SEARCH · PubMed Health

Results for “Breeding value”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18Linked to original sources

PubMedDate not supplied

Indirect arterial blood pressure measurement in nonsedated Irish wolfhounds: reference values for the breed.

Arterial blood pressure measurements were obtained from 158 healthy Irish wolfhounds using the oscillometric technique to establish reference values for the breed. In contrast to other sight hounds, Irish wolfhounds have low arterial blood pressure. Mean systolic pressure for the group was 116.0 mm Hg. Mean diastolic pressure was 69.2 mm Hg, and the mean value for mean arterial pressure was 87.8 mm Hg. Blood pressure measurements were higher in older wolfhounds than in young dogs. There was no difference between systolic and mean arterial blood pressures in lateral recumbency compared to standing position. However, diastolic pressure was slightly lower when standing. Calm dogs had lower pressure than anxious wolfhounds. There was a significant interaction between the effects of age, gender, and mood on systolic, diastolic, and mean arterial blood pressure values.

Animals↗

PubMed2006

Impact of dominance effects on sow longevity.

The purpose of the current study was to estimate variance components, especially dominance genetic variation, for overall leg action, length of productive life and sow stayability until third and fifth parity in the Finnish pig populations. The variance components were estimated in two purebred [Landrace (LR), n = 23 602 and Large White (LW), n =22 984] and crossbred (LR x LW, n = 17 440) data sets. Five different analyses were carried out for all the traits to compare the effect of sows' inbreeding, common litter environment and parental dominance in the statistical model when determining the genetic correlations of the traits for the two purebred and crossbred populations. Estimated heritabilities for the traits ranged from 0.04 to 0.06. The estimates for the proportion of dominance variance of phenotypic variance (d(2)) varied between 0.01 and 0.17, and was highest in the crossbred dataset. The genetic correlations of the same traits in purebred and crossbred were all high (>0.75). Based on current results, the effect of dominance should be accounted for in the breeding value estimation of sow longevity, especially when data from crossbred animals are included in the analyses. Because dominance genetic variation for sow longevity exists that variation should be utilized through planned matings in producing sows for commercial production.

Animals↗

PubMed1984

[Direct selection for fertility and health in cattle].

Financial losses in dairy cattle due to breeding inefficiency and health impairment are so high that they should be taken into account in cattle breeding. These disturbances tend to increase as productivity increases. Although these disturbances are quantitative characteristics, they can only be recorded qualitatively. Therefore the heritabilities of breeding inefficiency and health impairment are low. Several of these disturbances (mastitis, metabolic disorders) show a much higher incidence in cows than they do in heifers. Selection for production-traits is mainly based on heifer groups of bulls. Artificial selection designed to prevent disturbances will fail to produce positive results as the heritabilities are low for heifers and the current groups of heifers are too small to obtain a reliable estimate of the breeding value of a bull for disturbances of fertility or health. Natural selection against these disturbances should not be ruled out, and therefore it is advisable to record certain disturbances and to use this recording in the selection of bull dams.

Aging↗

PubMed2005

Genetic parameter estimates of portuguese dairy cows for milk, fat, and protein using a spline test-day model.

A spline animal model was fitted to 152,103 test-day milk, fat, and protein yield records from 14,423 first-lactation cows. The models included age at calving and the herd-test-month as fixed effects. Model fitting was carried out using Restricted Maximum Likelihood with ASREML. For milk yield, the heritability at 18 d in milk was 0.19, which increased to the maximum estimated value of 0.23 at midlactation and then decreased. On average, milk, fat, and protein yield heritabilities were 0.22, 0.14, and 0.19, respectively. For milk yield, all correlations were positive and ranged from 0.54 to 0.99 for the genetic component and from 0.32 to 0.78 for the phenotypic component. Genetic correlations were higher than phenotypic ones. For fat and protein yields, all genetic correlations were positive, ranging from 0.43 to 0.99. The phenotypic correlations for fat yield had the lowest correlations of the 3 traits. Curves of estimated breeding values for milk, fat, and protein over lactation had positive deviations from mean curves for sires with high genetic merit, but there was considerable variability in the shapes of the curves for different sires. More research is needed to compare the spline function with other mathematical functions used as submodels of lactation curve.

