Prediction of retail product and trimmable fat in beef cattle using ultrasound or carcass data

The most widely used system to predict percent retail product from the four primals in beef cattle is USDA yield grade. The purpose of this study was to determine if routine ultrasound measurements and additional rump measurements could be used to more accurately predict the percent lean from the four primals than the carcass measurements going into the USDA yield grade equation. This study utilized market cattle (n = 471) consisting of Angus bulls, Angus steers, and crossbred steers. The right side of each carcass was fabricated into retail cuts, lean trim, fat, and bone; weights of each component were recorded. Percent retail product from the four primals was then expressed as a percentage of side weight. Traditional carcass measures collected were: 1) hot carcass weight (HCW), 2) 12-13th rib fat thickness (CFAT), 3) 12-13th rib ribeye area (CREA), and 4) percent kidney, pelvic, and heart fat (KPH). Live animal ultrasound measures collected within seven days prior to harvest were: 1) scan weight (SCANWT), 2) 12-13th rib fat thickness (UFAT), 3) 12- 13th rib ribeye area (UREA), 4) subcutaneous fat thickness over the termination of the biceps femoris in the rump(reference point) (URFAT), 5) depth of gluteus medius under the reference point (URDEPTH), and 6) area of gluteus medius anterior to the reference point (URAREA). A stepwise regression was performed to develop models to predict percent retail product from the four primals based on carcass measures or ultrasound measures, and comparisons were made between the models. Significant measures (P \u3c 0.001) for the carcass data were CFAT, KPH, and CREA with a model R2 = 0.297. Significant measures (P \u3c 0.001) for the ultrasound data were UFAT, UREA, SCANWT, URDEPTH with a model R2 = 0.448. This study also validated 10 equations which had been either previously reported (n = 8), or modified (n = 2) from a previously reported equation to predict percent retail product in beef cattle. Validation of these equations included reporting R2, root mean squared error, and P-value for each equation

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)

Comparison of Ultrasound and Carcass Measures to Predict Percentage of Beef Retail Product from Four Primal Cuts—Final 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 retail product from the four primals (PRP4P). Data were collected on market ready cattle (n=471). Traditional carcass measures collected were: 1) hot carcass weight (HCW), 2) 12–13th rib fat thickness (CFAT), 3) 12–13th rib ribeye area (CREA), and 4) percentage of kidney, pelvic, and heart fat (CKPH). Live animal ultrasound measures collected were: 1) scan weight (SCANWT), 2) 12–13th rib fat thickness (UFAT), 3) 12–13th rib ribeye area (UREA), 4) subcutaneous fat thickness over the termination of the biceps femoris in the rump (reference point) (URFAT), 5) depth of the gluteus medius below the reference point (URDEPTH), and 6) area of the gluteus medius anterior to the reference point (URAREA). A model to predict PRP4P was developed for both carcass and RTU measures. Significant measures (P \u3c 0.001) for the carcass data were CFAT, CREA, and CKPH with a model R2 = 0.297. HCW was not a significant trait in the carcass data model (P = 0.171). Significant measures (P \u3c 0.001) for the RTU data were SCANWT, UFAT, UREA, and URDEPTH with a model R2 = 0.448

Prediction of Lean in the Round Using Ultrasound Measurements

Real-time ultrasound (RTU) images were collected on 170 Angus sired steers. These steers had routine carcass data collected, as well as lean mass weights after round fabrication. Lean weight in the round was determined by adding the peeled knuckle, inside round, and outside round weights together. There were four significant independent variables (P \u3c .05) used to predict lean in the round from live measurements. They were: live weight (WT), ultrasound fat thickness between the 12th and 13th ribs (UFT), ultrasound ribeye area between the 12th and 13th ribs (UREA), and gluteus medius lean depth (GM)

Beef Cattle Breeding Project Progress Report: Body Composition EPD 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

Beef Cattle Breeding Project Progress Report: Growth Trait EPDs for 1998-, 1999-, and 2000-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 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

Use of Linear and Non-linear Growth Curves to Describe Body Weight Changes of Young Angus Bulls and Heifers

The objectives of the current study were to describe bodyweight (BW) changes of purebred Angus bulls and heifer and to evaluate bias in the adjustment of weaning weight measures to a 205-d age. Linear and non-linear growth functions were used to evaluate changes in BW. Models used were a simple linear regression model fitting cubic polynomial of age at measurement (model I) and a Logistic model (model II) . Predicted mature weight for bulls was 763 kg (1,678.6 lbs.) as compared to 541.9 kg (1192.2 lbs.) for heifers. Bulls attained a maximum average daily weight gain (ADG) of 1.75 kg/d (3.85 lbs/d) at a mean age of 296 d. The maximum ADG attained by heifers was 1.24 lb/d (2.73 lb/d) at a mean age of 261 d. Beef Improvement Federation procedures underestimated 205 d BW of bull calves measured at relatively younger ages and overestimated those measured at later ages. However, the extent of this bias seems to vary depending on the rate of growth of individual calves. The current results suggest that producers should consider creating contemporary groups with a smaller spread in age

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