Research Topics
| L D Van VleckSummaryAffiliation: University of Nebraska Country: USA Publications
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Publications
Implications of cloning for breed improvement strategies: are traditional methods of animal improvement obsolete?L D Van Vleck
USDA, ARS, U S Meat Animal Research Center, A218 Animal Sciences, University of Nebraska, Lincoln 68583 0908, USA
J Anim Sci 77:111-21. 1999..Cloning has a place in that inventory but, in the long-term, the use of cloning will need to be managed to be cost effective for the improvement of quantitative characters...- Genetic parameters for six measures of length of productive life and three measures of lifetime production by 6 yr after first calving for Hereford cowsG E Martinez
Department of Animal Science, University of Nebraska, Lincoln, NE 68583-0908, USA
J Anim Sci 82:1912-8. 2004..10 (15.63) kg/yr, for L6, NB, NW, and CW, respectively. Selection for LPLIO or LP could be successful in a breeding program, but may be relatively slow due to the low magnitude of heritability and extended generation interval... - Genetic parameters for stayability, stayability at calving, and stayability at weaning to specified ages for Hereford cowsG E Martinez
Department of Animal Science, University of Nebraska, Lincoln, NE 68583, USA
J Anim Sci 83:2033-42. 2005..Selection for weaning and yearling weights resulted in little correlated response for any of the measures of stayability... - Genetic analysis of carcass traits of steers adjusted to age, weight, or fat thickness slaughter endpointsA Ríos-Utrera
Department of Animal Science, University of Nebraska, Lincoln 68583 0908, USA
J Anim Sci 83:764-76. 2005..For some carcass traits, however, magnitude of change would depend on effect of endpoint on h(2) and phenotypic variance. Correlated responses to selection would differ depending on endpoint... - Genetic evaluation of dairy cattle with test-day models with autoregressive covariance structures and with a 305-d modelR M Sawalha
Department of Animal Science, University of Nebraska, Lincoln, 68583 0908, USA
J Dairy Sci 88:3346-53. 2005..71 to 0.87 for sires and 0.80 to 0.87 for cows). More genetic improvement can be achieved by using TD models to select for animals for higher milk, fat, and protein yields, and lower SCS than by using models with 305-d lactation records... - Estimates of correlations among yield traits and somatic cell score with different models to adjust for bovine somatotropin effects on Holstein dairy cowsA Al Seaf
Department of Animal Science, University of Nebraska, Lincoln, NE, USA
Genet Mol Res 6:67-78. 2007..For all three data sets and all traits, no important differences in estimates of genetic parameters were found for the two models that adjusted for bST and the model that did not... - Influence of breed, heterozygosity, and disease incidence on estimates of variance components of respiratory disease in preweaned beef calvesG D Snowder
ARS, USDA, U S Meat Animal Research Center, Clay Center, NE 68933, USA
J Anim Sci 83:1247-61. 2005..The estimated heritability based on an underlying continuous scale was large (h2 = 0.48), inferring response to selection for BRD resistance could be large if the phenotype for BRD resistance was known... - Lack of evidence for cytoplasmic effects for four traits of Polypay sheepL D Van Vleck
ARS, USDA, U S Meat Animal Research Center, Lincoln 68583 0908, USA
J Anim Sci 83:552-6. 2005..There were 260 and 261 cytoplasmic lines for fleece weight and number born, and 861 and 882 for weaning and birth weights... - Impact of bovine somatotropin on ranking for genetic value of dairy sires for milk yield traits and somatic cell scoreA Al Seaf
Department of Animal Science, University of Nebraska, Lincoln, NE, USA
Genet Mol Res 6:79-93. 2007.... - Bovine respiratory disease in feedlot cattle: phenotypic, environmental, and genetic correlations with growth, carcass, and longissimus muscle palatability traitsG D Snowder
US Meat Animal Research Center, ARS, USDA, Clay Center, NE 68933, USA
J Anim Sci 85:1885-92. 2007.... - Number of calves born, number of calves weaned, and cumulative weaning weight as measures of lifetime production for Hereford cowsG E Martinez
Department of Animal Science, University of Nebraska, Lincoln, NE 68583-0908, USA
J Anim Sci 82:1903-11. 2004..37) kg/yr for WWL, YWL, IXL, and CTL, respectively. Selection for lifetime production as measured by NB, NW, or CW could be effective but would be relatively slow due to low estimates of heritability and to increased generation intervals... - Genetic relationships between sex-specific traits in beef cattle: mature weight, weight adjusted for body condition score, height and body condition score of cows, and carcass traits of their steer relativesK A Nephawe
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA
J Anim Sci 82:647-53. 2004..However, genetic correlations of cow traits, with the possible exception of BCS, with HCWT may be too large to ignore. Selection for steers with greater HCWT would lead to larger cows... 
