scholarly journals Changes over time in genetic parameters for growth in bulls and assessment of suitability of test methods

2014 ◽  
Vol 59 (No. 1) ◽  
pp. 19-25 ◽  
Author(s):  
A. Svitáková ◽  
J. Bauer ◽  
J. Přibyl ◽  
Z. Veselá ◽  
L. Vostrý
Keyword(s):  
Fixed Effects ◽  
Genetic Parameters ◽  
Additive Genetic Variance ◽  
Performance Testing ◽  
Growth Potential ◽  
Parameter Estimates ◽  
Progeny Testing ◽  
Study Results ◽  
Residual Variances ◽  
Over Time

Objectives of the study were to examine alternative measures of growth potential of bulls in testing stations, determine whether genetic parameter estimates of such traits changed over time, and examine whether existing methods for performance testing were appropriate. Records from 1980 to 2010 of 44 425 Fleckvieh bulls in Czech progeny testing stations were analyzed. The following traits were examined: weight at the beginning of the test (150<sup>th</sup> day of age), weight at the end of the test (530<sup>th</sup> day of age), gain from birth to the beginning of the test, and gain during the test. Fixed effects in five multi-trait animal models were station-year-season groups, linear and quadratic regressions on age, and regression on heterozygosity (proportion of an individual&rsquo;s loci with alleles from different ancestor breeds). Random effects included additive genetic, permanent environment, and residual variances. Separate analyses were conducted in four consecutive time periods (1980&ndash;1987, 1988&ndash;1992, 1993&ndash;1997, and 1998&ndash;2010). Across these time intervals, estimates of additive genetic variance decreased for all of the traits, while estimates of residual variances increased. In consequence, heritability estimates for all of the traits decreased over time. This decrease was most apparent for gain during the test, for which heritability declined by more than 50% over the course of the study. Results demonstrate that over three decades, the system of testing came into conflict with genetic improvement of the breed, possibly because the measured traits changed genetically over the course of selection. Regular analysis of the recorded data, re-estimation of genetic parameters in relation to time, and appropriate modification of existing methods of rearing/fattening in station tests are required. When such inspections are neglected, data from the testing stations may not accurately reflect genetic merit of individual animals.

scholarly journals Estimation of direct and maternal genetic parameters for weaning weight in Hungarian Simmental cattle

2021 ◽  
pp. 17-22
Author(s):  
Afees Abiola Ajasa ◽  
Imre Füller ◽  
Barnabás Vágó ◽  
István Komlósi ◽  
János Posta
Keyword(s):  
Fixed Effects ◽  
Genetic Parameters ◽  
Additive Genetic Variance ◽  
Random Effect ◽  
Ratio Test ◽  
Genetic Covariance ◽  
Weaning Weight ◽  
Simmental Cattle ◽  
Estimate Variance ◽  
Best Fit

The aim of the current research was to estimate variance components and genetic parameters of weaning weight in Hungarian Simmental cattle. Weaning weight records were obtained from the Association of Hungarian Simmental Breeders. The dataset comprised of 44,278 animals born from 1975 to 2020. The data was analyzed using the restricted maximum likelihood methodology of the Wombat software. We fitted a total of six models to the weaning weight data of Hungarian Simmental cattle. Models ranged from a simple model with animals as the only random effect to a model that had maternal environmental effects as additional random effects as well as direct maternal genetic covariance. Fixed effects in the model comprised of herd, birth year, calving order and sex. Likelihood ratio test was used to determine the best fit model for the data. Results indicated that allowing for direct-maternal genetic covariance increases the direct and maternal effect dramatically. The best fit model had direct and maternal genetic effects as the only random effect with non-zero direct-maternal genetic correlation. Direct heritability, maternal heritability and direct maternal correlation of the best fit model was 0.57, 0.16 and -0.78 respectively. The result indicates that problem of (co-)sampling variation occurs when attempting to partition additive genetic variance into direct and maternal components.

