Mean Heritability Research Articles

Inbreeding Depression and Purging in Fertility and Longevity Traits in Sheep Breeds from Germany

In the present study, we analysed fertility and longevity traits of 22 sheep breeds from Germany with a suitable quantity of data in the national database OviCap. The data comprised merino, meat, country and milk sheep breeds with 62,198 ewes and about 173,000 lambing records, until the fifth lambing. Across-breed means of heritabilities reached estimates of 0.13, 0.17 and 0.18 for number of lambings, average number of lambs born per lambing and number of lambs per lifetime, respectively. For age at first lambing, length of lifetime and productive life, mean heritabilities over breeds were 0.34, 0.17 and 0.32, respectively. The across-breed means of the individual rate of inbreeding were significantly negative for the average number of lambs born per lambing and number of lambs born per lifetime, and for number of lambings it was close to the significance threshold. We found declining slopes for inbreeding depression for the average number of lambs born per lambing and number of lambs born per lifetime in 16 breeds, and significantly negative slopes in five and seven breeds. For lifetime and productive life, 9/22 and 8/22 breeds showed significant inbreeding depression, while for age at first lambing, only 1/22 breeds showed significant inbreeding depression. A significant reduction in inbreeding depression due to purging effects was found for eight breeds. Fitness traits may be subject to forced directional selection. Therefore, sheep breeding programmes should give special consideration to fertility and longevity traits. Fitness related traits seem to be essential in conservation of genetic diversity within sheep breeds.

Genome wide association studies on three-dimensional aortic geometric indices measured with magnetic resonance imaging

Abstract Introduction To date, three-dimensional properties of the aorta have not been comprehensively quantified in a population level dataset, nor has there been a genome-wide association study (GWAS) to identify significant single nucleotide polymorphisms (SNPs) associated with geometric properties of the aorta. Methods We segmented the thoracic aorta of 48,045 subjects in the UK Biobank using a U-Net convolutional neural network. We then computed geometric measurements (centerline length, arch height, arch width, arch height-width ratio, curvature, and mean, minimum and maximum diameter) across six subsegments of the aorta. Centerline length was allometrically indexed to body height. Using generalized linear models, we performed GWAS on each geometric phenotype adjusted for the following covariates: (1) age, (2) sex, and (3) ten genetic principal components. SNPs with a minor allele frequency < 0.05 were excluded. We performed LD-based clumping with an r2 threshold of 0.001 to identify significant loci and used LDSC to compute the genetic heritability of each geometric phenotype. Results After performing LD clumping, we identified 457 significant(P<5e-8) SNPs across 36 aortic geometric parameters. GWAS-based heritability analyses showed a mean heritability of 13.8 (9.9) % across all aortic geometric parameters, with all intercepts being close to 1, suggesting minimal genomic inflation. Maximum aorta diameter exhibited the highest observed heritability of 34.5 (3.0) %. Allometric centerline length showed a heritability of 13.6 (1.5) %. Similarly, arch height and width showed heritability of 14.6 (1.5) %, and 13.64 (1.5) % respectively. Aortic curvature showed limited heritability at 8.54 (1.2) %, with arch curvature being further reduced to 7.6 (1.20) %. Conclusion To our knowledge, this was the first study that investigated the genetic architecture of aortic centerline length, aortic curvature, and aortic tortuosity. These results suggest that aortic remodeling associated with aging and pathological conditions has important genetic contributions. SNPs associated with aortic geometry may identify therapeutic targets to prevent aortic remodeling, which should be the focus of future work.significant_snpsheritability

A sex-stratified analysis of the genetic architecture of human brain anatomy

Large biobanks have dramatically advanced our understanding of genetic influences on human brain anatomy. However, most studies have combined rather than compared male and female participants. Here we screen for sex differences in the common genetic architecture of over 1000 neuroanatomical phenotypes in the UK Biobank and establish a general concordance between male and female participants in heritability estimates, genetic correlations, and variant-level effects. Notable exceptions include higher mean heritability in the female group for regional volume and surface area phenotypes; between-sex genetic correlations that are significantly below 1 in the insula and parietal cortex; and a common variant with stronger effect in male participants mapping to RBFOX1 - a gene linked to multiple neuropsychiatric disorders more common in men. This work suggests that common variant influences on human brain anatomy are largely consistent between males and females, with a few exceptions that will guide future research in growing datasets.