Animals↗

PubMedDate not supplied

The advantage of factorial mating under selection is uncovered by deterministically predicted rates of inbreeding.

Rates of inbreeding (DeltaF) in selected populations were predicted using the framework of long-term genetic contributions and validated against stochastic simulations. Deterministic predictions decomposed DeltaF into four components due to: finite population size, directional selection, covariance of genetic contribution of mates, and deviation of variance of family size from that expected from a Poisson distribution. Factorial (FM) and hierarchical (HM) mating systems were compared under mass and sib-index selection. Prediction errors were in most cases for DeltaF less than 10% and for rate of gain less than 5%. DelatF was higher with index than mass selection. DeltaF was lower with FM than HM in all cases except random selection. FM reduced the variance of the average breeding value of the mates of an individual. This reduced the impact of the covariance of contributions of mates on DeltaF. Thus, contributions of mates were less correlated with FM than HM, causing smaller deviations of converged contributions from the optimum contributions. With index selection, FM also caused a smaller variance of number of offspring selected from each parent. This reduced variance of family size reduced DeltaF further. FM increases the flexibility in breeding schemes for achieving the optimum genetic contributions.

Animals↗

PubMed2025

Haplotype stacking to improve stability of stripe rust resistance in wheat.

Genotype-by-environment interaction analysis and haplotype-level characterisation provide novel insights into the stability of stripe rust resistance. Breeding selection strategies are proposed to achieve rapid and stable genetic gains across environments. This study investigated stripe/yellow rust (YR) responses in the Vavilov wheat diversity panel evaluated across 11 field experiments conducted in Australia and Ethiopia during 2014-2021. Genotype-by-environment interaction (GEI) was analysed using a factor analytic (FA) model. Genotype-level selection was performed with overall performance (OP) and root-mean-square deviation (RMSD), which reflected average performance and stability of YR resistance across environments, respectively. Genomic estimated breeding values (GEBV) for these traits were calculated and compared with those from a multi-trait GBLUP model with average performance represented by the mean GEBV across environments and stability by the standard deviation of GEBV across environments. The FA-based and multi-trait GBLUP GEBV had high correlations. Haplotypes with large effects on OP and RMSD were identified using the local GEBV method. Favourable haplotypes were then used for stacking in breeding simulations, using the Vavilov collection as a base. Compared to truncation selection, optimal haplotype selection (OHS) using an artificial intelligence (AI)-based algorithm achieved longer-term genetic gains for both OP and RMSD (after many generations) by initially selecting founder parents that maximised favourable haplotypes. Simulations using YR responses from diverse environments that mimicked fluctuating environmental conditions across seasons were conducted to evaluate strategies for selection of YR resistance that is stable across years. Strategies which gave most weight to OP, but some weight to RMSD were optimal in these conditions, and substantially reduced variation of performance across years. This study provides useful information for breeding cultivars with both high YR resistance and high stability of resistance across environments.

Triticum↗

PubMed2001

Detection of quantitative trait loci affecting milk production traits on 10 chromosomes in Holstein cattle.

Sons (n = 71 to 75) of each of six Holstein sires were genotyped at 69 microsatellite loci covering a total of 676 cM on chromosomes 3, 5, 9, 10, 13, 15, 17, 20, 23, and 26. Estimates of quantitative trait loci (QTL) effect and location were made using a least squares interval mapping approach based on daughter yield deviations of sons for 305 d milk, fat, and protein yield and fat and protein percentage. Thresholds for statistical significance of QTL effects were determined from interval mapping of 10,000 random permutations of the data across the bull sire families and within each sire family separately. Analyses combining data across sires indicated the presence of QTL affecting milk, fat, and protein yield on chromosomes 20 and 26 and a QTL affecting fat and protein percentage on chromosome 3. Analyses within each sire family separately indicated the presence of segregating QTL in at least one family on 7 of the 10 chromosomes. Statistically significant estimates of QTL effects on breeding value ranged from 438 to 658 kg of milk, from 17.4 to 24.9 kg of fat, 13.0 to 17.0 kg of protein, 0.04 to 0.17% fat, and 0.07 to 0.10% protein.

