scholarly journals COMPARISON OF TANDEM AND INDEX SELECTION IN THE MODIFIED PEDIGREE METHOD OF BREEDING SELF-POLLINATED SPECIES

1969 ◽  
Vol 49 (6) ◽  
pp. 773-781 ◽  
Author(s):  
J. Pesek ◽  
R. J. Baker
Keyword(s):  
Environmental Variability ◽  
Selection Index ◽  
Genetic Effects ◽  
Index Selection ◽  
Two Stage ◽  
Economic Values ◽  
Correlated Traits ◽  
Selection For

Two-stage tandem selection and index selection were simulated for the modified pedigree method of breeding self-pollinated crops. We assumed that two traits were negatively correlated due to repulsion linkages, and considered correlations ranging from 0.00 to −0.95 corresponding to linkage intensities of 0.50 to 0.05. Each trait was controlled by five different loci with equal genetic effects. Three levels of environmental variability were assumed. Economic values were set at 0.5, 1.0 and 1.5 for one trait and 1.0 for the other.Index selection was superior to tandem selection for all combinations of parameters simulated. The efficiency of tandem selection was increased substantially by selecting the most valuable trait first. The efficiency of index selection can be increased by more frequent estimation of selection index coefficients.We did not consider positively correlated traits.

Preweaning losses of piglets as a result of index selection for reduced backfat thickness and increased growth rate

1993 ◽  
Vol 73 (2) ◽  
pp. 437-442 ◽  
Author(s):  
R. M. McKay
Keyword(s):  
Growth Rate ◽  
Key Words ◽  
Selection Index ◽  
Backfat Thickness ◽  
Index Selection ◽  
Selection For ◽  
Preweaning Period

Index selection for reduced backfat thickness and increased postweaning growth rate resulted in increased preweaning death losses due either directly or indirectly to the sow in the Yorkshire and Hampshire breeds. This resulted in a reduced percentage of piglets weaned in the Yorkshire breed. Key words: Swine, selection index, preweaning period, mortality, survival

SELECTION FOR NURSING ABILITY AND ADULT WEIGHT IN MICE

Genetics ◽  
1978 ◽  
Vol 88 (4) ◽  
pp. 761-780
Author(s):  
J Nagai ◽  
E J Eisen ◽  
J A B Emsley ◽  
A J McAllister
Keyword(s):  
Body Weight ◽  
Selection Index ◽  
Genetic Correlations ◽  
Regression Coefficients ◽  
Index Selection ◽  
Single Pair ◽  
Adult Weight ◽  
Selection For ◽  
Possible Cause ◽  
Line Generation

ABSTRACT Three selection treatments were conducted for 12 generations in each of two base populations (P and Q): (1) increased nursing ability of the mother (n12), as measured by mean 12-day weight of eight young within a crossfostering set (MP and MQ lines), (2) increased adult (42-day) body weight of the offspring (w42) (WP and WQ lines), and (3) performance combining the two traits (n12 and w42) into a selection index (BP and BQ lines). Lines CP and CQ were maintained as unselected controls in each population. In each line-generation subclass, 92 single-pair matings were made and the offspring assigned to balanced crossfostering sets of four dams each. Regression coefficients of mean performance (in grams) on generations were 0.080 ±0.029 and 0.054 ± 0.031 for n12 in MP and MQ, and 0.680 ± 0.039 and 0.868 ± 0.051 for w42 in WP and WQ, respectively. The BP and BQ lines showed genetic gains in n12 (0.090 and 0.053, respectively) and w42 (0.576 and 0.696) intermediate between the performance of MP and WP, and MQ and WQ, respectively, except for n12 of BQ. Realized heritabilities for n12 were 0.16 ± 0.05 and 0.11 ± 0.06 and those for w42 were 0.40 ± 0.02 and 0.43 ± 0.03 for P and Q, respectively. The realized genetic correlations between n12 and w42 were 0.70 ± 0.07 and 0.73 ± 0.08 in P and Q, respectively. The ratios of the predicted to observed responses in MP, BP and BQ were 0.99, 1.03 and 0.89, respectively. However, the predicted and observed responses differed in MQ, WP and WQ; the ratios were 1.29, 0.65 and 0.65, respectively. The observed combined responses for n12 and w42 in the index lines (BP and BQ) were smaller than the optimum expected from index selection. A possible cause was that the estimated genetic correlations (0.22 ± 0.16 and -0.17 ± 0.16 for BP and BQ, respectively) and heritabilities (0.39 ± 0.03 and 0.28 ± 0.02, respectively) for w42 that were used to construct the selection index were smaller than the respective realized parameters.

