Reproduction and Maternal Characteristics of Diverse Breeds of Cattle used for Beef production

Abstract

Grading up or straightbreeding to Shorthorns, Herefords and Angus was the dominant system employed in beef production from the late 1800's until the 1960's in the United States. Although most cattlemen had their favorite breed, the adage that "there is more variation within breeds than between breeds" was generally accepted as a truism among beef cattle breeders throughout this period. As, Lush¹ pointed out, stockmen were misled by this attitude into believing that genetic differences between breeds were "not real after all" or at least not very important. Recognition of the importance of heterosis (difference between mean for F₁ crosses and mean for parental breeds) from diallel crossing experiments conducted in the 1960's and interest in increasing output components fo beef production, stimulated interest in crossbreeding to breeds with greater genetic potential for milk production, growth rate and mature size. As a result, a large number of breeds, introduced from Europe via quarantine facilities in Canada, became available to North American beef producers. Interest in the newly introduced breeds and in other breeds previously considered only for dairying coincided with the establishment of the Roman L. Hruska U.S. Meat Animal Research Center (MARC) in the late 1960's. The Germ Plasm Evaluation (GPE) Program was initiated in 1969 at MARC to characterize a broad spectrum of breeds that differed widely in genetic potential for growth rate, milk production, carcass composition and mature size. The purpose of this paper is to review results from the GPE program concerning genetic variation among breeds relative to that within breeds for reproduction and maternal traits important to beef production.