Genetic parameters associated with characters effecting egg production in the domestic fowl. I. Heritability of total egg production during the pullet year

1956 ◽  
Vol 7 (6) ◽  
pp. 625 ◽  
Author(s):  
BL Sheldon
Keyword(s):  
Standard Error ◽  
Domestic Fowl ◽  
Egg Production ◽  
Genetic Parameters ◽  
Research Centre ◽  
Narrow Sense ◽  
White Leghorn ◽  
Components Of Variance ◽  
Production Index ◽  
The Mean

Egg production records of White Leghorn pullets hatched a t the Poultry Research Centre, Werribee, Vic., during 1947 to 1950 inclusive have been analysed both on a hen-housed (Production Index) and a survivor basis. Estimates of heritability were obtained by two methods: (1) by the analysis of components of variance between families of full sibs and half-sibs; (2) by estimating the intra-sire regression of the mean performance of offspring on dam's performance. Heritability, in the narrow sense, of Production Index during the pullet year is shown to be 23-30 per cent. with a reasonably low standard error, while heritability of survivors' production is slightly lower but not significantly so. Possible reasons are advanced for the low estimates of heritability of survivors' production.

Genetic parameters asociated with characters affecting egg production in the domestic fowl. II. Heritability of egg production for two part-annual periods of measurement and the genetic correlation between them

1956 ◽  
Vol 7 (6) ◽  
pp. 630 ◽  
Author(s):  
JA Morris
Keyword(s):  
Genetic Variation ◽  
Genetic Correlation ◽  
Domestic Fowl ◽  
Egg Production ◽  
Genetic Parameters ◽  
Genetic Variance ◽  
Production Index ◽  
Full Production ◽  
Breeding Groups ◽  
Using Data

Estimates of important genetic parameters have been obtained from an experimental flock using data collected over a period of 3 years. A total of 1784 progeny, obtained from 42 sires and 383 dams, supplied records for analysis. The information was mainly extracted using the analysis of variance and covariance from which estimates of genetic variance and covariance were obtained. Pooling the results within years and, where applicable, within breeding groups, estimates of heritability were obtained as follows: Production Index: part period, 32 per cent.; 72 weeks, 31 per cent. Survivor Index: part period, 33 per cent.; 72 weeks, 33 per cent. The low mortality rate should be borne in mind when comparing the estimates for the Production Index with those obtained by other workers. The estimated genetic correlation between the Production Index for these two periods was 0.72. The magnitude of the heritability estimates indicates the presence of a considerable amount of additive genetic variation. The proportion of this type of genetic variation has probably been increased by the minimizing of environmental variation effected by the randomization of birds over the housing space and, in the case of the part period of recording, by the corrections applied for hatching date influence. Early selection, based on partial records, has been shown to be approximately 1½ times as effective in producing genetic improvement as selection based on the full production.

scholarly journals Bayesian inference of genetic parameters for reproductive and performance traits in White Leghorn hens

2018 ◽  
Vol 63 (No. 6) ◽  
pp. 230-236 ◽  
Author(s):  
J.O. Rosa ◽  
G.C. Venturini ◽  
T.C.S. Chud ◽  
B.C. Pires ◽  
M.E. Buzanskas ◽  
...  
Keyword(s):  
Bayesian Inference ◽  
Fixed Effects ◽  
Egg Production ◽  
Genetic Parameters ◽  
Laying Hens ◽  
Reproductive Traits ◽  
A Posteriori ◽  
White Leghorn ◽  
Performance Traits ◽  
And Performance

This study estimated the genetic parameters for reproductive and performance traits and determined which ones can be used as selection criteria for egg production in laying hens using the Bayesian inference. The data of 1894 animals from three generations of White Leghorn laying hens were analyzed for fertility (FERT), hatchability (HATC), and birth rate measurements at 60 weeks of age (BIRTH), body weight at 16 and 60 weeks of age (BW16 and BW60), age at sexual maturity (ASM), egg height/width ratio, weight, and density at 28, 36, and 40 weeks of age (RHW28, RHW36, RHW40, WEGG28, WEGG36, WEGG40, DENS28, DENS36, and DENS40, respectively) traits. The genetic parameters were estimated by the Bayesian inference method of multi-trait animal model. The model included the additive and residual genetic random effects and the fixed effects of generation. The a posteriori mean distributions of the heritability estimates for reproductive traits ranged from 0.14 ± 0.003 (HATC) to 0.22 ± 0.005 (FERT) and performance from 0.07 ± 0.001 (RHW28) to 0.42 ± 0.001 (WEGG40). The a posteriori mean distributions of the genetic correlation between reproductive traits ranged from 0.18 ± 0.026 (FERT and HACT) to 0.79 ± 0.007 (FERT and BIRTH) and those related to performance ranged from –0.49 ± 0.001 (WEGG36 and DENS36) to 0.75 ± 0.003 (DENS28 and DENS36). Reproductive and performance traits showed enough additive genetic variability to respond to selection, except for RHW28. This trait alone would have little impact on the genetic gain because environmental factors would have a higher impact compared to those from the additive genetic factors. Based on the results of this study, the selection applied on the BIRTH trait can be indicated to improve FERT and HATC of eggs. Furthermore, the use of the WEGG40 could improve egg quality in this population.

