scholarly journals Genetic evaluation of eggshell color based on additive and dominance models in laying hens

2020 ◽  
Vol 33 (8) ◽  
pp. 1217-1223
Author(s):  
Jun Guo ◽  
Kehua Wang ◽  
Liang Qu ◽  
Taocun Dou ◽  
Meng Ma ◽  
...  
Keyword(s):  
Animal Model ◽  
Egg Production ◽  
Genetic Correlations ◽  
Phenotypic Variance ◽  
Dominance Model ◽  
Shell Color ◽  
Inbreeding Coefficients ◽  
L Value ◽  
Eggshell Color

Objective: Eggshells with a uniform color and intensity are important for egg production because many consumers assess the quality of an egg according to the shell color. In the present study, we evaluated the influence of dominant effects on the variations in eggshell color after 32 weeks in a crossbred population.Methods: This study was conducted using 7,878 eggshell records from 2,626 hens. Heritability was estimated using a univariate animal model, which included inbreeding coefficients as a fixed effect and animal additive genetic, dominant genetic, and residuals as random effects. Genetic correlations were obtained using a bivariate animal model. The optimal diagnostic criteria identified in this study were: L* value (lightness) using a dominance model, and a* (redness), and b* (yellowness) value using an additive model.Results: The estimated heritabilities were 0.65 for shell lightness, 0.42 for redness, and 0.60 for yellowness. The dominance heritability was 0.23 for lightness. The estimated genetic correlations were 0.61 between lightness and redness, –0.84 between lightness and yellowness, and –0.39 between redness and yellowness.Conclusion: These results indicate that dominant genetic effects could help to explain the phenotypic variance in eggshell color, especially based on data from blue-shelled chickens. Considering the dominant genetic variation identified for shell color, this variation should be employed to produce blue eggs for commercial purposes using a planned mating system.

scholarly journals Estimation of Additive and Non-Additive Genetic Variances of Body Weight, Egg Weight and Egg Production for Quails (Coturnix coturnix japonica) with an Animal Model Analysis

2006 ◽  
Vol 49 (3) ◽  
pp. 300-307 ◽  
Author(s):  
N. Mielenz ◽  
R. R. Noor ◽  
L. Schüler
Keyword(s):  
Animal Model ◽  
Body Weight ◽  
Egg Production ◽  
Additive Model ◽  
The Body ◽  
Phenotypic Variance ◽  
Egg Weight ◽  
Term Selection ◽  
Inbreeding Coefficients

Abstract. This study estimates the additive and non-additive variances for egg production and body weight traits of two lines of quails from a long-term selection with the help of the REML method. For the body weight of 42-day-old females (BW42f) and males (BW42m), a total of 7,934 records for line 1 and 7,214 records for line 2 from 21 generations were used in our analyses. Additionally, 1,717 records of females from line 1 and 1,671 records of females from line 2 contained information on their egg production at an age of 42 to 200 days (EN200), on the average egg weight for the first 11 weeks of their laying season (EW1), on the average egg weight from weeks 12 to 23 (EW2), and on their body weight at an age of 200 days (BW200f). A multivariate additive animal model and one-trait dominance models, which include the inbreeding coefficients as covariates, were fitted to the data. The estimates of the heritability gained from our dominance models were smaller than those from the additive model. For line 1, the heritability values decreased for EN200 from 0.35 to 0.32, for EW1 from 0.66 to 0.56, for BW200f from 0.42 to 0.38, and for BW200m from 0.51 to 0.49, respectively. For the first line, the respective ratio (d2) of the dominance variance to the phenotypic variance for EN200, EW1, BW200f and BW200m was 0.08, 0.22, 0.09 and 0.21, and the values for the second line were 0.12, 0.06, 0.001 and 0.23.

scholarly journals Genetische Parameter für Merkmale der Eiproduktion geschätzt mit additiven und Dominanzmodellen bei Legehennen

