Estimation of (co)variance components and genetic parameters of greasy fleece weights in Muzaffarnagari sheep

Abstract Background In honey bees, observations are usually made on colonies. The phenotype of a colony is affected by the average breeding value for the worker effect of the thousands of workers in the colony (the worker group) and by the breeding value for the queen effect of the queen of the colony. Because the worker group consists of multiple individuals, interpretation of the variance components and heritabilities of phenotypes observed on the colony and of the accuracy of selection is not straightforward. The additive genetic variance among worker groups depends on the additive genetic relationship between the drone-producing queens (DPQ) that produce the drones that mate with the queen. Results Here, we clarify how the relatedness between DPQ affects phenotypic variance, heritability and accuracy of the estimated breeding values of replacement queens. Second, we use simulation to investigate the effect of assumptions about the relatedness between DPQ in the base population on estimates of genetic parameters. Relatedness between DPQ in the base generation may differ considerably between populations because of their history. Conclusions Our results show that estimates of (co)variance components and derived genetic parameters were seriously biased (25% too high or too low) when assumptions on the relationship between DPQ in the statistical analysis did not agree with reality.

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Estimates of (co)variance components and genetic parameters of growth traits in Marwari sheep

Journal of Applied Animal Research ◽

10.1080/09712119.2014.987291 ◽

2014 ◽

Vol 44 (1) ◽

pp. 27-35 ◽

Cited By ~ 8

Author(s):

H. Singh ◽

U. Pannu ◽

H.K. Narula ◽

A. Chopra ◽

V. Naharwara ◽

...

Keyword(s):

Variance Components ◽

Genetic Parameters ◽

Growth Traits

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Estimation of variance components, genetic parameters and genetic trends for litter size of swines

Revista Brasileira de Zootecnia ◽

10.1590/s1516-35982010001000008 ◽

2010 ◽

Vol 39 (10) ◽

pp. 2155-2159 ◽

Cited By ~ 4

Author(s):

Leandro Barbosa ◽

Paulo Sávio Lopes ◽

Adair José Regazzi ◽

Robledo de Almeida Torres ◽

Mário Luiz Santana Júnior ◽

...

Keyword(s):

Litter Size ◽

Variance Components ◽

Genetic Parameters ◽

Random Effect ◽

Additive Model ◽

Fixed Effect ◽

Likelihood Method ◽

Phenotypic Variance ◽

Estimation Of Variance ◽

Genetic Trends

Records of Large White breed animals were used to estimate variance components, genetic parameters and trends for the character total number of born piglets (TNBP) as measure of litter size. For obtaining variance components and genetic parameters, it was used the Restricted Maximum Likelihood Method using MTDFREML software. Two mixed models (additive and repeatability) were evaluated. The additive model contained fixed effect of the contemporary group and the following random effects: direct additive genetic and residual effect for the first parturition. Repeatability model had the same effects of the additive model plus parturition order fixed effect and non-correlated animal permanent environment random effect for the second, third and forth parturition. Direct additive heritability estimates for TNBP were 0.15 and 0.20 for the additive and repeatability models, respectively. The estimate of the ration among variance of the non-correlated effect of animal permanent environment effect and the phenotypic variance, expressed as total variance proportion (c2) was 0.09. The estimates of yearly genetic trends obtained in the additive and repeatability models have similar behaviors (0.02 piglets/sow/year).

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Evaluación fenotípica y genética para características de crecimiento en la raza criolla colombiana Costeño con Cuernos

Ciencia y Tecnología Agropecuaria ◽

10.21930/rcta.vol7_num2_art:65 ◽

2007 ◽

Vol 7 (2) ◽

pp. 12 ◽

Cited By ~ 3

Author(s):

Rodrigo Alfredo Martínez ◽

Juan Esteban Pérez ◽

Teófilo Herazo

Keyword(s):

