scholarly journals Pre-selection against a lethal recessive allele in breeding schemes with optimum-contribution selection or truncation selection

2021 ◽  
Vol 53 (1) ◽  
Author(s):  
Line Hjortø ◽  
Mark Henryon ◽  
Huiming Liu ◽  
Peer Berg ◽  
Jørn Rind Thomasen ◽  
...  
Keyword(s):  
Genetic Gain ◽  
Recessive Allele ◽  
Selection Strategy ◽  
Carrier Status ◽  
Truncation Selection ◽  
Selection Strategies ◽  
Significant Difference ◽  
Selection Step ◽  
Breeding Schemes ◽  
Male Carriers

Abstract Background We tested the hypothesis that breeding schemes with a pre-selection step, in which carriers of a lethal recessive allele (LRA) were culled, and with optimum-contribution selection (OCS) reduce the frequency of a LRA, control rate of inbreeding, and realise as much genetic gain as breeding schemes without a pre-selection step. Methods We used stochastic simulation to estimate true genetic gain realised at a 0.01 rate of true inbreeding (ΔFtrue) by breeding schemes that combined one of four pre-selection strategies with one of three selection strategies. The four pre-selection strategies were: (1) no carriers culled, (2) male carriers culled, (3) female carriers culled, and (4) all carriers culled. Carrier-status was known prior to selection. The three selection strategies were: (1) OCS in which $$\Delta {\text{F}}_{{{\text{true}}}}$$ Δ F true was predicted and controlled using pedigree relationships (POCS), (2) OCS in which $$\Delta {\text{F}}_{{{\text{true}}}}$$ Δ F true was predicted and controlled using genomic relationships (GOCS), and (3) truncation selection of parents. All combinations of pre-selection strategies and selection strategies were tested for three starting frequencies of the LRA (0.05, 0.10, and 0.15) and two linkage statuses with the locus that has the LRA being on a chromosome with or without loci affecting the breeding goal trait. The breeding schemes were simulated for 10 discrete generations (t = 1, …, 10). In all breeding schemes, ΔFtrue was calibrated to be 0.01 per generation in generations t = 4, …, 10. Each breeding scheme was replicated 100 times. Results We found no significant difference in true genetic gain from generations t = 4, …, 10 between breeding schemes with or without pre-selection within selection strategy. POCS and GOCS schemes realised similar true genetic gains from generations t = 4, …, 10. POCS and GOCS schemes realised 12% more true genetic gain from generations t = 4, …, 10 than truncation selection schemes. Conclusions We advocate for OCS schemes with pre-selection against the LRA that cause animal suffering and high costs. At LRA frequencies of 0.10 or lower, OCS schemes in which male carriers are culled reduce the frequency of LRA, control rate of inbreeding, and realise no significant reduction in true genetic gain compared to OCS schemes without pre-selection against LRA.

scholarly journals Mendelian sampling terms as a selective advantage in optimum breeding schemes with restrictions on the rate of inbreeding

2004 ◽  
Vol 83 (1) ◽  
pp. 55-64 ◽  
Author(s):  
S. AVENDAÑO ◽  
J. A. WOOLLIAMS ◽  
B. VILLANUEVA
Keyword(s):  
Genetic Variation ◽  
Genetic Gain ◽  
Selective Advantage ◽  
Breeding Values ◽  
Truncation Selection ◽  
Joint Management ◽  
Breeding Schemes ◽  
Estimated Breeding Values ◽  
Available Information ◽  
Mendelian Sampling

Quadratic indices are a general approach for the joint management of genetic gain and inbreeding in artificial selection programmes. They provide the optimal contributions that selection candidates should have to obtain the maximum gain when the rate of inbreeding is constrained to a predefined value. This study shows that, when using quadratic indices, the selective advantage is a function of the Mendelian sampling terms. That is, at all times, contributions of selected candidates are allocated according to the best available information about their Mendelian sampling terms (i.e. about their superiority over their parental average) and not on their breeding values. By contrast, under standard truncation selection, both estimated breeding values and Mendelian sampling terms play a major role in determining contributions. A measure of the effectiveness of using genetic variation to achieve genetic gain is presented and benchmark values of 0·92 for quadratic optimisation and 0·5 for truncation selection are found for a rate of inbreeding of 0·01 and a heritability of 0·25.

scholarly journals Identification of superior parental lines for biparental crossing via genomic prediction