Animals↗

PubMedDate not supplied

The effect of obliquity on the radiographic appearance of the temporomandibular joint in dogs.

The temporomandibular joint is formed between the condyloid process of the mandible and the mandibular fossa of the temporal bone. The basic anatomy of this joint was assessed and described in a series of skulls including dolichocephalic, mesaticephalic and brachycephalic breeds. The facial index and rotational angles were measured with the facial index providing a useful method of classifying skull types but the rotational angle being of limited use in assessment of the temporomandibular joint until normal breed values are established. Equipment was designed to allow repeatable positioning of the temporomandibular joint for radiography at a variety of lateral and long axis rotational angles relative to the central x-ray beam. The regions of the joint and anatomic features visualized in each view are demonstrated. 10 degrees rotation was required in either axis to project the joints independently of each other. Lateral rotational angles of 10 to 30 degrees in mesaticephalic and dolichocephalic breeds and 20 to 30 degrees in brachycephalics and long axis rotational views of 10 to 30 degrees depending on the region of interest were considered to be the most useful.

Animals↗

PubMed1997

Estimates of genetic parameters and environmental effects for measures of hunting performance in Finnish hounds.

Data from field trials of Finnish Hounds between 1988 and 1992 in Finland were used to estimate genetic parameters and environmental effects for measures of hunting performance using REML procedures and an animal model. The original data set included 28,791 field trial records from 5,666 dogs. Males and females had equal hunting performance, whereas experience acquired by age improved trial results compared with results for young dogs (P < .001). Results were mostly better on snow than on bare ground (P < .001), and testing areas, years, months, and their interactions affected results (P < .001). Estimates of heritabilities and repeatabilities were low for most of the 28 measures, mainly due to large residual variances. The highest heritabilities were for frequency of tonguing (h2 = .15), pursuit score (h2 = .13), tongue score (h2 = .13), ghost trailing score (h2 = .12), and merit and final score (both h2 = .11). Estimates of phenotypic and genetic correlations were positive and moderate or high for search scores, pursuit scores, and final scores but lower for other studied measures. The results suggest that, due to low heritabilities, evaluation of breeding values for Finnish Hounds with respect to their hunting ability should be based on animal model BLUP methods instead of mere performance testing. The evaluation system of field trials should also be revised for more reliability.

Aging↗

PubMedDate not supplied

Segregation of a major gene influencing ovulation in progeny of Lacaune meat sheep.

Inheritance of the ovulation rate (OR) in the Lacaune meat breed was studied through records from a small nucleus of 36 hyper-prolific ewes screened on farms on the basis of their natural litter size, and from progeny data of three selected Lacaune sires. These sires were chosen at the AI centre according to their breeding values estimated for the mean and the variability of their daughters' litter size. Non-carrier Lacaune dairy ewes were inseminated to produce 121 F1 daughters and 27 F1 sons. Twelve sons (four from each sire) were used in turn to inseminate non-carrier Lacaune dairy ewes providing 260 BC progeny ewes. F1 and BC progeny were brought from private farms and gathered after weaning on an experimental farm where ovulation rates were recorded in the first and second breeding seasons. With an average of 6.5 records each, the mean OR of hyper-prolific ewes was very high (5.34), and 38.4% of records showed a rate of 6 or more. F1 data showed high repeatability of OR (r = 0.54) within ewe, with significant variability among ewes. High OR (> or = 4) were observed in each family. A segregation analysis provided a significant likelihood ratio and classified the three founders as heterozygous. BC ewes also displayed high repeatability of OR (r = 0.47) and the mean OR varied considerably between families (from 1.24 to 1.78). Seven of the 12 BC families presented high-ovulating ewes (at least one record > or = 4) and segregation analysis yielded a highly significant likelihood ratio as compared to an empirical test distribution. The high variability of the mean ovulation rate shown by a small group of daughters of BC ewes inseminated by putative carrier F1 rams, and the very high ovulation rate observed for some of these ewe lambs, confirmed the segregation of a major gene with two co-dominant alleles borne by an autosome. The difference between homozygous non-carriers and heterozygous ewes was about one ovulation on the observed scale and 2.2 standard deviations on the underlying scale.