scholarly journals Estimates of genetic parameters, and cluster and principal components analyses of breeding values related to egg production traits in a White Leghorn population

2011 ◽  
Vol 90 (10) ◽  
pp. 2174-2188 ◽  
Author(s):  
R.P. Savegnago ◽  
S.L. Caetano ◽  
S.B. Ramos ◽  
G.B. Nascimento ◽  
G.S. Schmidt ◽  
...  
Keyword(s):  
Principal Components ◽  
Egg Production ◽  
Genetic Parameters ◽  
Production Traits ◽  
White Leghorn ◽  
Breeding Values

The effect of different levels of management on the assessment of differences between varieties of chickens. II. Egg production, mortality and egg weight

1964 ◽  
Vol 6 (2) ◽  
pp. 195-205 ◽  
Author(s):  
J. C. Bowman ◽  
J. C. Powell
Keyword(s):  
Egg Production ◽  
Genetic Correlations ◽  
Egg Laying ◽  
Components Of Variance ◽  
Egg Weight ◽  
The Mean ◽  
Intensive Investigation ◽  
Optimum Management ◽  
Maximum Expression ◽  
Different Levels

1. The data relating to 16 multi-location trials involving several varieties of egg-laying chickens per trial have been analysed to obtain estimates of variety × location (genotype-environment) interactions for rearing and laying mortality, hen-month and hen-housed egg production and 32-week egg weight. Significant interactions were found in about a third of the trials for all five traits though in only two cases did the interaction variance account for more than 20% of the total variance.2. Genetic correlations for varieties between locations have been calculated as 0·49 for rearing mortality, 0·50 for laying mortality, 0·72 for hen-month production, 0·76 for hen-housed production and 0·91 for egg weight. These are in close agreement with previous published estimates.3. The between-and within-variety components of variance have been calculated for each trait on each location separately. The regressions within trials and pooled values of the components on the mean level of all varieties on the location have been calculated. For hen-month production the pooled regres-son of the within-variety component on mean was negative, whilst for all other traits the pooled regressions were positive. The pooled regressions of the between-variety components on mean were all positive. It is suggested that this information indicates that comparison of varieties for single traits should be carried out on locations favourable for maximum expression of the trait. The difficulties which variety comparisons, for several traits having different optimum management regimes, would cause and the need for a more intensive investigation of the conditions conducive to genotype-environment interactions are stressed.

Sire × hatching season interaction in egg production traits within flocks of domestic fowl

1979 ◽  
Vol 30 (5) ◽  
pp. 991
Author(s):  
BH Yoo ◽  
BL Sheldon
Keyword(s):  
Domestic Fowl ◽  
Variance Component ◽  
Egg Production ◽  
Production Traits ◽  
White Leghorn ◽  
Egg Weight ◽  
Sib Families ◽  
Selection For ◽  
Efficiency Of Selection ◽  
Season Interaction

The extent of sire x hatching season interaction in egg production characters has been studied in White Leghorn, Australorp and Synthetic flocks in which half-sib families bred from the same sires were mated largely to the same dams for spring and autumn hatchings. Interaction appeared to be more important in White Leghorn and Synthetic than in Australorp. The estimate of variance component for interaction was not consistent among the three flocks, and it was important only in certain flocks for different characters: age at first egg, part-annual hen-housed production (PHP), and egg weight at 34 and 62 (EWL) weeks of age in Synthetic; and annual survivors' production and egg specific gravity at 62 weeks of age (SGL) in White Leghorn. Comparison of within-season and across-seasons heritabilities showed that the former could be on average more than 45% higher than the latter in PHP, EWL, SGL and annual hen-housed production. As the estimates of the genetic correlation coefficient between seasons tend to be below 1.0 for many characters in White Leghorn and Synthetic, the sire x hatching season interaction may need to be taken into account and investigated further to improve the efficiency of selection for egg production.

scholarly journals Genetic parameters and principal component analysis for egg production from White Leghorn hens

2013 ◽  
Vol 92 (9) ◽  
pp. 2283-2289 ◽  
Author(s):  
G.C. Venturini ◽  
R.P. Savegnago ◽  
B.N. Nunes ◽  
M.C. Ledur ◽  
G.S. Schmidt ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Egg Production ◽  
Genetic Parameters ◽  
Principal Component ◽  
Component Analysis ◽  
White Leghorn

