Expected gain and status number following restricted individual and combined-index selection

Genome ◽  
1997 ◽  
Vol 40 (1) ◽  
pp. 1-8 ◽  
Author(s):  
R.-P. Wei ◽  
F. C. Yeh ◽  
D. Lindgren
Keyword(s):  
Genetic Gain ◽  
Real Life ◽  
Selection Criterion ◽  
Breeding Value ◽  
Index Selection ◽  
Expected Gain ◽  
Status Number ◽  
Efficiency Of Selection ◽  
Number Of Individuals ◽  
Restricted Selection

Imposition of restrictions on number of individuals selected from a family and number of families from which superior individuals are selected could markedly alter the consequences of individual and combined-index selection. Predicted genetic gain and diversity measured as status number following selection were studied to draw general conclusions. Selection and its prediction were applied to two sets of real-life data. Theoretical prediction gave results close to those from factual selection. Gain and status number varied with initial family number and size, sib type, heritability, selection proportion, restriction type and intensity, and selection criteria. Proper restriction on the number of individuals selected can control the reduction of status number to an acceptable level, particularly when breeding values are used as the selection criterion. Restriction on the number of families selected would effectively improve the gain efficiency of selection based on phenotypic values. Choosing combinations of both restrictions might produce higher gain without the loss of status number. Given constant population size, family number should be large enough to ensure that restricted selection will yield higher gain and status number.Key words: restricted selection, phenotype, breeding value, genetic gain, effective size.

Genetic gain with desired status number in breeding programs: a study on selection effects

1998 ◽  
Vol 28 (12) ◽  
pp. 1861-1869 ◽  
Author(s):  
R -P Wei ◽  
C R Hansen ◽  
N K Dhir ◽  
F C Yeh
Keyword(s):  
Genetic Gain ◽  
Breeding Population ◽  
Breeding Value ◽  
Index Selection ◽  
Selection Methods ◽  
Family Selection ◽  
Breeding Populations ◽  
High Heritability ◽  
Status Number ◽  
Restricted Selection

Genetic gain and average coancestry or status number was investigated for five selection methods: penalty index selection (PIS), family index selection (FIS), combined between-family and within-family selection (CBW), restricted individual selection (RIS), and combined index selection (RCS). PIS was a function of an individual's breeding value and family contributions, modelled as a stepwise procedure to select superior individuals one by one. A penalty would indicate the need to have low average coancestry or large status number. Breeding populations of unrelated families were investigated by Monte Carlo simulation to examine the genetic response of the five selection methods at a restricted selection intensity and average coancestry. PIS attained the greatest genetic gain, except at the selection limits of maximum genetic gain and minimum average coancestry where PIS might be identical to the other selection methods. FIS and RCS well approximated PIS at high average coancestry. RIS was similar to RCS when the heritability was high, particularly at low average coancestry. CBW attained the least genetic gain among the selection methods. For all selections, high heritability would contribute to a greater genetic gain and status number or low average coancestry. PIS was applied to a practical breeding program in Alberta that included several subpopulations. The results suggested that the selection efficiency for balancing genetic gain and average coancestry would increase when deploying a subpopulation strategy for breeding population management.

scholarly journals Genetic response to short-term index selection in females and mass selection in males of the Nigerian heavy local chicken ecotype

2020 ◽  
Vol 44 (2) ◽  
pp. 1-17
Author(s):  
C. C. Ogbu ◽  
C. C. Nwosu
Keyword(s):  
Body Weight ◽  
Genetic Gain ◽  
Egg Production ◽  
Index Selection ◽  
Mass Selection ◽  
Indigenous Chicken ◽  
Multiple Trait ◽  
Breeding Values ◽  
Expected Gain ◽  
Selection For

