HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Abdel-Azim, G. Articles by Freeman, A. E. Search for Related Content PubMed PubMed Citation Articles by Abdel-Azim, G. Articles by Freeman, A. E.

Superiority of QTL-Assisted Selection in Dairy Cattle Breeding Schemes

Department of Animal Science, Iowa State University, Ames 50011

Corresponding author:
G. Abdel-Azim; e-mail:
gaazim{at}iastate.edu.

The superiority of selection schemes employing information about a known quantitative trait locus (QTL) over conventional schemes is examined for dairy cattle breeding schemes. Stochastic simulation of a dairy cattle population with selection practices, structures, and parameters similar to the US Holstein population was implemented. Additive genetic effects were estimated by an animal model. Two schemes were compared: a QTL-assisted selection scheme in which the genotype of a known QTL was accounted for in the animal model as a fixed factor, and a QTL-free selection scheme in which the QTL was simulated but was not fit separately in the animal model. Under the QTL-assisted selection scheme, all animals in the mixed model were assumed to be genotyped for the QTL.

The effect of using QTL information on the genetic response, the frequency of the favorable QTL allele, and the accuracy of evaluation were examined. Moreover, the effect was studied in four distinct paths of selection: active sires, proven young bulls, bull dams, and first-lactation cows. Average superiority values of 4.6, 7.6, 11.7, and 1.1% for genetic response were observed over 16 yr of selection for active sires, young bulls, bull dams, and first-lactation cows, respectively. Frequency of the favorable QTL allele changed faster in bull dams than males, and was the slowest in first-lactation cows. Finally, accuracy of evaluation under the QTL-assisted selection scheme was higher than under the QTL-free selection scheme. Young bulls of the QTL-assisted selection scheme on average had 0.049 higher accuracy, and first-lactation cows had on average 0.185 higher accuracy than corresponding animals of the QTL-free selection scheme.

Abbreviation key: AS = active sires, BD = bull dams, BV = breeding value, EBV = estimated breeding value, FLC = first lactation cows, GFD = gene frequency difference, MAS = marker-assisted selection, QAS = QTL-assisted selection, QFS = QTL-free selection, YB = young bulls

Key Words: dairy cattle breeding scheme • quantitative trait loci • selection

This article has been cited by other articles:

				G. Abdel-Azim and S. Schnell Genetic Impacts of Using Female-Sorted Semen in Commercial and Nucleus Herds J Dairy Sci, March 1, 2007; 90(3): 1554 - 1563. [Abstract] [Full Text] [PDF]

				M. Tamassia, F. Nuttinck, P. May-Panloup, P. Reynier, Y. Heyman, G. Charpigny, M. Stojkovic, S. Hiendleder, J.-P. Renard, and S. Chastant-Maillard In Vitro Embryo Production Efficiency in Cattle and Its Association with Oocyte Adenosine Triphosphate Content, Quantity of Mitochondrial DNA, and Mitochondrial DNA Haplogroup Biol Reprod, August 1, 2004; 71(2): 697 - 704. [Abstract] [Full Text] [PDF]

				G. Abdel-Azim and A. E. Freeman Effects of Including a Quantitative Trait Locus in Selection Under Different Waiting Plans of Young Bulls J Dairy Sci, February 1, 2003; 86(2): 667 - 676. [Abstract] [Full Text] [PDF]