance components and breeding values for mean and dispersion of days from calving to first service in Holstein cow

Animal Production Science ◽

10.1071/an15643 ◽

2017 ◽

Vol 57 (4) ◽

pp. 760 ◽

Cited By ~ 1

Author(s):

Heydar Ghiasi ◽

Majbritt Felleki

Keyword(s):

Standard Deviation ◽

Genetic Correlation ◽

Additive Genetic Variance ◽

Joint Estimation ◽

Breeding Value ◽

Genetic Trend ◽

Breeding Values ◽

The Mean ◽

Estimated Breeding Values ◽

Genetic Standard Deviation

The present study explored the possibility of selection for uniformity of days from calving to first service (DFS) in dairy cattle. A double hierarchical generalised linear model with an iterative reweighted least-squares algorithm was used to estimate covariance components for the mean and dispersion of DFS. Data included the records of 27 113 Iranian Holstein cows (parity, 1–6) in 15 herds from 1981 to 2007. The estimated additive genetic variance for the mean and dispersion were 32.25 and 0.0139; both of these values had low standard errors. The genetic standard deviation for dispersion of DFS was 0.117, indicating that decreasing the estimated breeding value of dispersion by one genetic standard deviation can increase the uniformity by 12%. A strong positive genetic correlation (0.689) was obtained between the mean and dispersion of DFS. This genetic correlation is favourable since one of the aims of breeding is to simultaneously decrease the mean and increase the uniformity of DFS. The Spearman rank correlations between estimated breeding values in the mean and dispersion for sires with a different number of daughter observations were 0.907. In the studied population, the genetic trend in the mean of DFS was significant and favourable (–0.063 days/year), but the genetic trend in the dispersion of DFS was not significantly different from zero. The results obtained in the present study indicated that the mean and uniformity of DFS can simultaneously be improved in dairy cows.

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The genetic correlation between educational attainment, intracranial volume and IQ is due to recent polygenic selection on general cognitive ability

Open Behavioral Genetics ◽

10.26775/obg.2014.04.12 ◽

2014 ◽

Cited By ~ 1

Author(s):

Davide Piffer ◽

Emil O. W. Kirkegaard

Keyword(s):

Educational Attainment ◽

Cognitive Ability ◽

Genetic Correlation ◽

Intracranial Volume ◽

General Cognitive Ability ◽

Polygenic Selection

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Genetic and Environmental Influences on Executive Functions and Intelligence in the ABCD Study

10.31234/osf.io/xpba4 ◽

2020 ◽

Author(s):

Samantha M Freis ◽

Claire Morrison ◽

Jeffrey M. Lessem ◽

John K. Hewitt ◽

Naomi P. Friedman

Keyword(s):

Cognitive Development ◽

Executive Functions ◽

Genetic Correlation ◽

Middle Childhood ◽

Middle Age ◽

Environmental Influences ◽

Genetic Correlations ◽

Twin Studies

Executive functions (EFs) and intelligence (IQ) are phenotypically correlated and heritable; however, they show variable genetic correlations in twin studies spanning childhood to middle age. We analyzed data from over 11,000 children (9-10-year-olds, including 749 twin pairs) in the Adolescent Brain Cognitive Development (ABCD) Study to examine the phenotypic and genetic relations between EFs and IQ in childhood. We identified two EF factors – Common EF and Updating-Specific, which were both related to IQ (rs = .64-.81). Common EF and IQ were heritable (53-67%), and their genetic correlation (rG = .86) was not significantly different than 1. These results suggest that EFs and IQ are phenotypically but not genetically separable in middle childhood.

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EFFICIENCY AND COMPARISON OF THE TEST-DAY MODEL AND BLUP METHOD MODIFICATIONS FOR ASSESSING BULLS BREEDING VALUE IN SIMMENTAL CATTLE BREED

Molochnoe i miasnoe skotovodstvo ◽

10.33943/mms.2020.46.43.002 ◽

2020 ◽

Author(s):

А.И. МАМОНТОВА ◽

С.А. НИКИТИН ◽

Е.Е. МЕЛЬНИКОВА ◽

А.А. СЕРМЯГИН

Keyword(s):