The study aimed to determine genetic gain in growth and egg production in the Nigerian indigenous chicken (NIC) subjected to multiple trait index selection for females and mass selection for males. The experimental birds (G generation) were generated from a reference 0 population of NIC and reared according to sire families from hatch. At point of lay, females were housed individually in laying cages for egg production. Hens were selected based on index scores calculated using an index of weighted breeding values constructed from own performance in body weight at first egg (BWFE), egg weight (EW) and egg production (EN), trait heritabilities and relative economic weights while cocks were selected based on own performance in body weight at 39 weeks of age (BW ). Selected parents were mated to 39 generate the G generation which in turn yielded the parents of the G generation. A control 1 2 population was used to measure environmental effects. Data were analyzed using the Restricted Maximum Likelihood (REML) computer programme. For hens, expected average direct genetic gain per generation was 12.58, 2.98g and 25.04g for EN, EW and BWFE, respectively while realized genetic gain was 2.19 and 1.59 for EN, 1.65 and 0.26g for EW, and -25.60 and 123.64g for BWFE for G and G generations, respectively. The corresponding 0 1 values for ratio of realized to expected genetic gains were 2.27 and 1.22, 3.15 and 0.24, and 0.95 and 2.21, respectively. Heritability (h2) ranged from 0.12 to 0.24 for EN, 0.34 to 0.43 for EW and 0.57 to 0.69 for BWFE, across the three generations. Similar improvements in BW 39 were observed in males with an average expected gain of 508.50g per generation. In conclusion, growth and egg production in the NIC can be improved using mass selection for cocks and index of weighted breeding values for hens.

A simulation study of open nucleus and closed nucleus breeding systems in a sheep population

1995 ◽  
Vol 60 (1) ◽  
pp. 117-124 ◽  
Author(s):  
J. A. Roden
Keyword(s):  
Genetic Gain ◽  
Live Weight ◽  
Breeding Systems ◽  
Breeding Value ◽  
Linear Unbiased Prediction ◽  
Sheep Population ◽  
Best Linear Unbiased ◽  
Nucleus Breeding ◽  
Open Nucleus ◽  
Selection Of

AbstractStochastic simulation was used to compare the results of alternative breeding systems in a sheep population divided into 10 flocks of 120 ewes. The breeding systems compared were selection within closed flocks (CF), a closed nucleus system (CNS), an open nucleus system (ONS) and open nucleus systems with the selection of nucleus replacements being restricted to either nucleus born males (ONSRm) or nucleus born females (ONSRf). Selection was for a best linear unbiased prediction of breeding value for lamb live weight which had a heritability of 0·17. The open nucleus breeding systems (ONS, ONSRm, ONSRf) resulted in higher rates of genetic gain, more predictable selection responses and lower rates of inbreeding than either the closed nucleus system (CNS) or selection within closed flocks (CF). Initial genetic differences between flocks resulted in higher rates of genetic gain in the nucleus breeding systems due to the use of between flock genetic variance. In the ONS system up to 25% of nucleus sires and approximately 50% of nucleus dams were born in base flocks. Nevertheless if selection of either nucleus sires or dams was restricted to nucleus born animals there was very little change in genetic gain or rate of inbreeding.

scholarly journals Genetic gains under three methods of selection

1962 ◽  
Vol 3 (3) ◽  
pp. 417-423 ◽  
Author(s):  
D. J. Finney
Keyword(s):  
Linear Function ◽  
Genetic Gain ◽  
Index Selection ◽  
Genetic Gains ◽  
Independent Culling

Results obtained by Young for the expectation of genetic gain in an arbitrary linear function of several traits under selection by independent culling levels, under tandem selection, and under index selection have been obtained in slightly more general form and their dependence on basic genetic and phenotypic parameters exhibited. A warning is given about the effects of selection in modifying the distribution of traits; when the distribution has become appreciably non-normal, any calculation of genetic gains from formulae based on normality will tend to overestimation.

scholarly journals Decision making under interval uncertainty: toward (somewhat) more convincing justifications for Hurwicz optimism-pessimism approach

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Warattaya Chinnakum ◽  
Laura Berrout Ramos ◽  
Olugbenga Iyiola ◽  
Vladik Kreinovich
Keyword(s):  
Decision Making ◽  
Real Life ◽  
Interval Uncertainty ◽  
Lower And Upper Bounds ◽  
Worst Case ◽  
Content Type ◽  
Expected Gain ◽  
Utility Approach ◽  
Interval Valued ◽  
Weighted Combination

Purpose In real life, we only know the consequences of each possible action with some uncertainty. A typical example is interval uncertainty, when we only know the lower and upper bounds on the expected gain. A usual way to compare such interval-valued alternatives is to use the optimism–pessimism criterion developed by Nobelist Leo Hurwicz. In this approach, a weighted combination of the worst-case and the best-case gains is maximized. There exist several justifications for this criterion; however, some of the assumptions behind these justifications are not 100% convincing. The purpose of this paper is to find a more convincing explanation. Design/methodology/approach The authors used utility approach to decision-making. Findings The authors proposed new, hopefully more convincing, justifications for Hurwicz’s approach. Originality/value This is a new, more intuitive explanation of Hurwicz’s approach to decision-making under interval uncertainty.

