Comparison of Ultrasound and Carcass Measures to Predict the Percentage of Lean Beef from Four Primal Cuts – A Progress Report

The objective of this study was to determine how real-time ultrasound (RTU) measurements would compare with carcass measurements to predict the percentage of lean from the four primals (PERL4P)

Prediction of Percent Retail Product, Retail Product Weight and Hot Carcass Weight From Serially Measured Live Animal Traits

A total of 1,072 observations collected over a six-year period were used to develop prediction models for retail product (percentage and weight) and hot carcass weight from live cattle measures. Independent variables used were: ultrasound fat thickness (UFAT), ultrasound longissimus muscle Area (ULMA), age, hip height (HT), live weight (WT), ultrasound-predicted percent Intramuscular fat (UIMF) and breed composition. Pearson product moment correlations between the dependent and independent variables were often significant (P \u3c .01, P \u3c .05). In the prediction of percent retail product, UFAT accounted for 29 to 42% of the variation. A complete model including all the independent variables explained 20% more of the variation. In the prediction of retail product weight, WT remained a highly significant independent variable accounting for 32 to 78% of the variation. Similarly, WT accounted for 38 to 81% of the variation in hot carcass weight. When independent variables were adjusted to a constant age, models from data adjusted to earlier ages (M-414, M-382) explained more variation than models from data adjusted to a mean age at slaughter (M-448)

Beef Cattle Breeding Project Progress Report: Body Composition EPDs Determined from Ultrasound Measures

The Iowa State University beef cattle breeding project was initiated in 1996, and is being conducted at the Rhodes and McNay Research and Demonstration Farms. The project uses the field data of the American Angus Association (AAA) along with the research resource cattle of the farms to study questions that will enhance the genetic investigations using the field data

Beef Cattle Breeding Project Progress Report: Growth-Trait EPDs for 1998- and 1999-Born Calves

The Iowa State University beef cattle breeding project was designed to develop two selection lines of beef cattle for use as a research base to answer questions that influence genetic improvement. The project was started in 1996 and is being conducted at the Rhodes (central Iowa) and McNay (southern Iowa) research and demonstration farms

Trends in Genetic Parameter Estimates for Ultrasound Back Fat and Rump Fat Thickness Measures in Angus Bulls and Heifers

The objective of the current study was to evaluate heritability and repeatability of serially measured ultrasound 12–13th rib fat thickness (UBF) and rump fat thickness (URF) measures in purebred Angus bulls and heifers.Data included 5000 observations from 912 bulls and heifers.Results from multiple trait analysis showed h2 of 0.29 and 0.40 for yearling UBF and URF, respectively.However, the difference in h2 estimates between yearling measures based on random regression models was smaller.At one year of age, h2 of URF was 0.37 as compared to 0.33 for UBF.Heritability and repeatability values were at their optimum at one year of age. Therefore, yearling bull and 13 to 14 months old heifer ultrasound subcutaneous fat thickness measures from good quality images can be used to evaluate genetic potential of next generation parents in Angus cattle.Information from URF measures may not have an apparent advantage in terms of improving rate of genetic change in percentage retail product in yearling Angus cattle than what could be achieved through selecting against 12th and 13th rib fat thickness