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PubMed1998

Biological principles of heredity of and resistance to disease.

Understanding the biological principles of disease heredity and resistance to disease is a prerequisite for the incorporation of these factors into multi-trait breeding programmes. Mutations represent an evolutionary aspect of disease. The author reviews patterns of Mendelian inheritance and possible causes of non-Mendelian inheritance, such as multifactorial inheritance, expansion of trinucleotide repeats, mitochondiral inheritance and genomic imprinting, in relation to diseases of domestic animals. Host-pathogen interactions underlie genetic variability in resistance to disease. Infectious pathogens endowed with a high potential for evolutionary change use this potential to evade various host defence mechanisms. This interaction may have a competitive or co-evolutionary character. The host immune system copes with the variability of pathogens by using the potential of genetic diversity of lymphocytes in immunoglobulin, T-cell receptor and major histocompatibility complex genes. Possible mechanisms for maintenance of this diversity are discussed in the context of selection for disease resistance.

Animals↗

PubMed2026

Genomic dimensions deconstruct the clinical heterogeneity of bipolar disorder.

Bipolar disorder's (BD) clinical heterogeneity has an unresolved genetic basis. We meta-analyzed genome-wide association studies (GWAS) of 16 BD subphenotypes in 226,032 individuals from 57 cohorts (38,022 cases); 10 advanced to multivariate and multi-trait analyses. Four factors (compulsive, psychotic, dysregulated, internalizing) explained 82.8% of shared genetic variance. BD1 and BD2 loaded on distinct factors despite a high genetic correlation; 87.0% of common-factor loci were significant in neither subtype. Unipolar mania aligned with psychosis over internalizing, and was distinguishable from BD1, and rapid cycling showed heritable cross-domain liability. We identified 356 risk loci, 158 novel, including the first univariate-GWAS associations for psychosis, unipolar mania, rapid cycling and schizoaffective disorder-and 249 credible genes (89 high-confidence), 12 with approved-drug or clinical-phase annotations. Cell-type association showed a midbrain dopaminergic-GABAergic gradient along the psychotic factor. BD's genetic architecture appears hierarchical-a general liability resolving into dimensions of course and comorbidity, beyond subtypes.

Journal Article↗

PubMed2004

Psychometric Validation of the National Eye Institute Visual Function Questionnaire - 25 (NEI VFQ-25) French version: in a population of patients treated for ocular hypertension and glaucoma.

OBJECTIVE: Physicians need reliable, valid and sensitive questionnaires to assess QOL related to glaucoma or ocular hypertension. This article presents the psychometric properties of the French version of the National Eye Institute Visual Function Questionnaire - 25 (NEI VFQ-25). METHODS: A mail survey was sent to 20000 households. The survey identified 581 residents with glaucoma or ocular hypertension. Of these a random sample (n = 204) took part in a telephone survey during which the NEI VFQ-25 was completed by eligible patients (those taking at least one topical treatment for glaucoma or ocular hypertension on the day of the interview). Multi-trait analysis was performed to assess the construct validity of the questionnaire. Internal consistency reliability was assessed using Cronbach's alpha and the average inter-item correlation. Known groups validity was assessed by comparing patients grouped by duration of glaucoma, adjusted for age and gender. RESULTS: One hundred and seventy-three patients participated in the survey. Analysis of convergent validity showed that all of the items in each scale correlated above 0.40 with their own scale except for the 'driving' scale. The success rate of the discriminant validity ranged from 57.1% to 100% except for the 'driving' scale, which was 7.1%. Cronbach's alpha coefficients were all above 0.70 except the 'driving' score. Participants with glaucoma for less than 20 years consistently had better 'global', 'near vision', 'distant vision', 'driving', 'social function' and 'peripheral vision' scores than those with disease of 20+ years duration, indicating better QOL in patients with a shorter disease duration. CONCLUSION: The NEI VFQ-25 is a validated instrument to measure vision-targeted QOL in French populations with glaucoma.

Activities of Daily Living↗

PubMed1992

Multiple-trait restricted maximum likelihood for simulated measures of ovulation rate with underlying multivariate normal distributions.