2003 ◽  
Vol 46 (1) ◽  
pp. 77-84
Author(s):  
N. Mielenz ◽  
M. Kovac ◽  
E. Groeneveld ◽  
R. Preisinger ◽  
M. Schmutz ◽  
...  
Keyword(s):  
Animal Model ◽  
Egg Production ◽  
Laying Hens ◽  
Additive Model ◽  
Production Traits ◽  
Dominance Model ◽  
Egg Weight ◽  
Dominance Variance ◽  
Breeding Values ◽  
Inbreeding Coefficients

Abstract. Title of the paper: Genetic evaluation of egg production traits based on additive and dominance models in laying hens The study was conducted to estimate additive and dominance variances for egg production traits of two commercial purebred lines (A & D) of laying hens using an animal model analysis. Breeding values estimated from a dominance model were compared to those from an additive model. In total, 8625 records of line A and 8968 records of line D from three generations were used in the analysis. Every record contained information on the number of eggs laid between 20 and 28 (EN1-2), 28 and 48 (EN3-7) and between 20 and 48 (EN1-7) weeks of age. Further average egg weight (EW), egg weight at 28 (EW1), 33 (EW2) and 40 (EW3) weeks of age were available. An additive animal model and one- and three-trait dominance models including the inbreeding coefficients as covariates were fitted to the data. Simultaneous estimates of the additive and dominance variance components were obtained using the REML method. The estimates of h2 from the dominance models for EN1-2, EN3-7, EN1-7 and EW were 0.40, 0.15, 0.28 and 0.62 for line A and 0.38, 0.16, 0.26 and 0.53 for line D. The ratios d2 of the dominance variance to total variance were moderate for EN (0.12–0.13) and low for EW (0.04–0.07) within line A but relatively low for EN (0.03–0.12) and high for EW (0.12–0.21) within line D. Between the breeding values of the best 100 hens of each generation estimated with the additive and the dominance models for EN1-2, EN3-7, EN1-7 and EW high rank correlations (0.946, 0.896, 0.945 and 0.991 in line A and 0.996, 0.899, 0.971 and 0.951 in line D were found

scholarly journals Varianzkomponentenschätzung unter Berücksichtigung von Dominanz an simulierten Reinzuchtlinien

2004 ◽  
Vol 47 (4) ◽  
pp. 387-395
Author(s):  
M. Wensch-Dorendorf ◽  
N. Mielenz ◽  
E. Groeneveld ◽  
M. Kovac ◽  
L. Schüler
Keyword(s):  
Animal Model ◽  
Variance Components ◽  
Random Mating ◽  
Phenotypic Variance ◽  
Dominance Relationship ◽  
Gene Model ◽  
Dominance Model ◽  
Dominance Variance ◽  
Simulation Based ◽  
Estimation Of Variance

Abstract. Title of the paper: Estimation of variance components under dominance with simulated purebred lines A stochastic simulation based on a gene model was used to investigate the estimation of variance with dominance and additive animal models. For a heritability in broad sense of 0.5 three ratios of dominance variance (5, 10 and 25%) on the phenotypic variance were investigated under different degrees of dominance. No additionally biased estimations of the variance components as consequence of different dominance degrees were found. By using the dominance model for random mating as well as for selection the differences between true parameters and estimation values were small for all dominance degrees and ratios of dominance variance. Small, but significantly, differences can be explained by the change of the allele frequencies over the generations due to the influence of selection. By using the additive animal model, that ignores the dominance relationship, for high ratios of the dominance variance (25% or greater) important biased estimations of the variances were observed. For dominance ratios of 5% no significantly overestimation of the additive variances with the reduced model were found under selection and random mating.

scholarly journals Selection for feed efficiency using the social effects animal model in growing Duroc pigs: evaluation by simulation