Effect of pen mates on growth, backfat depth, and longissimus muscle area of swineW L Hsu
Department of Animal Science, University of Nebraska, Lincoln 68583 0908, USA
J Anim Sci 88:895-902. 2010....- Covariance functions and random regression models for cow weight in beef cattleJ A Arango
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA
J Anim Sci 82:54-67. 2004..Results suggest that although cow weights do not fit a repeatability model with constant variances as well as CF-RRM, a repeatability model might be an acceptable approximation for prediction of additive genetic effects... - Genetic response to selection for weaning weight or yearling weight or yearling weight and muscle score in Hereford cattle: efficiency of gain, growth, and carcass characteristicsR M Koch
Animal Science Department, University of Nebraska, Lincoln 68583-0908, USA
J Anim Sci 82:668-82. 2004..37, 0.14, and -0.54. Selection criteria in all lines improved efficiency of postweaning gain and increased the amount of salable lean meat on an age- or weight-constant basis, but carcasses had slightly lower marbling scores... - Estimates of genetic parameters and genetic change for reproduction, weight, and wool characteristics of Targhee sheepK J Hanford
Department of Animal Science, University of Nebraska, Lincoln 68583 0908, USA
J Anim Sci 81:630-40. 2003..Estimated changes in breeding values over time did not differ substantially for the single-trait and seven-trait analyses, except for traits highly correlated with another trait that was responding to selection... - Estimates of genetic parameters for Holstein cows for test-day yield traits with a random regression cubic spline modelB J DeGroot
Department of Animal Science, University of Nebraska, Lincoln, NE, USA
Genet Mol Res 6:434-44. 2007..Estimates of heritability were greater in lactations two and three. Estimates of heritability increased over the course of the lactation. Estimates of genetic and phenotypic correlations were smaller for test-days further apart... - Effects of age, weight, and fat slaughter end points on estimates of breed and retained heterosis effects for carcass traitsA Ríos-Utrera
Department of Animal Science, University of Nebraska, Lincoln, 68583 0908, USA
J Anim Sci 84:63-87. 2006..Rational exploitation of breeds requires special attention to use of different end points and levels of those end points, mainly for fat thickness... - Breed comparisons of Angus, Charolais, Hereford, Jersey, Limousin, Simmental, and South Devon for weight, weight adjusted for body condition score, height, and body condition score of cowsJ A Arango
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA
J Anim Sci 80:3123-32. 2002..Differences tended to increase when adjusted for condition score, especially in contrasts of continental vs British breeds. Differences among breed groups for height followed differences for weight closely... - Genetic parameters among weight, prolificacy, and wool traits of Columbia, Polypay, Rambouillet, and Targhee sheepC M Bromley
Department of Animal Science, University of Nebraska, Lincoln 68583 0908, USA
J Anim Sci 78:846-58. 2000..These estimates of genetic parameters between prolificacy, weight, and wool traits can be used to construct multiple-trait selection indexes for dual-purpose sheep... - Evaluation of autoregressive covariance structures for test-day records of Holstein cows: estimates of parametersR M Sawalha
Department of Animal Science, University of Nebraska, Lincoln, 68583 0908, USA
J Dairy Sci 88:2632-42. 2005..11 to 0.36. The autoregressive covariance structure among TD residual effects may help to prevent bias in heritability estimates for milk, fat and protein yields, and SCS... - Breed comparisons of Angus, Brahman, Hereford, Pinzgauer, Sahiwal, and Tarentaise for weight, weight adjusted for condition score, height, and body condition scoreJ A Arango
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA
