Multistage Selection for Genetic Gain by Orthogonal Transformation

In order to evaluate genetic gain in populations under selection it is necessary to be able to partition the observed response into genetic and environmental components. This requires estimates of the appropriate genetic and environmental (co)variances unless appropriate genetic controls are available. Growth rate is an important component of the breeding objective for sheep breeds used as terminal sires and, whereas older estimates of the contribution of genetic variation to differences in preweaning growth indicated heritabilities of the order of 0.1, more recent studies have indicated considerably higher values. The present report concerns analyses of preweaning growth data on purebred Suffolk and Texel sheep to estimate genetic parameters for preweaning growth traits and genetic trend in growth rate from birth to weaning.

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Environmental and genetic variation for grain yield and barley malting quality attributes

Australian Journal of Agricultural Research ◽

10.1071/ar99042 ◽

1999 ◽

Vol 50 (8) ◽

pp. 1425 ◽

Cited By ~ 4

Author(s):

M. Q. Lu ◽

L. O'Brien ◽

I. M. Stuart

Keyword(s):

Grain Yield ◽

Protein Content ◽

Genetic Gain ◽

Quality Attributes ◽

Malting Quality ◽

Malt Extract ◽

Progeny Testing ◽

Environment Interaction ◽

Wide Range ◽

Selection For

Genotype, environment, and genotype × environment interaction effects for malting quality attributes and grain yield were investigated using breeding lines from the F2, F3, and F4 generations and the parental varieties of 4 barley crosses. There were significant differences between the parental varieties for all attributes studied. Both malting quality and grain yield exhibited a wide range among progenies in all generations. While performance of the parental varieties and progeny for malting quality and grain yield were greatly influenced by environment, performance in one environment was predictive of that in other environments. Only for grain protein content was there evidence of crossover G × E interaction. Heritability was generally higher for F3 to F4 than for F2 to F3 for all malting quality attributes. F3 on F2 regression per cent heritability estimates for protein content, potential malt extract and grain weight were all highly significant with values generally medium in magnitude. Genetic gain was obtained from selection in both the F2 and F3 generations. Heritability and genetic gain varied from cross to cross for diastatic power. Progress from selection for the other quality attributes attests to the potential value of NIT (near infrared transmittance) spectroscopy for predicting potential malting quality. Heritability for F2 to F3 for grain yield was not significant in any cross, indicating selection for yield on the basis of individual F2 plant yield was ineffective. Heritability for grain yield from F3 to F4 was highly significant and medium in magnitude for 3 of the 4 crosses. The results of this study indicate that good genetic gain could be expected from early generation selection for potential malting quality using NIT spectroscopy and for grain yield using F3 progeny testing.

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Genetic response to within-family selection using molecular markers in some radiata pine breeding schemes

Canadian Journal of Forest Research ◽

10.1139/x01-009 ◽

2001 ◽

Vol 31 (5) ◽

pp. 779-785 ◽

Cited By ~ 10

Author(s):

Satish Kumar ◽

D J Garrick

Keyword(s):

Genetic Gain ◽

Radiata Pine ◽

Forest Tree ◽

Clonal Forestry ◽

Genetic Response ◽

Forest Tree Breeding ◽

Forward Selection ◽

Family Selection ◽

Marker Haplotype ◽

Selection For

Marker-assisted selection (MAS) provides an opportunity to increase the efficiency of within-family selection in forest tree breeding. Within-family MAS involves selection decisions first made on conventional breeding values and quantitative trait loci (QTL) information used for within-family selection. In this study genetic response obtained by using MAS was compared with conventional methods for three options: "full-sib family forestry," "clonal forestry," and "forward selection for deployment." This comparison was undertaken using stochastic simulation for a locus that explained 10 or 20% of the genetic variance. In the full-sib family forestry scenario, markers were used to select genotypes (among juvenile individuals in a family) for vegetative propagation. Markers were used to preselect genotypes for clonal testing in clonal forestry option. In case of forward selection for deployment option, offspring that have favourable marker haplotype and a superior phenotype were selected from each family. The comparison between the MAS and the conventional strategy was evaluated in genetic terms based on comparison of the average genetic merit of the genotypes used for deployment in production plantations. The relative genetic gain (%) using MAS were found to be 48% and 23% higher compared with conventional strategy for full-sib family forestry and clonal forestry options, respectively. In case of forward selection for deployment option, MAS was generally found to be providing higher genetic gain only when the heritability is low.