A data set that was used to estimate covariance components with REML for an animal model with eight measures of ovulation rate treated as separate traits was used as a template to simulate data sets of eight multivariate normal traits that were then truncated to binomial traits. The model for simulation included eight measures on 610 animals with 1,071 animals in the numerator relationship matrix. Heritabilities were equal for the eight measures, and both genetic and phenotypic correlations among the measures were equal. Ten replications for each combination of heritability (.15, .25, and .35) and genetic correlation (.50, .66, and .90) were simulated on the normal scale. For each replicate, estimates of the eight heritabilities and 28 genetic correlations were obtained by multiple-trait REML. The usual transformation of heritability estimated on the binomial scale overestimated heritability on the normal scale. Genetic correlations on the binomial scale seriously underestimated the correlations on the normal scale. Standard errors of the estimates obtained by replication were somewhat larger than the approximate SE from REMLPK (the multi-trait REML program of K. Meyer). A final set of 10 simulated replications with heritability of .25 and genetic correlation of 1.00 resulted in average estimates of .18 for heritability and of .66 for genetic correlation that agree closely with those from the analysis of measures of ovulation at eight estrous cycles used as a template; averages for heritability of .16 and for genetic correlation of .66 were obtained.

Animals↗

PubMed1994

Selection for litter size, body weight, and pelt quality in mink (Mustela vison): correlated responses.

In a five-generation selection experiment, separate lines of standard mink (Mustela vison) were subjected to selection for litter size at 3 wk (F line), body weight in September (BS line), underfur density (P line), or combined selection for litter size and body weight (I line). One unselected line served as a control (C line). The present paper focuses on correlated responses to selection regarding fertility and fitness traits, fur quality, and body size traits. Genetic and environmental parameters were estimated with REML (Restricted Maximum Likelihood) techniques using a multi-trait, reduced animal model in a derivative-free way. Genetic and phenotypic correlations were estimated from four subsets of data consisting of 1) female September weight, litter size, and kit mortality; 2) body size traits; 3) September weight and fur traits graded on live mink; and 4) fur traits graded on live mink and skins. September weight was found to be negatively correlated with fertility and fitness traits as well as with fur traits. Selection for underfur density resulted in an improvement in guard hair quality and in general impression of the fur and almost eliminated the fur defect metallic sheen.

Animals↗

PubMed1980

Genetic evaluation of animals for traits with categorical responses.

A method of genetic evaluation of polychotomies based on the logistic distribution is presented. Logarithmic transformations of counts are expressed as linear combinations of fixed effects and random variables. Realized values of random elements in the model are predicted by the solution of equations similar to Henderson's multi-trait best linear unbiased prediction, but with a variance-covariance matrix of the residuals estimated from the data. It is proved that the method yields consistent estimators and predictors of response probabilities for any desired linear function of the model, provided that the linear combination involving the fixed effects is estimable. The method appears to have properties similar to those of minimum logit chi-square estimators. An example is presented.

Animals↗

PubMed2026

Accounting for voluntary waiting period changes in US dairy herds: Adjusting daughter pregnancy rate and introducing first-service to conception.

The genetic evaluation of female fertility traits in dairy cattle in the United States has progressed over the past 2 decades, with 4 additional traits integrated into the national evaluation system since the introduction of daughter pregnancy rate (DPR) in 2004. However, concerns have arisen in the dairy sector, with reports of producers extending the voluntary waiting period (VWP), which is the time of initial breeding after calving, due to more persistent lactation yields. Since its inception, DPR calculations in the US evaluation have assumed a fixed 50-d VWP, which may not reflect modern reproductive strategies. Furthermore, producers may determine that some of their cows should have their VWP extended while others may follow the standard time. A re-evaluation of the current female fertility evaluation is necessary to ensure traits align with current management practices. Therefore, this study explores the addition of a potential new trait, First Service to Conception (FSC), along with a revised DPR formula that permits more flexibility with VWP. About 32 million records from the National Cooperator Database, covering 5 major dairy breeds (2003-2023), were used for this study. Data for cows calving before 2003 were unavailable because insemination records were not recorded prior. The findings suggest FSC enhances female fertility evaluations, providing a more comprehensive reproductive assessment independent of VWP. Another approach was an adjustment to the DPR calculation (DPRadj) to account for herd VWP on a herd-year and lactation group basis. The mean DPR value was 45.06%, while DPRadj increased the mean value to 52.58%. The mean FSC was 62.64 d. In an analysis using first lactation cows for cow traits and heifers for heifer traits, genetic correlations of FSC with other fertility traits were 0.97 with Cow Conception Rate (CCR) and DPR, 0.98 with DPRadj, 0.40 with Heifer Conception Rate (HCR), and 0.32 with Early First Calving (EFC). Predicted transmitting abilities (PTA) were calculated to assess the implications of adding FSC to, or replacing DPR with DPRadj within the CDCB multi-trait evaluation index, Net Merit $ (NM$). The highest correlation among the top 10% of bulls occurred when replacing DPR with DPRadj (0.99). Adding FSC to the original model reduced the latter correlation to 0.88, which indicates slight re-ranking of top bulls. Among animals with PTA reliability above 50%, the lowest correlation was between the original index and the index replacing DPR with FSC (0.95). This work advances genetic evaluation in dairy cattle, improving reproductive efficiency and productivity.