AN APPLICATION OF INDEX SELECTION TO THE IMPROVEMENT OF SELF-POLLINATED SPECIES

1970 ◽  
Vol 50 (3) ◽  
pp. 267-276 ◽  
Author(s):  
J. PESEK ◽  
R. J. BAKER
Keyword(s):  
Triticum Aestivum ◽  
Selection Index ◽  
Triticum Aestivum L ◽  
Hybrid Population ◽  
Index Selection ◽  
Index Method ◽  
Quantitative Characters ◽  
Economic Weights ◽  
Selection For ◽  
Genotypic Effects

Results of a genetic study of four quantitative characters in a cross of two cultivars of Triticum aestivum L. em Thell. indicated that heritability of yield was lower than the heritabilities of maturity and height and that interactions between genotypic effects and year environmental effects were nonsignificant. The modified selection index method, based upon desired genetic gains rather than relative economic weights of traits, is explained in detail and applied to selection for maturity, height and yield from a hybrid population of wheat. The methods and problems of using index selection in self-pollinated species are discussed.

Index selection for both current and future generation gains

1978 ◽  
Vol 26 (2) ◽  
pp. 111-118 ◽  
Author(s):  
J. W. James
Keyword(s):  
Body Weight ◽  
Selection Index ◽  
Future Generation ◽  
Index Selection ◽  
Economic Returns ◽  
Present Value ◽  
Individual Traits ◽  
Selection Decisions ◽  
Selection For ◽  
Combined Selection

ABSTRACTWhen economic returns from current and future generation gains are comparable in magnitude, selection decisions should take account of both sources of gain. A combined selection index is devised to maximize the present value of discounted returns from all sources. The index depends on genetic and phenotypic variances and covari-ances, population structure, discount rate and the relation of annual returns to individual traits. The combined index can be regarded as the sum of separate indices maximizing returns from each source. The method is illustrated with a simple example using wool weight and body weight in sheep.

Derivation of economic values for dairy cattle in Iran and comparison to other countries

2007 ◽  
Vol 2007 ◽  
pp. 72-72
Author(s):  
Ali Sadeghi-Sefidmazgi ◽  
Mohammad Moradi-Shahrbabak ◽  
Ardeshir Nejati-Javaremi ◽  
Abdolahad Shadparvar ◽  
Han A. Mulder
Keyword(s):  
Dairy Cattle ◽  
Milk Fat ◽  
Selection Index ◽  
Selection Strategy ◽  
Index Selection ◽  
Production Traits ◽  
Economic Values ◽  
Breeding Goal ◽  
Effective Selection ◽  
National Selection

Index selection is the most effective selection strategy to improve total merit. Index selection requires the economic values (EVs) of the traits in the breeding goal and the genetic parameters of the traits in the breeding goal and in the index (Hazel and Lush, 1942). According to this theory, in most countries a national selection index has been developed for dairy cattle (Miglior et al., 2005). In Iran a national selection index has not yet been developed. The first objective of this study was, therefore, to estimate economic values for production traits (milk, fat and protein yield) and longevity for Holsteins in Iran. The second objective was to compare the proposed Iranian selection index with selection indices of other countries in the world.

Hybrid maize breeding with doubled haploids. IV. Number versus size of crosses and importance of parental selection in two-stage selection for testcross performance

2008 ◽  
Vol 117 (2) ◽  
pp. 251-260 ◽  
Author(s):  
Thilo Wegenast ◽  
C. Friedrich H. Longin ◽  
H. Friedrich Utz ◽  
Albrecht E. Melchinger ◽  
Hans Peter Maurer ◽  
...  
Keyword(s):  
Doubled Haploids ◽  
Maize Breeding ◽  
Two Stage ◽  
Parental Selection ◽  
Testcross Performance ◽  
Selection For ◽  
Hybrid Maize

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.

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