scholarly journals Stillbirth (Co)Variance Components for a Sire-Maternal Grandsire Threshold Model and Development of a Calving Ability Index for Sire Selection

2007 ◽  
Vol 90 (5) ◽  
pp. 2489-2496 ◽  
Author(s):  
J.B. Cole ◽  
G.R. Wiggans ◽  
P.M. VanRaden ◽  
R.H. Miller
Keyword(s):  
Variance Components ◽  
Threshold Model ◽  
Ability Index ◽  
Maternal Grandsire ◽  
Sire Selection

scholarly journals Calving Ease (Co)Variance Components for a Sire-Maternal Grandsire Threshold Model

2003 ◽  
Vol 86 (5) ◽  
pp. 1845-1848 ◽  
Author(s):  
G.R. Wiggans ◽  
I. Misztal ◽  
C.P. Van Tassell
Keyword(s):  
Variance Components ◽  
Threshold Model ◽  
Calving Ease ◽  
Maternal Grandsire

Estimates of heritabilities of Canadian Holstein conformation traits by threshold model

1991 ◽  
Vol 71 (3) ◽  
pp. 629-632 ◽  
Author(s):  
J. Jamrozik ◽  
L. R. Schaeffer ◽  
E. B. Burnside ◽  
B. P. Sullivan
Keyword(s):  
Animal Model ◽  
Em Algorithm ◽  
Variance Components ◽  
Fixed Effects ◽  
Threshold Model ◽  
Model Data ◽  
Stage Of Lactation ◽  
Continuous Scale ◽  
Type Traits ◽  
Holstein Population

Sire variances for 30 conformation traits on Canadian Holsteins were estimated on the underlying continuous scale using a single trait threshold linear model. Data were linearized first classifications on 66 617 cows by 3305 sires, classified since February 1988. The model included a random sire effect and fixed effects of herd-round of classification-classifier, age at classification and stage of lactation at classification. Sires were assumed unrelated in this study. Variance components for sires were estimated by REML EM algorithm. Estimates of heritabilities were generally larger than those currently used in genetic evaluation for type traits in Canadian Holstein population. The new heritabilities are recommended for use in a traditional linear animal model procedure. Key words: Variance components, threshold model, type traits

scholarly journals Threshold models for the determination of genetic variability among reproductive traits in Nellore cattle

2020 ◽  
Vol 55 ◽  
Author(s):  
Leonardo Martin Nieto ◽  
Luiz Otávio Campos da Silva ◽  
Antônio do Nascimento Ferreira Rosa
Keyword(s):  
Genetic Variability ◽  
Threshold Model ◽  
Reproductive Traits ◽  
Threshold Models ◽  
Multiple Trait ◽  
Bayesian Procedures ◽  
Nellore Cattle ◽  
Heritability Estimates ◽  
Maternal Grandsire

Abstract: The objective of this work was to evaluate the potential of different threshold models to determine the genetic variability in Nellore cattle, with basis on the heritability estimates for the traits stayability (STA) and first calving probability at 36 months of age (CP36). Data came from the Nellore herds participating in the animal breeding program of the Embrapa-Geneplus partnership. Binomial and multi-threshold models were defined for the STA and CP36 traits. Heritability estimates were obtained following Bayesian procedures in the Multiple-trait Gibbs Sampler for Animal Models (MTGSAM) software, using a sire-maternal grandsire model. The heritability estimates, provided by the binary and alternative models, were, respectively, 0.08 and 0.12 for STA and 0.17 and 0.12 for CP36. The multi-threshold model can efficiently detect the genetic variability for stayability, but not for probability of calving for 36-month-old cows.

Genetic correlations among female fertility traits and milk production in different parities in Swedish dairy cattle

1999 ◽  
Vol 24 ◽  
pp. 177-181
Author(s):  
A. Roth ◽  
E. Strandberg ◽  
B. Berglund ◽  
U. Emanuelson ◽  
J. Philipsson
Keyword(s):  
Genetic Correlation ◽  
Variance Components ◽  
Genetic Correlations ◽  
Relationship Matrix ◽  
Phenotypic Variance ◽  
Bivariate Model ◽  
Service Period ◽  
Swedish Dairy ◽  
Fertility Traits ◽  
Maternal Grandsire