J Anim Sci 80:3142-9. 2002..Important changes for mature size of cows can be achieved by breed substitution with the breeds of sires used in this study... - Comparisons of Angus-, Braunvieh-, Chianina-, Hereford-, Gelbvieh-, Maine Anjou-, and Red Poll-sired cows for weight, weight adjusted for body condition score, height, and body condition scoreJ A Arango
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA
J Anim Sci 80:3133-41. 2002..Cows from Chianina sires were taller than Hereford-Angus cows by 14 to 15 cm across ages. In this study, breed of sire effects were significantly different for the mature size of their daughters... - Models with cytoplasmic effects for birth, weaning, and fleece weights, and litter size at birth for a population of Targhee sheepL D Van Vleck
USDA, ARS, US Meat Animal Research Center, Lincoln, NE 68583 0908, USA
J Anim Sci 81:61-7. 2003..The addition of unusual random effects to the model did not change estimates for the basic parameters. Although some of these effects were significant, especially for BW, the effects on genetic evaluations are likely to be small... - Effects of social interactions on empirical responses to selection for average daily gain of boarsC Y Chen
Department of Animal Science, University of Nebraska, Lincoln 68583 0908, USA
J Anim Sci 87:844-9. 2009..15, 94.03, 7.33, and 84.72 g with empirical correlated responses for genetic social effects from selection for direct effects of 0.93, 1.89, -2.19, and 3.52 g for lines 1 to 4... 
Identification of quantitative trait loci influencing traits related to energy balance in selection and inbred lines of miceD E Moody
Department of Animal Science, University of Nebraska, Lincoln, Nebraska 68583, USA
Genetics 152:699-711. 1999..The presence of a QTL influencing 6-wk weight was also confirmed. Suggestive evidence for additional QTL influencing heat loss, percentage subcutaneous fat, and percentage heart was found for chromosome 1...- Genetic parameters for sex-specific traits in beef cattleR K Splan
Department of Animal Science, University of Nebraska, Lincoln 68583 0908, USA
J Anim Sci 76:2272-8. 1998..These results indicate that selection for some traits expressed in one sex of beef cattle may result in undesirable responses in traits expressed in the opposite sex... - Genetic and environmental factors associated with incidence of infectious bovine keratoconjunctivitis in preweaned beef calvesG D Snowder
ARS, USDA, U S Meat Animal Research Center, Clay Center, NE 68933, USA
J Anim Sci 83:507-18. 2005..Significant breed differences for incidence of IBK may be important to some producers and management systems... - Identification of quantitative trait loci affecting reproduction in pigsJ P Cassady
Animal Science Department, University of Nebraska, Lincoln 68583 0908, USA
J Anim Sci 79:623-33. 2001..Ovulation rate and age at puberty are laborious to measure, and thus marker-assisted selection may provide a practical and efficient method of selection... - Models with nuclear, cytoplasmic, and environmental effects for production traits of Columbia sheepK J Hanford
USDA, ARS, U.S. Meat Animal Research Center, Lincoln, NE 68583-0908, USA
J Anim Sci 81:1926-32. 2003..Cytoplasmic effects were not important. Unusual random effects in the model did not change estimates for basic parameters. Although some effects were significant, especially for BW, effects on genetic evaluations are likely to be small... - Usefulness of subjective ovine milk scores: II. Genetic parameter estimatesG D Snowder
USDA, ARS, US Sheep Experiment Station, Dubois, ID 83423, USA
J Anim Sci 79:869-76. 2001..The need for increasing ewe milking performance and lamb growth rate at first parity in commercial range sheep production systems may be addressed by selection for milk score at first parity... - Usefulness of subjective ovine milk scores: I. Associations with range ewe characteristics and lamb productionG D Snowder
USDA, ARS, US Sheep Experiment Station, Dubois, ID 83423, USA