scholarly journals Simulation Study on the Integration of Health Traits in Horse Breeding Programs

Animals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1153
Author(s):  
Lisa Büttgen ◽  
Johannes Geibel ◽  
Henner Simianer ◽  
Torsten Pook
Keyword(s):  
Osteochondrosis Dissecans ◽  
Selection Index ◽  
R Package ◽  
Breeding Value ◽  
Index Selection ◽  
Threshold Selection ◽  
Horse Breeding ◽  
Frequency Of Use ◽  
Performance Traits ◽  
And Performance

Osteochondrosis dissecans (OCD) is a degenerative disease of the cartilage leading to osseous fragments in the joints. It is important in horse breeding both from an animal welfare and an economic perspective. To study adequate breeding strategies to reduce OCD prevalence, a lifelike simulation of the breeding program of German Warmblood horses was performed with the R package MoBPS. We simulated complex breeding schemes of riding horses with different selection steps and realistic age structure, mimicking the German situation. As an example, osseous fragments in fetlock and hock joints were considered. Different scenarios, either using threshold selection, index selection or genomic index selection, respectively, were compared regarding their impact on health and performance traits. A rigorous threshold selection as well as the integration of OCD in a selection index at the stage of stallion licensing and chosen frequency of use in breeding cases on a selection index that includes breeding values for OCD traits performed best on a comparable level. Simply integrating OCD in this breeding value was less effective in terms of OCD reduction. Scenarios with a higher reduction of OCD also showed a slightly reduced improvement in the riding horse performance traits.

scholarly journals Comparison of long-term selection responses of breeding policy in dairy herds

2011 ◽  
Vol 50 (No. 10) ◽  
pp. 439-449
Author(s):  
P. Šafus ◽  
J. Přibyl
Keyword(s):  
Embryo Transfer ◽  
Genetic Gain ◽  
Negative Selection ◽  
Milk Proteins ◽  
Breeding Value ◽  
Dairy Herds ◽  
Selection Intensity ◽  
Term Selection ◽  
Single Use ◽  
Selection Of

Genetic and economic responses to genetic gain were evaluated for these breeding arrangements: single use of bulls under testing; single and repeated use of proved bulls for two years and for three years (in combination with selection intensity 1%, 5% or 10% of the best bulls for the use of proved bulls); negative selection of cows in the herd &ndash; 10%, 20% or 30% of animals are discarded from reproduction and the animals are left in the herd and used for breeding by beef bulls; negative selection of first-calvers in the herd &ndash; 10%, 20% or 25% of animals are discarded for slaughter; discarding of heifers and purchase of animals with higher breeding value, and embryo transfer &ndash; a group of selected recipients accounts for 10%, 20% or 30% of the cows with lover breeding value in the dairy herds. Simulations for single use of breeding arrangements and their consequences over a fifty-year period were carried out for the above models using the gene flow method. Only minimum changes will occur since the 25<sup>th</sup> year of observation. A comparison of the particular models showed the highest gain of proved bulls selected from 1% of the best bulls whose cumulative genetic gain was 41.558 kg of milk proteins on average per cow for the whole observed period. Single use of bulls under testing in the herd resulted in the second highest cumulative genetic gain. Use of proved bulls selected with lower selection intensity (5% or 10%) had worse results. Culling of cows and discarding of first-calvers for slaughter led to lower genetic and economic contribution. The gain of embryo transfer was also lower; moreover, it is not economically advantageous for its very high costs, so it should not be used in production herds generally. High genetic and economic gain was recorded for replacement of all heifers by animals with higher breeding value from other populations. &nbsp;

Detection, location, and source mechanism determination with large noise variations in surface microseismic monitoring

Geophysics ◽  
2020 ◽  
Vol 85 (6) ◽  
pp. KS197-KS206
Author(s):  
Dmitry Alexandrov ◽  
Leo Eisner ◽  
Umair bin Waheed ◽  
SanLinn I. Kaka ◽  
Stewart Alan Greenhalgh
Keyword(s):  
Noise Level ◽  
Weighted Least Squares ◽  
Computational Cost ◽  
Real Life ◽  
Selection Criterion ◽  
Signal Amplitude ◽  
Threshold Level ◽  
Microseismic Monitoring ◽  
Source Mechanism ◽  
Source Mechanisms