AbstractThe main objective of this study was to estimate genetic correlations between fertility and production in first and second lactations as well as between fertility traits measured in the same way at different ages. The analyses were carried out for Swedish Red and White cows born from 1986 to 1996, in total about 578 000, 430 000, and 221 000 records in the heifer period, first lactation and second lactation, respectively. The fertility traits studied were: interval between calving and first insemination (CFI), interval between calving and last insemination (CLI), number of inseminations per service period (NINS) and number of treatments for reproductive disturbances (NREPT). Production was measured as the average of the energy-corrected milk yield from the second and third test-days in a lactation (ECM23). A linear, bivariate model that included effects of herd-year, month, age, and sire of the cow was applied. A relationship matrix containing sire and maternal grandsire of the sire was included. The (co)variance components for the random effects were estimated by use of a restricted maximum likelihood algorithm. The genetic correlations between fertility traits and production within first and second lactation were in the range of 0.1 to 0.3, all of them unfavourable. However, the genetic correlation between NREPT and ECM23 was close to zero within both lactations. The heritabilities, calculated without the herd-year variance included in the phenotypic variance, varied between 0.02 and 0.06 for the fertility traits with only minor differences between first and second lactation. The heritability of ECM23 was 0.35 in the first lactation and 0.28 in the second lactation. The genetic correlation between NINS during the heifer period and in first lactation was high, 0.7. The heritabilities for NINS and NREPT during the heifer period were very low, <0.01. In conclusion, there were only minor differences in inter-relationships between fertility and production in first and second lactation and the traits were negatively associated with each other. Based on the genetic correlation between NINS in the heifer period and NINS in first lactation, this study indicated that the traits at least partly are regulated by different sets of genes.

scholarly journals Genetic and nongenetic factors associated with the fate of maiden ewe lambs: slaughtered without ever lambing versus retained for breeding1

2019 ◽  
Vol 4 (1) ◽  
pp. 242-249 ◽  
Author(s):  
Noirin McHugh ◽  
Thierry Pabiou ◽  
Kevin McDermott ◽  
Eamon Wall ◽  
Donagh P Berry
Keyword(s):  
Mixed Models ◽  
Variance Components ◽  
Threshold Model ◽  
Genetic Correlations ◽  
Decision Support Tool ◽  
Data Set ◽  
Support Tool ◽  
Ewe Lambs ◽  
Ewe Lamb ◽  
First Time

Abstract The decision on which ewe lamb to retain versus which to sell is likely to vary by producer based on personal preference. What is not known, however, is if any commonality exists among producers in the characteristics of ewe lambs that influence their eventual fate. The objective of the present study was to determine what genetic and nongenetic factors associate with the fate of maiden ewe lambs. The fate of each ewe lamb born in the present study was defined as either subsequently: 1) having lambed in the flock, or 2) was slaughtered without any recorded lambing event. A total of 9,705 ewe lamb records from 41 crossbred flocks were used. The logit of the odds of the ewe lamb being retained for lambing was modeled using logistic regression. Variance components were then estimated for the binary trait representing the fate of the ewe lamb using animal linear and threshold mixed models. The genetic correlations between fate of the ewe lamb and preweaning, weaning, or postweaning liveweight were also estimated. From the edited data set, 45% of ewe lambs born entered the mature flock as ewes. Ewe lambs reared as singles, with greater levels of heterosis but lower levels of recombination loss, born to dams that lambed for the first time as hoggets, with greater breed proportion of the Belclare, Suffolk, Texel, and Llyen breeds were more likely (P &lt; 0.001) to eventually lamb in the flock than be slaughtered without ever lambing. Irrespective of the age of the animal when weighed, heavier ewe lambs were more likely to eventually lamb (P &lt; 0.001). The genetic SD and direct heritability of fate of the ewe lamb estimated in the univariate linear model was 26.58 percentage units and 0.31 (SE = 0.03), respectively; the heritability was 0.30 when estimated using the threshold model. The corresponding direct heritability of fate of the ewe lamb estimated in the bivariate analyses with liveweight ranged from 0.29 (SE = 0.03; preweaning weight) to 0.35 (SE = 0.04; postweaning weight). The genetic correlations estimated between fate of the ewe lamb and the liveweight traits were weak to moderate but strengthened as the age of the ewe lamb at weighing increased. Results from this study provide an understanding of the factors producers consider when selecting females for retention versus slaughter which may form useful parameters in the development of a decision support tool to identify suitable ewe lambs for retention.

Some factors affecting the estimation of genetic parameters for cattle dystocia under a threshold model

1991 ◽  
Vol 53 (2) ◽  
pp. 151-156 ◽  
Author(s):  
E. J. Manfredi ◽  
M. San Cristobal ◽  
J. L. Foulley
Keyword(s):  
Maternal Effects ◽  
Fixed Effects ◽  
Genetic Parameters ◽  
Threshold Model ◽  
Genetic Parameter ◽  
Random Effect ◽  
Large Data ◽  
Marginal Maximum Likelihood ◽  
Factors Affecting ◽  
Maternal Grandsire