Genetic effects on the skin methylome in healthy older twins

Whole-skin DNA methylation variation has been implicated in several diseases, including melanoma, but its genetic basis has not yet been fully characterized. Using bulk skin tissue samples from 414 healthy female UK twins, we performed twin-based heritability and methylation quantitative trait loci (meQTL) analyses for >400,000 DNA methylation sites. We find that the human skin DNA methylome is on average less heritable than previously estimated in blood and other tissues (mean heritability: 10.02%). meQTL analysis identified local genetic effects influencing DNA methylation at 18.8% (76,442) of tested CpG sites, as well as 1,775 CpG sites associated with at least one distal genetic variant. As a functional follow-up, we performed skin expression QTL (eQTL) analyses in a partially overlapping sample of 604 female twins. Colocalization analysis identified over 3,500 shared genetic effects affecting thousands of CpG sites (10,067) and genes (4,475). Mediation analysis of putative colocalized gene-CpG pairs identified 114 genes with evidence for eQTL effects being mediated by DNA methylation in skin, including in genes implicating skin disease such as ALOX12 and CSPG4. We further explored the relevance of skin meQTLs to skin disease and found that skin meQTLs and CpGs under genetic influence were enriched for multiple skin-related genome-wide and epigenome-wide association signals, including for melanoma and psoriasis. Our findings give insights into the regulatory landscape of epigenomic variation in skin.

Growth of Clones of Eucalyptus urophylla in Two Contrasting Soil Conditions in Plantations of Southeastern Mexico

Eucalyptus urophylla is important for the establishment of commercial forest plantations in Mexico. Genetic improvement programs are currently being implemented to increase timber productivity. The objectives of this study were to evaluate the adaptability and growth stability of 26 clonal lines of E. urophylla in Acrisol and Fluvisol soils and to identify the most suitable genotypes for each soil type. Tree survival, diameter at breast height, and total height were measured annually for six years. These variables were used to estimate individual volume, volume per hectare, and mean annual (MAIv) and current annual (CAIv) volume increment. Survival ranged from 14 to 100% in the Acrisol soil and from 0 to 89% in the Fluvisol soil. Volume per hectare ranged from 65.3 to 488.7 m3, MAIv from 11.1 to 83.1 m3 ha−1 year−1, and CAIv from 2.4 to 134.7 m3 ha−1 year−1. Individual heritability (Hi2) was moderate (0.29–0.49) while the mean heritability of the cloned lines was high (0.73–0.90), indicating that growth is subject to high genetic control. Diameter, height, and volume presented no genotype × environment interaction effects, demonstrating stability in the growth of the clonal lines in both soil types.

Evaluation and selection of cassava clones and exploitation of genetic covariance across multiple environments

AbstractClonal evaluation trials of cassava (Manihot esculenta Crantz), where the main selection of this crop takes place, are usually carried out in multiple environments. This study investigated the influence of genotype–environment (GE) interaction on selection and how to explore genetic information across environments in a mixed model approach by modeling different genetic covariance structures. Approximately 240 cassava clones were assessed in an augmented block design during the 2020/2021 growing season in Brazil. The unstructured model was the best suited and used to investigate several strategies of selection. The predicted genetic gains based on individual analyses varied greatly among environments (5.52%–12.62% for root yield; 1.00%–6.09% for dry matter content; and 4.01%–9.42% for dry matter yield), although the clones mean was similar. Moreover, most of the selected clones in each environment outperformed the best check (>80%), except for root yield and dry matter yield in one environment. By multi‐environment analysis, greater local gains were detected in each environment (means of 16.87% for root yield, 5.56% for dry matter content, and 17.27% for dry matter yield) and for mean heritability (0.52 for root yield, 0.76 for dry matter content, and 0.55 for dry matter yield). The coincidence of clones selected by individual and multi‐environment analyses was 64% for root yield, 73% for dry matter content, and 66% for dry matter yield. The best scenario for selection is when all environments are considered simultaneously, for which regional genetic gains of 16.71% were predicted for root yield, 5.40% for dry matter content, and 17.06% for dry matter yield.