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243159
Author(s):  
Ping-Yuan Chung ◽  
Chen-Tuo Liao
Keyword(s):  
Genetic Gain ◽  
Genomic Prediction ◽  
Genomic Diversity ◽  
Breeding Value ◽  
Selection Strategy ◽  
Parental Selection ◽  
Breeding Values ◽  
Truncation Selection ◽  
Selection Approach ◽  
Parental Lines

A parental selection approach based on genomic prediction has been developed to help plant breeders identify a set of superior parental lines from a candidate population before conducting field trials. A classical parental selection approach based on genomic prediction usually involves truncation selection, i.e., selecting the top fraction of accessions on the basis of their genomic estimated breeding values (GEBVs). However, truncation selection inevitably results in the loss of genomic diversity during the breeding process. To preserve genomic diversity, the selection of closely related accessions should be avoided during parental selection. We thus propose a new index to quantify the genomic diversity for a set of candidate accessions, and analyze two real rice (Oryza sativa L.) genome datasets to compare several selection strategies. Our results showed that the pure truncation selection strategy produced the best starting breeding value but the least genomic diversity in the base population, leading to less genetic gain. On the other hand, strategies that considered only genomic diversity resulted in greater genomic diversity but less favorable starting breeding values, leading to more genetic gain but unsatisfactorily performing recombination inbred lines (RILs) in progeny populations. Among all strategies investigated in this study, compromised strategies, which considered both GEBVs and genomic diversity, produced the best or second-best performing RILs mainly because these strategies balance the starting breeding value with the maintenance of genomic diversity.

scholarly journals Genetic gain of pure line selection and combined crossbred purebred selection with constrained inbreeding

2001 ◽  
Vol 72 (2) ◽  
pp. 225-232 ◽  
Author(s):  
P. Bijma ◽  
J.A. Woolliams ◽  
J.A.M. van Arendonk
Keyword(s):  
Genetic Gain ◽  
Selection Index ◽  
Computing Time ◽  
Genetic Correlations ◽  
Pure Line ◽  
Selection Strategies ◽  
Line Selection ◽  
Breeding Schemes ◽  
Estimated Breeding Values ◽  
Genetic Contributions

AbstractUsing deterministic methods, rates of genetic gain (Δ G) and inbreeding (Δ F) were compared between pure line selection (PLS) and combined crossbred purebred selection (CCPS), for the sire line of a three-way crossbreeding scheme. Purebred performance and crossbred performance were treated as genetically correlated traits assuming the infinitesimal model. Breeding schemes were compared at a fixed total number of purebred selection candidates, i.e. including crossbred information did not affect the size of the purebred nucleus. Selection was by truncation on estimated breeding values for crossbred performance. Rates of genetic gain were predicted using a pseudo-BLUP selection index. Rates of inbreeding were predicted using recently developed methods based on long-term genetic contributions. Results showed that changing from PLS to CCPS may increase ΔF by a factor of 2·14. In particular with high heritabilities and low purebred-crossbred genetic correlations, CCPS requires a larger number of parents than PLS, to avoid excessive ΔF. The superiority of CCPS over PLS was judged by comparing ΔG from both selection strategies at the same ΔF. At the same ΔF, CCPS was superior to PLS and the superiority of CCPS was only moderately reduced compared with the situation without a restriction on ΔF. This paper shows that the longterm genetic contribution theory can be used to balance ΔF and ΔG in animal breeding schemes within very limited computing time.

scholarly journals Drooms Store Strategy To Win Business Competition On E-Commerce Lazada

2021 ◽  
Vol 19 (1) ◽  
pp. 13
Author(s):  
Asep Sugara ◽  
MD Sukamto ◽  
Rida Ramdani
Keyword(s):  
Selection Strategy ◽  
Target Market ◽  
Promotion Strategy ◽  
Product Selection ◽  
Advertising Strategy ◽  
Selection Strategies ◽  
Research Activities ◽  
Business Analysis ◽  
Analysis Strategy ◽  
Product Sales

This study aims to determine the Droom Store strategy in winning business competition in Lazada E-Commerce and increasing customer satisfaction. The analytical approach used is to use a qualitative approach. Where the owner of Drooms Store used as key informants with data collection using triangulation techniques. The results of research at Drooms Store using the techniques above, strategies that can win business competition in Lazada E-Commerce are product selection strategies which are the basis of product sales in which there are product research activities, namely where the seller determines the scale of the benefits of a product. product, then the price of the product, and also the target market. Product advertising strategy which is the second stage after the product selection strategy where this product advertising strategy can reach consumers and attract consumers to buy products. Then there is a product promotion strategy that aims to boost sellers to increase. A business analysis strategy that aims to control the business at Drooms Store . In other words, Lazada's E-commerce for the strategy that we will use has been very well supported by Lazada

scholarly journals On a Class of Optimal Stopping Problems with Mixed Constraints