Animals↗

PubMed1995

Casein haplotypes and their association with milk production traits in the Finnish Ayrshire cattle.

Polymorphism of casein genes was studied in half-sib families of artificial insemination bulls of the Finnish Ayrshire dairy breed. Ten grandsires and 300 of their sons were genotyped for the following polymorphisms: alpha s1-casein (B, C), beta-casein (A1, A2), the microsatellite within the kappa-casein gene (ms5, ms4) and kappa-casein (A, B, E). Nine different combinations of these alleles, casein haplotypes, were found. Associations between casein haplotypes and milk production traits (milk and protein yield, fat and protein percentage and milking speed) were studied with ordinary least-squares analysis to find a direct effect of the haplotypes or an association within individual grandsire families using the granddaughter design. Estimated breeding values of sons were obtained from cow evaluation by animal model. No direct effect of the casein haplotypes on the traits was found. Within grandsire families, in one out of four families the chromosomal segment characterized by haplotype 3 (B-A2-ms4-A) was associated with an increase in milk yield (P < 0.01) and a decrease in fat percentage (P < 0.01) when contrasted with haplotype 8 (B-A1-ms4-E). The results provide evidence that in the Finnish Ayrshire breed at least one quantitative trait locus affecting the genetic variation in yields traits is segregating linked to either haplotype 3 (B-A2-ms4-A) or 8 (B-A1-ms4-E).

Animals↗

PubMed1994

Present and future uses of selection index methodology in dairy cattle.

Selection indexes have been extensively applied in the estimation of breeding value of dairy cattle for single traits as well as for combinations of traits for selection purposes. Milestones in methodology, such as multiple-trait evaluation procedures by BLUP, (co)variance component estimation, nonlinear models, discounted gene flow, dynamic programming, and international sire evaluations, together with increased computing power and the development of integrated AI and recording schemes, have contributed to efficient implementation of selection indexes and are reviewed in this article. Results of an international survey on evaluation practices and breeding programs are presented, demonstrating wide adoption of index selection for total merit and the need for further applications. Results from a simulation study on the efficiency of index selection for total merit are also presented; when the breeding goal includes, in addition to production traits, functional nonproduction traits such as mastitis resistance and fertility, failure to consider these traits in the selection index decreases efficiency 15 to 25%. Future applications are also discussed in view of advances in the areas of genome mapping, marker detection, and international comparisons. Further research should focus on functional nonproduction traits.

Animal Husbandry↗

PubMed1998

Development of an udder health index for sire selection based on somatic cell score, udder conformation, and milking speed.

Genetic parameters of subjectively scored milking speed and somatic cell score were estimated using REML and a sire model. Approximately 250,000 records were used. Heritabilities were 0.15 for milking speed and 0.14 and 0.16 for lactation mean somatic cell score (SCS) for first and second lactations, respectively. Genetic correlations between milking speed and SCS were 0.41 and 0.25 for first and second lactations, respectively, indicating that faster milking was associated with increased SCS. Genetic parameters for milking speed, SCS, and udder conformation were estimated using REML and an animal model. Records from approximately 120,000 cows were used. Genetic correlations were greatest for udder depth (-0.26) with SCS and for width of rear udder attachment (-0.24) with milking speed. An udder health index for use in sire selection was developed for an aggregate genotype that included subclinical mastitis in lactations 1 and > or = 2, clinical mastitis in lactations 1 and > or = 2, and milking time. Respective economic weights were -$12, -$31, -$15, -$59, and -$11 per genetic standard deviation. Traits in the selection index were milking speed, udder conformation, and SCS in first and later lactations. Standardized weights for a simple index for sires based on estimated breeding value from 50 daughter records were 5.5, -1.2, 3.5, -3.9, and -8.7 for udder depth, front teat length, milking speed, and SCS for first and later lactations, respectively. The accuracy of the index was 0.776, an increase of 15% over an index with only SCS.