J Anim Sci 79:811-8. 2001..Results suggest that milk score is an economically important trait in these four breeds and should be considered in management and breeding objectives; at a minimum, the incidence of low milk scores should be kept as small as possible... - Variance components and breeding values for growth traits from different statistical modelsG B Ferreira
Department of Animal Science, University of Nebraska, Lincoln 68583 0908, USA
J Anim Sci 77:2641-50. 1999..Other models resulted in changes in ranking for predicted breeding values and for estimates of direct and maternal heritability. Heritability estimates of direct effects were smallest with sire and sire-maternal grandsire models... - Comparisons of Angus, Charolais, Galloway, Hereford, Longhorn, Nellore, Piedmontese, Salers, and Shorthorn breeds for weight, weight adjusted for condition score, height, and condition score of cowsJ A Arango
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA
J Anim Sci 82:74-84. 2004..In general, breed differences for height followed those for weight except that F1 Nellore cows were tallest, which may in part be due to Bos taurus-Bos indicus heterosis for size... - Genetic parameters for yield traits of cows treated or not treated with bovine somatotropinA Al Seaf
Department of Animal Science, University of Nebraska, Lincoln 68583 0908, USA
J Dairy Sci 90:501-6. 2007.... - Estimation of genetic parameters for average daily gain using models with competition effectsC Y Chen
Department of Animal Science, University of Nebraska, Lincoln 68583 0908, USA
J Anim Sci 86:2525-30. 2008..We concluded that including either pen effects or environmental competition effects as random effects in the model avoids bias in estimates of genetic variances but that including pen effects is much easier... - Genetic relationship between milk score and litter weight for Targhee, Columbia, Rambouillet, and Polypay sheepR M Sawalha
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA
J Anim Sci 83:786-93. 2005..Although estimates are variable, the average of the estimates of the genetic correlation suggests that LW can be improved by selecting ewes for favorable MS... - Bovine respiratory disease in feedlot cattle: environmental, genetic, and economic factorsG D Snowder
USDA, ARS, US Meat Animal Research Center, Clay Center, NE, USA
J Anim Sci 84:1999-2008. 2006..The economic loss associated with lower gains and treatment costs for BRD infection in a 1,000-cattle feedlot was estimated as dollar 13.90 per animal, not including labor and associated handling costs... - Across-breed adjustment factors for expected progeny differences for carcass traitsL D Van Vleck
USDA, ARS, Roman L Hruska US Meat Animal Research Center, Lincoln, NE 68583 0908, USA
J Anim Sci 85:1369-76. 2007..65 to 2.82. The solutions for breed of sire, differences in mean EPD, and regression coefficients are then used to calculate adjustment factors for EPD of 11 breeds including the arbitrary base breed, Angus... - Effects of sire misidentification on estimates of genetic parameters for birth and weaning weights in Hereford cattleS L Senneke
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA
J Anim Sci 82:2307-12. 2004..Results of this study indicate that misidentification of sires would severely bias estimates of genetic parameters and would reduce genetic gain from selection... - Bias in genetic evaluations by records of cows treated with bovine somatotropinS Tsuruta
Department of Animal Science, University of Nebraska, Lincoln 68583 0908, USA
J Dairy Sci 83:2650-6. 2000..99. However, relatively large bias was found for individual animals. This result suggests that bias in genetic evaluation caused by ignoring bST treatment may be significant... - Multiple-trait Gibbs sampler for animal models: flexible programs for Bayesian and likelihood-based (co)variance component inferenceC P Van Tassell
Roman L Hruska U S Meat Animal Research Center, USDA ARS, University of Nebraska, Lincoln 68583 0908, USA