2010 ◽  
Vol Vol. 12 no. 2 ◽  
Author(s):  
F. Thomas Bruss
Keyword(s):  
Selection Strategy ◽  
Optimal Selection ◽  
Recursive Structure ◽  
Limiting Behavior ◽  
Mixed Constraints ◽  
Selection Strategies ◽  
International Audience ◽  
Optimal Stopping Problems ◽  
The Cost ◽  
Independent Identically Distributed

International audience Let X(1),X(2),...,X(n) be independent, identically distributed uniform random variables on [0, 1]. We can observe the outcomes sequentially and must select online at least r of them, and, moreover, in expectation at least mu >= r. Here mu need not be integer. We see X(k) as the cost of selecting item k and want to minimize the expected total cost under the described combined (r, mu)-constraint. We will see that an optimal selection strategy exists on the set S(n) of all selection strategies for which the decision at instant k may depend on the value X(k), on the number N(k) of selections up to time k and of the number n - k of forthcoming observations. Let sigma(r,mu)(n) be the corresponding S(n)-optimal selection strategy and v(r,mu)(n) its value. The main goal of this paper is to determine these and to understand the limiting behavior of v(r,mu)(n). After discussion of the specific character of this combination of two types of constraints we conclude that the S(n)-problem has a recursive structure and solve it in terms of a double recursion. Our interest will then focus on the limiting behavior of nv(r,mu)(n) as n -> infinity. This sequence converges and its limit allows for the interpretation of a normalized limiting cost L (r, mu) of the (r, mu)-constraint. Our main result is that L(r, mu) = g(r) ((mu - r)(2)/(2)) where g(r) is the r(th) iterate of the function g(x) = 1 + x + root 1 + 2x. Our motivation to study mixed-constraints problems is indicated by several examples of possible applications. We also shortly discuss the intricacy of the expectational part of the constraint if we try to extend the class of strategies S n to the set of full-history-dependent and/or randomized strategies.

scholarly journals Breeding schemes in reindeer husbandry

Rangifer ◽  
2003 ◽  
Vol 23 (2) ◽  
pp. 45 ◽  
Author(s):  
Lars Rönnegård ◽  
J. A. Woolliams ◽  
Öje Danell
Keyword(s):  
Genetic Gain ◽  
Mass Selection ◽  
Effective Population ◽  
Selection Programme ◽  
Breeding Schemes ◽  
The Difference ◽  
Genetic Contributions ◽  
Parameter Values ◽  
Open Nucleus

The objective of the paper was to investigate annual genetic gain from selection (G), and the influence of selection on the inbreeding effective population size (Ne), for different possible breeding schemes within a reindeer herding district. The breeding schemes were analysed for different proportions of the population within a herding district included in the selection programme. Two different breeding schemes were analysed: an open nucleus scheme where males mix and mate between owner flocks, and a closed nucleus scheme where the males in non-selected owner flocks are culled to maximise G in the whole population. The theory of expected long-term genetic contributions was used and maternal effects were included in the analyses. Realistic parameter values were used for the population, modelled with 5000 reindeer in the population and a sex ratio of 14 adult females per male. The standard deviation of calf weights was 4.1 kg. Four different situations were explored and the results showed: 1. When the population was randomly culled, Ne equalled 2400. 2. When the whole population was selected on calf weights, Ne equalled 1700 and the total annual genetic gain (direct + maternal) in calf weight was 0.42 kg. 3. For the open nucleus scheme, G increased monotonically from 0 to 0.42 kg as the proportion of the population included in the selection programme increased from 0 to 1.0, and Ne decreased correspondingly from 2400 to 1700. 4. In the closed nucleus scheme the lowest value of Ne was 1300. For a given proportion of the population included in the selection programme, the difference in G between a closed nucleus scheme and an open one was up to 0.13 kg. We conclude that for mass selection based on calf weights in herding districts with 2000 animals or more, there are no risks of inbreeding effects caused by selection.

scholarly journals Planungsrechnungen zur Optimierung von Zuchtplänen der Rasse Merinofleischschaf

1999 ◽  
Vol 42 (3) ◽  
pp. 267-280
Author(s):  
U. Müller ◽  
K. Strittmatter ◽  
G. Nitter
Keyword(s):  
Field Test ◽  
Genetic Gain ◽  
The Other ◽  
Test Scheme ◽  
Progeny Testing ◽  
Basic Scheme ◽  
Lean Meat ◽  
Meat Content ◽  
Selection Strategies ◽  
Step Selection

