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Dallas Center, IA, United States

Lupiani B.,Texas A&M University | Lee L.F.,U.S. Department of Agriculture | Kreager K.S.,Dallas Center | Witter R.L.,U.S. Department of Agriculture | Reddy S.M.,Texas A&M University
Avian Diseases | Year: 2013

Marek's disease (MD) is a lymphoproliferative disease of chickens caused by serotype 1 MD virus (MDV). Vaccination of commercial poultry has drastically reduced losses from MD, and the poultry industry cannot be sustained without the use of vaccines. Retrovirus insertion into herpesvirus genomes is an efficient process that alters the biological properties of herpesviruses. RM1, a virus derived from the virulent JM strain of MDV, by insertion of the reticuloendotheliosis (REV) long terminal repeat (LTR), was attenuated for oncogenicity but retains properties of the parental virus, such as lymphoid organ atrophy. Here we show that insertion of the REV LTR into the genome of vaccine strain CVI988 resulted in a virus (CVRM) that replicated to higher levels than parental CVI988 in cell culture and that remained apathogenic for chickens. In addition, CVRM showed protection indices similar or superior to those afforded by CVI988 virus in laboratory and field protection trials, indicating that it could be developed as a safe and efficacious vaccine to protect against very virulent plus MDV. © American Association of Avian Pathologists.

Brace R.C.,Iowa State University | Fehr W.R.,Iowa State University | Schnebly S.R.,Dallas Center
Crop Science | Year: 2011

Soybean [Glycine max (L.) Merr.] lines with the transgenic event DP-305423-1 produce a higholeate oil and those with the fan1(C1640) and fan3(RG10) alleles produce a low-linolenate oil. The objective of this study was to evaluate the agronomic and seed traits of high-oleate and low-linolenate (HOLL) lines, high-oleate and normal-linolenate (HONL) lines, and normal-oleate and normal-linolenate (NONL) lines selected from four single-cross populations segregating for the three genes. A minimum of 14 F 3:5 lines of each class in the four populations were evaluated in five environments during 2009. The mean fatty ester concentrations averaged across populations were 786 g kg -1 oleate and 24 g kg -1 linolenate for the HOLL lines, 784 g kg -1 oleate and 56 g kg -1 linolenate for the HONL lines, and 226 g kg -11 oleate and 75 g kg -1 linolenate for the NONL lines. The mean yield of the NONL lines was significantly greater than the HOLL lines by 4.5% and the HONL lines by 3.0%. Of the 10 highest yielding lines in each population, 60% were NONL, 25% HOLL, and 15% HONL, which indicated that it would be possible to select cultivars of both classes that yield as well as NONL cultivars. The overlap among the three classes in the distributions of lines for protein, oil, seed weight, maturity, height, and lodging indicated that it would be possible to develop HOLL and HONL cultivars comparable to NONL cultivars for those traits. © Crop Science Society of America.

Poultry breeding companies are facing a new paradigm. Since 2004, extensive resources have been developed to increase understanding of the fundamental biology of the chicken. The chicken genome has been sequenced and revised twice, millions of novel DNA variants have been identified, and new tools have been created that allow rapid and inexpensive detection of these DNA variations. These developments have led to the establishment of molecular-based breeding programs within major poultry breeding companies that are revolutionizing the primary poultry breeding industries. Costs of sequencing continue to drop and are predicted to eventually reach the point where it is feasible to sequence the entire genome of elite birds before selection. There are multiple challenges to be resolved before this information can be fully incorporated into a breeding program. These include handling and analyzing the extremely large data sets generated, understanding which genes, variants, or both are relevant for commercial production traits, development of new bio-informatic tools, and integration of molecular information with traditional breeding programs. The novel variation identified within elite commercial lines will lead to enhancements in commercial breeding programs. Applications of this information include whole genomic selection, parentage identification, trait association studies, and quality control. © 2014 Poultry Science Association Inc.

Wolc A.,University of Life Sciences in Poznan | Wolc A.,Iowa State University | Arango J.,Dallas Center | Settar P.,Dallas Center | And 2 more authors.
Poultry Science | Year: 2011

The objectives of this study were to estimate genetic parameters for egg production over the age trajectory in 3 layer lines, which represent different biotypes for egg production, and to validate the use of breeding values for slope as a measure of persistency to be used in the selection program. Egg production of more than 26,000 layers per line from 6 consecutive generations were analyzed with a random regression model with a within-hatch-nested fifth-order fixed-regression polynomial and linear polynomials for random additive genetic and permanent environmental effects. Daily records were cumulated into biweekly periods. In all lines, a nonzero genetic variance for mean and slope and a positive genetic correlation between mean and slope were estimated. Genetic variance of egg production by 2-wk period was low at the beginning of lay and increased as the birds aged for all 3 lines, which resulted in heritability estimates increasing with age. Breeding values for slope reflected the shape of the egg production curve well and can be used to directly select for persistency of egg production. © 2011 Poultry Science Association Inc.

Wolc A.,University of Life Sciences in Poznan | Wolc A.,Iowa State University | Arango J.,Dallas Center | Settar P.,Dallas Center | And 7 more authors.
Genetics Selection Evolution | Year: 2011

Background: The predictive ability of genomic estimated breeding values (GEBV) originates both from associations between high-density markers and QTL (Quantitative Trait Loci) and from pedigree information. Thus, GEBV are expected to provide more persistent accuracy over successive generations than breeding values estimated using pedigree-based methods. The objective of this study was to evaluate the accuracy of GEBV in a closed population of layer chickens and to quantify their persistence over five successive generations using marker or pedigree information. Methods. The training data consisted of 16 traits and 777 genotyped animals from two generations of a brown-egg layer breeding line, 295 of which had individual phenotype records, while others had phenotypes on 2,738 non-genotyped relatives, or similar data accumulated over up to five generations. Validation data included phenotyped and genotyped birds from five subsequent generations (on average 306 birds/generation). Birds were genotyped for 23,356 segregating SNP. Animal models using genomic or pedigree relationship matrices and Bayesian model averaging methods were used for training analyses. Accuracy was evaluated as the correlation between EBV and phenotype in validation divided by the square root of trait heritability. Results: Pedigree relationships in outbred populations are reduced by 50% at each meiosis, therefore accuracy is expected to decrease by the square root of 0.5 every generation, as observed for pedigree-based EBV (Estimated Breeding Values). In contrast the GEBV accuracy was more persistent, although the drop in accuracy was substantial in the first generation. Traits that were considered to be influenced by fewer QTL and to have a higher heritability maintained a higher GEBV accuracy over generations. In conclusion, GEBV capture information beyond pedigree relationships, but retraining every generation is recommended for genomic selection in closed breeding populations. © 2011 Wolc et al; licensee BioMed Central Ltd.

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