D W Beckman

Iowa State University, Ames, Iowa, United States

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Publications (6)4.22 Total impact

  • K L Shirley · D W Beckman · D J Garrick
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    ABSTRACT: Pulmonary arterial pressure (PAP) is an indicator of resistance to blood flow through the lungs and when measured at high altitude is a reliable predictor of susceptibility of an animal to brisket disease, a noninfectious cardiac pulmonary condition. (Co)-variance components for PAP, birth weight, and adjusted 205-d weaning weight were estimated from 2,305 spring-born, registered Angus cattle from a Colorado ranch at an elevation of 1,981 m. A single measure of PAP was collected after weaning on animals born from 1984 to 2003. The same licensed veterinarian measured every animal. Multitrait animal models with and without PAP maternal effects were fitted for a pedigree including 132 sires and 793 dams. The interaction of year x sex was a significant fixed effect (P <0.05) for PAP, but age of dam was not. Age at PAP testing was a significant (P <0.1) linear covariate for PAP, and scores increased 0.012 +/- 0.007 mmHg X d(-1) of age. Heritability of PAP direct was 0.34 +/- 0.05. Maternal heritability converged to a boundary at 0.0, and the model with maternal genetic effects for PAP was not significantly better than a model with only direct effects. Phenotypically, PAP was uncorrelated with birth or weaning weights. Genetically, PAP appeared to have positive, unfavorable relationships with direct effects for birth (0.49 +/- 0.12) and weaning weight (0.50 +/- 0.18). Positive correlations imply sires whose offspring exhibited resistance to brisket disease had lower weights and gains. A model that evaluated PAP in females and males as different traits had heritability estimates for each sex of 0.38 +/- 0.07 and 0.46 +/- 0.09, respectively, with a genetic correlation of 0.64 +/- 0.12 between the sexes and was not significantly better than the model assuming homogeneity by sex and a unit genetic correlation between sexes. The results suggest that PAP is moderately heritable in spring-born Angus cattle acclimatized and tested at high altitude, and selection for low PAP scores would be effective. Selection for growth at low altitude will produce cattle less suited to high altitude.
    No preview · Article · May 2008 · Journal of Animal Science
  • D W Beckman · R M Enns · S E Speidel · B W Brigham · D J Garrick
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    ABSTRACT: The objective of this study was to quantify the role of maternal effects on docility in Limousin cattle. Docility scores were obtained at weaning while animals were restrained in a squeeze chute. Scores 1 through 6 represented a docile to aggressive temperament, respectively, and were provided by the North American Limousin Foundation. Observations with unknown age of dam, contemporary groups containing less than 10 observations, contemporary groups with no variation, and single-sire contemporary groups were removed, leaving 21,932 observations. A 2-generation pedigree file compiled from animals with observations contained 49,459 animals. Fixed effects were weaning contemporary group and age of dam (2, > or =3 yr). Six animal models encompassed combinations of random factors: direct genetic, maternal genetic, and maternal permanent environmental effects. The model D was the most basic, containing direct genetic and residual effects, and it resembled the method currently used by the North American Limousin Foundation for genetic evaluation of docility. Maternal genetic or permanent environmental effects were separately added to the model D, denoted as models DM and DC, respectively. Model DMC contained all random factors. Models DM-Zero and DMC-Zero were equivalent to models DM and DMC, respectively, but with zero direct-maternal genetic covariance. Direct heritability estimates were moderate for all models (0.29 +/- 0.02 to 0.38 +/- 0.03). Maternal heritability estimates were low, ranging from 0.01 +/- 0.01 (DM-Zero) to 0.05 +/- 0.02 (DM). Negative direct-maternal genetic correlations of -0.41 +/- 0.09 and -0.55 +/- 0.09 were estimated for models DM and DMC, respectively. The proportion of phenotypic variance accounted for by maternal permanent environmental effects was 0.03 +/- 0.01, 0.04 +/- 0.01, and 0.02 +/- 0.01 for models DC, DMC, and DMC-Zero, respectively. Likelihood ratio tests indicated that model DMC best fit the data. Although maternal genetic and maternal permanent environmental effects were significant, they accounted for only 8% (model DMC) of the phenotypic variance, and a Spearman rank correlation of 0.99 between models D and DMC showed sires did not rank differently with or without inclusion of these effects. Given these results, inclusion of maternal effects to the genetic evaluation of docility in Limousin cattle does not seem warranted.
    No preview · Article · Apr 2007 · Journal of Animal Science
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    ABSTRACT: The ,objectives of this ,study were ,to compare,the current method,used for genetic evaluation of docility to a model including not only direct, additive effects but maternal effects as well and to determine ,the relative importance ,of maternal ,effects on docility. Docility scores are obtained at weaning where animals are evaluated,on aggressiveness in ,the processing ,chute. Scores 1 through 6 represent a continuum,from docile to aggressive, respectively. Data used in this study came from the North American Limousin Foundation (NALF). Observations,used ,in the ,analyses ,were ,from contemporary groups of 10 or greater resulting in 23,453 observations and a two generation pedigree of 56,521 animals. Docility was ,analyzed ,using ,a single ,trait multiple component ,animal ,model ,that included ,fixed effects of contemporary group, sex, age of dam; and random direct genetic, maternal genetic, maternal permanent,environmental; and residual effects. Direct and maternal,heritabilities for docility were ,.37±.03 and .04±.01, respectively. Permanent environment was calculated as explaining ,.04±.01 of the ,phenotypic variance. The genetic correlation between ,the direct and maternal effect was -.55±.08. Docility was also analyzed using a single trait single component,model equivalent to the current method. Direct heritability for docility was .66±.02 with the single component ,model. The original