Abstract. Title of the paper: Alternative selection strategies for the Mutton Merino breed to optimize breedine Systems This paper deals with the investigation of alternative selection strategies for the Mutton Merino breed to improve lamb meat production and fertility. A main topic is the application of ultrasonic scanning to evaluate the meat content on live animals. The aim of model calculations was the optimisation and comparison of five different selection strategies within three different schemes of gene dissimation. First a basic scheme was defined and optimised (selection on field records, one-step selection, no scanning). It was regarded as the reference scheme to which all other breeding Systems were related. The following schemes considered both, selection with and without scanning. A second scheme, also based on field records, includes two-step selection of rams (called improved field test scheme). In a third and fourth scheme a level of uniform environment was assumed for ram progeny testing. These are a central testing Station on the one hand with slaughtering and carcass evaluation on progeny, and one or more contract farms on the other (without slaughtering). For a fifth selection scheme an open nucleus was assumed with ram progeny testing in associated test herds. In a dcterministic approach using the ZPLAN Computer program, the monetary genetic gain for the breeding objeetive (traits lambs weaned, litter weight at weaning, postweaning daily gain and lean meat content) and the profit were calculated for each scheme after optimisation of various biological-technical coefficients. The highest profit was achieved with a nucleus scheme (DM 9,16). Due to low recording costs the basic scheme was second (DM 7,19) and, because of high costs, the Station scheme was last (DM 4,22). The other two schemes were intermediate (DM 6,98 for the scheme with contract farms and DM 6,58 for the improved field test scheme). On an average over all schemes, scanning resulted in a 0,24 DM (i.e. almost 30 per cent) increase of the monetary genetic gain and a threefold higher genetic gain for lean meat percentage. In all schemes scanning lead also to a higher profit because the higher retum of selection based on scanning exceeded the higher costs.

scholarly journals Selection responses for egg production of Fayoumi and Rhode Island Red breeds

2016 ◽  
Vol 19 (1-2) ◽  
pp. 66-73
Author(s):  
ME Haque ◽  
GK Deb ◽  
MN Hasan ◽  
MH Ali
Keyword(s):  
Rhode Island ◽  
Genetic Gain ◽  
Egg Production ◽  
Management Practices ◽  
Selection Responses ◽  
Lower Productivity ◽  
Significant Difference ◽  
F2 Generation ◽  
Foundation Stock ◽  
F1 Generation

This experiment estimated the selection responses for egg production of Fayoumi (Fay) and Rhode Island Red (RIR) breeds. A total of 3000; belonging Fay 2000 & RIR 1000 day old chicks were collected from Egypt and Bangladesh Livestock Research Institute (BLRI), Savar, Dhaka respectively, considered as foundation stock. The chicks were brooded for 5 weeks and reared up to 14 weeks of age providing standard feeding and management. After brooding, 640 Fay and 504 RIR pullets were reared in 40 and 36 individual pens respectively, considering as a family. Finally, 30 and 24 best families of Fay and RIR respectively were selected with 420 Fay and 288 RIR pullets at 15 weeks of age, on the basis of age at 1st egg lay, egg production and fertility. Salmonella and mycoplasma free eggs were collected on the basis of blood test (agglutinate test) from the selected families of both the breeds and hatched out for next generation. The experiment was continued up to 40 weeks of age for each generation. The study revealed that hen day egg production of Fay and RIR was higher in Foundation stock (64.39% in Fay and 68.54% in RIR) than that of F1 generation (58.6% in Fay and 46.8% in RIR) but no significant difference (P > 0.05) was observed for livability between Foundation stock and F1 generation. Reasons for lower productivity in F1 generation may be the poor management practices during growing period. In F2 generation, egg production was higher in both the breeds (64.09% in Fay and 62.05% in RIR) than in F1 generation. Egg production of RIR was not recorded for F3 generation, as their ability to adopt under farmers condition was very poor. However, in F3 generation, egg production of Fay was higher (65.82%) than in F2 generation. Genetic gain in Fay was 0.06%, 0.11% and 0.12% for F1, F2 and F3 generation, respectively. In case of RIR genetic gain was 0.07% in F1 and 0.18% in F2 generation. Due to selection slight genetic gain for egg production was obtained in Fay and RIR but further research with larger stock is needed for better understanding of selection responses of these breeds.Bangladesh J. of Livestock Res. 19(1-2): 66-73, Jan-Dec 2012

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