Plant & Animal Genome VI Conference

W19

IDENTIFICATION OF QTLS FOR GROWTH AND CARCASS QUALITY IN A CROSS BETWEEN Bos indicus AND Bos taurus

Department of Animal Science, Texas A&M University, College Station, TX USA 77843-2471

In the Spring of 1990, the Texas Agricultural Experiment Station dedicated the cattle and technical resources of the Angleton Research Station to the development of a resource herd which could be used to identify genes responsible for variation in growth and carcass quality traits. Angus and Brahman breeds were selected because of their importance to U.S. beef cattle production, because they are members of two distinct subspecies (Bos indicus and Bos taurus) and because of their between breed differences for marbling and tenderness. The Angleton resource families now comprise 701 individuals from grandparent, parent and progeny generations and we have completed genetic maps of all of the bovine chromosomes using 325 microsatellite markers which span the genome at a resolution of approximately 9 cM. To date, we have detected the presence of genes influencing many of the 62 traits examined in the study. Of particular importance, we have identified four genes that appear to influence marbling and another five genes that influence either taste panel or Warner-Bratzler Shear Force measures of beef tenderness. We have also detected genes that influence post-partum growth but not birth weight. One of these genes is located in the chromosome region which has recently been shown to contain myostatin which is responsible for double muscling. We have also produced a fine map of the region of chromosome 1 which contains the gene responsible for the horned and polled phenotypes in cattle.