scholarly journals Estimation of genetic parameters and comparison of random regression animal and sire models of production traits in the first three lactations of Iranian Holsteins

2014 ◽  
Vol 30 (2) ◽  
pp. 261-279 ◽  
Author(s):  
A. Mohammadi ◽  
S. Alijani
Keyword(s):  
Milk Fat ◽  
Genetic Parameters ◽  
Additive Genetic Variance ◽  
Genetic Correlations ◽  
Random Regression ◽  
Lactation Period ◽  
Production Traits ◽  
Environmental Variance ◽  
In The Beginning ◽  
Residual Variances

This study was conducted to compare of random regression (RR) animal and sire models for estimation of the genetic parameters for production traits of Iranian Holstein dairy cows. For this purpose, the test day records were used belonged to first three lactations of cows and for, milk, fat and protein yields traits where, collected from 2003 to 2010, by the national breeding center of Iran. The genetic parameters were estimated using restricted maximum likelihood algorithm. To compare the model, different criterion -2logL value, AIC, BIC and RV were used for considered traits. Residual variances were considered homogeneous over the lactation period. Obtained results showed that additive genetic variance was highest in the beginning and end lactation and permanent environmental variance was highest in beginning of lactation than other lactation period. Heritabilities estimate for milk, fat and protein yields by RR animal and sire models were found to be lowest during early lactation (0.05, 0.04 and 0.07; 0.05, 0.19 and 0.13; 0.14, 0.19 and 0.15, for milk, fat and protein yields and in first, second and third lactation respectively). However, estimated heritabilities during lactation did not vary among different order Legendre polynomials, and also between RR animal and sire models. The variation in genetic correlations estimate in the RR animal and sire models was larger in the first lactation than in the second and third lactations. Thus, based on the results obtained, it can be inferred that the RR animal model is better for modeling yield traits in Iranian Holsteins.

scholarly journals Random regression models using different functions to estimate genetic parameters for milk production in Holstein Friesians

2016 ◽  
Vol 46 (9) ◽  
pp. 1649-1655
Author(s):  
Mariana de Almeida Dornelles ◽  
Paulo Roberto Nogara Rorato ◽  
Luis Telo Lavadinho da Gama ◽  
Fernanda Cristina Breda ◽  
Carlos Bondan ◽  
...  
Keyword(s):  
Milk Production ◽  
Legendre Polynomials ◽  
Fixed Effects ◽  
Regression Models ◽  
Genetic Parameters ◽  
Random Regression ◽  
Residual Variance ◽  
Lower Estimation ◽  
The One ◽  
Residual Variances

ABSTRACT: The objective of this study was to compare the functions of Wilmink and Ali and Schaeffer with Legendre polynomials in random regression models using heterogeneous residual variances for modeling genetic parameters during the first lactation in the Holstein Friesian breed. Five thousand eight hundred and eighty biweekly records of test-day milk production were used. The models included the fixed effects of group of contemporaries and cow age at calving as covariable. Statistical criteria indicated that the WF.33_HE2, LEG.33_HE2, and LEG.55_HE4 functions best described the changes in the variances that occur throughout lactation. Heritability estimates using WF.33_HE2 and LEG.33_HE2 models were similar, ranging from 0.31 to 0.50. The LEG.55_HE4 model diverged from these models, with higher estimates at the beginning of lactation and lower estimates after the 16th fortnight. The LEG55_HE4, among the three better models indicated by the index, is the one with highest number of parameters (14 vs 34) and resulted in lower estimation of residual variance at the beginning and at the end of lactation, but overestimated heritability in the first fortnight and presented a greater difficulty to model genetic and permanent environment correlations among controls. Random regression models that used the Wilmink and Legendre polynomials functions with two residual variance classes appropriately described the genetic variation during lactation of Holstein Friesians reared in Rio Grande do Sul.