2020 ◽  
Vol 52 (1) ◽  
Author(s):  
William Herrera-Cáceres ◽  
Juan Pablo Sánchez
Keyword(s):  
Animal Model ◽  
Direct Reduction ◽  
Average Daily Gain ◽  
Genetic Correlations ◽  
Genetic Effects ◽  
Social Effects ◽  
High Rate ◽  
Phenotypic Variance ◽  
Feed Conversion ◽  
The Social

Abstract Background Traits recorded on animals that are raised in groups can be analysed with the social effects animal model (SAM). For multiple traits, this model specifies the genetic correlation structure more completely than the animal model (AM). Our hypothesis was that by using the SAM for genetic evaluation of average daily gain (ADG) and backfat thickness (BF), a high rate of improvement in feed conversion ratio (FCR) might be achieved, since unfavourable genetic correlations between ADG and BF reported in a Duroc pig line could be partially avoided. We estimated genetic and non-genetic correlations between BF, ADG and FCR on 1144 pigs using Bayesian methods considering the SAM; and responses to selection indexes that combine estimates of indirect (IGE) and direct (DGE) genetic effects for ADG and BF by stochastic simulation. Results Estimates of the ratio of the variance of DGE to the phenotypic variance were 0.31, 0.39 and 0.25 and those of the total genetic variance to the phenotypic variance were 0.63, 0.74 and 0.93 for ADG, BF and FCR, respectively. In spite of this, when the SAM was used to generate data and for the genetic evaluations, the average economic response was worse than that obtained when BV predictions from the AM were considered. The achieved economic response was due to a direct reduction in BF and not to an improvement in FCR. Conclusions Our results show that although social genetic effects play an important role in the traits studied, their proper consideration in pig breeding programs to improve FCR indirectly is still difficult. The correlations between IGE and DGE that could help to overcome the unfavourable genetic correlations between DGE did not reach sufficiently high magnitudes; also, the genetic parameters estimates from the SAM have large errors. These two factors penalize the average response under the SAM compared to the AM.

scholarly journals Genetic and nongenetic factors influencing ewe prolificacy and lamb body weight in a closed Romanov flock

2020 ◽  
Vol 98 (9) ◽  
Author(s):  
Thomas W Murphy ◽  
John W Keele ◽  
Brad A Freking
Keyword(s):  
Body Weight ◽  
Maternal Effects ◽  
Effective Means ◽  
Genetic Correlations ◽  
Genetic Effect ◽  
The United States ◽  
Additive Genetic Effect ◽  
Parameter Estimates ◽  
Phenotypic Variance ◽  
Inbreeding Coefficients

Abstract The U.S. Meat Animal Research Center was the first entity in the United States to import the Romanov breed and it has been maintained as a closed flock for over 30 yr. Incorporating this super-prolific breed into crossbred and composite populations has resulted in large improvements in ewe productivity. However, few have quantified factors contributing to genetic and nongenetic variation in ewe reproduction and lamb growth within purebred Romanov populations, which were the objectives of this study. The pedigree contained a total of 8,683 lambs born to 218 and 1,600 unique sires and dams, respectively. Number of lambs born on a per ewe exposed (NLBE) and lambing (NLBL) basis were analyzed in univariate repeatability animal models. As expected, the proportion of phenotypic variance (σP2) in litter size attributable to additive genetic (0.06 to 0.08) and permanent environmental (0.05 to 0.07) effects of the ewe was low. The service sire permanent environmental effect contributed to a small but significant amount of σP2 in NLBE (0.03) but not NLBL. However, the service sire additive genetic effect did not influence σP2 in NLBE or NLBL. Lamb body weight was recorded at birth (BWB) and upon weaning from either milk replacer (~30 d; BWW-N) or their dam (~60 d; BWW-D) and were analyzed in a three-trait model with random additive direct and maternal effects. Estimated direct heritabilities were low for all body weight (BW) traits (0.07 to 0.10). Maternal heritability was moderate for BWB (0.34) but low for weaning BW (0.11 to 0.18). This was the first to report direct and maternal genetic correlations between BW of nursery- and dam-reared lambs, and both were estimated to be moderate (0.43 to 0.47). Additionally, the direct and maternal effects of BWB were more strongly correlated with BWW-N (0.74 to 0.82) than BWW-D (0.17 to 0.33). Despite inbreeding coefficients having increased at a rate of 0.33% per birth year (1986 to 2019) in this flock, they were not consistently associated with reductions in ewe or lamb performance. Parameter estimates generally agreed with those from less-prolific breeds, and results indicate that selection can be an effective means of improving subcomponents of ewe productivity.

