| Ultrasound 101 |
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Due to the cost and delay associated with collecting carcass data, the seedstock industry is turning its attention more and more to ultrasound. The use of real time ultrasound has many advantages over carcass derived EPDs. First, data can be collected on both yearling bulls and replacement heifers without harvest. Also, ultrasound allows the opportunity to record information on an entire contemporary group as opposed to the various contemporary groups that are formed according to harvest date. In order to use body composition EPDs or ultrasound data to its full potential, a breeder must have an understanding of ultrasound and its terminology. DEFINITIONS Rib Fat: An external fat measurement taken between the 12th and 13th ribs that is measured in inches. Rib fat is the main factor in the USDA equation. Ribeye Area: Area of the longissimus muscle that is measured in square inches at the 12th rib interface on the beef forequarter. This image tends to be the most difficult to collect and requires the most highly skilled interpreting technician. Both rib fat and ribeye area are taken from the same image. Rump Fat: Measures the depth of fat at the juncture of the gluteus medius and superficial gluteus medius muscles. It is an external measurement taken from an image collected between the hooks and pins of the animal that is measured in inches. The rump fat measurement, coupled with the rib fat measurement, is used to determine more accurately the overall external body fat, enhancing the accuracy of predicting percent retail product (PRP). In most cases, an animal will exhibit more fat over the rump than the rib due to the physiological process of "laying on fat." Therefore, more variation is often displayed in the rump fat measurements of a contemporary group than the rib fat. This image is highly repeatable and is the least difficult to collect or interpret. Intramuscular Fat (%IMF): Percentage of fat in the ribeye area muscle (similar to marbling). This measurement should be collected when cattle are maintaining a high level of nutrition. The field technician collects four images and the values generated by the interpreting software are averaged for an overall %IMF. Scan Weight: This weight is an empty weight taken between 7 days before and 7 days after the scan date. The scan weight can also be collected at scanning. Adjustment factors have been calculated using empty body weights: therefore, it is advised the cattle be held off feed overnight before weighing. Turnaround Time: The National CUP Lab strives to meet a 7 business day turnaround time. If images are received on Monday, the 7th day is Wednesday of the following week (Saturday, Sunday, and holidays are not counted). The turnaround time can be extended if the images are on hold for any reason or if image quality or paperwork problems occur during lab time. Clipping: The National CUP Lab requires cattle to be clipped to within 1/2 inch in all areas of scanning. If cattle are not clipped to within 1/2 inch, they will not be processed. Clipping enhances image quality, and accuracy of the data gathered, and assures that all cattle within a contemporary group are treated as similarly as possible. Barnsheets: A breeder requests or receives barnsheets from the RAAA National Office. These barnsheets are NOT to be returned to the RAAA National Office but are to be handed over to the technician at the time of scanning. Contemporary grouping, management information, and scan weight information must be filled out on these forms in order for the technician to scan the cattle. This is the necessary tool for data to be forwarded to the Red Angus Association. Aloka vs. Classic: The National CUP Lab accepts images from both the Classic 200 and the Aloka 500. Both machines have had software models extensively researched and proven. The Aloka and Classic machines are comparable in size and structure and have its own acceptable calibration. The images displayed for both machines have the same landmarks. As far as data accuracy, the National CUP Lab views both technologies as equally reliable. Another area of ultrasound that does not have complete understanding is the lack of data reported for specific traits on certain animals. To help insure that a breeder does not receive rejected images, the breeder has a responsibility to provide the technician with adequate conditions for scanning. These include providing a squeeze chute with side panel doors to properly restrain the cattle but provide access to the region of scanning. Also, a safe electrical supply that has a grounded 110-volt outlet with a clean signal is required. Weather conditions also play a big role. Cattle must be dry in the region of scanning and out of direct or bright sunlight to allow for the images to be seen clearly on the monitor. Supplemental heat must be provided in the winter months for the equipment and oil. Last and most important of all, the cattle must be clipped and cleaned in the region of scanning. This means that cattle that have more than 1/2 inch of hair in the areas of scanning will not be scanned. Even with the best conditions and preparation some images will not make it though the interpretation process at the National CUP Lab for the following reasons: Image Quality: Each image is quality scored by a CUP Lab technician. The image must have certain landmarks on the image to be interpreted. The presence of these landmarks shows that the image has been properly collected. If landmarks are missing or not correctly represented, the image is rejected and cannot be interpreted. The rejection status could be caused by the animal moving and blurring the image, the technician placing the transducer (probe) in the wrong location, poor contact due to insufficient prepping of the animal, or improper equipment calibration. Narrow Image: Unlike missing or rejected images, an image that is too narrow will only occur with %IMF. The interpreting software has a 4.25cm box that is placed between the 12th and 13th ribs. The box must fit between the external fat and the top of the ribs on the image. If the loin is not deep enough for the box to be placed between the fat and the rib tops, it is considered too narrow. Narrows are most common in heifers and cattle on a low plane of nutrition. The cause is usually the lighter muscle or lighter weight of the cattle, but it can be technician error. It is recommended that breeders scan heifers toward the upper end of the age window to help avoid rejections due to narrow images. Missing Image: The image is missing and is therefore not available for interpretation. The technician could have neglected to save an image, the animal could have escaped the chute and was not returned, or it could be due to technical difficulties. Ultrasound data is a performance trait and should therefore be treated as such. With any performance trait there may be differences in the averages from year to year. Variations in management such as feed, drought, age of scanning, etc. can cause ultrasound data to differ from year to year. To keep ultrasound data in perspective please remember the following points: 1) Ranking of the animals is the most important. Is the ranking among herd sires consistent from year to year? If yes, the data is consistent from year to year. Differences in averages usually are the result of differences in management. 2) Avoid adding variables from year to year. Find the optimum time to scan yearling cattle and stay close to the same average days of age each consecutive year. Find the ultrasound technician that you feel comfortable with and utilize that person. Cattle that are slick shorn in the area of scanning will produce the most consistent data in a contemporary group. Keep contemporary grouping as accurate as possible. 3) If management practices do change, ultrasound averages may reflect those changes. 4) If different herd sires are used, ultrasound averages may reflect any differences in sire potential. 5) EPDs and ratios are more useful than actual data. It allows ranking of the cattle and gives the best genetic prediction of the carcass merit of the animal. Overall, Ultrasound technology is a great advancement for the beef industry due to the fact that it saves time and allows producers to get a good head start on the genetic prediction of carcass merit for their herd. Anyone in the cattle industry knows that anything that saves time will eventually save money and of course that is the bottom line. All registered Red Angus animals that have ultrasound data collected after January 1, 2002 will be charged $1.00 per head. This charge will be separate from other fees that are assessed by technicians or the CUP Lab and will be billed by the RAAA National Office. The $1.00 per head charge was a decision made by the board at the June, 2001 board meeting and will serve as a processing fee. |