Prospects for genetic improvement of milk production traits of Sahiwal cattle in Kenya

2007 ◽  
Vol 2007 ◽  
pp. 69-69
Author(s):  
E.D. Ilatsia ◽  
T. K. Muasya ◽  
W. B. Muhuyi ◽  
A. K. Kahi
Keyword(s):  
Animal Model ◽  
Milk Production ◽  
Genetic Parameters ◽  
Genetic Relationships ◽  
Additive Genetic Variance ◽  
Parameter Estimates ◽  
Production Traits ◽  
Milk Production Traits ◽  
Phenotypic Parameter ◽  
Sahiwal Cattle

The primary emphasis of the long-term Sahiwal cattle breeding programme is to increase milk yield by selecting cows based on their performance in first three lactations. It is therefore important to have knowledge on the extend of additive genetic variance and genetic parameters for these traits. Genetic and phenotypic parameter estimates normally apply directly to the specific population and environment from which the data were collected. In the Sahiwal cattle in Kenya, very little is known about the genetic variation of milk production traits and their genetic relationships. Furthermore, genetic and phenotypic parameter estimates for the Sahiwal cattle based on multivariate animal model are scarce. This paper presents estimates of variance components and genetic parameters for milk production traits using trivariate animal model.

scholarly journals Genetic Parameters of Conformation Traits in Young Polish Holstein-Friesian Bulls

2014 ◽  
Vol 14 (4) ◽  
pp. 831-840
Author(s):  
Agnieszka Otwinowska-Mindur ◽  
Ewa Ptak ◽  
Wojciech Jagusiak ◽  
Andrzej Żarnecki
Keyword(s):  
Fixed Effects ◽  
Genetic Parameters ◽  
Dominant Role ◽  
Genetic Correlations ◽  
Progeny Testing ◽  
Multiple Trait ◽  
Holstein Friesian ◽  
Type Traits ◽  
Genetic And Phenotypic Correlations ◽  
Final Score

Abstract The objective of this study was to estimate the genetic parameters of conformation traits in Polish Holstein-Friesian bulls evaluated for registration in the herd book and for entry into progeny testing. Data were 8 linearly scored (1-9 scale) and 6 composite (scored from 50 to 100) conformation traits of 2,738 young bulls born between 2001 and 2011. The multiple-trait REML method was applied for (co)variance component estimation. The linear model included fixed linear regressions on age at evaluation (from 10 to 23 months), fixed effects of year of birth, fixed effects of herd-classifier, and random animal effect. Heritability estimates for all analysed traits were within the range of 0.04-0.37. Among the 6 composite type traits, heritability was highest for size and for overall conformation score. The lowest heritability was for feet and legs. Among the linearly scored traits, heritability was the lowest for rear legs - side view and foot angle, and the highest for rump angle and muscularity of front end. Composite traits showed the highest genetic correlations with muscularity and final score playing the dominant role. Genetic correlations among linear traits were low and moderate (0.02-0.53). The relatively low genetic and phenotypic correlations indicated that no conformation trait of bulls can be improved by indirect selection alone. More research is needed to establish relationship between bull conformation traits and the conformation of their progeny.

Genetic aspects of growth and carcass quality in veal calves

1969 ◽  
Vol 11 (1) ◽  
pp. 43-45 ◽  
Author(s):  
C. J. M. Hinks ◽  
B. Bech Andersen
Keyword(s):  
Genetic Improvement ◽  
Genetic Parameters ◽  
Carcass Traits ◽  
Performance Testing ◽  
Carcass Quality ◽  
Progeny Testing ◽  
Genetic Incompatibility ◽  
Body Dimensions ◽  
Veal Calves ◽  
Heritability Estimates

SUMMARYGenetic parameters of veal calves were estimated from data on 510 Danish Red male calves by 39 sires.Heritability estimates for the growth and carcass traits were low, those for body dimensions and dressing percentage high.Correlations between the growth and carcass traits indicated no genetic incompatibility in selection.The problem of achieving simultaneous improvement in the dairy, carcass and growth qualities is discussed. It is suggested that the adoption of performance testing for growth and carcass quality prior to the entry of bulls into AI service, followed by progeny testing for milk and fat yields, would provide the best method of genetic improvement.