Animals↗

PubMed2003

Progeny testing and selection intensity for Holstein bulls in different countries.

International Bull Evaluation Service (Interbull) Holstein evaluations from February 1995 through February 2003 were used to determine characteristics of progeny testing for Holstein bulls in Australia, Canada, Denmark, France, Germany, Italy, New Zealand, Sweden, The Netherlands, and the United States. The decision to graduate a bull from progeny test (PT) was assumed to have been made based on the second Interbull evaluation, and graduation was defined as the addition of 200 daughters in the period 2.5 to 4.5 yr later. Mean bull age at PT decision varied across countries by 12 mo. Mean numbers of herds and daughters ranged from 39 to 111 and 54 to 144, respectively. Countries with higher requirements for official evaluations generally had more herds and daughters but older bulls at PT decision. Mean estimated breeding values for yield traits of sires of tested bulls were most similar across countries for fat, differing by only 6.4 kg. The four countries highest for sire protein differed only by 1 kg; however, the range was 12 kg. Percentages of bulls graduated ranged from 4.4 to 14.7 across countries. Selection intensities (standardized selection differentials) tended to be about 1.0 for yield traits. Selection intensities for somatic cell score were generally unfavorable, reflecting selection for negatively correlated yield traits. Reflecting variation in national breeding goals, selection intensities for stature were positive for most countries and highly negative for New Zealand. Selection intensity for fore udder was generally the lowest among the traits examined. All but one country showed positive selection for udder support. These statistics permit comparison of the components of PT programs across country, illustrating possible opportunities for improvement.

Animals↗

PubMed2004

Comparison of methods for handling censored records in beef fertility data: field data.

The purpose of this study was to compare methods for handling censored days to calving records in beef cattle data, and verify results of an earlier simulation study. Data were records from natural service matings of 33,176 first-calf females in Australian Angus herds. Three methods for handling censored records were evaluated. Censored records (records on noncalving females) were assigned penalty values on a within-contemporary group basis under the first method (DCPEN). Under the second method (DCSIM), censored records were drawn from their respective predictive truncated normal distributions, whereas censored records were deleted under the third method (DCMISS). Data were analyzed using a mixed linear model that included the fixed effects of contemporary group and sex of calf, linear and quadratic covariates for age at mating, and random effects of animal and residual error. A Bayesian approach via Gibbs sampling was used to estimate variance components and predict breeding values. Posterior means (PM) (SD) of additive genetic variance for DCPEN, DCSIM, and DCMISS were 22.6d2 (4.2d2), 26.1d2 (3.6d2), and 13.5d2 (2.9d2), respectively. The PM (SD) of residual variance for DCPEN, DCSIM, and DCMISS were 431.4d2 (5.0d2), 371.4d2 (4.5d2), and 262.2d2 (3.4d2), respectively. The PM (SD) of heritability for DCPEN, DCSIM, and DCMISS were 0.05 (0.01), 0.07 (0.01), and 0.05 (0.01), respectively. Simulating trait records for noncalving females resulted in similar heritability to the penalty method but lower residual variance. Pearson correlations between posterior means of animal effects for sires with more than 20 daughters with records were 0.99 between DCPEN and DCSIM, 0.77 between DCPEN and DCMISS, and 0.81 between DCSIM and DCMISS. Of the 424 sires ranked in the top 10% and bottom 10% of sires in DCPEN, 91% and 89%, respectively, were also ranked in the top 10% and bottom 10% in DCSIM. Little difference was observed between DCPEN and DCSIM for correlations between posterior means of animal effects for sires, indicating that no major reranking of sires would be expected. This finding suggests little difference between these two censored data handling techniques for use in genetic evaluation of days to calving.