Animal Model ◽

Milk Yield ◽

Cattle Breed ◽

Breeding Value ◽

Am1 Method ◽

Production Traits ◽

Genetic Trend ◽

Sire Model ◽

The Russian Federation ◽

Simmental Cattle

Целью проведенных исследований являлась отработка и адаптация применения методик BLUP AM (Animal Model — модель животного) и TDM (Test-Day Model — модель тестового дня) для прогнозирования племенной ценности быков-производителей и оценки селекционно-генетических параметров на популяции скота симментальской породы четырех регионов РФ. Проведен сравнительный анализ указанных методов с более ранним методом BLUP SM (Sire Model — модель отца). Рассчитана племенная ценность быков и коров симментальской породы по признакам молочной продуктивности: удой за 305 дней, выход молочного жира, выход молочного белка. Анализ полученных средних значений достоверности оценок быков-производителей, рассчитанных на основе сопоставляемых методов, свидетельствует, что достоверность для признака «удой за 305 дней» при переходе от метода SM1 к AM1 увеличивается на 2,4%, а при переходе от SM1 к TDM1 — на 7,8%. Даны варианты генетического тренда по удою с использованием различных уравнений моделей расчета племенной ценности. На основании полученных данных можно сделать вывод о том, что модель тестового дня позволяет не только повысить точность оценок быков, но и более рельефно выявить их ранги, а также несколько уменьшить срок получения достоверных оценок производителей по качеству потомства по продуктивным признакам. The purpose of this research was to develop and adapt the application of BLUP AM (Animal Model) and TDM (Test-Day Model) methods for predicting the sires breeding value and evaluating genetic parameters for Simmental cattle population in four regions of the Russian Federation. A comparative analysis of these methods with the earlier BLUP SM (Sire Model) method is performed. The breeding value for sires and cows of Simmental breed was calculated by milk production traits: milk yield for 305 days; milk fatyield; milk proteinyield. The sires reliability of average breeding value calculated by different methods reveal that milk yield for 305 days when switching from the SM1 to AM1 method increases by 2.4%, and when switching from SM1 to TDM1 — by 7.8%.The variants of the genetic trend for milk yield are given using various equations of BLUP and TDM. Based on the obtained data, it can be concluded that the Test-Day model allows increasing the accuracy of bull’s evaluation and also more clearly identifying their ranks, as well as slightly reducing the time for obtaining reliable estimates of bulls by offspring for production traits.

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GENETIC CORRELATION BETWEEN GROWTH RATE AND LITTER SIZE IN MICE

Genetics ◽

10.1093/genetics/54.6.1423 ◽

1966 ◽

Vol 54 (6) ◽

pp. 1423-1429 ◽

Cited By ~ 1

Author(s):

G W Rahnefeld ◽

R E Comstock ◽

Madho Singh ◽

S R NaPuket

Keyword(s):

Growth Rate ◽

Genetic Correlation ◽

Litter Size

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Realized Sampling Variances of Estimates of Genetic Parameters and the Difference Between Genetic and Phenotypic Correlations

Genetics ◽

10.1093/genetics/143.3.1409 ◽

1996 ◽

Vol 143 (3) ◽

pp. 1409-1416 ◽

Cited By ~ 1

Author(s):

Kenneth R Koots ◽

John P Gibson

Keyword(s):

Genetic Correlation ◽

Genetic Parameters ◽

Genetic Parameter ◽

Genetic Correlations ◽

Phenotypic Correlation ◽

Parameter Estimates ◽

Sampling Variance ◽

Phenotypic Correlations ◽

Genetic And Phenotypic Correlations ◽

Heritability Estimates

Abstract A data set of 1572 heritability estimates and 1015 pairs of genetic and phenotypic correlation estimates, constructed from a survey of published beef cattle genetic parameter estimates, provided a rare opportunity to study realized sampling variances of genetic parameter estimates. The distribution of both heritability estimates and genetic correlation estimates, when plotted against estimated accuracy, was consistent with random error variance being some three times the sampling variance predicted from standard formulae. This result was consistent with the observation that the variance of estimates of heritabilities and genetic correlations between populations were about four times the predicted sampling variance, suggesting few real differences in genetic parameters between populations. Except where there was a strong biological or statistical expectation of a difference, there was little evidence for differences between genetic and phenotypic correlations for most trait combinations or for differences in genetic correlations between populations. These results suggest that, even for controlled populations, estimating genetic parameters specific to a given population is less useful than commonly believed. A serendipitous discovery was that, in the standard formula for theoretical standard error of a genetic correlation estimate, the heritabilities refer to the estimated values and not, as seems generally assumed, the true population values.

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