daughter pregnancy rate↗

PubMed2000

Strategies for estimating the parameters needed for different test-day models.

Currently, most analyses of parameters in test-day models involve two types of models: random regression, where various functions describe variability of (co)variances with regard to days in milk, and multiple traits, where observations in adjacent days in milk are treated as one trait. The methodologies used for estimation of parameters included Bayesian via Gibbs sampling, and REML in the form of derivative-free, expectation-maximization, or average-information algorithms. The first method is simpler and uses less memory but may need many rounds to produce posterior samples. In REML, however, the stopping point is well established. Because of computing limitations, the largest estimations of parameters were on fewer than 20,000 animals. The magnitude and pattern of heritabilities varied widely, which could be caused by simplifications in the model, overparameterization, small sample size, and unrepresentative samples. Patterns of heritability differ among random regression and multiple-trait models. Accurate parameters for large multi-trait random regression models may be difficult to obtain at the present time. Parameters that are sufficiently accurate in practice may be obtained outside the complete prediction model by a constructive approach, where parameters averaged over the lactation would be combined with several typical curves for (co)variances for days in milk. Obtained parameters could be used for any model, and could also aid in comparison of models.

Analysis of Variance↗

PubMed2002

Energy balance profiles for the first three lactations of dairy cows estimated using random regression.

Daily animal solutions were predicted using random regression analysis for feed intake, milk yield, live weight, and condition score recorded on 189 cows at the Langhill Dairy Cattle Research Centre. All cows had three successive lactations. Energy balance for days 1 to 305 of each of the three lactations was calculated both from daily measures of feed intake and milk output and from weekly measures of live weight and condition score. Cows returned to positive energy balance at days 72, 75, and 95 in lactations 1, 2, and 3, respectively, based on energy balance calculated from feed intake and milk output records (EB1), and at days 77, 83, and 73 based on energy balance calculated from body energy state changes (EB2). Correlations between energy balance at the same time in successive lactations ranged from 0.01 to 0.66 depending on the method of calculation and the stage of lactation. Energy balance over three lactations was modelled using sinusoidal functions which were associated with individual cows and allowed to vary between cows. The parameters of these curves are potentially useful since they have a biological interpretation. The phase relates to the period from calving to return to positive energy balance, and the amplitude relates to the degree of body energy loss (and recovery). The sinusoidal functions fitted to the curve removed a significant proportion of the variation, but accounted for only 45% and 40% of the variation in EB1 and EB2, respectively. The relationship between energy balance in the first three lactations is likely to be more complex than a simple linear function, but the profile of energy balance over the first three lactations may be a useful selection criteria in a multi-trait index. Energy balance profile over lactations one to three can be modelled with moderate accuracy using sinusoidal functions, and this warrants further research.

Animals↗

PubMed1989

Estimation of genetic parameters for production and reproduction in Finnish Ayrshire cattle.

Records of AI-sired cows born between 1978 and 1982 were used to form two composite production and reproduction data sets. First (second) consisted of 35,568 (26,443) first lactations of daughters of 270 (237) sires. Traits were FCM, heifer, and first parity nonreturn rates, days between calving and first insemination, and days open, with means 5075 (5280) kg, .62 (.62), .44 (.49), 81 (81) d and 110 (111) d. (Co)variance components were estimated by REML with an expectation maximization algorithm. Sire model included age, month, herd-year effects, and relationships among sires. Records on animals with observations missing on some traits were included. Estimates of heritabilities, averaged over data sets, were nonreturn rates for heifers and for cows, .02; FCM, .32; days to first insemination, .19; and days open, .10. Genetic correlations between first parity fertility and yield were unfavorable; the highest, .43, was between FCM and days open. Heifer nonreturn rate had a .09 correlation with production and a .26 correlation with cow nonreturn rate. Phenotypic correlations were in the same direction as genetic correlations but were smaller in magnitude. Results suggest that selection only for production would cause deterioration in level of fertility. When economical, AI sires should be evaluated for daughter fertility. A multi-trait model including milk production, days open and relationships among bulls is recommended for genetic evaluation.