Animals↗

PubMed1989

The influence of the BoLA-A locus on reproductive traits in cattle.

Associations between the major histocompatibility complex (MHC) and reproductive performance have been reported in humans, mice, rats, pigs and chickens. Only the A locus of the bovine major histocompatibility complex (BoLA-A) has been well characterized, and 42 alleles of this locus have been identified in American cattle. Four studies were conducted to examine the association between alleles of the BoLA-A locus and reproductive performance. Testis size, which is an indicator of early puberty and increased fertility in young bulls, was examined in 440 yearling bulls from nine breeds with a gene substitution model that included the effects of breed, sire, age of dam and age or weight of the bull. Estimated breeding value for twinning was examined with a gene substitution model with 204 cattle from a herd with a high frequency of twinning. Fertility of potential partners having BoLA-A locus alleles in common was examined in a prospective study involving 101 pure-bred Hereford cows mated by artificial insemination to four pure-bred Hereford bulls. The effect of homozygosity on birth weight, preweaning weight gain and post-weaning weight gain was estimated in a sample of 683 calves from nine breeds; 22% of the calves were apparently homozygous and 78% were heterozygous at the BoLA-A locus. There were significant and large effects of some BoLA-A locus alleles on paired testicular volume, but the analyses on the other traits did not show significant associations. Substitution of the W6.1 allele for the W9A allele reduced paired testicular volume by 150 +/- 44 cm3. The W6.1 allele has now been shown to influence a reproductive trait, a production trait and susceptibility to an economically important disease. Selection for these traits may influence the frequency of the large number of alleles at the BoLA-A locus.

Alleles↗

PubMed1992

Divergent selection for immune responsiveness in chickens: estimation of realized heritability with an animal model.

With the aim of improving general disease resistance, chickens were divergently selected for their antibody titers 5 d after immunization with sheep red blood cells for nine generations. Selected and control lines differed significantly for primary and secondary responses after three generations. Heritability of the antibody titer was estimated by REML fitting an animal model using a derivative-free algorithm. The heritability estimate using data on all lines simultaneously was .31. Realized heritability of the antibody titer in the selected lines was estimated by using either the phenotypic cumulative response as the deviation from the control line or the mean breeding values obtained with an animal model. Values from the two methods were consistent, giving a realized heritability of .21 and .25 in the high and low lines, respectively. The genetic trend was not linear and the response to selection tended to accelerate over generations.

Animals↗

PubMed1996

Impacts of cytoplasmic inheritance on genetic evaluations.

Simulation was used to examine the consequences of ignoring cytoplasmic effects on genetic evaluations. Effects on variance component estimation, accuracy of selection, genetic trend, and selection of bull-dams were considered. Comparisons were made for sire and animal models, several levels of cytoplasmic variance, and definition of cytoplasmic effects as either fixed or random. Ten replications with approximately 9000 cows and 20,000 records were simulated for each model and level of cytoplasmic variance. Derivative-free REML was used for estimation of variance components. Ignoring cytoplasmic effects caused overestimation of heritability with an animal model. Permanent environmental variance was underestimated with an animal model and overestimated with a sire model. Results were used for simulation of large (approximately 200,000 cow) data files for analysis of effects on accuracy of selection. Accuracy of selection increased when cytoplasmic effects were accounted for properly. Improvement of predicted breeding values was greater for cows than for sires and increased as cytoplasmic variance increased. Genetic trend also increased slightly, primarily as a function of increased accuracy of bull-dam selection. Little practical difference was detected when cytoplasmic effects were considered to be fixed rather than random.

Animals↗