Potential Value of Ultrasound to Sort Feeder Cattle into More Uniform Groups for Finishing and Marketing

Cattle in three experiments were scanned with ultrasound as feeders to measure ribeye area and thickness of fat cover to determine if cattle could be sorted into outcome groups with respect to carcass yield. Sorting the cattle into low fat cover or large ribeye groups resulted in improved carcass yield grades. There were no effects on carcass quality grades related to sorting of the cattle. Cattle with greater fat cover at the beginning of the feeding period were heavier, seemed to be more mature and had less muscle growth during the finishing period. There were no significant differences in gain among the groups, but cattle with more fat cover had poorer feed efficiency. Ultrasound seems to have potential to sort feeder cattle, but before it can be used in practice, growth curves need to be developed to predict final end points of individual cattle

Long Versus Short Feeding Period for Steer Calves of Three Frame Sizes Fed High Energy Finishing Diets

An experiment was conducted using Angus cross steer calves of three frame sizes (small, medium, and large) to compare performance of two different grow/finish feeding programs. Half of the cattle in each frame size group were fed a high energy ration through the growing period, similar to calves going directly into the feedlot. The other half was fed a low energy ration, similar to a backgrounding diet, for a period prior to the finishing phase. All cattle were fed a high energy ration through the finishing period. The data showed the cattle fed the low energy growing diet experienced some compensatory gains as shown by ultrasound backfat and average daily gains coupled with intakes greater than the increases seen in the high energy treatment. Carcass data and overall performance data showed no ill effects due to the low energy growing ration

Use of Ultrasound Backfat Estimates to Form Marketing Groups Prior to Finishing for Feedlot Steers

An experiment was conducted using 95 Continental crossbred steers. The cattle were sorted by ultrasound 160 days before slaughter into a low backfat group (Low BF) and a higher backfat group (High BF). Half of the Low BF and half of the High BF were implanted whereas the other halves were not. Data from the experiment were used in two hypothetical markets. One market was a high yield beef program (HY) that did not allow the use of implants. The second market was a commodity beef program (CM) that allowed the use of implants. The cattle were priced as an unsorted group (ALL) and two sorted groups (Low BF and High BF) within the HY (non-implanted) and CM (implanted) markets. The CM program had a base price of $1.05/lb hot carcass weight (HCW) with a$0.15/lb HCW discount for quality grade (QG) Select and a $0.20/lb HCW discount for yield grade (YG) 4. The HY program used a base price of$1.07/lb HCW with premiums ($/lb HCW) paid for YG £ .9 (.15), 1.0 - 1.4 (.10), and 1.5 - 1.9 (.03). The carcasses were discounted ($/lb HCW) for YG 2.5 - 2.9 (.03), 3.0 - 3.9 (.15), and ³ 4.0 (.35). This data set provides good evidence that the end point at which to sell a group of cattle depends on the particular market. Sorting had an economic advantage over ALL in the HY Low BF and the CM High BF groups. The HY High BF cattle should have been sold sooner due to the discounts recieved for increased YG. The increased YG was directly affected by an increase in BF. Furthermore, the CM Low BF group should have been fed longer to increase the number of carcasses grading Choice

Estimating Ribeye Area Using a Longitudinal Ultrasound Image of the 12th and 13th Rib Section

A study was performed to determine the feasability of using a measurement of ribeye depth (RED) from a longitudinal ultrasound image to estimate ribeye area (REA). The correlation between RED obtained with ultrasound and REA from a tracing was high for both implanted (r = .49) and non-implanted (r = .45) steers. The mean bias between predicted REA and actual REA was not different from zero. This analysis shows that RED could be an accurate indicator of REA

Using Real-Time Ultrasound During the Feeding Period to Predict Cattle Composition.

A feedlot trial to monitor ribeye area growth, 12th rib backfat, and intramuscular fat accretion was conducted. Data were collected using 112 yearling beef steers. The steers were fed at three intake levels (ad libitum, 95% of ad libitum, or 90% of ad libitum), which when combined with three feeding times (once daily in the morning, once daily in the afternoon, or twice daily), produced nine dietary treatments. Feedlot performance and carcass composition of beef steers was also determined. After analysis of ultrasound measures and animal performance data, equations were developed that described the ribeye area development (R2 = .97), 12th rib fat accretion (R2 = .81), and changes in intramuscular fat percentage (R2 = .79)

Evaluation of Ultrasound Measurement of Fat Thickness and Ribeye Area, II. Repeatability of Measurements.

Data from two feeding trials were used to evaluate repeatability of ultrasound measurements of fat thickness and ribeye area. In each trial, steers were scanned three or four times by one technician. Two beef improvement federation (BIF)-certified technicians with different levels of experience interpreted images from the last scan. Each technician interpreted the image of an individual steer twice on two different days. Repeatability was evaluated as an intra-class correlation. Additional statistics used to evaluate repeatability were the slope and intercepts from a regression analysis, RMSE, and ESD. Ultrasound measurements of fat thickness and ribeye area were repeatable both within and across technicians. The only exception was the across-technician measurements of ribeye area, where an apparent difference in variances of measurements was observed

Evaluation of Ultrasound Measurements of Fat Thickness and Ribeye Area, I. Assessment of Technician Effect on Accuracy

Data from two feeding trials were used to estimate accuracy of ultrasound measurements of fat thickness and ribeye area. In each trial, steers were scanned three or four times by one technician. Two beef improvement federation (BIF)-certified technicians with different levels of experience interpreted images from the last scan taken just before slaughter. Each technician interpreted the image of an individual steer twice on two different days. Accuracy of interpretation was evaluated using simple statistical measures, including means, standard deviations, regression and correlation coefficients, RMSE, and ESD. The overall technician biases for ultrasound measurements of fat thickness and ribeye area were -0.17 cm and 0.63 cm2, respectively. Mean bias by technician indicated a similar direction and amount of bias (-0.14 vs -0.20 cm). However, bias in the measurement of ribeye area by the two technicians took an opposite direction ( -1.28 vs 2.54 cm2). In all cases, technician bias was within the acceptable range for BIF certification. Pearson product moment correlations between carcass and ultrasound measurements of fat thickness and ribeye area were 0.70 and 0.40, respectively. In general, fat thickness for 52% of the steers was measured within ±0.254 cm and for 85.2 % of the steers, fat thickness was measured within ±0.508 cm. For ribeye area, ±51.2 % and ±71.4 % of the steers had measurements within ±6.65 cm2 and ±12.99 cm2, respectively

Effects of Bovine Somatotropin and Revalor-S® on Growth Performance and Carcass Leanness in Beef Cattle

Twenty crossbred steers were used to evaluate bovine somatotropin (bST) and an anabolic steroid implant, Revalor-S® (REV), to improve growth and increase carcass leanness. During the first 70 days on feed, bST-treated steers tended to improve live weight gains, consume more feed, and numerically improve feed utilization for growth. The implanted steers grew faster and utilized feed better than steers not implanted with REV. The improvement in gain and feed utilization for growth was maintained throughout the feeding period for REV-implanted steers. At slaughter, REV steers had heavier carcasses which resulted in more pounds of muscle, bone, and fat. When adjusted for hot carcass weight, bST increased leanness of the carcass as evident by the increased weight of the semitendinosus muscle, more pounds of dissected lean, and fewer pounds of dissected fat. Thus, REV and bST can be used to improve growth performance and increase carcass leanness