Real Time Ultrasound

Scott Bothwell, Technical Services Representative

June 1997

What is Real Time Ultrasound?

First of all, ultrasound consists of soundwaves with frequencies above what the human ear can detect. These soundwaves are sent out and received back through the ultrasound probe or transducer. As the soundwaves pass through different materials with different densities, these soundwaves bounce back to the transducer at different rates and the tissue density can be detected. For example, in beef cattle the hide, fat and muscle have different densities and can therefore be detected and show up as different areas on the ultrasound image.

 

Quite often you will hear the phrase, "Real-Time Ultrasound". This is a type of ultrasound that lets the operator view the image or ultrasound picture on a monitor in "live" time or real time. This is the kind of ultrasound we use on beef cattle.

 

Why Use Ultrasound?

The greatest advantage in making use of ultrasound is knowing objectively and inexpensively the carcass merit of a potential herd sire before purchasing. Ultrasound can be used on a bull to rank him for the carcass traits - Backfat, Rib Eye Area, and Marbling. Before ultrasound, progeny trials were used to determine carcass merit of a sire. These trials took time and money and the sire had to be used before the results were available. With the use of ultrasound, we can get a handle on the carcass merit of a bull, before he is selected for breeding.

 

How Do I Use Ultrasound Data?

First, a little on how the data is collected. Most Ultrasound data on bulls is taken at the grading site. An image is taken between the 12th and 13th ribs. Using image analysis software, backfat is measured at the "grading site" and the Rib Eye Area is measured. A second and different image is used for a marbling estimate.

 

Ultrasound is most useful for ranking animals within a group. That is, we can rank animals into thirds consistently. For a trait such as backfat the animals can be ranked into the top, middle, and bottom third. The top one-third would be those animals that have the most backfat, the bottom one-third those with the least backfat, and the rest of the animals in the middle with average backfat. The same is true for Rib Eye Area, and marbling. If desired you can define the top and bottom differently, but the key point is the idea of ranking the animals.

 

To use in selection, you need to look at the cows and assess them. Are your cows easy fleshing or lean, lightly muscled or heavily muscled? Currently, our grading system determines lean yield by the interaction of backfat and Rib Eye area at the 12th-3th rib site (grading site). Essentially, those animals with a low backfat (must be at least 4mm) and large Rib Eye Area will have a higher lean meat yield.

 

With this in mind, you can look at the ultrasound rankings on bulls and select a bull that when mated to your cows, will move the herd towards your goals - whether it be increased lean meat yield or niche markets.

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