Birth Weight ◽

Variance Components ◽

Fixed Effects ◽

Genetic Parameters ◽

Growth Traits ◽

Phenotypic Correlation ◽

Phenotypic Variance ◽

Direct Effects ◽

Weaning Weight ◽

Number Of Births

Se establecieron componentes de varianza, así como parámetros fenotípicos y genéticos, respecto de las variables ‘peso al nacimiento’, ‘peso al destete’ (ajustado a los 270 días) y ‘peso a los 480 días’ en un hato del ganado criollo colombiano Costeño con Cuernos. Se analizaron 2.281 registros de pesos al nacer, 1.722 de pesos al destete y 1.086 de pesos ajustados a los 480 días utilizando la metodología de máxima verosimilitud restringida (DFREML). También se ajustó un modelo animal que incluyó efectos genéticos directos, maternos y de ambiente permanente, asumiendo como efectos fijos el año de nacimiento, el sexo del ternero y el número de partos de la madre; finalmente, se estimaron los parámetros genéticos ‘heredabilidad’, ‘repetibilildad’ y se establecieron correlaciones genéticas y fenotípicas. Se reportan bajas estimaciones de heredabilidad de los efectos directos, que varían entre 0,17 ± 0,001 y 0,21 ± 0,074 para los pesos al nacer y al destete, respectivamente; así mismo, fue baja la heredabilidad de los efectos genéticos maternos con relación al peso al nacimiento, aunque estos estimados aumentaron respecto de los pesos al nacer y al destete. Las correlaciones entre efectos directos y maternos fueron negativas, pero el mayor valor se encontró para el peso al nacimiento (-0,89). La contribución del ambiente permanente como proporción de la varianza fenotípica total fue baja y disminuyó a medida que aumentó la edad del animal. Genetic and phenotypic evaluation to characterize growth traits of the native Colombian breed Costeño con CuernosFor a herd of native Colombian breed of cattle -Costeño con Cuernos (CCC)- estimates of variance components for phenotypic and genetic parameters were obtained for birth weight, weight at weaning (adjusted to 270 days) and weight at 480 days. Using the restricted maximum likelihood (REMI) methodology, 2281 birth weight records (PN), 1722 weaning weight records and 1086 weight records adjusted to 480 days were analyze by fitting a model which included direct and maternal genetics effects as well as permanent environmental effects, assuming that fixed effects were year of birth weight, calf gender and the mother number of births. The genetic parameters for heritability, repeatability, genetic and phenotypic correlation were estimated and genotypic and phenotypic correlation was established. Heritability estimates for direct effects are low and range from 0.17 ± 0.001 and 0.21 ± 0.074 for birth and weaning weight respectively; while estimates for maternal genetics effects were also low for PN, they were higher for weaning weight and weight at 480 days. There was a negative correlation between direct and maternal effects, and the higher value was for PN (-0.89). The contribution of the variable permanent environment measured as the contribution of the phenotypic variance was low and diminished as animal age increased.

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Estimation of variance components of milk, fat, and protein yields of Tunisian Holstein dairy cattle using Bayesian and REML methods

Archives Animal Breeding ◽

10.5194/aab-59-243-2016 ◽

2016 ◽

Vol 59 (2) ◽

pp. 243-248 ◽

Cited By ~ 3

Author(s):

Hafedh Ben Zaabza ◽

Abderrahmen Ben Gara ◽

Hedi Hammami ◽

Mohamed Amine Ferchichi ◽

Boulbaba Rekik

Keyword(s):

Dairy Cattle ◽

Bayesian Methods ◽

Milk Fat ◽

Variance Components ◽

Genetic Parameters ◽

Genetic Correlations ◽

Bayesian Procedure ◽

Milk Traits ◽

Residual Variances ◽

Estimation Of Variance

Abstract. A multi-trait repeatability animal model under restricted maximum likelihood (REML) and Bayesian methods was used to estimate genetic parameters of milk, fat, and protein yields in Tunisian Holstein cows. The estimates of heritability for milk, fat, and protein yields from the REML procedure were 0.21 ± 0.05, 0.159 ± 0.04, and 0.158 ± 0.04, respectively. The corresponding results from the Bayesian procedure were 0.273 ± 0.02, 0.198 ± 0.01, and 0.187 ± 0.01. Heritability estimates tended to be larger via the Bayesian than those obtained by the REML method. Genetic and permanent environmental variances estimated by REML were smaller than those obtained by the Bayesian analysis. Inversely, REML estimates of the residual variances were larger than Bayesian estimates. Genetic and permanent correlation estimates were on the other hand comparable by both REML and Bayesian methods with permanent environmental being larger than genetic correlations. Results from this study confirm previous reports on genetic parameters for milk traits in Tunisian Holsteins and suggest that a multi-trait approach can be an alternative for implementing a routine genetic evaluation of the Tunisian dairy cattle population.

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Estimates of (co)variance components and genetic parameters for body weights and growth efficiency traits in the New Zealand white rabbit

World Rabbit Science ◽

10.4995/wrs.2017.7057 ◽

2017 ◽

Vol 25 (4) ◽

pp. 329 ◽

Cited By ~ 1

Author(s):

M. Sakthivel ◽

D. Balasubramanyam ◽

P. Kumarasamy ◽

H. Gopi ◽

A. Raja ◽

...