Microseismic monitoring aims at detecting as weak events as possible and providing reliable locations and source mechanisms for these events. Surface monitoring arrays suffer from significant variations of noise levels across receiver lines. When using a large monitoring array, we use a stacking technique to detect microseismic events through maximizing the signal-to-noise ratio (S/N) of the stack. But some receivers with a high noise level do not contribute to improving the S/N of the stack. We have derived a theoretical concept for the proper selection of receivers that best contribute to the stack for a constant strength of a signal across the array. This receiver selection criterion, based on the assumption of constant signal amplitude, provides a robust estimate of the noise threshold level, which could be used to discard or suppress contribution from the receivers that do not improve the S/N of the stack. We found that limiting the number of receivers for stacking improves the location accuracy and reduces the computational cost of data processing. Although the assumption of a constant signal never holds in real-life seismic applications, the noise level varies across the surface receivers in a significantly wider range than the signal amplitude. These noise variations can also increase the uncertainty of the source mechanism inversion and should be accounted for. Synthetic and field data examples show that weighted least-squares inversion with receiver weighting according to the noise level produces more accurate estimates for source mechanisms compared to the inversion that ignores information about noise.

Selection indices for terminal sires to improve lean meat production from sheep in the United Kingdom

1987 ◽  
Vol 45 (1) ◽  
pp. 87-96 ◽  
Author(s):  
A. C. Parratt ◽  
G. Simm
Keyword(s):  
Growth Rate ◽  
Carcass Composition ◽  
Breeding Value ◽  
Meat Production ◽  
Lean Meat ◽  
The United Kingdom ◽  
Ct Measurements ◽  
Selection Indices ◽  
Efficiency Of Selection ◽  
Terminal Sire

AbstractSelection indices to improve lean meat production of terminal sire breeds of sheep were derived. An aggregate breeding value which comprised growth rate, killing-out proportion and carcass lean proportion was examined. Selection criteria included growth rate and ultrasonic or X-ray computer tomography (CT) estimates of carcass composition. Correlations betwen the index and the aggregate breeding value were about 0·38 for indices using ultrasonic fat measurements, and about 0·40 for those using CT measurements. Dropping ultrasonic or CT measurements from the indices reduced the correlations with the aggregate breeding value by only about 0·01 and 002 respectively, indicating that selection on growth rate alone under current economic conditions was highly efficient. Changes in economic weights, and genetic parameters had little effect on the efficiency of selection. The total national discounted value of returns from a single round of selection on the indices was expected to be between £6 and £30·5 million, depending on penetration rates of improved stock, the breeding scheme used, and with a time horizon of 20 years.

Selection indices to improve the efficiency of lean meat production in cattle

1986 ◽  
Vol 42 (2) ◽  
pp. 183-193 ◽  
Author(s):  
G. Simm ◽  
C. Smith ◽  
J. H. D. Prescott
Keyword(s):  
Growth Rate ◽  
Birth Weight ◽  
Conversion Efficiency ◽  
Breeding Value ◽  
Meat Production ◽  
Food Conversion ◽  
Lean Meat ◽  
Selection Indices ◽  
Efficiency Of Selection ◽  
Food Conversion Efficiency

ABSTRACTSelection indices to improve the efficiency of lean meat production in cattle were derived with an aggregate breeding value which comprised growth rate, food conversion efficiency, killing-out proportion and carcass lean proportion. Index measurements were growth rate, food conversion efficiency and ultrasonic fat area. Relative economic values of traits in the aggregate breeding value were calculated for an 18/20-month beef system, assuming a fixed national output of lean meat. Literature estimates of phenotypic and genetic parameters were used. Two indices were derived, one with a complete restriction on genetic changes in birth weight, and the other without restriction. Correlations between the index and the aggregate breeding value were 0·53 for the restricted index, and 0·57 for the unrestricted index. The maximum proportional reduction in expected economic response, due to complete restriction of birth weight was about 0·08. Selection on either index would actually lead to a slight decrease in carcass lean proportion, but this was less than the decrease expected from selection solely on growth rate. Correlations between the indices and the aggregate breeding value (measuring the accuracy of selection) fell by only about 0·01 when ultrasonic measurements were omitted from the index, but fell by about 0·09 when food conversion efficiency was omitted. Sensitivity of the indices to changes in parameters was also examined. With proportional changes of ±0·5 in individual economic weights, or absolute changes of ±0·2 in genetic correlations or −0·2 in heritabilities, the efficiency of selection ranged from 0·93 to 1·00.

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