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Expected efficiency of selection for growth in a French beef cattle breeding scheme II. Prediction of asymptotic genetic gain in a heterogeneous population

Genetics Selection Evolution ◽

10.1186/1297-9686-27-2-171 ◽

1995 ◽

Vol 27 (2) ◽

pp. 171 ◽

Cited By ~ 1

Author(s):

F Phocas ◽

JJ Colleau ◽

F Ménissier

Keyword(s):

Beef Cattle ◽

Genetic Gain ◽

Heterogeneous Population ◽

Breeding Scheme ◽

Cattle Breeding ◽

Selection For ◽

Efficiency Of Selection ◽

French Beef

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Inheritance of spiral grain in the juvenile core of Pinus radiata

Canadian Journal of Forest Research ◽

10.1139/x06-202 ◽

2007 ◽

Vol 37 (1) ◽

pp. 116-127 ◽

Cited By ~ 12

Author(s):

Washington Gapare ◽

Adrian Hathorn ◽

Dominic Kain ◽

Colin Matheson ◽

Harry Wu

Keyword(s):

Pinus Radiata ◽

Genetic Gain ◽

Radiata Pine ◽

Correlated Response ◽

Lower Grade ◽

Tangential Plane ◽

Individual Tree ◽

Spiral Grain ◽

Grain Angle ◽

Selection For

Spiral grain is the angular arrangement of fibres in a tangential plane with reference to the pith or vertical tree axis. Spiral grain angles exceeding 5° can cause wood to twist, which may result in a considerable amount of waste and degrade. We assessed spiral grain at breast height in two related progeny tests of radiata pine (Pinus radiata D. Don) aged 8 and 9 years established at two different sites in Australia. Radial trends for grain angle at the two sites were similar. Mean spiral grain (MSG) across the two trials was 4.3° with a standard deviation of 1.5° and a range of 0.8–10°. Estimates of individual tree heritabilities on a single-site basis for individual rings and MSG suggested that spiral grain is lowly to highly inherited (h2 = 0.11 ± 0.08 to 0.66 ± 0.21 for individual rings and 0.44 ± 0.12 for MSG). Additive genotypic correlations between individual rings grain angle and MSG were generally high, above 0.71, suggesting a favourable expected correlated response of mean grain angle in the juvenile wood to selection for grain angle of individual rings. Selection to reduce spiral grain on any of rings 2–4 (at a selection intensity of 1.755, i.e., selecting the best 10% of trees) would result in a predicted correlated genetic gain in MSG of 1.0°. Our results suggest that selection could be performed in any of the individual rings 2, 3, or 4 (equivalent to ages 4–6) and still achieve at least 75% of the genetic gain possible from selection on the mean of all rings 1–5 (MSG). This suggests that there is an optimum stage (rings 2–4) in which selection for this trait should take place. Our results suggest that a reduction in spiral grain angle in the juvenile core is one strategy to reduce the amount of lower grade timber owing to twist.

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Genetic gain from selection for rooting ability and early growth in vegetatively propagated clones of loblolly pine

Tree Genetics & Genomes ◽

10.1007/s11295-006-0058-9 ◽

2006 ◽

Vol 3 (3) ◽

pp. 227-238 ◽

Cited By ~ 26

Author(s):

Brian S. Baltunis ◽

Dudley A. Huber ◽

Timothy L. White ◽

Barry Goldfarb ◽

Henry E. Stelzer

Keyword(s):

Loblolly Pine ◽

Genetic Gain ◽

Early Growth ◽

Rooting Ability ◽

Selection For

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The effectiveness of genomic selection for milk production traits of Holstein dairy cattle

Asian-Australasian Journal of Animal Sciences ◽

10.5713/ajas.19.0546 ◽

2020 ◽

Vol 33 (3) ◽

pp. 382-389 ◽

Cited By ~ 1

Author(s):

Yun-Mi Lee ◽

Chang-Gwon Dang ◽

Mohammad Z. Alam ◽

You-Sam Kim ◽

Kwang-Hyeon Cho ◽

...

Keyword(s):

Genomic Selection ◽

Milk Production ◽

Genetic Gain ◽

Milk Fat ◽

Breeding Value ◽

Production Traits ◽

Milk Production Traits ◽

Data Set ◽

Selection For ◽

Estimated Breeding Value

Objective: This study was conducted to test the efficiency of genomic selection for milk production traits in a Korean Holstein cattle population.Methods: A total of 506,481 milk production records from 293,855 animals (2,090 heads with single nucleotide polymorphism information) were used to estimate breeding value by single step best linear unbiased prediction.Results: The heritability estimates for milk, fat, and protein yields in the first parity were 0.28, 0.26, and 0.23, respectively. As the parity increased, the heritability decreased for all milk production traits. The estimated generation intervals of sire for the production of bulls (LSB) and that for the production of cows (LSC) were 7.9 and 8.1 years, respectively, and the estimated generation intervals of dams for the production of bulls (LDB) and cows (LDC) were 4.9 and 4.2 years, respectively. In the overall data set, the reliability of genomic estimated breeding value (GEBV) increased by 9% on average over that of estimated breeding value (EBV), and increased by 7% in cows with test records, about 4% in bulls with progeny records, and 13% in heifers without test records. The difference in the reliability between GEBV and EBV was especially significant for the data from young bulls, i.e. 17% on average for milk (39% vs 22%), fat (39% vs 22%), and protein (37% vs 22%) yields, respectively. When selected for the milk yield using GEBV, the genetic gain increased about 7.1% over the gain with the EBV in the cows with test records, and by 2.9% in bulls with progeny records, while the genetic gain increased by about 24.2% in heifers without test records and by 35% in young bulls without progeny records.Conclusion: More genetic gains can be expected through the use of GEBV than EBV, and genomic selection was more effective in the selection of young bulls and heifers without test records.

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