    No preview · Article · Jan 2004
  • D. W. Beckman · D. J. Garrick
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    ABSTRACT: Analyses of docility in Limousin cattle have shown models including maternal or sire by herd interactions as random effects fit significantly better than a model limited to direct genetic and residual random effects. Variance of docility scores between herds is not homogeneous due to the subjective nature of scoring, with some breeders avoiding use of undesirable scores. Most sires have very few progeny and are represented in only a single herd, whereas a very small proportion of sires are widely used across herds. Sire effects that contribute to the estimation of variance components may therefore exhibit heterogeneity, biasing the apparent fit of models that assume homogeneity. The objective of this study was to determine whether maternal or sire by herd interaction effects are appropriate, or an artifact of the nature of this data. Heterogeneous variance was examined in a two- step process. First, absolute estimated residuals were obtained from a model with direct genetic, maternal genetic, sire by herd interaction and residual random effects. Second, these were analyzed in a fixed effects model using SAS. Results indicated sire by herd (P = 0.027) was significant. However, sums of squares for herd effects (F = 4.62) was nearly twice that of sire effects (F = 2.68), and over four times that of the sire by herd interaction (F = 1.09), implying herd effects account for most of the heterogeneity observed in docility scores. Absolute residuals were further analyzed in a random effects model using ASReml. As expected, there was no genetic variation in direct or maternal genetic effects. However, the proportion of phenotypic variance accounted for by the interaction between sire and herd was 0.02 ± 0.01. These results imply significance of maternal and sire by herd interaction effects inferred by previous research is, in fact, an artifact of the data. Heterogeneous variance due to herd effects is likely a result of the subjective method used to allocate docility scores.
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    D W Beckman · S E Speidel · B W Brigham · D J Garrick · R M Enns
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    ABSTRACT: Stayability (ST) is an economically relevant trait in most cow/calf production systems and body condition score (BCS) is a potential indicator of ST. Stayability, defined as a binary trait in most published genetic evaluations, is achieved when females calve at both two and six years of age. The objective of this research was to estimate genetic parameters for BCS and ST and determine whether a genetic relationship exists that would allow BCS to be used as an early indicator of ST. Early indicators of ST could be incorporated in the genetic evaluation of ST to improve accuracy of EPD at earlier ages. Data and pedigree information came from the Red Angus Association of America (RAAA). Stayability and body condition score were analyzed as continuous traits. Three separate linear analyses were performed. Each contained fixed effects of body condition score (BCSCG) and stayability (STCG) contemporary groups. REML procedures were used to estimate random direct genetic and residual variances for BCS and ST from a two trait animal model for stayability to 2, 3, and 4 years of age.. Separate bivariate analyses were conducted for ST to 6 years and BCS at two (AGE2), three (AGE3), or four years of age (AGE4). Estimates of heritability (SE) for BCS were 0.15 (0.03), 0.12 (0.03), and 0.16 (0.04) for AGE2, AGE3 and AGE4 and for ST were 0.19 (0.05), 0.15 (0.04) and 0.08 (0.04) for each of the subsets of the data, respectively. Genetic correlations between BCS and ST were -0.14 (0.17), -0.12 (0.18), and -0.22 (0.27) for AGE2, AGE3 and AGE4. Introduction Stayability is a complex trait, reflective of a beef females fertility, maternal ability and health (Martinez et al., 2003). The measure of lifetime success of a female is profit driven, based on her ability to avoid culling. Females who remain in the herd longer reduce the number of replacements kept and the cost associated with their development, as well as increasing productivity as more females remain in higher-producing age groups (Martinez et al., 2004). Difficulties encountered when analyzing stayability (ST) are the result of the binary nature of the trait, which increases computational demand. Also, females with stayability observations have been culled (failure) or are in the later stages of there life (success), making accurate predictions and selection more challenging. Some studies have investigated traits associated with stayability for a better understanding of the underlying process involved. Rogers et al. (2004) found that early indicators of longevity such as age at first calving and calf birth weight were not useful predictors of subsequent longevity. Dystocia and larger maternal breeding values for pre-weaning gain were found to significantly increase the risk of a female being culled. The objective of this study was to estimate genetic parameters for BCS and ST for females ages two, three and four and to determine the magnitude of the genetic relationship between these with the goal to use BCS as an early indicator of ST.
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Publication Stats

31 Citations
4.22 Total Impact Points

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  • 2008
    • Iowa State University
      • Department of Animal Science
      Ames, Iowa, United States
  • 2007
    • Colorado State University
      • Department of Animal Sciences
      Fort Collins, Colorado, United States