Age Factors↗

PubMed1990

Relationships between reproduction traits, age and body weight at calving, and days dry in first lactation Ayrshires and Holsteins.

Individual cow test day records collected between December 1979 and June 1986 were used to calculate measures of reproductive performance, age and weight at calving, and days dry for 7824 Ayrshire and 79,755 Holstein cows in first lactation. Separate analyses by breed were carried out according to a multiple-trait mixed model. Sixty-two Ayrshire and 369 Holstein sires were treated as random in the analyses. Ayrshires were, on average, older and lighter at calving than Holsteins, but the breeds differed little in reproduction measures and days dry. Heritabilities of fertility traits, days to first breeding, days open, and services per conception were all less than .015 in the multi-trait analyses. With the exception of body weight, heritability estimates for the other traits were less than .05. Phenotypic correlations between traits were almost identical for the two breeds, and genetic correlations tended to be similar. Exceptions involved the trait days to first breeding and services per conception, but heritabilities of these traits were close to zero (p less than .008) in Ayrshires. Fertility traits were positively correlated genetically. Genetic correlations between days open and both age and body weight at calving were small. The genetic correlation between age and weight at calving was -.90 and -.68 in Ayrshires and Holsteins, respectively. Genetic correlations between days dry and all traits except body weight were moderate and positive.

Aging↗

PubMed2026

Dissecting the genetics of forage quality traits in soft red winter wheat in the U.S. southeast region.

Winter wheat plays a viable role in agriculture, not only as a primary grain crop but also as a valuable forage source that bridges fall-spring forage gaps in many regions, including the southeastern (SE) U.S. Despite its nutritive potential, genetic basis of forage-quality traits remains insufficiently understood, limiting breeding efforts for dual-purpose cultivars. This study aimed to dissect the genetic architecture of forage quality in 182 soft red winter wheat (SRWW) genotypes adapted to the SE U.S. using genome-wide association study (GWAS). Field experiments were carried out in randomized complete block design across three Georgia locations over two growing seasons (2023-2025), with forage sampled at the end of tillering and evaluated using near-infrared reflectance spectroscopy. Significant phenotypic variation was observed for dry matter (DM), crude protein (CP), acid and neutral detergent fiber (ADF, NDF), acid detergent lignin (ADL), total digestible nutrients (TDN), sugars (SUG), and relative forage quality (RFQ). Heritability estimates ranged from low-to-moderate in combined environments and from low-to-high within individual locations. Correlation analysis revealed strong positive associations among fiber-related traits and negative associations with TDN, RFQ, and SUG, while CP declined with increasing fiber. Genome-wide association analysis identified 282 significant marker-trait associations (P < 1×10-4) across 19 chromosomes, which were consolidated into 121 QTLs, including 27 major-effect QTLs. Three QTLs QRfq.uga-3B.1, QRfq.uga-3B.2 (RFQ) and QDm/Sug.uga-7A (DM, SUG) were stable across locations while QAdf/Adl.uga-2A (ADF, ADL) and QDm/Sug.uga-7A (DM, SUG) indicated multi-trait control. Notably, 25 of the 27 major QTLs were putatively novel, highlighting substantial untapped allelic diversity for forage-quality improvement in SE SRWW. Favorable allele accumulation resulted in an overall improvement in forage quality, increasing desirable nutritive traits (DM, RFQ, SUG, CP) while reducing undesirable traits (ADF, ADL). Candidate gene analysis linked six major QTLs with genes implicated in abiotic stress response, plant development, and metabolic regulation, supporting their functional relevance in forage-quality determination. Incorporating these loci into breeding programs provides a robust genetic framework for marker-assisted selection, enabling the development of dual-purpose wheat cultivars with enhanced forage quality, thereby strengthening wheat's utility as a reliable forage resource during periods of seasonal feed scarcity in SE production systems.

GWAS↗

PubMed2025

Shared Genetic Architecture Between Atopic Dermatitis and Autoimmune Diseases.