The effect of mild inbreeding in two lines of White Leghorn

1962 ◽  
Vol 13 (2) ◽  
pp. 362 ◽  
Author(s):  
JA Morris
Keyword(s):  
Egg Production ◽  
Adult Stage ◽  
Random Mating ◽  
Continuous Selection ◽  
Differential Sensitivity ◽  
Time Of Death ◽  
White Leghorn ◽  
The Mean ◽  
Selection For ◽  
June July

The reaction of two flocks of White Leghorn to slow inbreeding has been examined. One flock, the M line, has been subject to continuous selection for egg production or an associated character since 1947, and the other, the C line, has been propagated by means of random mating without artificial selection for a corresponding period. Mean inbreeding, as measured by Wright's coefficient (F), increased steadily in both flocks to reach a maximum of 25.1% in the M line and 16.2% in the C line. Significant intra-year regressions of survivors' production (72 weeks), hatchability of fertile eggs, and egg production during the winter months of June–July, on computed F values, were observed for both lines. In addition, significant regressions for the 72-week production index, age at first egg, and pauses during June–July were observed for the M line. Viability of chickens, both during early rearing (hatching date to 3½ weeks of age) and during adult stage (approximately 20 weeks to 72 weeks of age), was not affected by small changes in degree of inbreeding. Intra-year regressions on F of age at death and production up to time of death were non-significant for both lines. Highly significant differences between yearly regressions of egg production, and pauses during the two winter months, on F values were observed. These differences could indicate a differential sensitivity of response to inbreeding associated with seasonal adversity. It was not possible to substantiate the existence of a differential response to a stress factor when mortality during a severe heat wave was examined, as the mean computed F value of birds dying was not significantly greater than the corresponding F value of survivors. The stress was reasonably severe, as 15.4% of all birds died within a couple of days.

The effect of different levels of management on the assessment of differences within a variety of chicken

1967 ◽  
Vol 9 (1) ◽  
pp. 121-125 ◽  
Author(s):  
M. W. Oakes
Keyword(s):  
Egg Production ◽  
Genetic Correlations ◽  
Environment Interaction ◽  
Components Of Variance ◽  
Genotype Environment Interaction ◽  
Single Location ◽  
Body Weights ◽  
The Mean ◽  
Maximum Expression ◽  
Different Levels

The data relating to twenty single location trials, involving the progeny of seven sires from one variety mated with random females from another, have been analysed to obtain estimates of sire × location (genotype–environment) interaction for egg production, 23- and 64-week body weights and 32-and 45-week egg weights. In no case was a significant interaction found, indicating genetic correlations not significantly different from unity.The between- and within-sire components of variance have been calculated for each trait on each location separately. The regressions of these components on the mean levels at the locations have been obtained. Though low and non-significant, they tend to support the use of those locations giving maximum expression of a trait for comparisons involving that trait.

Multi-Center Calibration of the Second Reference Material for Thromboplastin, Rabbit, Plain, Coded CRM 149R

1991 ◽  
Vol 65 (03) ◽  
pp. 263-267 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Reference Material ◽  
Standard Error ◽  
Standard Errors ◽  
Sensitivity Index ◽  
Long Term Stability ◽  
Significant Bias ◽  
The Mean ◽  
The Relationship ◽  
International Sensitivity Index

SummaryIn a collaborative trial of eleven laboratories which was performed mainly within the framework of the European Community Bureau of Reference (BCR), a second reference material for thromboplastin, rabbit, plain, was calibrated against its predecessor RBT/79. This second reference material (coded CRM 149R) has a mean International Sensitivity Index (ISI) of 1.343 with a standard error of the mean of 0.035. The standard error of the ISI was determined by combination of the standard errors of the ISI of RBT/79 and the slope of the calibration line in this trial.The BCR reference material for thromboplastin, human, plain (coded BCT/099) was also included in this trial for assessment of the long-term stability of the relationship with RBT/79. The results indicated that this relationship has not changed over a period of 8 years. The interlaboratory variation of the slope of the relationship between CRM 149R and RBT/79 was significantly lower than the variation of the slope of the relationship between BCT/099 and RBT/79. In addition to the manual technique, a semi-automatic coagulometer according to Schnitger & Gross was used to determine prothrombin times with CRM 149R. The mean ISI of CRM 149R was not affected by replacement of the manual technique by this particular coagulometer.Two lyophilized plasmas were included in this trial. The mean slope of relationship between RBT/79 and CRM 149R based on the two lyophilized plasmas was the same as the corresponding slope based on fresh plasmas. Tlowever, the mean slope of relationship between RBT/79 and BCT/099 based on the two lyophilized plasmas was 4.9% higher than the mean slope based on fresh plasmas. Thus, the use of these lyophilized plasmas induced a small but significant bias in the slope of relationship between these thromboplastins of different species.

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