Genetic Variation in Provenance-Progeny Trials of Cupre-ssus sempervirens in Türkiye

In this study, the genetic and phenotypic relations among tree height, diameter at breast height and survival at 18 years of age were investigated in Mediterranean cypress (Cupressus sempervirens L. var. horizontalis (Mill.) Gordon) provenance-progeny trials established in two locations in southern Türkiye. It was found that the variation among families within one provenance was higher than among different provenances. At the joint analysis, the narrow-sense heritability (hi2) was 0.36 for height, and 0.24 for diameter. Family mean heritability (hf2) was 0.78 for height, while it was 0.53 for diameter. Diameter showed higher (13.98%) genetic diversity than height (12.71%). Genetic correlation between traits was high (0.84). According to the breeding values of the families estimated by the BLUP method, when the best 50 families by two traits are selected separately, 12.5% genetic gain in terms of height and 13.2% in terms of diameter can be achieved. In the selection of the best 30 families, the estimated genetic gain calculated was 15.2% for height and 16.3% for diameter.

Assessment of the salt tolerance of diverse bread wheat (Triticum aestivum L.) genotypes during the early growth stage under hydroponic culture conditions

ObjectivesSoil salinity affects the growth of crop plants, leading to reduced productivity, and is a major challenge for wheat production worldwide. Various adaptations and mitigation approaches in combination with tolerant wheat genotypes can be useful for the sustainability of crop production in saline environments. However, the development of salt-tolerant wheat genotypes is one of the best and most efficient solutions for obtaining desirable yields. Considering these issues, an investigation was carried out under hydroponic nutrient culture conditions to assess the genetic variability and selection of salt-tolerant wheat genotypes by categorizing inequitable morphophysiological and genetic variability as well as multivariate analysis. MethodsTo meet the objectives of this study, 100 wheat genotypes were tested hydroponically in 0 (control) and 15 dS m−1 salt solutions. ConclusionFor all the wheat genotypes grown under saline conditions, the shoot length (SL), root length (RL), shoot fresh weight (SFW), root fresh weight (RFW), total fresh weight (TFW), shoot dry weight (SDW), root dry weight (RDW), and total dry weight (TDW) decreased significantly. Furthermore, significant variation was observed among the genotypes in terms of their characteristics only under saline conditions. In the case of genetic diversity analysis, a high genotypic coefficient of variation (GCV), phenotypic coefficient of variation (PCV), genetic advance in the percentage of the mean (GAM) and high heritability (h2b) were recorded for all tested wheat genotypes based on the SDW, RDW and TDW. Correlation analysis for both genotypic and phenotypic relationships revealed strong positive correlations for TDW, SDW, TFW and SFW. Principal component analysis (PCA) revealed that TDW, TFW, SDW, and SFW were the most discriminative variables for the wheat genotypes, which was confirmed by discriminant function analysis (DFA). PCA-biplot analysis also revealed significant positive correlations between SDW and SFW and between TDW and TFW. Hierarchical cluster analysis was performed for ten clusters based on the relative performance of the genotypes, where the genotypes were characterized into salt-tolerant, medium-salt-tolerant, medium-salt-susceptible and salt-susceptible groups. Among the genotypes, G11, G25 and G29 under cluster VII were categorized as salt tolerant based on their outstanding performance in terms of characteristics only under saline conditions. D2 analysis proved that the wheat genotypes of this cluster were highly divergent from the other cluster genotypes; as a result, these genotypes might be utilized as parents in the development of salt-tolerant wheat genotypes. The current study concluded that SDW and TDW could be employed as criteria for selecting and defining salt-tolerant genotypes during the early growth stage of wheat.

Bridging temperament and the Big Five in children: A genetically informative study.

Early temperament precedes children's emerging Big Five personality, but shared models of temperament and personality are scarce. We wanted to estimate the genetic factor structure underlying both temperament and the Big Five in children, employing a genetically informed study. Within the Norwegian Mother and Child Cohort Study, we selected 26,354 twins, siblings, and cousins. Mothers rated their children's temperament three times between the ages of 1.5 and 5 years, and the children's Big Five personality at the age of 8. We analyzed the data using biometric modeling. The mean heritability of single-time temperamental traits and Big Five personality traits was .48 and .45, respectively. The mean genetic correlations of temperament across time were .80. The genetic correlations of temperament at 5 years and the Big Five at 8 years revealed two factors, the first comprising reversed Big Five Neuroticism, Agreeableness, Conscientiousness, and reversed EAS Emotionality, the second comprising Big Five Extraversion, Openness to Experience, EAS Activity, Sociability, and reversed Shyness. A confirmatory factor analysis estimated the two factors showing heritabilities of .96 and .72, respectively. The two factors mirrored the metatraits Stability and Plasticity by John M. Digman. Temperament and personality in childhood can be meaningfully bridged using just two metafactors. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Genetic parameter estimates for methane emission from breath during lactation and potential inaccuracies in reliabilities assuming a repeatability versus random regression model

