Ohio Bull Test Data Collection Procedures

Throughout the Ohio Bull Test, tremendous amounts of information and data is collected on each bull on test. Every 28 days, weights are collected on each bull as a progress report for average daily gains. This information helps consignors know how their bulls are performing and allows the management staff to monitor individual's performance. On the 84-day weight period (February 23, 1999) several other measurements are taken.

First the bulls are lined up in the working alley.

Then the bulls are clipped along the right-hand side over the 12^th and 13^th ribs.

Removing this hair and dirt allows an ultrasound technician to collect a clearer image of the longissimus dorsi (ribeye muscle) between the 12^th and 13^th ribs.

This image can then processed to determine ribeye area (REA) and fat thickness. The REA is determined by actually tracing the outline of the ribeye with the aid of a computer software program. The computer processes the area within the traced outline (see image below, left) and a REA figure is determined. REA is reported in square inches to the nearest tenth of an inch. These "raw" REA data figures must then be adjusted by breed factors that will determine an Adjusted REA to a 365-day basis. This allows for the truest comparisons to be made between bulls.

Fat thickness is also measured on the same image taken from between the 12^th and 13^th ribs (see image above, right). The measurement point is located ¾ of the distance from the chine end (along the backbone) of the longissimus dorsi muscle to the lateral end. Fat thickness is reported to the nearest hundredth of an inch. Fat thickness is not adjusted.

There are several reasons that the image is collected between the 12^th and 13^th rib. Ultrasound data is used to make comparisons between animals, therefor the 12^th and 13^th rib location allows for a standardized collection point on every animal. Beef carcasses are also broken into front and hindquarters between the 12^th and 13^th ribs. After a beef carcass has chilled, the carcasses is "ribbed" between the 12^th and 13^th ribs. This allows USDA Graders to use this as a standardized collection point on every carcass. From this collection point, USDA Graders evaluate the distribution of intramuscular fat (marbling) within the ribeye muscle. This "marbling score" is then a major determinate in establishing a USDA Quality Grade. In addition USDA Graders evaluate the ribeye area and fat thickness in the same fashion that is used in ultrasound image processing. Ribeye area and fat thickness along with hot carcass weight and percent kidney, pelvic, and heart fat are then used to determine USDA Yield Grades.

In addition to collecting ultrasound data, the bulls are also measure for hip height. This measurement is collected directly over the hooks and is recorded in inches. This hip height is then entered into a national Beef Improvement Federation formula, along with days of age at height collection, to determine a frame score. Frame score is a convenient way of describing the skeletal size of cattle. With appropriate height growth curves, most animals should maintain the same frame score throughout their life, while their actual height increases with age. This allows one frame score value to be used regardless of when the animal was evaluated. However, the frame score will change for animals that mature earlier or later when compared with average animals.

Next, scrotal circumferences are collected. Yearling scrotal circumference gives an indication of a bull's ability to produce sperm and is related to age at puberty. The measurement is taken at the largest diameter of the scrotum by snugly placing a flexible measuring tape around the scrotum after both testicles have been positioned beside each other in the scrotum. The actual measurement of scrotal circumference is recorded in centimeters and is adjusted using breed factors and days of age at scrotal circumference collection to determine an adjusted scrotal circumference.

Finally the bulls are weighed and returned to the pens. The weights are collected to determine figures such as average daily gain, 28-day average daily gain, and 84-day ratio based upon average daily gain within breed test groupings.

For more information about data collection in bull testing, contact Stephen Boyles at 614-292-7669.