scholarly journals Analysis of (co) variance components and estimation of breeding value of growth and production traits in Dahlem Red chicken using pedigree relationship in an animal model

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0247779
Author(s):  
U. Rajkumar ◽  
L. Leslie Leo Prince ◽  
K. S. Rajaravindra ◽  
S. Haunshi ◽  
M. Niranjan ◽  
...  
Keyword(s):  
Animal Model ◽  
Maternal Effects ◽  
Variance Components ◽  
Egg Production ◽  
Genetic Correlations ◽  
The Body ◽  
Breeding Value ◽  
Egg Mass ◽  
Residual Variance ◽  
Production Traits

Variance and covariance components of growth and production traits were analyzed employing REML animal model to assess the Dahlem Red (PD-3) chicken population for direct additive genetic, maternal effects and to estimate the estimated breeding value (EBV), genetic parameters, genetic trends and rate of inbreeding (ΔF) utilizing seven generation’s data. The generation and hatch had significant (P≤0.01) effect on the body weight at 0 day (BW0), 2 (BW2), 4 (BW4) and 6 weeks (BW6) and shank length at six weeks of age (SL6). The average least squares means (LSM) for BW6 and SL6 were 273.93±0.62 g and 53.97±0.05 mm, respectively. All the production traits were significantly (P≤0.01) influenced by generation and hatch. The average LSM for age at sexual maturity (ASM), egg production up to 40 weeks (EP40) and egg mass up to 40 weeks (EM40) were 168.82±0.25 d, 72.60±0.41 eggs and 4.21±0.07 kg, respectively. Model 5 with additive direct, maternal genetic, maternal permanent environmental and residual variance components was the best for BW0, BW2 and BW4 based on the AIC values obtained in WOMBAT. Model 4 was the best model for BW6, SL6, ASM, EP40 and EM40 with additive direct, maternal permanent environmental and residual variance components. Maternal effects were higher during early age, decreased with age, and remained present until 20 weeks of age. The heritability (h2) estimates were low to moderate in magnitude for all the growth traits and ranged from 0.02±0.03 to 0.19±0.03. The maternal heritability was high at hatch (0.35±0.06), decreased gradually until 4th week (0.02±0.01) and ceased afterwards. The heritabilities of EP40 (0.11±0.03) and EM40 (0.12±0.04) were low. The direct additive genetic correlations (ra) between BW2, BW4, BW6 and SL6 were high and positive (P≤ 0.05). The additive genetic and maternal permanent environmental correlation between EP40 and EM40 were high and positive (P≤ 0.05). The EBV of EM40 was significant (P≤ 0.05) with 0.48 kg/generation in PD-3 chicken at the end of the seventh generation. The EBV of EP40 showed an increasing trend with a genetic gain of 1.87 eggs per generation. The average inbreeding coefficient of the population was 0.019 and average ΔF was 0.007 over the last seven generations of selection. The EBV trends for primary and associated traits showed linear trends in the desired direction and negligible inbreeding.

scholarly journals No evidence that selection for egg production persistency causes loss of bone quality in laying hens