J Anim Sci 74:2586-97. 1996..Correlations between estimates from MTGSAM using flat priors and MTDFREML all exceeded .99... - Genetic correlations for daily gain between ram and ewe lambs fed in feedlot conditions and ram lambs fed in Pinpointer unitsL D Van Vleck
Roman L Hruska U S Meat Animal Research Center, ARS, USDA Lincoln, NE 68583 0908, USA
J Anim Sci 78:1155-8. 2000..83 suggest that daily gain of rams fed in Pinpointer units will reflect genetic expression for daily gain in both ram and ewe lambs fed under feedlot conditions... - Bayesian analysis of twinning and ovulation rates using a multiple-trait threshold model and Gibbs samplingC P Van Tassell
Roman L Hruska U S Meat Animal Research Center, USDA, ARS, Lincoln, NE 68583 0908, USA
J Anim Sci 76:2048-61. 1998..517. Use of a threshold model could allow for more rapid genetic improvement of the twinning herd through improved identification and selection of genetically superior animals because of higher heritability on the underlying scale... - Prediction of genetic values for feed intake from individual body weight gain and total feed intake of the penA J Cooper
Department of Animal Science, University of Nebraska, Lincoln 68583 0908, USA
J Anim Sci 88:1967-72. 2010.... - Genetic parameters for weight, weight adjusted for body condition score, height, and body condition score in beef cowsJ A Arango
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA
J Anim Sci 80:3112-22. 2002..67 for CS. Genetic correlations were 0.80, 0.86, 0.43, and -0.04 for CW-CH, WA-CH, CW-CS, and CH-CS, respectively. Results suggest that repeatability models can be used to model weights and heights in this population... - Estimates of genetic parameters and selection strategies to improve the economic efficiency of postweaning growth in lambsG D Snowder
USDA, ARS, U S Meat Animal Research Center, Clay Center, NE 68933, USA
J Anim Sci 81:2704-13. 2003..Selection for ADG may be a practical approach for indirectly improving efficiency of gain in lambs... - Genetic and phenotypic parameters for dietary selection of mountain big sagebrush (Artemisia tridentata Nutt. ssp. vaseyanaG D Snowder
USDA, ARS, US Sheep Experiment Station, Dubois, ID 83423, USA
J Anim Sci 79:486-92. 2001..These results contribute to a greater understanding of dietary preferences in freely grazing sheep, and suggest opportunities to improve production efficiency and forage management through selection for dietary preferences... - Genetic relationships between scrotal circumference and female reproductive traitsG Martínez-Velázquez
Department of Animal Science, University of Nebraska, Lincoln 68583 0908, USA
J Anim Sci 81:395-401. 2003..These results suggest that genetic response in female reproductive traits through sire selection on yearling SC is not expected to be effective... - Technical note: Calculation of standard errors of estimates of genetic parameters with the multiple-trait derivative-free restricted maximal likelihood programsS D Kachman
Department of Statistics, University of Nebraska, Lincoln 68583 0963, USA
J Anim Sci 85:2375-81. 2007.... - Estimates of parameters between direct and maternal genetic effects for weaning weight and direct genetic effects for carcass traits in crossbred cattleR K Splan
University of Nebraska, Lincoln, USA
J Anim Sci 80:3107-11. 2002..33), fat percentage (0.33), ribeye area (0.29), marbling score (0.28) and adjusted fat thickness (0.25), indicating that maternal effects for weaning weight may be correlated with genotype for propensity to fatten in steers... - Unexpected estimates of variance components with a true model containing genetic competition effectsL D Van Vleck
ARS, USDA, Roman L Hruska U S Meat Animal Research Center, Lincoln 68583 0908, USA
J Anim Sci 83:68-74. 2005..Based on these results, we conclude a high estimate of pen variance may indicate genetic competition effects are important, and ignoring either the pen or competition effects will bias estimates of other components... - Effect of parentage misidentification on estimates of genetic parameters for milk yield in the Mediterranean Italian buffalo populationE Parlato
