Univ. of Guelph scientists determined genetic parameters for ten growth and ultrasound traits in 2,172 yearling beef bulls and four carcass traits in 1,031 finished feedlot steers. Following is a summary of results (Bergen et al. 2005. Can. J. Anim. Sci. 84:37). • Except for loin muscle width, heritabilities for most traits were moderate to high, ranging from 0.25 for loin muscle depth to 0.83 for hip height, suggesting that selection for these traits would be quite effective. • Genetic correlations indicated that selecting yearling bulls for increased growth rate and hip height would result in greater carcass weight, increased loin muscle area, and reduced carcass marbling in steers. • Bull ultrasound fat depth was positively correlated with both carcass fat (0.78) and carcass marbling (0.73). • Bull ultrasound intramuscular fat content was negatively correlated with bull loin muscle area (-0.49) and width (-0.79).