AbstractGenetic parameters for dystocia in the Main-Anjou breed were estimated. Data consisted of 28 178 birth records collected between 1978 and 1989 in 995 herds, with 161, 71 and 12 415 sires, maternal grandsires and dams, respectively, represented. Original scores (1 through 5) were collapsed in order to set two dystocia definitions: dystocia 1 (scores 1+2 v. 3+4+5) and dystocia 2 (scores 1 v. 2+3+4+5). Four models were proposed for genetic parameter estimation: (1) fixed effects plus sire effects; (2) model 1 plus maternal grandsire effect; (3) model 2 plus dam within maternal grandsire effects; (4) same as model 3 but a random effect ‘herds’ replaced a fixed effect ‘regions’. Two methods of fitting models were applied: marginal maximum likelihood and the ‘tilde-hat’ approach. Estimates of genetic parameters by the two methods were similar. Models ignoring maternal effects overestimated the heritability of direct effects especially in the case of dystocia 2. Dystocia definition was responsible for the greatest difference among estimated genetic parameters. Possible reasons for this are discussed. When analysing large data sets, it is recommended judiciously to collapse dystocia categories and to apply approximate statistical procedures to complete models including maternal effects.

scholarly journals Genetic parameters for longevity measures in Brazilian Holstein cattle using linear and threshold models

2014 ◽  
Vol 57 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Elisandra Lurdes Kern ◽  
Jaime Araujo Cobuci ◽  
Cláudio Napolis Costa ◽  
José Braccini Neto ◽  
Gabriel Soares Campos ◽  
...  
Keyword(s):  
Variance Components ◽  
Genetic Parameters ◽  
Threshold Model ◽  
Holstein Cows ◽  
Holstein Cattle ◽  
Threshold Models ◽  
Productive Life ◽  
Selection For ◽  
Estimate Variance ◽  
Genetic Evaluations

Abstract. The aim in this study was to estimate variance components and heritability of different longevity measures related to productive life and survival at a specified age, using linear and threshold models, to specify the more appropriate measure to express longevity in Brazilian Holstein cows. Production and reproduction records of Holstein cows were collected from 1991 to 2010, for cows born between 1987 and 2006. Variance components were obtained by restricted maximum likelihood (REML) for measures of productive life and a Bayesian analysis for survival measures. The heritability estimates for longevity measures ranged from 0.06 to 0.09, using the linear model and from 0.05 to 0.18 for traits using the threshold model. This suggests an inexpressive genetic gain using selection for these traits, whereas improvements in environmental factors which affect these animals may lead to greater phenotypic gains. Survival up to 48 months from first calving was the measureing point defined as the most appropriate to be included in future official genetic evaluations of Holstein cattle in Brazil.

scholarly journals Heritability and repeatability of the number of lambs born and reared estimated using linear and threshold models

2011 ◽  
Vol 54 (3) ◽  
pp. 271-279
Author(s):  
D. Piwczyński ◽  
B. Kowaliszyn ◽  
S. Mroczkowski
Keyword(s):  
Linear Model ◽  
Gibbs Sampling ◽  
Variance Components ◽  
Genetic Parameters ◽  
Linear Models ◽  
Threshold Model ◽  
Standard Errors ◽  
Threshold Models ◽  
Similar Tendency ◽  
Average Information

Abstract. The research was conducted on 3 844 Polish Merino lamb dams born in 1991‑2001, used in 15 flocks from the Pomerania and Kujawy region in Poland. The assessed parameters were the number of lambs born from a dam after lambing (LSB) (1, 2, 3) and the number of lambs reared (LSW) (0, 1, 2, 3). The genetic parameters LSB and LSW were estimated with the use of two methods: Average Information – REML (AI-REML) and Gibbs sampling (GS). For estimation of components by means of the AI-REML method the animal’s linear model was used, and in the case of the GS method a threshold model was also used alongside the linear one. The LSB heritability estimated using the AI-REML and GS methods in combination with a linear model were similar and their values were respectively 0.025 and 0.029, with similar standard errors for variance components. Applying the GS method combined with a threshold model resulted in a two times higher heritability (0.054) compared to when linear models were used. A similar tendency was found to exist in respect of estimated repeatability. When using linear models, the obtained values were closely matched: 0.064 (AI-REML) and 0.065 (GS). The highest repeatability occurred when a threshold model was used (0.118). The LSW heritability was low and, depending on the model and method (0.016-0.020). Similar values LSW repeatability were obtained with the use of linear models (0.048 – REML and 0.049 – GS), and when a threshold model was used the result was higher – 0.070.

scholarly journals On biased inferences about variance components in the binary threshold model

1997 ◽  
Vol 29 (2) ◽  
pp. 145 ◽  
Author(s):  
C Moreno ◽  
D Sorensen ◽  
LA García-Cortés ◽  
L Varona ◽  
J Altarriba
Keyword(s):  
Variance Components ◽  
Threshold Model
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