Methane emissions will be added to many national ruminant breeding programs in the coming years. Little is known about the covariance structure of CH4 traits over a lactation, which is important for optimizing recording strategies and establishing optimal genetic evaluation models. Our aim was to study CH4 over a lactation using random regression (RR) models, and to compare the accuracy to a fixed regression repeatability model under different phenotyping strategies. Data were available from repeated measurements of CH4 concentrations (ppm) recorded in the feed bins of milking robots on 52 commercial dairy farms in the Netherlands. In total, 36,370 averaged weekly records were available from 4,664 cows. Genetic parameters were estimated using a fixed regression model, and a RR model with first- to fifth-order Legendre polynomials for the additive genetic and within-lactation permanent environmental effect. The mean heritability (± SE) was 0.17 ± 0.04, and the mean within-lactation repeatability was 0.56 ± 0.03. The genetic correlations between DIM were high and ranged from 0.34 ± 0.36 to 1.00 ± <0.01. Permanent environmental correlations showed large deviations and ranged from -0.73 ± 0.08 to 1.00 ± <0.01. With a large number of full lactation daughter CH4 records per bull, the reliability was not sensitive to using the fixed versus the RR model. However, when shorter periods were recorded at the start and end of the lactation, the fixed regression model resulted in a loss of reliability up to 28% for bulls. Assuming the fixed model when the true (co)variance structure is reflected by the RR model, more than twice as long of a recording from the start of lactation was required to achieve maximum reliability for a bull. Thus, a too simplistic model could result in implementing too little recording, and in lower genetic gains than predicted from the reliability.

The genetic basis of dispersal in a vertebrate metapopulation.

Dispersal affects evolutionary processes by changing population size and genetic composition, influencing the viability and persistence of populations. Investigating which mechanisms underlie variation in dispersal phenotypes and whether populations harbour adaptive potential for dispersal is crucial to understanding the eco-evolutionary dynamics of this important trait. Here, we investigate the genetic architecture of dispersal among successfully recruited individuals in an insular metapopulation of house sparrows. We use an extensive long-term individual-based ecological data set and high-density single-nucleotide polymorphism (SNP) genotypes for over 2500 individuals. We conducted a genome-wide association study (GWAS), and found a relationship between dispersal probability and a SNP located near genes known to regulate circadian rhythm, glycogenesis and exercise performance, among other functions. However, this SNP only explained 3.8% of variance, suggesting that dispersal is a polygenic trait. We then used an animal model to estimate heritable genetic variation (σA 2 ), which composes 10% of the total variation in dispersal probability. Finally, we investigated differences in σA 2 across populations occupying ecologically relevant habitat types (farm vs. non-farm) using a genetic groups animal model. We found different adaptive potentials across habitats, with higher mean breeding value, σA 2 , and heritability for the habitat presenting lower dispersal rates, suggesting also different roles of environmental variation. Our results suggest a complex genetic architecture of dispersal and demonstrate that adaptive potential may be environment dependent in key eco-evolutionary traits. The eco-evolutionary implications of such environment dependence and consequent spatial variation are likely to become ever more important with the increased fragmentation and loss of suitable habitats for many natural populations.

Unclenching the potentials of global core germplasm for root nodulation traits for increased biological nitrogen fixation and productivity in chickpea (Cicer arietinum L.)

Chickpea being an important food legume crop is able to fix the atmospheric nitrogen and form root nodules that support biologicalnitrogen fixation- a sustainable alternative for nitrogen supply to agriculture worldwide. In order to support findings on nodule formation in chickpeas, a diverse core set of 300 chickpea genotypes, including four checks, was evaluated for morphological and nodulation traits in four different environments. The maximum genotypic and phenotypic coefficient of variation was observed for a number of nodules, nodule fresh weight, shoot fresh weight, and number of seeds per plant. The heritability for most of the characters ranged from 26.56 for days to 50% flowering to 99.61 for a number of pods per plant. The genotypic and phenotypic correlation coefficient analysis revealed that the number of nodules was positively correlated with seed yield. Further, seed yield was partitioned into direct and indirect effects at genotypic and phenotypic levels through path coefficient analysis. Significant genotypic correlations and direct positive effects were exhibited by a number of nodules and number of pods per plant on grain yield. Based on the D2 statistics, the number of seeds per plant, number of pods per plant, shoot fresh weight and number of nodules have been identified as top-ranking yield contributing traits. The genotypes ICC1013 and ICC16569 for a number of nodules and ICC1049 for the trait number of seeds per plant were identified as potential stable donors for the respective traits with high mean yield, heritability and genetic advance across the locations and can be used as donors in the chickpea breeding programs for increasing biological nitrogen fixation and enhancement of the crop productivity.

