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PubMed2003

Psychometric performance of the NEI VFQ-25 in visually normal Latinos: the Los Angeles Latino Eye Study.

PURPOSE: To characterize the psychometric performance of the National Eye Institute 25-item Visual Function Questionnaire (NEI VFQ-25) in visually normal Latinos (Mexican Americans). METHODS: The Los Angeles Latino Eye Study (LALES) is a population-based study to assess the prevalence of eye disease and self-reported visual functioning in Latinos aged 40 or more years. Self-reported visual functioning was assessed by using English and Spanish versions of the NEI VFQ-25. Psychometric properties of the NEI VFQ-25, including internal consistency of the subscales and the individual items, were assessed through the Multi-trait Analysis Program-Revised (MAP-R) analysis. Adjusted mean and median subscale scores were compared between English and Spanish speakers to identify any systematic differences. RESULTS: Of the 1917 participants from two census tracts, 1171 participants with no visual impairment were included in this analysis. The mean age of the participants was 52.3 years, 57% of the participants were female, and 67.5% of the participants were Spanish speaking. Median scores for Spanish-speaking participants were significantly lower than those of the English-speaking participants on four subscales: Ocular Pain, General Vision, Vision-Specific Mental Health, and General Health (P < 0.05). Internal consistency for three of eight measurable subscales for the study group was poor (Cronbach alpha < 0.6). CONCLUSIONS: This study reveals psychometric inconsistencies in the NEI VFQ-25 when administered to visually normal Latinos. The difference in mean subscale scores between Spanish and English speakers must be integrated into the development of population norms of visual function. Further detailed psychometric evaluation is needed to determine the validity of this instrument in Latino populations.

Activities of Daily Living↗

PubMed2026

Decoding Primary Open-Angle Glaucoma: A Multi-Omics Approach to Identify Druggable Effector Genes.

PURPOSE: Genomewide association studies (GWAS) have identified numerous primary open angle glaucoma (POAG) risk loci, yet most reside in non-coding regions with unclear function. Mapping these loci to effector genes can elucidate disease mechanisms, identify functionally conserved variants, improve cross-ancestry risk prediction by reducing population-specific noise, and uncover shared therapeutic targets. METHODS: Here, we integrate European POAG GWAS with six types of multi-omics molecular Quantitative Trait Locis (xQTLs) using multi-trait colocalization to identify candidate effector variants and evaluate their cross-population relevance using genetic risk score (GRS) analysis, and their therapeutic potential through drug target prioritization. RESULTS: We identified 25 POAG effector variants colocalized with at least one xQTLs. In non-European populations, effector variants showed stronger effect size correlations with Europeans than non-colocalized variants (Pearson r2 = African 0.85 vs. 0.71; East Asian 0.81 vs. 0.69; and Latin American 0.91 vs. 0.75). Effector variants also had smaller allele frequency variations across populations (average interquartile range [IQR] = 0.15 vs. 0.20). The genetic risk score based on effector variants performed comparably to the genome-wide significant single-nucleotide polymorphism (SNP)-based GRS in non-European populations. Drug prioritization identified zinc, copper, sunitinib, probucol, and astemizole as potential common therapeutic agents for POAG and its subtypes. CONCLUSIONS: Our findings offer deeper insight into the molecular mechanisms underlying glaucoma and effector variants for developing more robust GRS models and broadly effective therapeutic strategies for POAG.

Humans↗

PubMed2026

Imaging and genomics in stroke.

Imaging after ischemic and hemorrhagic stroke may allow measurement of key phenotypes of injury and recovery for which targeted therapies are still lacking. Such imaging endophenotypes provide quantifiable and heritable biomarkers that can represent mechanistic aspects of disease processes better than clinical measures. Artificial intelligence is allowing extraction of these imaging biomarkers in large cohorts, which can be paired with genomic and other omics data. This will allow the evaluation of what genetic and other biologic variations impact stroke injury and recovery. Integration of these analyses with bioinformatics tools (such as Mendelian randomization and multi-trait analysis) could further dissect how stroke complications overlap with other biologic processes and how they may be causally linked to risk factors. Further work is required to confirm the translational impact of these methods in elucidating mechanisms and drug targets for stroke. However, global collaborations are accelerating analyses on large multi-ethnic stroke cohorts, with availability of imaging data facilitated by federally-funded repositories such as the Imaging Repository for the Cerebrovascular Disease Knowledge Portal (iCDKP).

Humans↗

PubMedDate not supplied

Use of the EM algorithm to detect QTL affecting multiple-traits in an across half-sib family analysis.