2021 ◽  
Vol 53 (1) ◽  
Author(s):  
Ian C. Dunn ◽  
Dirk-Jan De Koning ◽  
Heather A. McCormack ◽  
Robert H. Fleming ◽  
Peter W. Wilson ◽  
...  
Keyword(s):  
Rhode Island ◽  
Bone Quality ◽  
Egg Production ◽  
Breaking Strength ◽  
Genetic Correlations ◽  
Egg Laying ◽  
White Leghorn ◽  
Medullary Bone ◽  
Selection For

Abstract Background The physiological adaptations that have evolved for egg laying make hens susceptible to bone fractures and keel bone damage. In modern laying hen breeds, longer periods of egg laying could result in a greater risk of poor bone quality, and selection for increased egg production has frequently been stated to be a cause. However, the existing literature does not support this hypothesis. To test the hypothesis that egg production is associated with quality, breaking strength and density of bone, genetic correlations between these traits were estimated in White Leghorn and Rhode Island Red breeds. Genetic correlations of cortical and medullary bone material chemical properties with bone quality were also estimated, in order to identify methods to improve bone quality with appropriately targeted measurement of key traits. Results Estimates of heritability for bone quality traits were moderate (0.19–0.59) for both White Leghorn and Rhode Island Red breeds, except for the keel bone trait, which had a heritability estimate equal to zero. There was no evidence for genetic or phenotypic relationships between post-peak egg production and bone quality. In the White Leghorn breed, the estimate of the genetic correlation between pre-peak production/age at first egg and bone quality was significant and negative (− 0.7 to − 0.4). Estimates of heritability of thermogravimetric measurements of tibial medullary bone mineralisation were significant (0.18–0.41), as were estimates of their genetic correlations with tibia breaking strength and density (0.6–0.9). Conclusions The low genetic correlation of post-peak egg production with bone quality suggests that selection for increased persistency of egg production may not adversely affect bone quality. Onset of puberty and mineralisation of the medullary bone, which is a specialised adaptation for egg laying, were identified as important factors associated with the quality of the skeleton later during egg production. These are traits for which genetic, as well as environmental and management factors can positively impact the overall quality of the skeleton of laying hens.

Age-regulated expression of genetic and environmental variation in fitness traits. 1. Genetic effects and variances for egg production in a factorial mating of six selected Leghorn strains

1999 ◽  
Vol 79 (3) ◽  
pp. 253-267 ◽  
Author(s):  
L.-E. Liljedahl ◽  
R. W. Fairfull ◽  
R. S. Gowe
Keyword(s):  
Egg Production ◽  
Genetic Correlations ◽  
Genetic Effect ◽  
Genetic Effects ◽  
The Other ◽  
Additive Genetic Effect ◽  
Phenotypic Variance ◽  
Age Changes ◽  
Genotypic Variance ◽  
Factorial Mating

White Leghorn strains were crossed reciprocally in a complete factorial mating system producing 6 pure strains and 30 strain-crosses, which were kept in individual cages for two laying cycles, 133–496 and 547–909 d of age. The egg production in the second cycle (C2) of the various genotypes started about 10 – 20% lower and had a more linear and less persistent course than in the first cycle (C1). Strains exhibited very different patterns of age changes in both additive and non-additive genetic effects as well as in cytoplasmic effects. The additive autosomal and sex-linked genes (Ai and Zi) active in one laying cycle were quite different from those active in the other laying cycle as shown by low strain genetic correlations between their effects in C1 and C2. Further, the sets of Ai and Zi genes responded with effects quite opposite to each other in both C1 and C2 as indicated by highly negative strain genetic correlations between the Ai and Zi effects. The average non-additive genetic effect of sire strain i or dam strain j over all its crosses with other strains (hi) and the non-additive genetic effect due to the specific combination of genes occurring in each of the two reciprocal crosses between strain i and strain j (sij), showed very divergent patterns of age changes with a conspicuously greater divergence as age advanced. The overall non-additive genetic effect (mean heterosis) increased significantly with age across the two cycles. The strain crosses that most successfully maintained their rate of lay until the end of C2, also most successfully developed a rising age trend for total heterosis. The non-additive genes active in one laying cycle were significantly different from those active in the other laying cycle as shown by the moderately low strain genetic correlations between their effects in C1 and C2. The genotypic variance and its various components increased markedly with age, however, with a tendency to reach a plateau towards the end of both the first and the second laying cycle. The environmental variance increased parallel to the genotypic variance. Consequently, the phenotypic variance followed the same pattern of age changes. The results are discussed in relation to the theoretical aspects of ageing genetics. A model compatible with all the age trends of the genetic and environmental effects and variances is set up, assuming that ageing is composed of two main opposing forces. Finally, the results are briefly discussed from the animal breeding point of view. Key words: Ageing, fitness, laying hens, genetic effects, variation, expression