Molecular and Morphological Characterization of Wheat Genotypes under Drought Condition in Nigerian Sudan Savannah

Drought stress is one of the most important abiotic constrains affecting cereal crop in the world that causes serious yield loses and threat to sustainability and food security especially in wheat thereby causing the insufficient supply of food. Therefore, understanding the genetic characterization of drought stress response is very important. This study was designed to reveal the morphological and molecular characterization of wheat genotypes using simple sequence repeat (SSR) markers and to estimate the genetic diversity and relationships among the cultivars subjected to drought conditions. A total of 15 wheat genotypes were evaluated for quantitative morphological traits such as plant height, number of seeds per spike, 1000 seed weight, spike length, flag leaf length, grain weight and proline content. Molecular characterization was done using a set of simple sequence repeat (SSR) markers. A total of 12 SSR markers were used to analyze the varieties and the genetic diversity and relationship among them. The results showed that, the drought-stressed plants had lower plant height, number of seeds per spike, 1000 seed weight, spike length, flag leaf length and grain weight than the non-stressed plants, while proline content was found to be higher in stressed plants than the non-stressed. Molecular analyses indicated significant variation among the genotypes with the mean PIC value of 0.64, mean heritability ratio of 0.67 and mean allele number of 8.9. This study also indicates the significance of SSRs as a useful tool in marker-assisted breeding about drought tolerance and for developing strategies for improving drought tolerance in cereals.

Estimation of genetic parameters and single-step genome-wide association studies for eating time and rumination time in Holstein dairy cows

The aims of this study were to estimate genetic parameters and to identify genomic regions associated with eating time (ET) and rumination time (RUT) in Holstein dairy cows. Genetic correlations among ET, RUT, and milk yield traits were also estimated. The data were collected from 2019 to 2022 in 6 dairy herds located in the Walloon Region of Belgium. The dataset consisted of daily ET and RUT records on 284 Holstein cows, from which 41 cows had records only for the first parity (P1), 101 cows had records from both the first and second parities, and 142 cows had records only for the second parity (P2). The number of daily ET and RUT records in the P1 and P2 cows were 18,569 (on 142 cows) and 34,464 (on 243 cows), respectively. Data on 28,994 SNPs located on 29 Bos taurus autosomes (BTA) of 747 animals (435 males) were used. Random regression test-day models were used to estimate genetic parameters through the Bayesian Gibbs sampling method. The SNP solutions were estimated using a single-step genomic best linear unbiased prediction approach. The proportion of genetic variance explained by each 20-SNP sliding window (with an average size of 1.52 Mb) was calculated, and regions accounting for at least 1.0% of the total additive genetic variance were used to search for candidate genes. Mean (standard deviation; SD) averaged daily ET and RUT were 327.0 (85.66) and 559.4 (77.69) min/d for cows in P1 and 316.0 (82.24) and 574.2 (75.42) min/d for cows in P2, respectively. Mean (standard deviation; SD) heritability estimates for daily ET and RUT were 0.42 (0.09) and 0.45 (0.06) for cows in P1 and 0.45 (0.04) and 0.43 (0.02) for cows in P2, respectively. Mean (SD) daily genetic correlations between daily ET and RUT were 0.27 (0.07) for P1 and 0.34 (0.08) for P2. Genome-wide association analyses identified 6 genomic regions distributed over 5 chromosomes (BTA1, BTA4, BTA11, 2 regions of BTA14, and BTA17) associated with ET or RUT. The findings of this study increase our preliminary understanding of the genetic background of feeding behavior in dairy cows; however, larger datasets are needed to determine whether ET and RUT might have the potential to be used in selection programs.