QTL detection experiments in livestock species commonly use the half-sib design. Each male is mated to a number of females, each female producing a limited number of progeny. Analysis consists of attempting to detect associations between phenotype and genotype measured on the progeny. When family sizes are limiting experimenters may wish to incorporate as much information as possible into a single analysis. However, combining information across sires is problematic because of incomplete linkage disequilibrium between the markers and the QTL in the population. This study describes formulae for obtaining MLEs via the expectation maximization (EM) algorithm for use in a multiple-trait, multiple-family analysis. A model specifying a QTL with only two alleles, and a common within sire error variance is assumed. Compared to single-family analyses, power can be improved up to fourfold with multi-family analyses. The accuracy and precision of QTL location estimates are also substantially improved. With small family sizes, the multi-family, multi-trait analyses reduce substantially, but not totally remove, biases in QTL effect estimates. In situations where multiple QTL alleles are segregating the multi-family analysis will average out the effects of the different QTL alleles.

Algorithms↗

PubMedDate not supplied

Genetic parameters and responses of performance and body composition traits in pigs selected for high and low growth rate on a fixed ration over a set time.

Two lines of Large White pigs of common genetic origin were divergently selected over four years for high and low growth rate during a 6 week post-weaning test period in which all pigs were fed the same total amount of food (80% of estimated ad libitum intake). Genetic parameters and direct and correlated responses in performance and carcass traits were estimated on 2884 pigs with pedigrees comprising a total of 5324 animals, with restricted maximum likelihood and best linear unbiased prediction methods applied to a multi-trait animal model. Estimates of heritability (+/-SE) were 0.19 +/- 0.04 for lifetime daily gain (LDG), 0.16 +/- 0.03 for test daily gain (TDG), 0.25 +/- 0.04 for ultrasound P2 backfat (UBF) and 0.16 +/- 0.03 for food conversion ratio during test (TFC), and 0.15 +/- 0.04 for daily carcass weight gain (CDG), 0.43 +/- 0.06 for carcass backfat (CFT) and 0.40 +/- 0.06 for carcass lean percentage (LEAN). Common litter effects for TDG, UBF and TFC were less than 5% and for LDG, 17% of total phenotypic variance. Genetic correlations between performance and carcass traits were moderately to highly favourable. After four years of divergent selection for growth rate, the selection responses in estimated breeding value (EBV) for TDG were 40.14 and -41.11 g (SED 2.95) for the high and low growth lines, respectively. The regressions of EBV on year of birth, indicate that the annual genetic trend for TDG, was 8.73 g/yr in the high and -8.48 g/yr in the low lines (P <0.001). Correlated genetic responses in the high and low lines respectively were 5.28 g and -12.40 g (SED 2.09) in LDG, -0.35 mm and 0.56 mm (SED 0.009) in UBF, -0.145 units and 0.185 units (SED 0.012) in TFC, 3.17 g and -10.97 g (SED 1.53) in CDG, -1.13 mm and 1.01 mm (SED 0.155) in CFT and 1.24% and -1.27% (SED 0.150) in LEAN. It was concluded that selection for increased post-weaning daily gain on a ration of fixed amount reduces the age at slaughter and the level of backfat and increases the efficiency of food utilisation, weight and leanness of pig carcasses.

Animals↗

PubMed2026

Integrated functional genomics and safety assessment of plant-growth-promoting Caryophanales from post-maize-cultivation soils.

This study aimed to evaluate six environmental bacterial strains isolated from post-maize cultivation soils as candidates for agricultural biopreparation development, using an integrated functional genomic and safety assessment framework. Building on experimental validation of plant-growth-promoting activities, the analysis included: plant-growth-promoting traits (PGPT-Pred) using PLABase; carbohydrate-active enzymes (CAZymes) relevant for lignocellulosic crop residue degradation (dbCAN3); secondary metabolite profiles (antiSMASH); and screening for virulence factors and antibiotic resistance genes (ABRicate, BTyper3).All analyzed strains possess 1,449-1,617 predicted PGPT-encoding genes (24.1-35.9% of total genes), which are strongly shaped by taxonomic relatedness, as confirmed by congruence testing against ANI-based genomic divergence. Paenibacillus amylolyticus 5mez and Priestia megaterium 7psych showed distinct functional profiles compared to Bacillus spp., while Bacillus subtilis sensu lato strains were most similar to each other. Genomic predictions suggest involvement in nutrient acquisition (N, P, K, Fe) and stress mitigation. Secondary metabolite analysis revealed high biosynthetic potential, with non-Bacillus species harbouring a large proportion of unknown gene clusters, indicating underexplored metabolite diversity. CAZyme profiling identified P. amylolyticus 5mez as the most enzyme-rich strain, while B. cereus s.s. zielonkawy showed ligninolytic potential despite low overall CAZyme abundance. The safety assessment identified B. cereus s.s. zielonkawy as toxigenic and unsuitable for use. Of the remaining strains, P. amylolyticus 5mez and Pr. megaterium 7psych demonstrated the most favourable safety profiles, exhibiting no detectable virulence factors or antibiotic resistance genes, justifying their priority use in agricultural biopreparations, pending phenotypic validation. Given the high-dimensional, low-sample-size nature of multi-trait datasets in applied microbial genomics, tailored statistical approaches, including noise-reduction-validated PCA and distance-based congruence testing, were applied; their rationale and limitations are discussed.

