Abstract
Many beef cattle producers are becoming interested in retaining ownership of their cattle through the entire production chain and than selling them to the packer on a grade and yield basis. To be successful, a ranch must know what quality of cattle they are producing. With this knowledge producers can maintain or alter their breeding program as needed to achieve the goal of producing high quality cattle. The McAllen Ranch, located in Raymondville, Texas is one operation that is trying to identify the actual quality of their cattle and where changes to their breeding program might be beneficial. Parentage, growth and carcass data on 602 purebred Beefinaster steers, bulls and heifers commercially fed and slaughtered between 1991 and 1995 were submitted for analysis. From this data, a final set consisting of information on 329 steers sired by 29 different bulls was created and analyzed using Harvey's Mixed Model Least-Squares and Maximum Likelihood Computer Program. The effects of sire, sex, slaughter age and slaughter group were analyzed on the various growth and carcass traits submitted. When compared to two sets of proposed sets of industry standards, both the steers and the bulls performed well in the areas of hot carcass weight, Longissimus muscle area and yield grade. However, both were weaker in the areas of fat thickness, marbling score and quality grade. Improvement of marbling score and quality grade may be difficult without sacrificing lean yield in the near future. Six bulls with the highest progeny means for fat thickness generally sired steers with marbling scores and quality grades which were below the overall mean for these two traits. Significant sire effects were identified in birth weight, adjusted 205 day weight, marbling score and quality grade. Lack of significant sire effects for many of the traits, and the lower estimates of heritabilities than expected may be attributed to the uniform selection for growth traits employed by the McAllen Ranch.
Schick, James B. (1996). Growth and carcass traits and sire effects on growth and carcass traits in purebred beefmaster cattle. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1996 -THESIS -S34.