Single-step genome-wide association analyses for milk urea concentration in Walloon Holstein cows

The aims of this study were to conduct a single-step genome-wide association to identify genomic regions associated with milk urea (MU) and to estimate genetic correlations between MU and milk yield (MY), milk composition (calcium content [CC], fat percentage [FP], protein percentage [PP], and casein percentage [CNP]), and cheese-making properties (CMP; coagulation time [CT], curd firmness after 30 min from rennet addition [a30], and titratable acidity [TA]). The used data have been collected from 2015 to 2020 on 78,073 first-parity (485,218 test-day records) and 48,766 second-parity (284,942 test-day records) Holstein cows distributed in 671 herds in the Walloon Region of Belgium. Data of 565,533 SNP located on 29 BTA of 6,617 animals (1,712 males) were used. Random regression test-day models were used to estimate genetic parameters through the Bayesian Gibbs sampling method. The SNP solutions were estimated using a single-step genomic BLUP approach. The proportion of the total additive genetic variance explained by windows of 50 consecutive SNPs (with an average size of ∼216 kb) was calculated, and the top-3 genomic regions explaining the largest rate of the genetic variance were considered promising regions and used to identify potential candidate genes. Mean (SD) MU was 25.38 (8.02) mg/dL and 25.03 (8.06) mg/dL in the first and second lactation, respectively. Mean heritability estimates for daily MU were 0.21 and 0.23 for the first and second lactation, respectively. The genetic correlations estimated between MU and MY, milk composition, and CMP were quite low (ranged from -0.10 [CC] to 0.10 [TA] and -0.05 [CT] to 0.13 [TA] for the first and second lactations, respectively). The top-3 regions associated with MU were located from 80.61 to 80.74 Mb on BTA6, 103.26 to 103.41 Mb on BTA11, and 1.59 to 2.15 Mb on BTA14. Genes including KCNT1, MROH1, SHARPIN, TSSK5, CPSF1, HSF1, TONSL, DGAT1, SCX, and MAF1 were identified as positional candidate genes for MU. The findings of this study can be used for a better understanding of the genomic architecture underlying MU in Holstein cattle.

Brain imaging endophenotypes by unsupervised deep learning

AbstractBackgroundUnderstanding the genetic architecture of brain structure and Alzheimer’s disease is challenging, partly due to difficulties in designing robust, non‐biased descriptors of the brain.MethodWe present approaches to derive robust brain imaging phenotypes using unsupervised deep representation learning. Training a 3‐D convolutional autoencoder model with reconstruction loss, we derived a vector representation (termed endophenotype) that captures rich morphological information of the brain. Further, we developed a perturbation‐based decoder interpretation approach that can highlight brain regions that are most relevant to individual endophenotypes.ResultUsing UK Biobank data, we trained the model using over 6,000 UK Biobank (UKBB) participants’ T1 or T2‐FLAIR (T2) brain MRIs. The model is used to derive 128 endophenotypes. The endophenotypes have a mean heritability of 0.3 and the GWAS of which have identified 43 independent loci in the held‐out UKBiobank dataset (discovery n = 22,962/replication n = 12,848), among which 13 loci have not been previously reported by the UK Biobank Big40 study.ConclusionUsing UK Biobank data, we show that, compared to traditional brain image‐derived phenotypes (IDPs), our endophenotypes are more heritable and have higher power for genetic discovery.

Balancing wood production and water use efficiency in the selection of open-pollinated families of Gmelina arborea

Global climate crisis and severe water scarcity worldwide demand alternative genotypes that allow an adequate balance between production and water use while ensuring benefits for foresters. The genetic improvement of water use efficiency (WUE) in forest plantations could reduce water use without compromising yield. Above-ground biomass (AGB), saw-wood volume up to small-end diameter of 15 cm (V15), wood density (WD) and intrinsic WUE (WUEi) from wood carbon isotopic discrimination was evaluated in forty open-pollinated families of G. arborea grown in a tropical dry forest known as a water-limited environment, to select superior genotypes considering a balance in wood production and water use. Heritability of open-pollinated family means were moderate with values of h2f = 0.554 for AGB, h2f = 0.541 for V15, h2f = 0.608 for WD and h2f = 0.495 for WUEi. Significant genetic correlations between both WD and WUEi and production traits (p < 0.05) and a nonsignificant genetic correlation between WD and WUEi were found. Although production traits and WUEi showed moderate narrow-sense and family means heritabilities, considerable responses to selection of up to 13.7% in AGB, 15.5% in V15, 2.5% in WD and 3.0% in WUEi could be achieved from intensive selection of superior families. Our results showed that it may be possible balancing wood production and WUE by selecting open-pollinated families of G. arborea with higher V15 and WUEi. The deployment of these superior families can be used as a forest management strategy to adapt the species to future drought scenarios associated with global climate change.