Keyword(s):

Body Weight ◽

New Zealand ◽

Variance Components ◽

Environmental Effect ◽

Genetic Parameters ◽

Growth Traits ◽

Genetic Effect ◽

Growth Efficiency ◽

Body Weights ◽

Heritability Estimates

The genetic parameters of growth traits in the New Zealand White rabbits kept at Sheep Breeding and Research Station, Sandynallah, The Nilgiris, India were estimated by partitioning the variance and covariance components. The (co)variance components of body weights at weaning (W42), post-weaning (W70) and marketing (W135) age and growth efficiency traits viz., average daily gain (ADG), relative growth rate (RGR) and Kleiber ratio (KR) estimated on a daily basis at different age intervals (42 to 70 d; 70 to 135 d and 42 to 135 d) from weaning to marketing were estimated by restricted maximum likelihood, fitting 6 animal models with various combinations of direct and maternal effects. Data were collected over a period of 15 yr (1998 to 2012). A log-likelihood ratio test was used to select the most appropriate univariate model for each trait, which was subsequently used in bivariate analysis. Heritability estimates for W42, W70 and W135 were 0.42±0.07, 0.40±0.08 and 0.27±0.07, respectively. Heritability estimates of growth efficiency traits were moderate to high (0.18 to 0.42). Of the total phenotypic variation, maternal genetic effect contributed 14 to 32% for early body weight traits (W42 and W70) and ADG1. The contribution of maternal permanent environmental effect varied from 6 to 18% for W42 and for all the growth efficiency traits except for KR2. Maternal permanent environmental effect on most of the growth efficiency traits was a carryover effect of maternal care during weaning. Direct maternal genetic correlations, for the traits in which maternal genetic effect was significant, were moderate to high in magnitude and negative in direction. Maternal effect declined as the age of the animal increased. The estimates of total heritability and maternal across year repeatability for growth traits were moderate and an optimum rate of genetic progress seems possible in the herd by mass selection. The genetic and phenotypic correlations among body weights and between growth efficiency traits were also estimated. Moderate to high heritability and higher genetic correlation in body weight traits promise good scope for genetic improvement provided measures are taken to keep the inbreeding at the lowest level.

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(Co)variance components and genetic parameters for growth rate and Kleiber ratio in fat-tailed Mehraban sheep

Archives Animal Breeding ◽

10.7482/0003-9438-56-055 ◽

2013 ◽

Vol 56 (1) ◽

pp. 564-572 ◽

Cited By ~ 1

Author(s):

F. Ghafouri-Kesbi

Keyword(s):

Growth Rate ◽

Variance Components ◽

Genetic Parameters ◽

Average Daily Gain ◽

Genetic Correlations ◽

Phenotypic Variance ◽

Genetic Progress ◽

Kleiber Ratio ◽

Derivative Free ◽

Maternal Heritability

Abstract. The aim of the present study was to estimate (co)variance components and genetic parameters for average daily gain from birth to weaning (ADGa), weaning to 6 months (ADGb), weaning to 9 months (ADGc), 6 months to 9 months (ADGd) and corresponding Kleiber ratios (KRa, KRb, KRc and KRd) in Mehraban sheep. A derivative-free algorithm combined with a series of six univariate linear animal models was used to estimate phenotypic variance and its direct, maternal and residual components. In addition, bivariate analyses were done to estimate (co)variance components between traits. Estimates of direct heritability (h2) were 0.10, 0.11, 0.16, 0.09, 0.13, 0.13, 0.15 and 0.08 for ADGa, ADGb, ADGc, ADGd, KRa, KRb, KRc and KRd, respectively and indicate that in Mehraban sheep genes contribute very little to the variance of the growth rate and Kleiber ratio. Estimates of maternal heritability (m2) were 0.10, 0.08 and 0.05 for ADGa, KRa and KRb, respectively. Direct additive genetic correlations ranged from −0.32 (KRa-KRd) to 0.99 (ADGb-KRb) and phenotypic correlations ranged from −0.53 (ADGa- ADGd) to 0.99 (ADGa-KRa). Estimates of direct heritability and genetic correlations show that genetic improvement in efficiency of feed utilization through selection programmes is possible, though it would generate a relatively slow genetic progress.

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Heritability of egg production in laying hens under cumulative, multitrait and repeated measurement animal models

Czech Journal of Animal Science ◽

10.17221/2282-cjas ◽

2008 ◽

Vol 52 (No. 8) ◽

pp. 254-260 ◽

Cited By ~ 8

Author(s):

A. Wolc ◽

M. Lisowski ◽

T. Szwaczkowski

Keyword(s):

Animal Models ◽

Variance Components ◽

Egg Production ◽

Genetic Parameters ◽

Laying Hens ◽

Genetic Effects ◽

Repeated Measurement ◽

Repeated Measurements ◽

The Other ◽

Highly Correlated

Six generations of three layer lines (13 770 recorded individuals of A22 line, 13 950 of A88, 9 351 of K66) were used to estimate genetic effects on egg production under cumulative, multitrait and repeatability models. Variance components were estimated by the AI-REML algorithm. The heritability of cumulative records ranged from 0.08 to 0.1. For the repeated measurements model the following genetic parameters were obtained: heritability 0.02–0.03, repeatability 0.04–0.38. The first two months of egg production were found to differ from the other periods: heritability was relatively high (h2 > 0.35) and low or negative correlations with the other periods were found. Heritability was low (h2 < 0.1) from the peak production until the end of recording and the consecutive periods were highly correlated. Further studies on monthly records are suggested.

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