Since the time of domestication more than 10,000 years ago, cattle have played an increasingly crucial role in the development of human civilizations. Progress has been quite remarkable since the turn of the century; the sequencing of the bovine genome in 2009 launched new avenues for furthering our understanding of theoretical and practical aspects of cattle genetics. Covering a vast array of questions, this book reviews major topics from molecular and developmental genetics, disease resistance and immunogenetics to genetic improvement of dairy and beef breeds, addressing all current problems in the field. This second edition includes a new team of authors and completely new chapters on the genetics of fat production, nutrition, feed intake and efficiency, growth and body composition. Fully updated throughout, it provides a valuable resource on cattle genetics for researchers, breeders, veterinarians and postgraduate students.

Experimental designs historically used for quantitative trait loci (QTL) mapping in cattle have captured a limited number of parental chromosomes and therefore have only detected the few heterozygous QTL within these parents. Consequently, most genome scans have found only a small number of QTL to influence any one trait and genetic improvement in cattle by marker-assisted selection (MAS) has been hindered by this limited information. By using a twenty-nine generation mapping population (N=1,769) that represents the major commercial bloodlines within American Angus, we have captured the majority of the chromosomes represented within the breed. Our experimental design allows the flexibility of using several different analytical approaches which exploit both the full pedigree information and within family variation. This design maximizes the potential for identifying all of the QTL of large effect that segregate within Angus cattle. Our analyses revealed that a large number of QTL of moderate to large effect influence all of the economically important growth and carcass traits, even for traits under strong selection. Despite considerable selection pressure by Angus producers on economically important traits over the past 30 years there remains a wide range in the allele frequency of trait-enhancing QTL. Thus genetic improvement programs that use information at only one, or a few QTL will have little value in beef cattle. Strategies must quickly be devised to simultaneously test for multiple QTL for MAS to be economically viable. The identification of multiple QTL underlying variation in carcass, growth and reproductive traits in this study will assist in the development of QTL tests. Ideally, QTL information will be integrated with available phenotypic data for the estimation of EPDs in cattle to allow producers to select for genetically superior animals.

Quantitative Trait Loci (QTL) is a topic of major agricultural significance for efficient livestock production. This book covers various statistical methods that have been used or proposed for detection and analysis of QTL and marker-and gene-assisted selection in animal genetics and breeding.

The general goal of the present work was to map QTL (quantitative trait loci) for economically important traits in beef cattle.

Covers all aspects of the beef industry from paddock to plate.