3,531 research outputs found
Selection index theory for populations under directional and stabilizing selection
Full text linkBACKGROUND: The purpose of a selection index is that its use to select animals for breeding maximizes the profit of a breed in future generations. The profit of a breed is in general a quantity that predicts the satisfaction of future owners with their breed, and the satisfaction of the consumers with the products that are produced by the breed. Many traits, such as conformation traits and product quality traits have intermediate optima. Traditional selection index theory applies only to directional selection and cannot achieve any further improvement once the trait means have reached their optima. A well-founded theory is needed that extends the established selection index theory to cover directional as well as stabilizing selection as limiting cases, and that can be applied to maximize the profit of a breed in both situations. RESULTS: The optimum selection index shifts the trait means towards the optima and, in the case of stabilizing selection, decreases the phenotypic variance, which causes the phenotypes to be closer to the optimum. The optimum index depends not only on the breeding values, but also on the squared breeding values, the allele contents of major quantitative trait loci (QTL), the QTL heterozygosities, the inbreeding coefficient of the animal, and the kinship of the animal with the population. CONCLUSION: The optimum selection index drives the alleles of major QTL to fixation when the trait mean approaches the optimum because decreasing the phenotypic variance shifts the trait values closer to the optimum, which increases the profit of the breed. The index weight on the kinship coefficient balances the increased genetic gain that can be achieved in future generations by outcrossing, and the increased genetic gain that can be achieved under stabilizing selection by reducing the phenotypic variance. In a model with dominance variance, it can also account for the effect of inbreeding depression. The combining ability between potential mating partners, which predicts the total merit of their offspring, could become an important parameter for mate allocation that could be used to further shift the phenotypes towards their optimum values. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12711-023-00776-4
Defining valid breeding goals for animal breeds
Full text linkAbstract Background The objective of any valid breeding program is to increase the suitability of a breed for its future purposes. The approach most often followed in animal breeding for optimizing breeding goals assumes that the sole desire of the owners is profit maximization. As this assumption is often violated, a generalized approach is needed that does not rely on this assumption. Results The generalized approach is based on the niche concept. The niche of a breed is a set of environments in which a small population of the breed would have a positive population growth rate. Its growth rate depends on demand from prospective consumers and supply from producers. The approach involves defining the niche that is envisaged for the breed and identifying the trait optima that maximize the breed’s adaptation to its envisaged niche within the set of permissible breeding goals. The set of permissible breeding goals is the set of all potential breeding goals that are compatible with animal welfare and could be reached within the planning horizon of the breeding program. In general, the breed’s adaptation depends on the satisfaction of the producers with the animals and on the satisfaction of the consumers with the products produced by the animals. When consumers buy live animals, then the breed needs to adapt to both the environments provided by the producers, and the environments provided by the consumers. The profit function is replaced by a more general adaptedness function that measures the breed’s adaptation to its envisaged niche. Conclusions The proposed approach coincides with the traditional approach if the producers have the sole desire to maximize their income, and if consumer preferences are well reflected by the product prices. If these assumptions are not met, then the traditional approach to breeding goal optimization is unlikely to result in a valid breeding goal. Using the example of companion breeds, this paper shows that the proposed approach has the potential to fill the gap
Happy Hour with Robin Sacks
No full textRobin Sacks is the author of Get Off My Bus!: How to Get Clarity, Get in the Driver\u27s Seat, and Get Moving in Your Life! Introduction by Kristen Kuhlman, LSW, LHNA, MBA/HCM DHA Candidate
Genomic dominance variance analysis of health and milk production traits in German Holstein cattle
No full textGenomic analyses commonly explore the additive genetic variance of traits. The non-additive variance, however, is usually small but often significant in dairy cattle. This study aimed at dissecting the genetic variance of eight health traits that recently entered the total merit index in Germany and the somatic cell score (SCS), as well as four milk production traits by analysing additive and dominance variance components. The heritabilities were low for all health traits (between 0.033 for mastitis and 0.099 for SCS), and moderate for the milk production traits (between 0.261 for milk energy yield and 0.351 for milk yield). For all traits, the contribution of dominance variance to the phenotypic variance was low, varying between 0.018 for ovarian cysts and 0.078 for milk yield. Inbreeding depression, inferred from the SNP-based observed homozygosity, was significant only for the milk production traits. The contribution of dominance variance to the genetic variance was larger for the health traits, ranging from 0.233 for ovarian cysts to 0.551 for mastitis, encouraging further studies that aim at discovering QTLs based on their additive and dominance effects.Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/50110000165
Genomewide Mapping of Selection Signatures and Genes for Extreme Feather Pecking in Two Divergently Selected Laying Hen Lines
No full textFeather pecking (FP) is a longstanding serious problem in commercial flocks of laying hens. It is a highly polygenic trait and the genetic background is still not completely understood. In order to find genomic regions influencing FP, selection signatures between laying hen lines divergently selected for high and low feather pecking were mapped using the intra-population iHS and the inter-population FST approach. In addition, the existence of an extreme subgroup of FP hens (EFP) across both selected lines has been demonstrated by fitting a mixture of negative binomial distributions to the data and calculating the posterior probability of belonging to the extreme subgroup (pEFP) for each hen. A genomewide association study (GWAS) was performed for the traits pEFP and FP delivered (FPD) with a subsequent post GWAS analysis. Mapping of selection signatures revealed no clear regions under selection. GWAS revealed a region on Chromosome 1, where the existence of a QTL influencing FP is likely. The candidate genes found in this region are a part of the GABAergic system, which has already been linked to FP in previous studies. Despite the polygenic nature of FP, selection on these candidate genes may reduce FP
Public management : Reinventing Government: a symposium. by Robin Butler
No full texttag=1 data=Public management : Reinventing Government: a symposium. by Robin Butler
tag=2 data=Butler, Robin
tag=3 data=Public Administration,
tag=4 data=72
tag=5 data=2
tag=6 data=Summer 1994
tag=7 data=263-270.
tag=8 data=MANAGEMENT%PUBLIC SERVICE
tag=10 data=The author indicates how the major themes of the book [Reinventing Government] can be seen to correspond with many of the recent management initiatives in UK government.
tag=11 data=1994/6/8
tag=12 data=94/0490
tag=13 data=CABThe author indicates how the major themes of the book [Reinventing Government] can be seen to correspond with many of the recent management initiatives in UK government
Robin Becker, 16th Annual ODU Literary Festival
No full textRobin Becker is the author of Giacometti’s Dog, published in 1990 by the University of Pittsburgh Press. Her previous books are Backtalk and Personal Effects, both published by Alice James Books She has received fellowships in poetry from the Massachusetts Artists Foundation and the National Endowment for the Arts. Her poems appear in many journals including Agni, The American Poetry Review, The Kenyon Review, and Ploughshares. She has published book reviews in Belles Lettres, The Boston Globe, The Boston Review, Prairie Schooner and The Women’s Review of Books She teaches in the Program in Writing and Humanistic Studies at Massachusetts Institute of Technology. This year she is Visiting Poet at Pennsylvania State University. Robin Becker serves as Poetry Editor for The Women’s Review of Books and as a member of the board of directors of Associated Writing Programs
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