Soil Microbiology↗

PubMed2025

Post-genome-wide association study dissects genetic vulnerability and risk gene expression of Sjögren's disease for cardiovascular disease.

OBJECTIVES: This study aims to clarify the genetic associations between Sjögren's Disease (SD) and cardiovascular disease (CVD) outcomes, and to conduct an in-depth exploration of specific pleiotropic susceptibility genes. METHODS: We performed two-sample and multivariable Mendelian randomization (MR) analysis to investigate the association between SD and the risk of ischemic heart disease (IHD) and stroke. Linkage disequilibrium score regression (LDSC) and Bayesian co-localization analyses were employed to assess the genetic associations between traits. Cross-phenotype analyses were employed to identify shared variants and genes, followed by a Transcriptome-Wide Association Study (TWAS) and Multi-marker Analysis of Genomic Annotation (MAGMA) based on Multi-Trait Analysis of GWAS (MTAG) results. To validate the pleiotropic genes, we further analyzed tissue-specific differentially expressed genes (DEGs) related to SD using RNA sequencing data. RESULTS: The two-sample and multivariable MR analyses revealed that SD confers a genetic vulnerability to IHD and stroke. LDSC and co-localization analyses indicated a strong genetic linkage between SD and CVDs. Cross-phenotype analyses identified 38 and 37 pleiotropic single nucleotide polymorphisms (SNPs) for SD-Stroke and SD-IHD, respectively, primarily located within the MHC class region on 6p21.32:33 loci. Additionally, TWAS and MAGMA analyses identified pleiotropic genes located outside the MHC regions-seven associated with stroke (UHRF1BP1, SNRPC, BLK, FAM167A, ARHGAP27, C8orf12, and PLEKHM1) and two associated with IHD (UHRF1BP1 and SNRPC). Proxy variants within these genes in SD suggested an increased causal risk for stroke or IHD. Co-localization analysis further reinforced that SD and stroke share significant SNPs within the loci of FAM167A, BLK, C8orf12, SNRPC, and UHRF1BP1. DEG analysis revealed a significant up-regulation of the identified genes in SD-specific tissues. CONCLUSIONS: SD appears genetically predisposed to an increased risk of CVDs. Moreover, this research not only identified pleiotropic genes shared between SD and CVDs, but also, for the first time, detected key gene expressions that elevate CVD risk in SD patients-findings that may offer promising therapeutic targets for patient management.

Humans↗

PubMed2024

Genomic selection for tolerance to aluminum toxicity in a synthetic population of upland rice.

Over half of the world's arable land is acidic, which constrains cereal production. In South America, different rice-growing regions (Cerrado in Brazil and Llanos in Colombia and Venezuela) are particularly affected due to high aluminum toxicity levels. For this reason, efforts have been made to breed for tolerance to aluminum toxicity using synthetic populations. The breeding program of CIAT-CIRAD is a good example of the use of recurrent selection to increase productivity for the Llanos in Colombia. In this study, we evaluated the performance of genomic prediction models to optimize the breeding scheme by hastening the development of an improved synthetic population and elite lines. We characterized 334 families at the S0:4 generation in two conditions. One condition was the control, managed with liming, while the other had high aluminum toxicity. Four traits were considered: days to flowering (FL), plant height (PH), grain yield (YLD), and zinc concentration in the polished grain (ZN). The population presented a high tolerance to aluminum toxicity, with more than 72% of the families showing a higher yield under aluminum conditions. The performance of the families under the aluminum toxicity condition was predicted using four different models: a single-environment model and three multi-environment models. The multi-environment models differed in the way they integrated genotype-by-environment interactions. The best predictive abilities were achieved using multi-environment models: 0.67 for FL, 0.60 for PH, 0.53 for YLD, and 0.65 for ZN. The gain of multi-environment over single-environment models ranged from 71% for YLD to 430% for FL. The selection of the best-performing families based on multi-trait indices, including the four traits mentioned above, facilitated the identification of suitable families for recombination. This information will be used to develop a new cycle of recurrent selection through genomic selection.

Oryza↗

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↗