Abstract
BackgroundPreselection of candidates, hereafter referred to as preselection, is a common practice in breeding programs. Preselection can cause bias and accuracy loss in subsequent pedigree-based best linear unbiased prediction (PBLUP). However, the impact of preselection on subsequent single-step genomic BLUP (ssGBLUP) is not completely clear yet. Therefore, in this study, we investigated, across different heritabilities, the impact of intensity and type of preselection on subsequent ssGBLUP evaluation of preselected animals.MethodsWe simulated a nucleus of a breeding programme, in which a recent population of 15 generations was produced with PBLUP-based selection. In generation 15 of this recent population, the parents of the next generation were preselected using several preselection scenarios. These scenarios were combinations of three intensities of preselection (no, high or very high preselection) and three types of preselection (genomic, parental average or random), across three heritabilities (0.5, 0.3 or 0.1). Following each preselection scenario, a subsequent evaluation was performed using ssGBLUP by excluding all the information from the preculled animals, and these genetic evaluations were compared in terms of accuracy and bias for the preselected animals, and in terms of realized genetic gain.ResultsType of preselection affected selection accuracy at both preselection and subsequent evaluation stages. While preselection accuracy decreased, accuracy in the subsequent ssGBLUP evaluation increased, from genomic to parent average to random preselection scenarios. Bias was always negligible. Genetic gain decreased from genomic to parent average to random preselection scenarios. Genetic gain also decreased with increasing intensity of preselection, but only by a maximum of 0.1 additive genetic standard deviation from no to very high genomic preselection scenarios.ConclusionsUsing ssGBLUP in subsequent evaluations prevents preselection bias, irrespective of intensity and type of preselection, and heritability. With GPS, in addition to reducing the phenotyping effort considerably, the use of ssGBLUP in subsequent evaluations realizes only a slightly lower genetic gain than that realized without preselection. This is especially the case for traits that are expensive to measure (e.g. feed intake of individual broiler chickens), and traits for which phenotypes can only be measured at advanced stages of life (e.g. litter size in pigs).
Highlights
Preselection of candidates, hereafter referred to as preselection, is a common practice in breeding programs
Results of the genetic evaluations in which single-step genomic BLUP (ssGBLUP) was used in the subsequent evaluations are in Tables 3 and 4
true realised genetic gain (TRGG) and estimated realised genetic gain (ERGG) decreased, by 5.2 to 10.1% and 4.1 to 7.4%, respectively, from no preselection to very high genotypic preselection (GPS), depending on heritability (Table 3). These results show that, with ssGBLUP evaluations following GPS, it is possible to achieve a level of genetic gain that is similar to that achieved without preselection
Summary
Preselection of candidates, hereafter referred to as preselection, is a common practice in breeding programs. Preselection is a common practice in the nuclei of breeding programs, where only a few hundred to a few thousand replacement animals are Jibrila et al Genet Sel Evol (2020) 52:42 required per generation. For traits for which phenotypes can be measured only at advanced stages of life (e.g. litter size in pigs), preselection is used to reduce the cost of raising the animals until phenotyping. Preselection has mostly been based on correlated trait(s) that can be measured and cheaply early in life Preselection is often based on genomic estimated breeding values (GEBV) of young selection candidates, and in the literature this type of preselection is called genomic or genotypic preselection Preselection is often based on genomic estimated breeding values (GEBV) of young selection candidates, and in the literature this type of preselection is called genomic or genotypic preselection (GPS; e.g. [4, 5, 9])
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