scholarly journals Purebred-crossbred genetic parameters for reproductive traits in swine

2021 ◽  
Author(s):  
Luke M Kramer ◽  
Ania Wolc ◽  
Hadi Esfandyari ◽  
Dinesh M Thekkoot ◽  
Chunyan Zhang ◽  
...  
Keyword(s):  
Genetic Parameters ◽  
Additive Genetic Variance ◽  
Genetic Correlations ◽  
Reproductive Traits ◽  
Allele Frequencies ◽  
Superior Performance ◽  
Joint Analysis ◽  
Genomic Relationship Matrix ◽  
Parameter Estimates ◽  
Relationship Matrix

Abstract For swine breeding programs, testing and selection programs are usually within purebred (PB) populations located in nucleus units that are generally managed differently and tend to have a higher health level than the commercial herds in which the crossbred (CB) descendants of these nucleus animals are expected to perform. This approach assumes that PB animals selected in the nucleus herd will have CB progeny that have superior performance at the commercial level. There is clear evidence that this may not be the case for all traits of economic importance and, thus, including data collected at the commercial herd level may increase the accuracy of selection for commercial CB performance at the nucleus level. The goal for this study was to estimate genetic parameters for five maternal reproductive traits between two PB maternal nucleus populations (Landrace and Yorkshire) and their CB offspring: Total Number Born (TNB), Number Born Alive (NBA), Number Born Alive &gt; 1 kg (NBA&gt;1kg), Total Number Weaned (TNW), and Litter Weight at Weaning (LWW). Estimates were based on single-step GBLUP by analyzing any two combinations of a PB and the CB population, and by analyzing all three populations jointly. The genomic relationship matrix between the three populations was generated by using within population allele frequencies for relationships within a population, and across population allele frequencies for relationships of the CB with the PB animals. Utilization of metafounders for the two PB populations had no effect on parameter estimates, so the two PB populations were assumed to be genetically unrelated. Joint analysis of two (one PB plus CB) versus three (both PB and CB) populations did not impact estimates of heritability, additive genetic variance, and genetic correlations. Heritabilities were generally similar between the PB and CB populations, except for LWW and TNW, for which PB populations had about four times larger estimates than CB. Purebred-crossbred genetic correlations () were larger for Landrace than for Yorkshire, except for NBA&gt;1kg. These estimates of indicate that there is potential to improve selection of PB animals for CB performance by including CB information for all traits in the Yorkshire population, but that noticeable additional gains may only occur for NBA&gt;1kg and TNW in the Landrace population.

Genetic parameter estimates for growth traits of Gansu Alpine Finewool sheep

2012 ◽  
Vol 52 (5) ◽  
pp. 321 ◽  
Author(s):  
Wenhui Li ◽  
Ian W. Purvis
Keyword(s):  
Fixed Effects ◽  
Genetic Parameters ◽  
Growth Traits ◽  
Average Daily Gain ◽  
Genetic Effects ◽  
Western China ◽  
Parameter Estimates ◽  
Weaning Weight ◽  
Likelihood Ratio Testing ◽  
Daily Gain

Estimation of genetic parameters for growth traits of Gansu Alpine Finewool sheep that separately identify maternal effects has not been previously conducted. (Co)variance components and corresponding genetic parameters for lamb growth traits were estimated from Gansu Alpine Finewool sheep maintained at Gansu Sheep Breeding Technology Extension Station in north-western China. Records of 17 703 lambs at birth, born over 9 years (2000–2008) and sired by 315 rams, were used in the study. Birth type, sex, dam age, record age and birth year were fitted as fixed effects. Analyses were carried out using a restricted maximum likelihood procedure (ASReml). Six different animal models were fitted for all traits and the most appropriate model was selected through log-likelihood ratio testing. After identifying the appropriate model through single-trait analysis, bivariate analyses were used to obtain the phenotypic and genetic correlations among the growth traits. In addition to the direct genetic effect, and maternal genetic effects, significant negative correlations between direct genetic and maternal genetic effects were found for all the growth traits. The maternal permanent environmental effects were only significant for birthweight, weaning weight and pre-weaning growth rate. The estimates of direct heritability for birthweight, weaning weight, pre-weaning average daily gain, post-weaning average daily gain and yearling weight were 0.22, 0.16, 0.15, 0.27 and 0.19 respectively. The maternal heritability estimates were relatively high and ranged from 0.17 to 0.27. The study provides the breed and its associated finewool sheep industry with a more encompassing basis for designing more effective breeding programs for improvement of growth traits of Gansu Alpine Finewool sheep.