Atopic dermatitis (AD) and autoimmune diseases exhibit epidemiological comorbidity, yet the shared genetic architecture remains incompletely understood. We investigated the genetic overlap between AD and three autoimmune disorders including inflammatory bowel disease (IBD), rheumatoid arthritis (RA), and vitiligo, leveraging genome-wide association data. Despite modest evidence for global genetic correlations, we found 113 independent pleiotropic loci shared among AD and autoimmune diseases, with 11 displaying a concordant effect across all 3 pairwise comparisons. Gene-set and tissue enrichment analyses evidenced the inflammatory background of pleiotropic associations. Multi-trait colocalization analysis prioritized 22 loci, linking the tissue-specific expression of DOK2, GPR132, RERE, RERE-AS1, SUOX, TNFRSF11A, and TRAF1 pleiotropic genes with AD risk. Mendelian randomization revealed no causal effect of genetic liability to AD on autoimmune diseases. Nevertheless, genetic liability to IBD increased AD risk, while vitiligo exhibited a protective effect post outlier correction. Our findings provide mechanistic insights into the multimorbidity of atopic dermatitis (AD) and autoimmune diseases, offering additional evidence for the pleiotropic genetic architecture of AD that contributes to systemic immune dysregulation across multiple organ systems.

Humans↗

PubMed2026

Advances in Understanding Salt Stress Effects on Growth and Productivity in Sorghum (Sorghum bicolor L. Moench).

Salinity is a growing problem for cereal cultivation because it imposes multiple stresses, including osmotic, ionic, nutritional, and oxidative constraints, on the crop. Sorghum (Sorghum bicolor L. Moench) is considered a climate-smart C4 cereal for food, feed, fodder, forage, and bioenergy, but recent studies indicate that salinity continues to hinder establishment, biomass formation, reproductive growth, and yield. This review compiles the literature on the impacts of salinity on sorghum from 2021 to 2026, with a focus on germination, vegetative growth, physiological and biochemical responses, ion homeostasis, genetic control, productivity, mitigation, and future breeding priorities. In total, 160 records were identified, 118 records were screened after duplicate removal, and 44 recent sources were included in the synthesis. Across comparable sorghum studies, saline/NaCl treatments of approximately 60-200 mM commonly reduced germination by about 20-40%, root and shoot elongation by 25-50%, and biomass by 20-55%, while tolerant genotypes generally maintained higher K+/Na+ balance, 40-60% greater biomass retention, or two- to five-fold stronger ion homeostasis indicators than sensitive lines under similar conditions. Salt stress also lowers leaf expansion, chlorophyll stability, gas exchange, dry matter accumulation, panicle fertility, and grain filling. Tolerant genotypes show greater antioxidant potential, osmotic adjustment, photosynthetic stability, and root system resilience. Recent omics and genome-wide association studies suggest that salinity tolerance in sorghum is polygenic and involves genes related to ion transport, stress signalling, antioxidant regulation, osmolyte metabolism, and growth maintenance. This review recommends a shift from descriptive trait lists to full-cycle field validation, multi-trait selection indices, and integrated packages combining breeding with seed priming, soil water management, amendments, and beneficial microorganisms.

PRISMA↗

PubMed1999

Cross-cultural adaptation of a health status classification system in children with cancer. First results of the French adaptation of the Health Utilities Index Marks 2 and 3.

Our objective was to adapt and validate the Health Utilities Index Mark 2 (HUI 2) and HUI 3 health status classification systems self-report questionnaire in a population of children with cancer, a group of 42 children already included in a multi-centre database designed by the Group on Brain Tumors in Children of the French Society for Pediatric Oncology. Children were recruited during a routine consultation. Most of them had completed treatment. The version of the questionnaire for French adults was adapted linguistically for children. Open-ended queries by children about the comprehensiveness of the questions and very low non-response rates showed a good acceptability of the questionnaire. The main psychometric properties of the HUI 2 and HUI 3 classification systems were assessed in 3 groups of raters (child, parent, physician): construct validity was tested against the rating of the child's health state on a Likert scale and through comparison with clinical data, and internal consistency was determined through multi-trait analysis. Weighted and unweighted kappa values were used to measure the inter-rater agreement between the child's, parent's and physician's assessment of the child's health state. The convergent validity was satisfactory, with better results when the physician's assessment was used. The most affected attributes were the expected ones (i.e., cognition, pain and emotion). Disagreement was observed between the 3 raters, more often in the same direction: taking the child's assessment as the reference, the parents tended to under-estimate the health status while physicians tended to over-estimate it.

