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Ram Test|Department of Animal Science

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UW Ram Test
University of Wyoming
Department #3684
1000 E. University Avenue
Laramie, WY 82071
Phone: (307) 766-3706

Ram Test Procedures

Fiber diameter

Is determined by measuring 2000 fibers on a Sirolan Laserscan from core samples of each fleece. This procedure provides an accuracy of ± 0.25 micron, depending on the variability of the sample.

Because the "core" samples fibers from all parts of a fleece, it is considered superior to a side sample for describing the average fiber diameter of a fleece.

The standard deviation and coefficient of variation (C.V.) provide indications of the variability in diameter of the fibers measured. A fleece with a small C.V. should be considered more uniform, and therefore preferable to one with a large C.V. Also, according to the "official standards" of the United States for grades of wool: If the variability in fiber diameter exceeds the maximum for wool of that average diameter, the next coarser grade is assigned. This procedure was followed to describe the fleeces in this test (see fiber diameter uniformity guide and wool data for each fleece).

Staple length

Is determined by measuring, with a ruler, ten unstretched locks of wool taken from side samples.

Clean wool production

Is determined by taking thirty-one 1/2" cores from each fleece. These cores were washed, dried, and residual non-wool components removed. "Clean wool" is reported in this test at "standard condition."

Average daily gain

Is determined by dividing the total fleece free gain for the test period by 140 days.

Weight for day of age

Is determined by dividing final weight by age in days of the rams at completion of the test. Birth weight was not removed.

Face and wrinkle scores

Is determined by averaging subjective scores from three people. Scores were assigned on a 1-to-4 basis, with 1 being completely open-faced or free from wrinkles and 4 being wool blind or severely wrinkled.

Scrotal circumference

Is determined by measuring the circumference of both testicles immediately after shearing.

Belly wool scores

1 = absence of belly type wool on the side; 2 = belly type wool present on bottom 1/3 of the side; 3 = belly type wool present on the bottom 1/2 of the side; 4 = belly type wool extending above the bottom 1/2 of the side.

Index was determined by the following formula:

Index = 60 (average daily gain in pounds) +

4.0 (365-day adjusted staple length in inches (up to 5.5 in) +

4.0 (365-day adjusted clean wool in pounds +

fiber diameter and variability points

according to the following schedule:

Fiber diameter (microns)

(22.0 - actual micron) X 3

 *With a maximum of " 9 pts.


(22.0 - actual Coefficient of Variation) X 1.25

*With a maximum of " 5 pts.

Also, all animals nominated as Certified Rams were inspected by a committee to insure that all rams approved for this classification meet acceptable standards from the standpoint of body type, amount of skin folds, freedom from anatomical weaknesses and wool defects, including extremely hairy britch or excessive amounts of belly type wool. All certified Rams must have a minimum of 4 inches staple length, 9 lbs. clean wool, must grade 60's or finer, a maximum of 2.7 face cover score, and must have gained at least 0.55 pounds per day on test

Index ratio's are recorded, and the formula for this is: (individual index value/the average index value for all rams on test x 100). The ram with an average index value would get a ratio of 100. A ram with an index ratio of 110 has an index value of 10% above the average.

Rib Eye Areas are measured via ultrasound. These measurements are expressed in total square inches and square inches per 100 lbs. of body weight (cwt-bw).


For specific questions concerning these measurements and their use, please e-mail Robert Stobart at or call 307-766-5212, or write to Box 3684, University of Wyoming, University Station, Laramie, WY 82070.

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