Estimation of genetic parameters for litter size in sheep: a comparison of a repeatability and a multivariate model

1998 ◽  
Vol 66 (3) ◽  
pp. 685-688 ◽  
Author(s):  
M. J. de Vries ◽  
E. H. van der Waaij ◽  
J. A. M. van Arendonk
Keyword(s):  
Animal Model ◽  
Genetic Correlation ◽  
Litter Size ◽  
Genetic Parameters ◽  
Genetic Correlations ◽  
Multivariate Model ◽  
Phenotypic Variance ◽  
Multiple Trait ◽  
Environmental Correlations ◽  
Estimation Of Genetic Parameters

AbstractGenetic parameters were estimated for litter size in two prolific sheep breeds, i.e. the Zwartbles and the synthetic breed Swifter. Genetic parameters and breeding values for litter size in different parities were estimated using both a repeatability and a multivariate animal model. The estimated heritability from the repeatability model was 0·10 for the Zwartbles and 0·12 for the Swifter. For the multivariate model, heritability of litter size in first, second and third parity was 0·05, 0·07 and 0·10 for the Zwartbles and 0·09, 0·12 and 0·09 for the Swifter. Genetic correlation for litter size in Swifter was 0·81 between parity 1 and 2 and 0·99 between parity 2 and 3. For the Zwartbles genetic correlations were all very close to unity. Environmental correlations between litter size in subsequent parities were not constant over parities. Phenotypic variance in litter size in both breeds was 0·309 in first parity and was almost 50% higher in later parities. Based on the results it is recommended to apply a multiple trait model.

Estimates of genetic parameters relevant in selection for certain aspects of egg quality

1964 ◽  
Vol 15 (4) ◽  
pp. 719 ◽  
Author(s):  
JA Morris
Keyword(s):  
Shell Thickness ◽  
Egg Production ◽  
Genetic Parameters ◽  
Egg Quality ◽  
Genetic Correlations ◽  
Direct Selection ◽  
Early Measurement ◽  
Shell Quality ◽  
Selection For

Thick albumen quality of eggs laid by pullets at the approximate ages of 34 and 64 weeks was measured both for fresh eggs and for eggs stored under reasonably uniform conditions for a period of 14 days. Subsequent analyses provided estimates of heritability of these various traits as well as genetic correlations between them. Heritability was high in all cases except for the 64-weeks measurements on stored eggs. Theoretically, selection based on 34-weeks measurements of albumen quality of fresh eggs should be equally as effective, per generation, as direct selection in improving 64weeks fresh quality. Furthermore, this indirect selection is more effective than direct selection in improving the quality of stored eggs, at both 34 and 64 weeks of age. The heritability of egg specific gravity (used as an indicator of shell thickness) is of intermediate to high value for estimates made both early and late in the pullet year. The genetic correlation between the early and late measurements is high, and selection based on the early measurement should be almost as effective (when assessed per generation) as on the late measurement in causing genetic improvement in late shell quality. All quality traits examined showed positive genetic relationship with each other, although many of the correlations are of low value. The only serious genetic antagonism disclosed was between each of the two assessments of shell thickness and total egg production. There was no evidence of genetic antagonism between albumen quality and total egg production.

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