Adolescent↗

PubMed2002

[French validation of the revised Piper Fatigue Scale].

The need for a valid and reliable multi-dimensional instrument in French to enable nurses and clinicians to assess intensity and changes in cancer-related fatigue (CRF) and evaluate efficacy of intervention stratégies on patient outcome, prompted us to translate the Piper Fatigue Scale (PFS) and assess its psychometric properties in a French speaking population. The revised PFS is a 22 item self-report instrument with four sub-scales: behavioural/severity, affective, sensory and cognitive/mood. The PFS was translated using a procédure of translation and back translation and tested on 20 bilingual subjects. Correlation coefficients were measured between the item scores of the English and French version of the PFS. The French version of the PFS was adjusted and then completed by 229 adult cancer patients with solid tumours under-going treatment by chemo-, radio-, hormono- or immunotherapy. A factorial analysis and a multi-traits analysis were used to assess the reliability and the dimensional structure of the translated version of the PFS. Cronbach's alpha correlations ranged between 0.85 and 0.92 for the various sub-scales, thus indicating good sub-scale reliability. Item internal consistency was good with 100% of item-scale correlations greater than or equal to 0.4. Item discriminant validity checking showed 3 items to be insufficiently discriminating. Item-scale correlations greater than the correlation of the item with other sub-scales were 98%. The Cognitive/Mood dimension appeared to group 2 separate dimensions. Convergent validity, tested by correlating the PFS with a Visual Analogue Scale measuring fatigue and with the OMS Physical Performance Status Scale, revealed significant relationships. A five sub-scale model of the PFS is proposed containing 22 items to increase performance of the French version of the PFS comparatively to the 4 sub-scale model of the original PFS. Translation of 2 items has been slightly modified to reduce ambiguity. The overall results of this preliminary study are satisfactory. We expect results to be further improved by the modifications proposed and testing is now underway in homogenous populations to evaluate the sensitivity of the instrument to changes over time. This will enable us to ascertain the definitive French version of the Piper Fatigue Scale.

Activities of Daily Living↗

PubMed2002

A statistical model for the genetic origin of allometric scaling laws in biology.

Many biological processes, from cellular metabolism to population dynamics, are characterized by particular allometric scaling (power-law) relationships between size and rate. Although such allometric relationships may be under genetic determination, their precise genetic mechanisms have not been clearly understood due to a lack of a statistical analytical method. In this paper, we present a basic statistical framework for mapping quantitative genes (or quantitative trait loci, QTL) responsible for universal quarter-power scaling laws of organic structure and function with the entire body size. Our model framework allows the testing of whether a single QTL affects the allometric relationship of two traits or whether more than one linked QTL is segregating. Like traditional multi-trait mapping, this new model can increase the power to detect the underlying QTL and the precision of its localization on the genome. Beyond the traditional method, this model is integrated with pervasive scaling laws to take advantage of the mechanistic relationships of biological structures and processes. Simulation studies indicate that the estimation precision of the QTL position and effect can be improved when the scaling relationship of the two traits is considered. The application of our model in a real example from forest trees leads to successful detection of a QTL governing the allometric relationship of third-year stem height with third-year stem biomass. The model proposed here has implications for genetic, evolutionary, biomedicinal and breeding research.

Animals↗

PubMed1992

[The genetic analysis of long-term index selection--a simulation experiment].

The genetic effects of long-term index selection were investigated by means of Monte Carlo Method. The response and the effect on genetic structure of population to selection using four methods, that is theoretical index, emperical index, restricted index and single-trait selection, were compared. Results obtained from 50 generations demonstrated that much greater response was achieved in large populations, and selection in small ones led to a decrease in selection limit. Genetic correlation played an important role on response in small populations. Emperical index selection was more effective than theoretical index, restricted index had less response in the early period of selection but greater response in later period and also had less effect on genetic structure of population even if the genetic correlation was intense. Meanwhile, index selection could cause decrease in additive genetic variance and beritabilities while genetic correlation changed depending on the coefficients of index formulae. The suggestion is that emperical index or restricted index should be used for long-term selection for multi-traits.

Computer Simulation↗