Department of Animal Science, University of Nebraska, Lincoln 68583 0908, USA
J Dairy Sci 95:4059-64. 2012..Implementation of artificial insemination programs and DNA testing to identify sires are the keys for increasing genetic progress in the Italian buffalo population... - A general review of competition genetic effects with an emphasis on swine breedingC Y Chen
Department of Animal Science, University of Nebraska, Lincoln, NE, USA
Genet Mol Res 6:594-606. 2007.... - Estimates of genetic parameters and genetic change for reproduction, weight, and wool characteristics of Columbia sheepK J Hanford
Department of Animal Science, University of Nebraska, Lincoln 68583 0908, USA
J Anim Sci 80:3086-98. 2002..Estimated changes in breeding values over time did not differ substantially for single-trait and multiple-trait analyses, except for traits highly correlated with another trait that was responding to selection... - Comparison of models for estimation of genetic parameters for mature weight of Hereford cattleJ M Rumph
Department of Animal Science, University of Nebraska, Lincoln 68583 0908, USA
J Anim Sci 80:583-90. 2002..69, 0.13, -0.65, 0.00, and 0.04, respectively. Mature weight is a highly heritable trait that could be included in selection programs and maternal effects should not be ignored when analyzing mature weight data... - Technical note: Use of marker-based relationships with multiple-trait derivative-free restricted maximal likelihoodZ Zhang
Institute for Genetic Diversity, Cornell University, Ithaca, NY 14853, USA
J Anim Sci 85:881-5. 2007..The strategy behind this modification and its design is described. An application is illustrated in a QTL association study for canine hip dysplasia... - Effect of duration of performance test on variance component estimates for lamb growth rateG D Snowder
USDA, ARS, US Sheep Experiment Station, Dubois, ID 83423, USA
J Anim Sci 80:2078-84. 2002..These results indicate that a period of 8 wk or greater was sufficient to observe differences among animals for ADG due to direct genetic effects under this environment... - Effect of competition on gain in feedlot bulls from Hereford selection linesL D Van Vleck
Roman L Hruska US Meat Animal Research Center, Clay Center, NE 68933, USA
J Anim Sci 85:1625-33. 2007.... - Computing numerator relationships between any pair of animalsL D Van Vleck
Roman L Hruska U S Meat Animal Research Center, ARS USDA, Lincoln, NE, USA
Genet Mol Res 6:685-90. 2007..We then multiply the inbreeding coefficient for a dummy animal by two to obtain the numerator relationship between the two animals designated as parents... - Genetic parameters and responses of linear type, yield traits, and somatic cell scores to divergent selection for predicted transmitting ability for type in HolsteinsB J DeGroot
Department of Animal Science, University of Nebraska, Lincoln 68583 0908, USA
J Dairy Sci 85:1578-85. 2002..In this study, divergent selection on PTAT of sires had a significant effect on udder and body traits, but little or no effect on feet and leg traits... - Estimates of genetic parameters for growth traits in Kermani sheepM R Bahreini Behzadi
Department of Animal Sciences, Faculty of Agriculture, Yasouj University, Iran
J Anim Breed Genet 124:296-301. 2007..Maternal effects are significant sources of variation for growth traits and ignoring maternal effects in the model would cause inaccurate genetic evaluation of lambs... - Heritability and repeatability of sexual performance scores of ramsG D Snowder
USDA, ARS, U.S. Sheep Experiment Station, Dubois, ID 83423, USA
J Anim Sci 80:1508-11. 2002..04) and repeatability was high (0.72). These results imply that one screening for sexual performance provides a reliable measure of sexual performance and that favorable response to selection for ram serving capacity may be expected...