Estimated genetic parameters for mature cow live weights during lactation in a multi-breed dairy cattle population

ABSTRACT Live weight (LWT) is an important trait for dairy production systems as it influences both maintenance feed requirements and beef revenue from culled cows and from offspring surplus to replacements. The breeding goal for the New Zealand dairy industry includes LWT. This study estimated genetic parameters for LWT during lactation from some animals in the New Zealand multi-breed dairy cattle population. A total of 31,922 LWT records from 11,222 lactating dairy cattle born from 1988 to 2015 were used for the analysis. Estimation of (co)variance components used Gibbs sampling from pedigree-based models. The posterior mean heritability estimates using scale weights were consistently high across six lactations and ranged from 0.57 to 0.64. There were high genetic correlations between the scale weights measured during different lactations (>0.95). We further estimated the posterior mean heritability for subjective liveweight scores recorded from first lactation using trained inspectors and the estimate was 0.36, lower than those heritability estimates from scaled weight. Further, the genetic correlations between subjective liveweight score and scale weights at various lactations ranged from 0.91-0.92. It is recommended that only scale weights be used for national genetic evaluation.

Genetic and phenotypic parameters for sexual precocity and parasite resistance traits in Nellore cattle.

Indicator traits of sexual precocity are widely used as selection criteria for the genetic improvement of beef cattle; however, the impact of selection for these traits on resistance to endoparasites and ectoparasites is unknown. Therefore, this study aimed to estimate the genetic and phenotypic parameters for indicator traits of sexual precocity and parasite resistance in Nellore cattle. The sexual precocity traits evaluated were probability of first calving (PFC) and scrotal circumference at 12 and 18months of age (SC12 and SC18). The resistance-related traits included tick (TC), gastrointestinal nematode egg (NEC), and Eimeria spp. oocyst (EOC) counts. (Co)variance components were estimated by Bayesian inference using multitrait animal models. The mean heritabilities for PFC, SC12, SC18, TC, NEC, and EOC were 0.23, 0.38, 0.42, 0.14, 0.16, and 0.06, respectively, and suggest that selection will change the mean values of these traits over time. The genetic and phenotypic correlations for most pairs formed by a precocity and a resistance trait were not different from zero, suggesting that selection for sexual precocity traits will not result in changes in resistance traits. Thus, selection for indicator traits of sexual precocity does not elicit unfavorable correlated responses in resistance to endoparasites and ectoparasites, and joint selection aimed at improving these traits can be performed using multitrait selection methods, when necessary.

Cinco ciclos de seleção recorrente intrapopulacional em progênies de meioirmãos de milho fresco

ABSTRACT Fresh corn is a highly appreciated vegetable in Brazil; this crop has high added value and profitability when compared to dry corn. Despite the consumer market demand for quality, cultivars are not launched every crop season and there is a small number of cultivars available to growers. This denotes a need for breeding programs focused on generating information and genotypes that can occupy this market niche. The objective of this work was to evaluate the progress of five cycles of intrapopulation recurrent selection in half-sib progenies of fresh corn, in the southwest region of Goiás. A randomized block experimental design was used, with evaluation of 64 progenies of corn half-sib progenies and selection intensity of 30% per cycle, with three replications, in the 2011-2012, 2013-2014, 2015-2016, 2017-2018, and 2020-2021 summer crop seasons. The half-sib progenies of fresh corn exhibited genetic variability through intrapopulation recurrent selection in the different selection cycles, which is still promising for further selections after five cycles, with evaluation of 64 progenies per cycle. The base population from crossings between hybrids for tropical and temperate climates showed to be promising for increasing the genetic base of fresh corn populations, with satisfactory gains over the five cycles, presenting mean heritability between the cycles of approximately 78.9% for relative chlorophyll index, 62.2% for plant height, 75.1% for ear insertion height, 70% for ear diameter, 56.6% for ear length, 71.4% for unhusked ear yield, and 71% for marketable ear yield.