Genetic parameters of British Landrace bacon pigs

1965 ◽  
Vol 7 (3) ◽  
pp. 291-301 ◽  
Author(s):  
C. Smith ◽  
G. J. S. Ross
Keyword(s):  
Genetic Parameters ◽  
Previous Analysis ◽  
Genetic Relationships ◽  
Principal Component ◽  
Parameter Estimates ◽  
Progeny Testing ◽  
Large White ◽  
Correlation Pattern ◽  
Genetic And Phenotypic Correlations ◽  
Good Agreement

SUMMARYGenetic parameters were estimated among 26 traits in British Landrace bacon pigs. The data involved 2,296 pigs from 250 boars tested at the five British national pig progeny testing stations from 1959 to 1961 inclusive. Separate analyses were performed for each sex and for the litter totals, adjustments being made to the data for differences among periods within stations and for differences in age at start of test and in weight at slaughter. The genetic parameters were estimated from the sire components in a conventional hierarchical analysis of variance.Estimates of heritability and genetic and phenotypic correlations among the 26 traits are presented and discussed. The parameter estimates were in very good agreement with figures obtained in a previous analysis with Large White pigs. They indicate that a large part of the variation and covariation among the 26 traits is genetic in origin, and the traits involved would change in response to selection. Moreover, with regard to their concurrent improvement there were no serious antagonisms in the genetic relationships among the traits studied. There was however, evidence of an interaction of sire and sex of progeny for nine of the 26 traits.A principal component analysis was used in an attempt to summarise the correlations among the 26 traits. The first two components gave a reasonable fit to the correlation pattern and these were associated with fat depth, measures of muscling and dressing-out percentage.

scholarly journals Phenotypic and Genetic Parameter Estimates for Racing Traits of Thoroughbred Horses in Turkey

2005 ◽  
Vol 48 (2) ◽  
pp. 121-129 ◽  
Author(s):  
B. Ekiz ◽  
Ö. Kocak ◽  
A. Yilmaz
Keyword(s):  
Fixed Effects ◽  
Genetic Parameters ◽  
Genetic Parameter ◽  
Parameter Estimates ◽  
Thoroughbred Horses ◽  
Significant Heritability ◽  
Breeding Programmes ◽  
Annual Earnings ◽  
Entire Dataset ◽  
Age And Sex

Abstract. This study was carried out to investigate the fixed effects influencing racing traits of Thoroughbred horses and to estimate the genetic parameters for these traits, which are needed to design breeding programmes. The racing records used in the study were obtained from the Turkish Jockey Club. The traits used in the study were racing time, best racing time, rank, annual earnings, earnings per start, log annual earnings and log earnings per start. Genetic parameters were estimated by REML procedure using DFREML programme. The effects of age and sex were significant for each trait. The effect of year was significant on earning traits and time traits, except for best racing time on turf track. The effects of month on time traits were also significant. Heritability estimates of entire dataset were 0.317, 0.467, 0.132, 0.194, 0.291, 0.188 and 0.341 for racing time, best racing time, rank, annual earnings, earnings per start, log annual earnings and log earnings per start, respectively. Estimates of repeatability varied from 0.293 to 0.465 for racing time, from 0.373 to 0.531 for best racing time and from 0.215 to 0.232 for rank depending on the dataset used in the analyses.

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